Class 12

Odisha State Board CHSE Odisha Class 12 Biology Important Questions Chapter 1 Reproduction in Organisms Important Questions and Answers.

CHSE Odisha 12th Class Biology Important Questions Chapter 1 Reproduction in Organisms

Reproduction in Organisms Class 12 Important Questions CHSE Odisha

Very Short Answer Type Questions

Choose the correct option

Question 1.
The factors which determine type of reproduction in an organism are
(a) habitat
(b) internal physiology
(c) environmental conditions
(d) All of the above
Answer:
(d) All of the above

Question 2.
A division which occurs at an angle to the transverse axis is called
(a) transverse binary fission
(b) longitudinal binary fission
(c) oblique binary fission
(d) simple binary fission
Answer:
(c) oblique binary fission

Question 3.
Conidia formation is seen in
(a) Amoeba
(b) Paramecium
(c) Aspergillus
(d) Planaria
Answer:
(c) Aspergillus

Question 4.
Sponges reproduce asexually by forming
(a) external buds
(b) gemmules
(c) merozoites
(d) None of these
Answer:
(b) gemmules

Question 5.
Cell division itself is a mode of reproduction in
(a) Amoeba
(b) Paramecium
(c) Both (a) and (b)
(d) None of these
Answer:
(c) Both (a) and (b)

Question 6.
Which one group of plants is propagated through underground roots?
(a) Bryophyllum and Kalanchoe
(b) Pistia and pineapple
(c) Ginger, potato and onion
(d) Sweet potato, Dahlia and Tapioca
Answer:
(d) Sweet potato, Dahlia and Tapioca

Question 7.
Vegetative propagation in mint occurs by
(a) offset
(b) rhizome
(c) sucker
(d) runner
Answer:
(c) sucker

Question 8.
A horizontal underground stem is a
(a) corm
(b) phylloclade
(c) rhizome
(d) rhizoid
Answer:
(c) rhizome

Question 9.
The process by which scion is inserted successfully into the stock to form a new plant is called
(a) layering
(b) cutting
(c) grafting
(d) budding
Answer:
(c) grafting

Question 10.
Micropropagation is a technique
(a) of production of true plants
(b) of production of mutants
(c) of production of variant species
(d) All of the above
Answer:
(a) of production of true plants

Question 11.
Bryophyllum undergoes vegetative propagation by means of
(a) leaf buds
(b) bulbil
(c) stem
(d) nodes
Answer:
(a) leaf buds

Correct the statements, if required, by changing the underlined word(s)

Question 1.
Yeasts generally reproduce asexually by fission.
Answer:
Yeasts generally reproduce asexually by budding.

Question 2.
External budding is the characteristic feature of Spongilla.
Answer:
External budding is the characteristic feamre of Hydra.

Question 3.
Bacteria mostly reproduce by gemmules.
Answer:
Bacteria mostly reproduce by transverse binary fission.

Question 4.
In higher organisms, cell division in itself is a mode of reproduction.
Answer:
lower

Question 5.
Onion and garlic are examples of corm.
Answer:
Onion and garlic are examples of bulb.

Question 6.
Almonds can be grown successfully if stock and scion are of different species.
Answer:
Almonds can be grown successfully if stock and scion are of related species.

Question 7.
In layering, roots are artificially induced to grow on the branches before they are detached from the parent plant.
Answer:
gootee

Question 8.
Rhizome, runner and bulb are the examples of underground stem.
Answer:
tuber

Fill in the blanks

Question 1.
The morphologically and genetically identical offsprings produced by asexual reproduction are called ………… .
Answer:
clones

Question 2.
A type of binary fission, occurring in the Euglena is called …………. .
Answer:
longitudinal binary fission

Question 3.
An.organism reproducing by fragmentation is …………… .
Answer:
Planaria

Question 4.
In Euglena, ………… binary fission is observed. (simple/longitudinal/transverse/oblique)
Answer:
longitudinal

Question 5.
Non-motile, exogenous spores of Penicillium are …………. (zoospores/oospores/conidia/ascospores)
Answer:
conidia

Question 6.
Transverse binary fission is observed in …………… . (Euglena, Paramecium, Amoeba)
Answer:
Paramecium

Question 7.
…………. is commonly practiced for root induction.
Answer:
Layering

Question 8.
In grafting, the rooted-plant is called stock and stem cutting of donor plant is called ………. .
Answer:
scion

Question 9.
Conifer cutting is practiced for propagating …………….. .
Answer:
pine

Question 10.
Rooting in stem cuttings is stimulated by using ………….. .
Answer:
auxin

Question 11.
The vegetative propagule in Agave is …………. .
Answer:
bulbil

Express the following in one or two word(s)

Question 1.
The process by which a living organism produces its offspring.
Answer:
Reproduction

Question 2.
Binary fission is seen in which phylum?
Answer:
Protozoa

Question 3.
An organism which performs internal budding.
Answer:
Spongilla

Question 4.
A process by which an organism develops its lost body part.
Answer:
Regeneration

Question 5.
What are the totipotent cells of Planaria called?
(Neoblasts, Sertoli cells, Follicular cells, Helper cells)
Answer:
Neoblasts

Question 6.
Name the biological process that enables continuity of species.
Answer:
Reproduction

Question 7.
The process of formation of spores in Aspergillus.
Answer:
Sporulation

Question 8.
Formation of 2-3 layered strong envelope around cyst.
Answer:
Encystment

Question 9.
Mode of vegetative propagation in Pistia.
Answer:
Offset

Question 10.
Name the undifferentiated mass of cells formed during culturing of cells.
Answer:
Callus

Question 11.
The alternative term used for air layering.
Answer:
Gootee

Question 12.
In which plant, air layering is done?
Answer:
Lemon

Question 13.
Name the vegetative propagules in Chrysanthemum.
Answer:
Sucker

Question 14.
A medicinal plant propagated by micropropagation.
Answer:
Atropa belladona

Short Answer Type Questions

Question 1.
Why is reproduction essential for the organisms?
Answer:
Reproduction is an important biological process that is essential for the organisms because

• it maintains life on earth.
• it results in addition of new individuals to the population, which finally leads to perpetuation of species.
• it creates variation among populations, which plays an important role in evolution.

Question 2.
Write a short note on multiple fission.
Answer:
Fission is a phenomenon of asexual reproduction in which the parent body divides into two or more daughter individuals. Multiple fission is a type of fission in which parent body divides into many small daughter individuals simultaneously, e.g. Plasmodium (the malarial parasite), Amoeba (during unfavourable conditions).

Question 3.
How does multiple fission occur in Amoeba?
Answer:
Amoeba reproduces by multiple fission during unfavourable conditions. It secretes three-layered protective cyst around itself. Its nucleus divides repeatedly to form several daughter nuclei.
Each daughter nucleus with a small amount of cytoplasm forms a daughter Amoeba called amoebae. Under favourable conditions, the cyst wall breaks up releasing young amoebae. Each young one develops pseudopodia, feeds and grows into an adult Amoeba.

Question 4.
Why is it that there is no natural death in single-celled organisms like Amoeba and bacteria?
Answer:
In single-celled organisms like Amoeba and bacteria, the parental body itself divides into two parts and becomes daughter cells. Each of these divided cell rapidly grows into an adult organism. Therefore, the parent cannot be said to have died, it continues its life as daughter cells.

Question 5.
Write a short note on sporulation.
Answer:
Spoliation
Sometimes the products of multiple fission become individually surrounded by resistant coats, i.e. cyst walls before their release from parent, the process is known as sporulation and the encysted products are known as spores.
It is not only the fastest method of reproduction but also helps to overcome unfavourable conditions. Sporulation is generally found in monerans, protistans, algae and lower fungi.

Question 6.
Draw the sketches of a zoospore and a conidium. Mention two dissimilarities between them and at least one feature common to both the structures.
Answer:
Sketches of a zoospore and a conidium are given below

The two dissimilarities between them (zoospore and conidium) are as follows

Zoospore	Conidium
It is found usually in algae.	It is found usually in fungi.
Flagellated	Non-flagellated
Formed inside a sporangium (endogenously).	Formed at the tip of conidiophores (exogenously).

The feature that is common in zoospores and conidia is that both of these spores facilitate the process of reproduction in asexually reproducing organisms.

Question 7.
Write a short note on budding in Hydra
Answer:
Budding is an asexual method of reproduction that takes place in Hydra. In this, the ectodermal interstitial cells multiply to form an outgrowth called bud, The bud grows consisting of ectoderm, endoderm and gastrovascular cavity. The bud develops mouth and tentacles at its free end. The fully grown bud separates from the parent body of the Hydra and grows into an adult.

Question 8.
Write a short note on gemmules.
Answer:
Gemmules They are internal buds formed during unfavourable condition. They give rise to new individuals in favourable conditions.
They are formed inside the body of sponges. Their formation is called as internal budding or endogenous budding.

Gemmule in sponge

Question 9.
How does asexual reproduction take place in sponges?
Answer:
Freshwater sponges (e.g. Spongilla) reproduce asexually by forming gemmules.
Gemmules They are internal buds formed during unfavourable condition. They give rise to new individuals in favourable conditions.
They are formed inside the body of sponges. Their formation is called as internal budding or endogenous budding.

Gemmule in sponge

Question 10.
How will an organism be benefitted if it reproduces through spores?
Answer:
There are some benefits for the organism which reproduces through spore formation such as

• Reproduction through spores is a simple as well as faster mode of reproduction.
• The spores are light in weight, thus keep floating in the water/air. This helps in their dispersal.
• The spores are covered with a thick layer which enables them to survive in unfavourable conditions.

Question 11.
Briefly discuss different types of fission in organisms.
Answer:
Fission It is the phenomenon of division of the parent body into two or more daughter individuals.
Fission can be of following types

1. Binary fission It is the type of fission in which parent body divides into two small, nearly equal ‘ sized daughter individuals. Each grows into an adult, e.g. Amoeba, Paramecium, etc.
2. Multiple fission It is the type of fission in which parent body divides into many small daughter individuals simultaneously, e.g. Plasmodium (the malarial parasite), Amoeba (during unfavourable conditions).

Question 12.
Why vegetative propagation is considered as a type of asexual reproduction?
Answer:
Vegetative propagation is considered as a type of asexual reproduction because .

• it is uniparental reproduction.
• cells divide by mitosis and no reductional division occurs.
• it does not involve genetic variations.

Question 13.
Write short note on air layering.
Answwer:
Air layering (gootee) In this method, about 3.5 cm ring of bark is removed from the base of an aerial shoot. This area is then covered by a thick plaster of grafting clay. It consists of hay, cowdung, clay and water with small quantity of root promoting hormone (such as NAA or IBA).

A set up for micropropagation requires an explant. The most commonly used explants are the meristematic ends of the plants, i.e. stem tip, root tip, axillary bud, etc. This is because meristematic cells have high rate of cell division. These explants, along with culture vessel, cell division media and instruments, etc., are sterilised. The explant is then inoculated into a semi-solid nutrient medium contained in a culture vessel. This is followed by incubation of culture vessel at room temperature. After some time, multiple shoots start developing from the axillary buds. This is called axillary bud proliferation.

Question 14.
Why do internodal segments of sugarcane fail to propagate vegetatively even when they are in contact with damp soil?
Answer:
On the stems, new buds develop from the nodes. So, for vegetative reproduction of a plant through stem cutting it should have atleast one node. As internodal segments of the sugarcane do not have nodes, they fail to propagate vegetatively even when they are in contact with the damp soil.

Question 15.
Is it possible to consider vegetative propagation observed in certain plants like Bryophyllum, water hyacinth, ginger, etc., as a type of asexual reproduction? Give two/three reasons.
Answer:
The formation of new plants from vegetative units (vegetative propagules) such as buds, tubers, rhizomes, etc., is called vegetative propagation (vegetative reproduction).
Vegetative propagation is considered as a type of asexual reproduction because

• it is uniparental reproduction.
• cells divide by mitosis and no reductional division occurs.
• it does not involve genetic variations.

Question 16.
Observe the diagram given below and answer the questions that follows

(i) What does the given diagram show?
(ii) Name any two plants (other than the one shown in fig.) which reproduce by the same method.
(iii) What are these plant parts referred to?
Answer:
(i) The given diagram shows a bulbil of Agave.
(ii) Two other plants which reproduce by the same method are Oxalis and lily.
(iii) These plant parts which help in vegetative (asexual) reproduction are referred to as vegetative propagules.

Question 17.
Write a short note on bulbils.
Answer:
Bulbils
These are fleshy buds produced in the axil of foliage leaves in place of axillary buds. They grow to form new plants, when shed/fall on the ground, e.g. Agave, Oxalis, Allium sativum, lily, etc.
Adventitious buds

Vegetative propagules (a) Leaf buds of Bryophyllum , (b) Bulbil of Agave

The new plantlets in the plants like potato, sugarcane, banana, Dahlia, ginger, etc., arise invariably from the nodes present in the modified stems of these plants. When these nodes come in the contact of damp soil or water, they produce roots and new plants because of the presence of meristematic cells.

Question 18.
Write a short note on micropropagation.
Answer:
Micropropagation (Propagation by plant tissue culture) This method includes propagation of plants by culturing the cells, tissues and organs. It is called as tissue culture. Initially, the culturing of cells or tissues results in the formation of an undifferentiated mass of cells called callus, which later differentiates to form a large number of plantlets.

These plantlets are transferred to separate pots or nursery to grow them into plants. Tissue culture technique is useful in obtaining virus-free plants, disease-free plants, homozygous diploids and in quick commercial propagation of orchids, Gladiolus, Chrysanthemum, other ornamental plants.

Question 19.
Mention the advantages and disadvantages of vegetative propagation.
Answer:
Advantages of Vegetative Propagation

1. It is the only method of multiplication (rapid) in seedless plants, e.g. sugarcane, banana, seedless grape, seedless orange, etc.
2. The important advantage of vegetative propagation is that a plant can be retained and multiplied indefinitely without any change or variation.
3. Vegetative propagation by plant tissue culture (micropropagation) has been applied for the production of disease-free plants.

Disadvantages of Vegetative Propagation

1. Vegetative propagules get easily decayed and are prone to viral, bacterial and fungal diseases.
2. There are no variations. Therefore, the plants may show degeneration and in such plants there is a less adaptability to changed environment.
3. There is no dispersal of vegetative propagules. Therefore, it causes overcrowding.

Differentiate between the following (for complete chapter)

Question 1.
Binary fission and Multiple fission.
Answer:
Differences between binary fission and multiple fission are as follows

Binary fission	Multiple fission
It is the process of division of the parent body into two small, nearly equal sized daughter individuals where each grows into an adult.	It is the process of division of the parent body into many small daughter individuals simultaneously.
The nucleus divides once and is immediately followed by cytoplasmic division.	The nucleus several times. Thus, it is  not followed cytoplasmic division.
It occurs under favourable conditions.	It occurs under unfavourable conditions.
e.g. Amoeba, Paramecium.	e.g. Plasmodium, Amoeba

Question 2.
Sporogony and Budding.
Answer:
Differences between sporogony and budding are as follows

Sporogony	Budding
In this, reproduction takes place by spore formation.	In this reproduction, an outgrowth or bud developing on the parent body develops into a new individual.
Spores are single-celled, reproductive bodies released from the parent body and are capable of growing into a new organism themselves, e.g. Penicillium, etc.	The daughter individual or bud remains attached tathe parent body until it is fully grown, e.g. Hydra, etc.

Question 3.
Simple binary Fission and Transverse binary fission.
Answer:
Differences between simple binary fission and transverse binary fission are as follows

Simple binary fission	Transverse binary fission
In this, fission of a parent into two daughter cells takes place along any possible plane.	In this, fission of a parent cell into two daughter cells takes place along the transverse or horizontal.
Plane of fission is not predetermined.	Plane of fission is predetermind.
The nucleus divides by mitosis, e.g. Amoeba.	The meganucleus divides by amitosis while the micronucleus divides by mitosis, e.g. Paramecium. Differentiate between the following (for complete chapter)

BSE Odisha 12th Class Biology Important Questions (+2 2nd Year)

• Chapter 1 Reproduction in Organisms Important Questions
• Chapter 2 Sexual Reproduction in Flowering Plants Important Questions
• Chapter 3 Human Reproduction Important Questions
• Chapter 4 Reproductive Health Important Questions
• Chapter 5 Heredity and Variation Important Questions
• Chapter 6 Sex Determination Important Questions
• Chapter 7 Molecular Basis of Inheritance Important Questions
• Chapter 8 Evolution Important Questions
• Chapter 9 Health and Diseases Important Questions
• Chapter 10 Improvement in Food Production Important Questions
• Chapter 11 Microbes in Human Welfare Important Questions
• Chapter 12 Principles and Processes of Biotechnology Important Questions
• Chapter 13 Applications of Biotechnology Important Questions
• Chapter 14 Organisms and Environment Important Questions
• Chapter 15 Ecosystem Important Questions
• Chapter 16 Biodiversity and its Conservation Important Questions
• Chapter 17 Environmental Issues Important Questions

CHSE Odisha Class 12 Textbook Solutions

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 17 Environmental Issues Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 17 Question Answer Environmental Issues

Environmental Issues Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
Which gas leaked from Union Carbide’s Pesticide Plant in December 1984 is responsible for Bhopal Gas Tragedy?
(a) Methyl salicylate
(b) Methyl isocyanate
(c) Ammonia
(d) Hydrogen sulphide
Answer:
(b) Methyl isocyanate

Question 2.
Minamata disease is caused by the consumption of fish contaminated with
(a) lead
(b) copper
(c) zinc
(d) mercury
Answer:
(d) mercury

Question 3.
The toxic metal used as an anti-knocking agent in petrol for automobiles is
(a) chelated copper
(b) tetraethyl lead
(c) iron sulphide
(d) lead chloride
Answer:
(b) tetraethyl lead

Question 4.
Bharat Stage Emission standards came into force from the year
(a) 1998
(b) 2000
(c) 2008
(d) 2010
Answer:
(b) 2000

Question 5.
Bone and tooth decay disease is caused by drinking water contaminated with
(a) fluoride
(b) borate
(c) silicate
(d) aluminium
Answer:
(a) fluoride

Express in one or two word(s)

Question 1.
Removal of toxic substances from water by using living organisms.
Answer:
Bioremediation

Question 2.
Toxic compound formed by the reaction of carbon monoxide with haemoglobin in blood.
Answer:
Carboxyhaemoglobin

Question 3.
Enrichment of water bodies with excess amount of nutrients as a result of runoff from surrounding land leading to overgrowth of plants and algae.
Answer:
Eutrophication

Question 4.
A kind of air pollutant named for the mixture of smoke and fog in the air.
Answer:
Smog

Correct the statements, if required, by changing the underlined word (s)

Question 1.
Fifth June of each year is usually observed as Word Food security Day.
Answer:
Environment

Question 2.
The process of nutrient enrichment in water bodies is called as biomagnification.
Answer:
Eutrophication

Question 3.
Particulate matter formed by the combination of gas and water vapour is called as smog.
Answer:
Statement is correct

Question 4.
Chipko Movement was organised for the protection of water bodies.
Answer:
Forest

Fill in the blanks

Question 1.
The Environment Protection Act was enacted in
the year
Answer:
1986

Question 2.
The common refrigerant responsible for the , depletion of ozone layer of the atmosphere is ……………. .
Answer:
chlorofluorocarbon

Question 3.
Carbon monoxide binds with haemoglobin forming …………….. .
Answer:
carboxyhaemoglobin

Question 4.
Depletion of ozone layer is speeded up by the …………. atom present in CFC.
Answer:
chlorine

Short Answer Type Questions

Write within three valid points

Question 1.
Aerosol.
Answer:

• Aerosol is a colloid of fine solid particles or liquid droplets in air or another gas.
• Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog and geyser steam.
  Examples of artificial aerosols are haze, dust, particulate, air pollutant and smoke.
• These are emitted through jet and supersonic aeroplanes. It causes depletion of ozone layer.

Question 2.
Greenhouse effect.
Answer:
Greenhouse Effect
The term, ‘greenhouse effect’ has been derived from a phenomenon, which occurs inside a greenhouse. In a greenhouse, the glass panel lets the light in, but does not allow heat to escape. This results in warming up of the greenhouse.

The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of earth’s surface and its atmosphere. Without greenhouse effect, the average temperature at surface of earth would have been chilly, i.e. approximately -18°C rather than the present average of 15°C.

Question 3.
Eutrophication.
Answer:
Eutrophication The process of eutrophication occurs in young lake where water is cold and clear to support life. It is the accelerated ageing of lakes due to the sewage, agricultural and industrial wastes.
The water body gets enriched with excess of nutrients such as nitrates and phosphorous promoting the overgrowth of microbes and algae. The algae release toxins in water and gradually cause deficiency of dissolved oxygen in water.

Question 4.
Acid rain.
Answer:

1. The term acid rain was given by Robert August. It is rainfall with a pH of less than 5.65.
2. Acid rain is a mixture of H₂SO₄ and HN₃ and the ratio of the two may vary depending on the relative quantities of oxides of sulphur and nitrogen emitted on an average 60-70% of acidity is ascribed to H₂SO₄ and 30-40 % to HNO₃.
3. It damages foliage and growing points of plant. Causes leaching of essential minerals of soil like Ca, Mg, NO₃^– and SO₄^-2

Question 5.
Photochemical smog.
Answer:
Photochemical Smog:
Smog refers to a combination of smoke and fog formed during winter. Its formation takes place when water vapour surrounds the smoke, dust or soot particles resulting in the formation of secondary particles. These particles remain suspended in the air.

The vehicular emissions consisting of oxides of nitrogen, sulphur and hydrocarbons undergo a series of photochemical reactions forming many photochemical oxidants. This process takes place during warmer sunny days photochemical oxidants react with troposphere ozone resulting in the formation of a brownish hozy fume which is known as photochemical smog.

Question 6.
Global warming.
Answer:
Global Warming
The gradual and continuous increase in average temperature of surface of the earth has resulted in global warming.
Climate Earth temperature has increased by 0.6°C during past century, most of it in last three decades. This increased temperature caused changes in precipitation patterns.

Differentiate between the following

Question 1.
Aerosol and Smog.
Answer:
Differences between aerosol and smog are as follows

Aerosol	Smog
These are present in the vapour form. Refrigerators and air conditioners use aerosol as refrigerant.	It is an opaque or dark fog having condensed water vapours, dust, smoke and gases.
It causes depletion of ozone layer.	It causes silvering / glazing and necrosis in plants, allergies and asthma/bronchitis in humans.

Question 2.
Renewable resources and Non-renewable resources.
Answer:
Differences between renewable resources and non-renewable resources are as follows

Renewable resources	Non-renewable resources
These resources have an ability to renew themselves in a given period of time.	These resources connot be renewed after exhaustion.
These are the energy resources which cannot be exhausted.	They are the energy resources which can be exhausted one day.
It has low carbon emission and hence environment friendly.	It causes high carbon emission and hence not environment friendly.
Solar energy, wind energy, tidal energy etc., are the examples of renewable resources.	Goal, petroleum, natural gases are the examples of non-renewable resources.

Question 3.
Bioremediation and Eutrophication.
Answer:
Differences between bioremediation and eutrophication are as follows

Bioremediation	Eutrophication
It is a waste management technique that involves the use of biological organisms to neutralize pollutants from a contaminated site.	It is the enrichment of a water body with nutrients.
Microorganisms used to perform the function of bioremediation are known as bioremediators.	This process induces growth of plants and algae and due to the biomass load may result oxygen depletion of the water body
It is of two types, i.e., in-situ and ex situ.	It is also of two types, i.e. accelerated and natural eutrophication.
It reduces pollution.	It occurs as a result of water pollution.

Question 4.
Primary pollutants and Secondary pollutants.
Answer:
Differences between primary pollutants and secondary pollutants are as follows

Primary pollutants	Secondary pollutants
These pollutants enter the environment directly from the source.	These pollutants are produced by the interaction of primary pollutants with other constituents.
They are less harmful.	They are more harmful.
They are of various categories such as particulate matter, aerosols and gases, which remain in their original form.	They generally undergo wide range of photochemical reactions and get modified.
e.g. CO, CO2, arsenic.	e.g. ozone, sulphuric and nitric acids.

Long Answer Type Questions

Question 1.
Give an account of secondary air pollutants.
Answer:
Secondary Pollutants:
These are not directly emitted but are formed when primary pollutants react in atmosphere, e.g. ozone, sulphuric acid, nitric acid, Peroxyacetyl Nitrate (PAN), etc.

1. Tropospheric Ozone:
Under the influence of UV-radiation, the nitrogen dioxide released in atmosphere undergoes dissociation. This results in the formation of nitric oxide (NO) and nascent oxygen (O). This nascent oxygen undergoes reaction with molecule oxygen and forms ozone in the troposphere. Ozone traps heat causing greenhouse effect and also causes formation of photochemical smog.

Chemical reactions in the troposphere generating ozone.

2. Peroxyacetylnitrate (PAN):
The emission from vehicles contains a lot of primary pollutants.
The precursors of PAN are methyl glyoxyl, acetaldehyde and several byproducts of oxidation of aromatic compounds. The sunlight undergoes reaction with non-methane hydrocarbons and nitrogen oxides resulting in the formation of PAN. PAN is one of the important component of photochemical smog.

3. Photochemical Smog:
Smog refers to a combination of smoke and fog formed during winter. Its formation takes place when water vapour surrounds the smoke, dust or soot particles resulting in the formation of secondary particles. These particles remain suspended in the air.

The vehicular emissions consisting of oxides of nitrogen, sulphur and hydrocarbons undergo a series of photochemical reactions forming many photochemical oxidants. This process takes place during warmer sunny days photochemical oxidants react with troposphere ozone resulting in the formation of a brownish hozy fume which is known as photochemical smog. This photochemical smog causes damage to vegetation, rubber goods and irritation in eyes and lungs.

4. Acid Rain:
Primary pollutants like oxides of nitrogen, sulphur dioxide and chlorine are released in atmosphere from the fossij fuel burning, vehicular exhaust, forest fire, etc. These primary pollutants react with water vapour present in atpiosphere resulting in the formation of acids such as nitrip acid and sulphuric acid. Their acids fall on the surface of earth in the form of rain known as acid rain. The acid present in rain has harmful effects on living organisms. Acid rain causes deterioration of historical monuments. One of the examples of deterioration of monuments include Taj Mahal in Agra.

Question 2.
How can the industrial and vehicular emissions be controlled? Describe.
Answer:
Control of Industrial Emission
Industrial emission can be controlled by two practices either by confining the pollutants of gaseous nature at the source or by diluting them in the atmosphere. The first practice involves two methods.

It can be done by modifying the process of formation of pollutants so that their formation does not occur beyond the permissible level. The second method involves reducing the concentration of pollutants before they are released into the environment. These practises takes place via the following steps

(a) Combustion It is performed when the pollutants are of organic nature. It comprises of flame combustion and catalytic combustion. It is involved in the conversion of pollutants to water vapour and less harmful carbon dioxide. Catalytic combustion makes use of catalytic converters and flame combustion uses incinerator.
(b) Absorption A scrubber is used to remove or modify emitted gas. It contains a liquid absorbent through which emitted gas is passed.
(c) Adsorption In this process, the gas is passed through a porous solid adsorbent, like activated carbon silica gel and lime stone. The pollutants are held at the interface of the adsorbent.

The working of a scrubber can be described as follows Scrubber is used to remove harmful gases like SO₂ from the industrial exhausts. The exhaust is passed through a spray of lime or water. Water dissolves the gases and lime reacts with SO₂ to form a precipitate of calcium sulphate and sulphide.

Scrubber

Control of Vehicular Emission:
Catalytic converters are fitted into automobiles (major cause of air pollution in metro cities) for reducing emissions of poisonous gases like CO and NO₂. They are made with expensive metals like- platinum-palladium and rhodium as catalysts. As the exhaust passes through catalytic converter, following changes occur
(i) Unburnt hydrocarbons get burnt completely into CO₂ and H₂O.
(ii) Carbon monoxide and nitric oxide are converted into CO₂ and N₂ gases, respectively.
Motor vehicles equipped with catalytic converter should use unleaded petrol, as lead present in petrol inactivates the catalyst.

Question 3.
Write the causes of ground water pollution and state how this can be controlled.
Answer:
Ground water pollution occurs when pollutants are released to the ground and make their way down into groundwater contaminants found in groundwater cover a broad range of physical, inorganic chemical, organic chemical, bacteriological and radioactive material.

Ground water pollutants Arsenic and fluoride have been the major pollutant of ground water. The metalloid arsenic can occur naturally in groundwater. Arsenic in groundwater can also be present where mining operations or mine waste dumps that will leach arsenic. Pathogens contained in faeces can lead to ground water pollution. Viruses and protozoans commonly found in polluted groundwater. Ground water that is contaminated with pathogens can lead to fatal faecal-oral transmission of diseases.

Nitrate is the most common chemical contaminant in the world’s groundwater and aquifers. Nitrate levels above 10 mg/L in ground water can cause Blue baby syndrome.

Organic compounds are a dangerous contaminant of groundwater. They are generally introduced to the environment through careless industrial practices.

Causes of Ground Water Pollution % Natural causes The natural arsenic pollution occurs because aquifer sediments contain organic matter that generates anaerobic conditions in the aquifer. These conditions generate arsenic.
Sanitation system Ground water pollution with pathogens and nitrate can also occur from the liquids infiltrating into the ground from on site sanitation system such as pit latrines and septic tanks.

Fertilisers and pesticides Nitrate can also enter the groundwater via excessive use of fertilisers, including manure spreading. High application rates of nitrogen- containing fertilisers combined with the high water- solubility of nitrate leads to increased runoff into surface water well as leaching into groundwater.

Commercial and industrial leaks A wide variety of both inorganic and organic pollutants have been found in aquifers underlying commercial and industrial activities.

Prevention of Ground Water Pollution:

• Landfills should be properly designed, maintained and operated, located away from sensitive groundwater areas.
• Underground storage tanks should be able to meet regulatory compliance policies on their installation and maintenance.

Deep groundwater should be regularly tested and inspected.

• Fertilisers should be used in minimum amount

Question 4.
Write about the different classes of solid wastes.
Answer:
Classes of Solid Wastes:
The various classes are

1. Domestic wastes These include wastes from homes, offices, schools, etc. It generally consists of paper, leather, textile, rubber, glass, waste food materials, etc.

2. Industrial wastes These include wastes like scraps, toxic heavy metals, flyash (oxides of iron, silica and aluminium), etc., generated by industries.

3. Biomedical wastes These include disinfectants and other harmful chemicals generated by the hospitals.

4. Electronic wastes (e-wastes) comprise the damaged electronic goods and irreparable computers. It contains harmful chemicals like copper, zinc, aluminium, etc.

5. Defunct ships Old defunct ships are broken down in developing countries like India, Bangladesh and Pakistan because of cheap labour and demand for scrap metal. These ships however, possess a number of toxic materials like asbestos, lead, mercury and polychlorinated biphenyls. The people involved in ship breaking are exposed to these toxic materials and thus suffer from various diseases. The coastal areas where ship breaking is undertaken also become polluted.

6. Agricultural wastes Solid organic wastes from agricultural practice during the growing and harvesting seasons are dumped on the soil, which decompose and are washed away into nearby water bodies. These bring about eutrophication of water bodies, which affects the local biotic potential.

7. Radioactive waste Radioactive waste is generated from nuclear power plants, nuclear weapon manufacturing facilities, cancer treating hospitals and research laboratories using radioisotopes in investigations. This waste is to be disposed off safely by observing the standard guideline because if it remains for a very long period and continues to emit ionising radiation, it will be extremely hazardous to health of all forms of life.

8. Construction waste Due to demolition or construction of buildings a large amount of waste material in different forms is produced in urbon areas.

9. Extraction and processings industry waste mining and quarrying operations also produce solid wastes. Food processing industries produce a large amount of organic waste.

10. Plastic It is non-biodegradable and also increase the volume of municipal waste. Plastic has an adverse effect on animals and birds who consume it.
Burning of these results in the generation of toxic fumes which add to air pollution.

11. Waste from natural disasters Disasters like flood, earthquake, volcanic eruption and cyclone generate a lot of ash, slag, dust, smoke and organic silt.

Question 5.
What are greenhouse gases? Write about their effects on the environment.
Answer:
Greenhouse Gases
These are the gases which trap the heat causing greenhouse effect. The carbon dioxide is the most prominent one. The various greenhouse gases are
(i) Carbon Dioxide:
It is most common and abundant greenhouse gas. Its rise has been due to the large scale deforestation, change in land use and large scale combustion of fossil fuels.
Burning of petrol and diesel contributes 36%, coal contributes 35% and natural gas contributes 20% of the carbon dioxide. The carbon dioxide level has increased from 315 ppm (parts per million) in 1958 to 355 ppm in 1992 4nd then to 389 ppm in 2010. The countries which are major contributors of carbon dioxide are USA, Russia, European countries and China.

(ii) Methane
Its concentration was 700 ppb in pre-industrial times and 1750 ppb in 2000. Methane is produced by incomplete biomass combustion and incomplete decomposition mostly by anaerobic methanogens.

(iii) Nitrous Oxide
It is produced by combustion of nitrogen rich fuels, livestock wastes, breakdown of nitrogen fertilisers in soil, nitrate contaminated water, etc.

(iv) Chlorofluorocarbons(CFCs)
It is used as a common refrigerant and aerosol propellant. Bromine atom from halon used in fire extinguishers has a similar effect. These two are potent greenhouse gases.

Relative contribution of various greenhouse gases to total global warming

(v) Water Vapour:
It has the capacity to trap heat radiating from the surface of the earth. Rain along with the presence of sunshine causes increase in temperature. Such climate is referred to as hot and humid.

(vi) Fluorinated Gases
These include perfluorocarbons and sulphur hexafluoride. They are industrial byproducts. They are also used as substitutes for CFCs.

(vii) Tropospheric Ozone
Nitrogen dioxide dissociates into nitric oxide and nascent oxygen in presence of UV-radiation. The nascent oxygen produced reacts with molecular oxygen forming ozone which acts as a greenhouse gas.

Question 6.
Write the causes and consequences of global warming.
Answer:
Global Warming
The gradual and continuous increase in average temperature of surface of the earth has resulted in global warming.

Effects of Global Warming:
It has been estimated by computer application studies that there may be a rise of 3°C by the year 2100 on an average.
The major effects of global warming include
1. Climate Earth temperature has increased by 0.6°C during past century, most of it in last three decades. This increased temperature caused changes in precipitation patterns.
2. Glaciers and ice caps Scientists have proposed that this rise in temperature causes deleterious changes in the environment, resulting in odd climatic changes. Thus, leading to melting of the polar ice caps and Himalayan snow caps.
3. Animals and humans The new warmer temperature conditions lead to eruption of diseases in animals and thousands of species will become extinct in a very short period of time. People from coastal areas will start migrating due to climate change.
4. Ocean and coasts The increase in temperature causes melting of polar ice caps and glaciers. This will result in the rise of ocean water level. The increased level of ocean water will cause the submerging of many island nations and coastal cities. The high temperature will cause accelerated vanishing of coral reefs.
5. Water and agriculture The increased temperature will cause decreased productivity in agricultural practice.

Reducing Greenhouse Gases
Due to the harmful effets of global warming, there was a need to control it. For this following steps were taken
1. World Meterological Organisation and United Nations Environment Programme (UNEP) jointly set up the Intergovernmental Panel on Climate Change (IPCC) in 1988.
2. At Earth Summit (1992), there was created the United Nations Framework Convention on Climate Change (UNFCC) which came into force in 1994.
3. Kyoto Protocol (1997) was signed by 160 countries to reduce the emission of CO 2 NO, CH4 by 5% and also to reduce CFCs emission.
4. Copenhagen conference was held in 2009 under UNFCC. However, it failed as there was no unanimity in agreement among the participating countries.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 16 Biodiversity and its Conservation Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 16 Question Answer Biodiversity and its Conservation

Biodiversity and its Conservation Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
Genetic diversity refers to
(a) variation in the genetic material
(b) variation in the populations
(c) variation in the number of species
(d) variation in the animal distribution
Answer:
(a) variation in the genetic material

Question 2.
Species diversity means
(a) number of species
(b) relative abundance of species
(c) pecies composition
(d) genetic diversities
Answer:
(b) relative abundance of species

Question 3.
The Forest Conservation Act was enacted in
(a) 1972
(b) 1952
(c) 1980
(d) 1991
Answer:
(c) 1980

Question 4.
Conservation of wild animals and plants in sanctuaries and national parks is
(a) ex situ conservation
(b) in vivo conservation
(c) in vitro conservation
(d) in situ conservation
Answer:
(d) in situ conservation

Question 5.
Corbett national park is situated in
(a) Uttarakhand
(b) Jharkhand
(c) Uttar Pradesh
(d) Himachal Pradesh
Answer:
(a) Uttarakhand

Question 6.
Following mass extinctions, recovery to the same level of biodiversity has taken
(a) hundreds of years
(b) millions of years
(c) thousand of years
(d) billions of years
Answer:
(b) millions of years

Express in one or two words

Question 1.
A species originated in one place and found no where else.
Answer:
Endemic species

Question 2.
Organism whose no living representative is seen.
Answer:
Extinct

Question 3.
Biogeographic region with high endemism and habitat destruction.
Answer:
Biodiversity hotspot.

Question 4.
Conservation of biodiversity in its natural site.
Answer:
In situ conservation.

Question 5.
Diversity of all life forms in the earth.
Answer:
Biodiversity.

Correct the statement by changing the underlined word(s)

Question 1.
Hybrid plants of a species are the source of disease resistant genes.
Answer:
Disease resistant

Question 2.
Bhitarkanika is a hotspot.
Answer:
national park of India.

Question 3.
Hotspots are characterised by low endemism and habitat destruction.
Answer:
high

Question 4.
Botanical gardens are meant for in situ conservation of biodiversity.
Answer:
ex situ

Question 5.
WWF has enlisted endangered species in Red Data Book.
Answer:
IUCN

Fill in the blanks

Question 1.
The term ‘biodiversity’ was coined by ……….. .
Answer:
Thomas E. Lovejoy

Question 2.
The three levels of biodiversity are ………… diversity, species diversity and ……….. diversity.
Answer:
genetic, ecological

Question 3.
There are ……….. numbers of megabiodiversity countries in the world.
Answer:
17

Question 4.
India had ………….. numbers of biodiversity hotspots.
Answer:
three

Question 5.
The Wildlife Protection Act was enacted in …………… .
Answer:
1972

Question 6.
The UN conference of human environment was held in ……………. in 1972.
Answer:
Stockholm

Question 7.
The expanded form of IUCN is …………….. .
Answer:
International Union of Conservation of Nature and Natural Resources.

Question 8.
The first national park of India is …………. national park.
Answer:
Hailey (Jim Corbett)

Question 9.
Odisha has ……….. numbers of national park.
Answer:
two

Question 10.
There are ………… numbers of wildlife sanctuaries in Odisha.
Answer:
19

Question 11.
India has …………. numbers of biosphere reserves.
Answer:
18

Question 12.
The concept of biosphere reserve made a beginning under ……….. programme instituted by a UN body, namely ……….. .
Answer:
Man and Biosphere (MAB), UNESCO

Short Answer Type Questions

Write short note on each of the following

Question 1.
Ecological diversity
Answer:
Ecological Diversity (Diversity among Communities):
It explains about the variety of ecosystems present in the biosphere. The community composition, i.e., assemblage of several interacting populations in a given space at a particular time is affected directly by the environment. Thus, it is the diversity at the level of communities and ecosystems of a region.

Question 2.
Wildlife Protection Act (1972).
Answer:
Wildlife Protection Act (1972) It was enacted to provide protection to wild flora and fauna and other natural resources. This act offers protection based on two approaches that are
(a) Species based approach for specific endangered species which are protected by special projects such as Project Tiger.
(b) Habitat based approach which is conservation of endangered wild flora and fauna in National Parks and Wildlife Sanctuaries.

Question 3.
In situ conservation.
Answer:
It involves the to protection of plants, animals and microorganisms within their natural ecosystems. The i in situ conservation is the most effective way of protecting the species and improving the quality of the habitat they live in. The in situ approach is preferable because of the fact that not much diversity can be conserved outside the centres of diversity.

Biodiversity at all its levels can be conserved in situ by comprehensive system of protected areas such as the national parks, wildlife sanctuaries, natural reserves, natural monuments, cultural landscapes, biosphere reserves, wetlands, etc. So far, in situ practice is considered most effective method of protecting and propagating the species and improving the quality of their habitats.

Question 4.
Ex situ conservation
Answer:
Ex situ (Off-site) Conservation:
It refers to conservation of biological diversity outside the boundaries of their natural habitats by perpetuating sample population in genetic resource centres, e.g. zoos, botanical gardens, culture collections, etc., or in the form of gene pools and gametes storage for fish, germplasm banks for seeds, pollen, semen, ova, cell, etc. Zoos also help in captive breeding of organisms which are endangered, whereas botanical gardens have seed gene banks, tissue culture labs and other technologies for storing and growing germplasm.

Question 5.
Biosphere reserve
Answer:
These are large tracts of protected land used for preserving the genetic diversity of an ecosystem by preserving wildlife. The creation of biosphere reserves was initiated in 1975 under the Man and Biosphere (MAB) programme of UNESCO. It is category V protected area designated by IUCN.

Each biosphere reserve integrates human activities and has following zonation

• Core zone Strictly protected.
• Buffer zone Sustainable and recreation activities allowed.
• Transition zone Anthropogenic activities like research and sustainable development allowed.
• Zone of human encroachment Normal anthropogenic activities allowed.

Differentiate between the following

Question 1.
In situ and Ex situ conservations.
Answer:
Differences between in situ conservation and ex situ conservation are as follows

In situ conservation	Ex situ conservation
It is the conservation of species in their natural habitats.	It is the conservation of species outside their natural habitats.
The endangered species are protected from predators.	The endangered species are protected from all adverse factors.
Augmentation of depleted resources is done.	Animals or plants are kept under human supervision and provided with all the essential necessities for survival.
e.g. national parks, sanctuaries and biosphere reserves.	e.g. zoos, botanical gardens, cultural collections, etc.

Question 2.
Genetic diversity and Species diversity.
Answer:
Differences between genetic diversity and species diversity are as follows

Genetic diversity	Species diversity
It is related to the number and type of genes and their alleles found in organisms.	It is related to the number, type and distribution of species found in given area.
It is the trait of the species.	It is the trait of the community.
It influences adaptability and distribution of a species in diverse habitat.	it influences biotic interaction and stability of the community.

Question 3.
National park and Sanctuary.
Answer:
Differences between national park and sanctuary are as follows

National park	Sanctuary
It is meant for protection of flora and fauna of the area.	It is meant for protection of one or more group of wild animals.
Cultivation of land, grazing and forestry are not allowed.	Cultivation of land, grazing and forestry are allowed.
Private ownership is not permitted.	Private ownership is permitted.
Boundary is well demarcated.	Boundary is not well demarcated.
e.g. Corbett National Park (Uttarakhand)	e.g. Bird Sanctuary Chilika (Odisha).

Question 4.
Extinct species and Endangered species
Answer:
Differences between extinct species and endangered species is as follows

Extinct species	Endangered species
A taxon is extinct when there is no reasonable doubt that the last individual has died, e.g. Indian cheetah.	A species is endangered when it is facing a very high risk of extinction in the wild in the near future, e.g. giant panda, polar bear.

Long Answer Type Questions

Question 1.
What is meant by biodiversity? Write the causes of loss of biodiversity.
Answer:
The term ‘biodiversity’ was first used by Thomas E. Lovejoy (1980) to refer the number of species of a region. It is the degree of variation of life occurring at different levels like genetic, organismal and ecological. These levels forms a hierarchy of biodiversity

Loss of Biodiversity:
The loss of biodiversity is a global crisis. Extinction of species is a natural phenomenon aided by the physical changes in the environment. However, the accelerated rates of species extinctions, that the world is facing now are largely due to human activities.
Till now, five episodes of mass extinction of species have occured in the history of biological evolution. The sixth episode of extinction of species however, is credited to human activities, which otherwise would not have occurred.

According to IUCN estimates, 12259 species have become extinct since the time of origin of life on the earth. The major cause of the biodiversity losses are called drivers, which belong to two classes namely, direct and indirect.

Direct Drivers Factors
The directly influence the ecosystem processes which bring about the mass extinction of species.
The various processes associated with direct drivers includes

1. Habitat destruction and fragmentation Conversion of forest land for agriculture, development projects, mining operation, etc., leads to the destruction of the natural habitats of the organisms.
Indiscriminate agricultural practices involving use of chemical fertilisers and pesticides are potent factors for the destruction of habitats. When a large population fragments into smaller ones there is more inbreeding and inbreeding pressure leading to population decline.

2. Overexploitation of natural resources Humans are dependent on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to overexploitation.

To meet the need for increased housing, the natural habitats of animals and plants are being destroyed. This results in habitat loss and extinction of species. It has caused extinction of many species in last 500 years. In addition, indiscriminate hunting of wild animals has made their status in Red book as endangered or critically endangered.

3. Introduction of alien invasive species When alien species are intentionally or unintentionally introduced in a particular area, they might turn invasive and cause decline or extinction of endogenous species, e.g., Eichhornia is known as the ‘Terror of Bengal’. It was introduced as ornamental plants but it became wild in India because of invasiveness.
Similarly, Lantana and Parthenium were important due to their ornamental and food values, respectively but, they become wide spread due to favourable environmental conditions.

4. Climate change The global climate is changing, due to the anthropogenic activities like greenhouse gases and it has led to global warming. This is causing melting of glaciers, polar ice caps, etc. This may submerge low lying coastal habitats and also plants and animals are unable to adapt themselves to this change which is causing their elimination.

5. Environmental pollution It is another major factor for species extinction. Pollution may reduce and eliminate populations of sensitive species. Environmental pollution is most commonly caused by accumulation of non-biodegradeble wastes like plastics. Agricultural chemicals like pesticides enters the food chain and get deposited in the body of higher organisms. This effects the population of fish eating birds and falcons by disturbing their reproductive process.

Question 2.
How can the biodiversity be conserved? Add a note on importance of biodiversity.
Answer:
Biodiversity is directly or indirectly involved in maintaining the well-being of human society. Thus, scientists have classified the values of diversity as ecosystem goods, i.e., natural products harvested from ecosystems and directly used by humans and ecosystem services, involving different ecosystem processes which indirectly benefit human life.

Biodiversity Conservation:

The protection, uplift and scientific management of biodiversity at its optimum level for present and future generations is known as biodiversity conservation.
The International Union for Conservation of Nature and Natural Resources (IUCN) or World Conservation Union, World Wide Fund for Nature (WWF), Food and Agricultural Organisation (FAO) and United Nations Educational Scientific and Cultural_Organisation (UNESCO) formed the world conservation strategy in 1980 for the conservation and sustainable use of biological resources. For this, two major types of conservation strategies were framed. These are

1. In situ (On-site) Conservation:
It involves the to protection of plants, animals and microorganisms within their natural ecosystems. The i in situ conservation is the most effective way of protecting the species and improving the quality of the habitat they live in. The in situ approach is preferable because of the fact that not much diversity can be conserved outside the centres of diversity.

Biodiversity at all its levels can be conserved in situ by comprehensive system of protected areas such as the national parks, wildlife sanctuaries, natural reserves, natural monuments, cultural landscapes, biosphere reserves, wetlands, etc. So far, in situ practice is considered most effective method of protecting and propagating the species and improving the quality of their habitats.

2. Ex situ (Off-site) Conservation:
It refers to conservation of biological diversity outside the boundaries of their natural habitats by perpetuating sample population in genetic resource centres, e.g. zoos, botanical gardens, culture collections, etc., or in the form of gene pools and gametes storage for fish, germplasm banks for seeds, pollen, semen, ova, cell, etc. Zoos also help in captive breeding of organisms which are endangered, whereas botanical gardens have seed gene banks, tissue culture labs and other technologies for storing and growing germplasm.

Biodiversity Preservation Methods and Sites

A protected area, as defined by IUCN, is an area (either land or sea) especially dedicated for the protection and maintenance of biological diversity through legal and ‘ other effective ways. IUCN has classified protected area into six different types. Some of these protected areas are, discussed below

National Parks:
India’s first National Park (IUCN category-II protected area) was Hailey National Park, now known as Jim Corbett National Park, established in 1935. According to National Wildlife Database, there were 103 National parks in India as in April, 2015. A national park is an area maintained by government and dedicated to conserve the environment, natural and historical objects and the wildlife therein. Operations such as plantation, cultivation, grazing forestry are not allowed in national parks. Private ownership rights and habitat manipulation are also prohibited. IUCN (1975) has adopted following keypoints to define a national park.

1. A national park is a relatively large area reserved for the betterment of the wildlife. The habitats of native plant and animals becomes the site of scientific, educational and recreative interests along with maintenance of its aesthetic values.
   Since, human intervention is nil or limited, the operating ecosystem remains unaltered and conserved.
2. It is also defined as an area where the highest authority take measures to prevent exploitation and enforce conservation measures.
3. A place where visitors are permitted to enter only in special conditions like inspirational, cultural and recreative purposes.
   

Hotspots of Biodiversity:
The concept of hotspot was given by Norman Myers in 1988. Hotspots are areas that are extremely rich in species diversity, have high endemism and are under constant threat. There are 34 hotspots which cover less than 2% of earth land area of the world. In these sites nearly 75% population of world’s most threatened mammals, birds and amphibians, approximately 50% plants and 42% land vertebrates are conserved (Conservation International, 2003).

According to Myers, the key criteria for an area to be assigned as biodiversity hotspot are

• It must contain atleast 0.5% or 1,500 of the world’s 3,00,000 species of vascular plants as endemics.
• It should have lost atleast 70% of its primary vegetation.

Tropical forests appear in 15 hotspots, Mediterranean – type zones in 5, 9 hotspots are mainly or completely made up of islands and 16 hotspots are in the tropics. About 20 % of the human population lives in the hotspot regions.

Tropical Andes hotspot has 20,000 endemic plants and 1567 vertebrates and it is at the top of the list. Four regions of India that fulfills the criteria of hotspots are The Western Ghats and Sri Lanka, The Eastern Himalayas, Indo-Burma (North-Eastern India South of Brahmaputra river)and Sundarland (Nicobar Islands). These sites are also known as Gade of speciation.

The Western Ghats are a chain of hills that lies parallel to the Western coast of peninsular India. These regions have moist deciduous forest and rain forest and have high species diversity and high levels of endemism. Nearly 77% of the amphibians and 62% of the reptile species found here are found nowhere else. Over 6000 vascular plants of over 2500 genera are found in this hotspot, of which over 3000 are endemic.

Much of the world’s species like black pepper and cardamom have their origins in the Western Ghats. It also harbors over 450 bird species, about 140 mammalian species, 260 reptiles and 175 amphibians. Over 60% of the reptiles and amphibians are completely endemic to this hotspot.

The Eastern Himalayan hotspot has approximately 163 globally threatened species including the one-horned rhinoceros, the Wild Asian Water buffalo and in all 45 mammals, 50 birds, 17 reptiles, 12 amphibians, 3 invertebrate and 36 plant species.
Thus, hotspots are the most precious sites for biodiversity conservation and should be protected from exploitation.

Wildlife Sanctuary:
It is IUCN category IV of protected area. A wildlife sanctuary can be established by a gazette notification from the State Forest Department, where protection is provided to vulnerable, endangered and critically endangered wild animals life. Operations such as procuring timber and minor forest products and private ownership are allowed provided they do not cause any adverse effects on the animals. Till 2015, there were 520 wildlife sanctuaries in India, covering 122867.34 km2 (3.74%) of land in India. The state of Odisha has 19 wildlife sanctuaries, which are listed below

Biosphere Reserve:
These are large tracts of protected land used for preserving the genetic diversity of an ecosystem by preserving wildlife. The creation of biosphere reserves was initiated in 1975 under the Man and Biosphere (MAB) programme of UNESCO. It is category V protected area designated by IUCN. Today, India has 18 biosphere reserves, some of which are also included under National Parks and Odisha has a share of one in Simlipal.

Each biosphere reserve integrates human activities and has following zonation

1. Core zone Strictly protected.
2. Buffer zone Sustainable and recreation activities allowed.
3. Transition zone Anthropogenic activities like research and sustainable development allowed.
4. Zone of human encroachment Normal anthropogenic activities allowed.

Out of 18 biosphere reserves, 8 of them are a part of world network of Biosphere Reserves based on MAB Programme of UNESCO.

The objectives of this programme are

• Conserving representative samples of ecosystems.
• In situ conservation of genetic diversity.
• Facilitating basic and applied research in ecology and environmental biology on site.
• Create opportunities for environmental education k and training.
• Promoting and creating awareness about sustainable management of living resources.
• Promoting international cooperation.

Therefore, the biosphere reserves have three junctions, that includes

• Conservation of ecosystems and genetic variations.
• Promotion of sustainable economic and human development.
• They serve as examples of education and training local, regional, national and international issues of sustainable development.

A protected area to be declared as a biosphere reserve should have the following essential features

• Abundant genetic diversity should be present.
• It should be unique in itself.
• The area should be legally protected for long term.
• Appropriate size for effective maintenance of natural populations so that there is no genetic drift.
• Sufficient natural resource available for ecological research, education and training. It should be a natural home for the endangered species of plants and animals.

Question 3.
Give an account of biodiversity and its conservation measures.
Or
Give an account of the concept of biodiversity.
Answer:
The term ‘biodiversity’ was first used by Thomas E. Lovejoy (1980) to refer the number of species of a region. It is the degree of variation of life occurring at different levels like genetic, organismal and ecological. These levels forms a hierarchy of biodiversity. The integration of several sciences such as ecology and genetics to sustain biological diversity at all its levels is called conservation biology.

Levels of Biodiversity

In 1986, Norse and Me Manus explained the three levels of biodiversity. These include

1 Genetic Diversity:
It involves variations in genetic composition among the individuals of a species. This variations could be in the nucleotides, genes, entire genome or chromosomes. This type of diversity arises due to genetic recombination during sexual reproduction and mutation.

Variations in the genes of a species increases with the increase in size and environmental parameters of the habitat. Genetic diversity is useful as it helps an individual to adapt to changing environmental condition, natural selection and is essential for healthy breeding. It also helps in speciation or evolution of new species.

2. Organismal or Species Diversity (Diversity among Species):
It is the variety in the number and richness of a species of a region. Sometimes, a species remains confined to a particular area and is found only in that area. Such species are said to be endemic, e.g., Indian giant squirrel is endemic to Panchmarhi hills in Madhya Pradesh.

The IUCN (International Union for Conservation of Nature and Natural Resources) recognises three types of species diversity, i.e.

• Alpha (α) diversity It refers to the variety of species within a community. It is also referred to as species richness, i.e., the number of species per unit area.
• Beta (β) diversity It refers to the diversity of species among communities.
• Gamma (γ) diversity It refers to the diversity of species across a wide geographical range.

The important features of species diversity to the ecosystem are as follows

• Increased biodiversity provides resistance to the ecosystem against natural disasters.
• Ecosystem with more species shows more yields and greater productivity with variation of biomass.
• Community with more species generally tends to be more stable than those with less species.

3. Ecological Diversity (Diversity among Communities):
It explains about the variety of ecosystems present in the biosphere. The community composition, i.e., assemblage of several interacting populations in a given space at a particular time is affected directly by the environment. Thus, it is the diversity at the level of communities and ecosystems of a region.

Patterns of Biodiversity

Biodiversity is not uniform throughout the world. It varies with the changes in latitude and altitude. For many groups of animals and plants, there are specific patterns in diversity based on the favourable environmental conditions.
The pattern of biodiversity among different regions is discussed below

Latitudinal Gradients:
Species diversity decreases as we move away from the equator towards the poles. It means biodiversity is more at lower latitude (equator) than the higher latitude (poles). The biodiversity gradient is steep in Northern hemisphere than the Southern hemisphere.

Biodiversity in Tropics
Tropics (latitudinal range of 23.5°N to 23.5°S) harbour more species than temperate or polar areas, e.g., Colombia located near the equator, has 1,400 species of birds.

New York located at 41°N has 105 species of birds, while Greenland at 71°N has only 56 species of birds. India, with most of its area in tropical latitude has more than 1200 species of birds. A forest of equal area in tropical region (like equator) has 10 times more species of vascular plants than in temperate region (like Mid-West of USA). Amazonian rainforest in South America has the greatest biodiversity on the earth with more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals and amphibians, 378 of reptiles and more than 1,25000 of invertebrates.

Reasons for Greater Biodiversity in Tropics
The factors making tropical rainforests rich in biodiversity are

1. Tropical latitudes have remained undisturbed for million of years allowing speciation.
2. Tropical environments are relatively constant throught the year which promotes niche specialisation and greater diversity.
3. High productivity leads to greater diversity. It is also found that species diversity increases with area (species area curves), how it peaks in areas with intermediate productivity or intermediate rates of disturbance. The more variable the habitat, the greater the species diversity within it. This pattern was offered as one of the reasons why there are more species in bigger area as more area covers a greater variety of habitat.

Importance of Biodiversity

Biodiversity is directly or indirectly involved in maintaining the well-being of human society. Thus, scientists have classified the values of diversity as ecosystem goods, i.e., natural products harvested from ecosystems and directly used by humans and ecosystem services, involving different ecosystem processes which indirectly benefit human life.

Direct Value

1. Food It includes all the plant and animal products used as food by humans, e.g., cereals, pulses, vegetables, fruits, milk, beverages, etc.
2. Clothing It includes natural fabric made out of cotton, jute and natural silk (harvested from silk moth).
3. Shelter It includes raw material obtained from ecosystem for making houses, e.g., wood, etc.
4. Medicines Large number of substances with therapeutic properties are obtained from variety of plant species and animals, e.g.
   1. Quinine Antimalarial drug, obtained from the bark of Cinchona plant.
   2. Anticoagulants Antihemorrhagic drugs, extracted from blood sucking animals.
   3. Snake venom and toxins Drugs for neural and muscular disorders.
   4. Penicillin, tetracyclins and streptomycins Antibiotics extracted from microorganisms.
   5. Biocidal compounds Used in manufacturing antibiotics, extracted from beetles, millipedes, snails and ants.
5. Industrial products A variety of industrial products are directly made out of biological resources, e.g. timber, fuel, dyes, oil, etc., from plants and leather, etc., from animals skin.

Indirect Value:

1. Biological control It is the use of microorganisms for the manufacture of antibiotics, oral contraceptives, etc., and management of pests, increasing soil fertility, cleaning oil spill (super bug), treatment of sewage and solid waste, recovery of metals (bioleaching), monitoring pollution generating biofuel, etc.

2. Environmental modulation. It includes some animals and plants which influence and modulate the environment directly and indirectly. Such animals and plants are known as ecosystem engineers. One of these are keystone species whose extinction reduces abundance of other species in the community.

A well known example of ecosystem engineer is beaver (a mammal). It influence plant and animal communities and the entire biodiversity of watershed area by
(a) Creating dams using logs in river channels
(b) Modifying nutrient cycling
(c) Influencing decomposition dynamics.

3. Ecosystem functions and services Biodiversity plays a major role in many ecosystem services and functions such as replenishing oxygen through photosynthesis, pollination through bees, regulation of global climate, retention of rainwater in aquifers and reservoir, control of floods, etc.
Nature always key a check on these activities to maintain a state of equilibrium (homeostasis), which further helps in the sustainable development of resources. However, overexploitation of biolgical resources by humans leads to destabilisation of ecosystem balance.
For example,

• Decreased flora of an area leads to CO₂ increase in the atmosphere which causes temperature elevation of that area.
• Increased carnivore population decreases the herbivore population by predation which then increase the vegetation.
• Declined population of microflora prevents the recycling between complex organic matter and simple inorganic matter.

4. Ecotourism The diverse biological resource of a country motivates people from around the world to undertake recreational activities like tours to enjoy the diverse wildlife and charismatic landscape. In return the host country earns a large sum of foreign exchange as revenue.

Loss of Biodiversity

The loss of biodiversity is a global crisis. Extinction of species is a natural phenomenon aided by the physical changes in the environment. However, the accelerated rates of species extinctions, that the world is facing now are largely due to human activities.

Till now, five episodes of mass extinction of species have occured in the history of biological evolution. The sixth episode of extinction of species however, is credited to human activities, which otherwise would not have occurred.

According to IUCN estimates, 12259 species have become extinct since the time of origin of life on the earth. The major cause of the biodiversity losses are called drivers, which belong to two classes namely, direct and indirect.

Direct Drivers Factors

The directly influence the ecosystem processes which bring about the mass extinction of species.
The various processes associated with direct drivers includes

1. Habitat destruction and fragmentation Conversion of forest land for agriculture, development projects, mining operation, etc., leads to the destruction of the natural habitats of the organisms.
Indiscriminate agricultural practices involving use of chemical fertilisers and pesticides are potent factors
for the destruction of habitats. When a large population fragments into smaller ones there is more inbreeding and inbreeding pressure leading to population decline.

2. Overexploitation of natural resources Humans are dependent on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to overexploitation.
To meet the need for increased housing, the natural habitats of animals and plants are being destroyed. This results in habitat loss and extinction of species. It has caused extinction of many species in last 500 years. In addition, indiscriminate hunting of wild animals has made their status in Red book as endangered or critically endangered.

3. Introduction of alien invasive species When alien species are intentionally or unintentionally introduced in a particular area, they might turn invasive and cause decline or extinction of endogenous species, e.g., Eichhornia is known as the ‘Terror of Bengal’. It was introduced as ornamental plants but it became wild in India because of invasiveness.

Similarly, Lantana and Parthenium were important due to their ornamental and food values, respectively but, they become wide spread due to favourable environmental conditions.

4. Climate change The global climate is changing, due to the anthropogenic activities like greenhouse gases and it has led to global warming. This is causing melting of glaciers, polar ice caps, etc. This may submerge low lying coastal habitats and also plants and animals are unable to adapt themselves to this change which is causing their elimination.

5. Environmental pollution It is another major factor for species extinction. Pollution may reduce and eliminate populations of sensitive species. Environmental pollution is most commonly caused by accumulation of non-biodegradeble wastes like plastics. Agricultural chemicals like pesticides enters the food chain and get deposited in the body of higher organisms. This effects the population of fish eating birds and falcons by disturbing their reproductive process.

Indirect Drivers
These influences or changes one or more the direct driver. They include

1. Population growth Rapid increase in human population causes loss of biodiversity becatise population explosion results in rapid growth of exploitation of natural resources such as water, food and minerals. If this trend of population growth continue, the resources will be depleted faster and most species will face the risk of extinction.
2. Income and lifestyle Today people’s income has increased tremendously which has led to more luxurious lifestyle of people. For leading this, they tend to use more and more of natural resources which causes pollution, degradation of environment and biodiversity loss.

Extinction of Species

In the history of earth many species have disappeared and new ones got evolved over million of years. The major threat to biodiversity is extinction of species Extinction is the total elimination or dying out of species (fossilisation) form the earth. As, we already know, the extinction of species is a natural process which accelerates due to human activities.

There are generally three types of extinction
1. Natural extinction It is a slow process of replacement of existing species with the better adapted species due to alternate evolution, changes in environmental condition, predation and diseases. Extinction of species occurs due to combination of genetic and demographic factors.

2. Mass extinction It occur due to catastrophes, which struck the earth several times. A mass extinction occurred about 225 million years ago in Permian period when 90% of shallow marine invertebrates disappeared.
Another mass extinction occurred between cretaceous and tertiary period over 60 million years ago when dinosaurs and a number of other organisms disappeared.

3.  Anthropogenic extinction These are extinction of organisms due to human activities like hunting, overexploitation and habitat destruction, e.g. dodo (Raphus cucullatus), Tasmanian wolf, etc. Anthropogenic extinction is causing a sixth extinction of species. It is 100-1000 times more faster than the rate of natural extinctions.

IUCN and Red List
IUCN is International Union of Conservation of Nature and Natural Resources which is now called World Conservation Union (WCU). It has its headquarters at Morges, Switzerland. IUCN maintains a Red Data Book (RDB) or Red List which is a catalogue of taxa facing risk of extinction. Red Data Book was initiated in 1963.
The purpose of red list is to

(i) Provide awareness to the degree of threat to biodiversity.
(ii) Provide global index about already declined of biodiversity.
(iii) Identification and documentation of species at high risk of extinction.
(iv) Preparing conservation priorities and help in conservation plan.
(v) Information about international agreements like conservation on biological diversity and CITES (Convention on International Trade in Endangered Species) of Wild Fauna and Flora.

The IUCN Red List 2004 has recorded a total loss of 784 species in the last 500 years. These include 733 animals (mostly vertebrates and molluscs), 110 plants and one red alga. The extinction of dodo in Mauritius, quagga in Africa were notable extinctions in the recent years.

The species that became extinct in 2003 was the plant Nesiota elliptica, St. Helena Olive (a small tree in Saint Helena Island) in the South Atlantic Ocean. The IUCN red list of threatened species founded in 1964, is the worlds most comprehensive inventory of global conservation status of biological species.The IUCN Red List has listed 132 species of plants and animals from India as ‘Critically Endangered’.

Red List assign categories to each species. These are as follows

1. Extinct A taxon is extinct when there is no reasonable doubt that its last individual has died, e.g. dodo, Indian cheetah.
2. Extinct in the Wild (EW) A number of domesticated animals and plants have become extinct in the wild. A taxon is extinct in the wild when it is known to survive only under cultivation.
3. Critically Endangered (CR) A taxon is critically , endangered when it is facing an extremely high risk of extinction in the wild in immediate future (925 animals and 1014 plants), e.g, One horned rhinoceros.
4. Endangered (EN) A taxon is endangered when it is not critically endangered, but facing a very high risk of extinction in the wild in near future, e.g, Giant panda and polar bear.
5. Vulnerable (VU) A taxon is vulnerable when it is not critically endangered or endangered, but it is facing a high risk of extinction in the wild in the medium term future, e.g. sparrow.
6. Threatened Species is the one which is liable to become extinct if not allowed to realise its full biotic potential by providing protection from the exotic species, e.g. in black buck.
7. Low Risk (LR) A taxon is at low risk when evaluated, it does not qualify for any of the categories like critically endangered, endangered or vulnerable.
8. Data Deficient (DD) A taxon is data deficient when there is inadequate information to make a direct or indirect assessment of its risk of extinction based on its distribution or population status.
9. Not Evaluated (NE) A taxon is under the category of not evaluated, when it has not yet been assessed against above criteria.

Biodiversity is directly or indirectly involved in maintaining the well-being of human society. Thus, scientists have classified the values of diversity as ecosystem goods, i.e., natural products harvested from ecosystems and directly used by humans and ecosystem services, involving different ecosystem processes which indirectly benefit human life.

Biodiversity Conservation:

The protection, uplift and scientific management of biodiversity at its optimum level for present and future generations is known as biodiversity conservation.
The International Union for Conservation of Nature and Natural Resources (IUCN) or World Conservation Union, World Wide Fund for Nature (WWF), Food and Agricultural Organisation (FAO) and United Nations Educational Scientific and Cultural_Organisation (UNESCO) formed the world conservation strategy in 1980 for the conservation and sustainable use of biological resources. For this, two major types of conservation strategies were framed. These are

1. In situ (On-site) Conservation:
It involves the to protection of plants, animals and microorganisms within their natural ecosystems. The i in situ conservation is the most effective way of protecting the species and improving the quality of the habitat they live in. The in situ approach is preferable because of the fact that not much diversity can be conserved outside the centres of diversity.

Biodiversity at all its levels can be conserved in situ by comprehensive system of protected areas such as the national parks, wildlife sanctuaries, natural reserves, natural monuments, cultural landscapes, biosphere reserves, wetlands, etc. So far, in situ practice is considered most effective method of protecting and propagating the species and improving the quality of their habitats.

2. Ex situ (Off-site) Conservation:
It refers to conservation of biological diversity outside the boundaries of their natural habitats by perpetuating sample population in genetic resource centres, e.g. zoos, botanical gardens, culture collections, etc., or in the form of gene pools and gametes storage for fish, germplasm banks for seeds, pollen, semen, ova, cell, etc. Zoos also help in captive breeding of organisms which are endangered, whereas botanical gardens have seed gene banks, tissue culture labs and other technologies for storing and growing germplasm.

Biodiversity Preservation Methods and Sites

A protected area, as defined by IUCN, is an area (either land or sea) especially dedicated for the protection and maintenance of biological diversity through legal and ‘ other effective ways. IUCN has classified protected area into six different types. Some of these protected areas are, discussed below

National Parks:
India’s first National Park (IUCN category-II protected area) was Hailey National Park, now known as Jim Corbett National Park, established in 1935. According to National Wildlife Database, there were 103 National parks in India as in April, 2015. A national park is an area maintained by government and dedicated to conserve the environment, natural and historical objects and the wildlife therein. Operations such as plantation, cultivation, grazing forestry are not allowed in national parks. Private ownership rights and habitat manipulation are also prohibited. IUCN (1975) has adopted following keypoints to define a national park.

1. A national park is a relatively large area reserved for the betterment of the wildlife. The habitats of native plant and animals becomes the site of scientific, educational and recreative interests along with maintenance of its aesthetic values.
   Since, human intervention is nil or limited, the operating ecosystem remains unaltered and conserved.
2. It is also defined as an area where the highest authority take measures to prevent exploitation and enforce conservation measures.
3. A place where visitors are permitted to enter only in special conditions like inspirational, cultural and recreative purposes.
   

Hotspots of Biodiversity:
The concept of hotspot was given by Norman Myers in 1988. Hotspots are areas that are extremely rich in species diversity, have high endemism and are under constant threat. There are 34 hotspots which cover less than 2% of earth land area of the world. In these sites nearly 75% population of world’s most threatened mammals, birds and amphibians, approximately 50% plants and 42% land vertebrates are conserved (Conservation International, 2003).

According to Myers, the key criteria for an area to be assigned as biodiversity hotspot are

• It must contain atleast 0.5% or 1,500 of the world’s 3,00,000 species of vascular plants as endemics.
• It should have lost atleast 70% of its primary vegetation.

Tropical forests appear in 15 hotspots, Mediterranean – type zones in 5, 9 hotspots are mainly or completely made up of islands and 16 hotspots are in the tropics. About 20 % of the human population lives in the hotspot regions.

Tropical Andes hotspot has 20,000 endemic plants and 1567 vertebrates and it is at the top of the list. Four regions of India that fulfills the criteria of hotspots are The Western Ghats and Sri Lanka, The Eastern Himalayas, Indo-Burma (North-Eastern India South of Brahmaputra river)and Sundarland (Nicobar Islands). These sites are also known as Gade of speciation.

The Western Ghats are a chain of hills that lies parallel to the Western coast of peninsular India. These regions have moist deciduous forest and rain forest and have high species diversity and high levels of endemism. Nearly 77% of the amphibians and 62% of the reptile species found here are found nowhere else. Over 6000 vascular plants of over 2500 genera are found in this hotspot, of which over 3000 are endemic.

Much of the world’s species like black pepper and cardamom have their origins in the Western Ghats. It also harbors over 450 bird species, about 140 mammalian species, 260 reptiles and 175 amphibians. Over 60% of the reptiles and amphibians are completely endemic to this hotspot.

The Eastern Himalayan hotspot has approximately 163 globally threatened species including the one-horned rhinoceros, the Wild Asian Water buffalo and in all 45 mammals, 50 birds, 17 reptiles, 12 amphibians, 3 invertebrate and 36 plant species.
Thus, hotspots are the most precious sites for biodiversity conservation and should be protected from exploitation.

Wildlife Sanctuary:
It is IUCN category IV of protected area. A wildlife sanctuary can be established by a gazette notification from the State Forest Department, where protection is provided to vulnerable, endangered and critically endangered wild animals life. Operations such as procuring timber and minor forest products and private ownership are allowed provided they do not cause any adverse effects on the animals. Till 2015, there were 520 wildlife sanctuaries in India, covering 122867.34 km2 (3.74%) of land in India. The state of Odisha has 19 wildlife sanctuaries, which are listed below

Biosphere Reserve:
These are large tracts of protected land used for preserving the genetic diversity of an ecosystem by preserving wildlife. The creation of biosphere reserves was initiated in 1975 under the Man and Biosphere (MAB) programme of UNESCO. It is category V protected area designated by IUCN. Today, India has 18 biosphere reserves, some of which are also included under National Parks and Odisha has a share of one in Simlipal.

Each biosphere reserve integrates human activities and has following zonation

1. Core zone Strictly protected.
2. Buffer zone Sustainable and recreation activities allowed.
3. Transition zone Anthropogenic activities like research and sustainable development allowed.
4. Zone of human encroachment Normal anthropogenic activities allowed.

Out of 18 biosphere reserves, 8 of them are a part of world network of Biosphere Reserves based on MAB Programme of UNESCO.

The objectives of this programme are

• Conserving representative samples of ecosystems.
• In situ conservation of genetic diversity.
• Facilitating basic and applied research in ecology and environmental biology on site.
• Create opportunities for environmental education k and training.
• Promoting and creating awareness about sustainable management of living resources.
• Promoting international cooperation.

Therefore, the biosphere reserves have three junctions, that includes

• Conservation of ecosystems and genetic variations.
• Promotion of sustainable economic and human development.
• They serve as examples of education and training local, regional, national and international issues of sustainable development.

A protected area to be declared as a biosphere reserve should have the following essential features

• Abundant genetic diversity should be present.
• It should be unique in itself.
• The area should be legally protected for long term.
• Appropriate size for effective maintenance of natural populations so that there is no genetic drift.
• Sufficient natural resource available for ecological research, education and training. It should be a natural home for the endangered species of plants and animals.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 5 Heredity and Variation Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 4 Question Answer Heredity and Variation

Heredity and Variation Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
The experimental plant material used by Mendel was
(a) cowpea
(b) garden pea
(c) wild pea
(d) sweet pea
Answer:
(b) garden pea

Question 2.
Which of the following characters is not among the seven characters considered by Mendel for his hybridisation experiments?
(a) Seed colour
(b) Pod shape
(c) Flower position
(d) Flower shape
Answer:
(d) Flower shape

Question 3.
Which law Mendel would not have proposed, if the phenomenon of linkage was known to him?
(a) Law of unit character
(b) Law of dominance
(c) Law of segregation
(d) Law of independent assortment
Answer:
(d) Law of independent assortment

Question 4.
The number of genotypes produced in F2-generation in Mendel’s monohybrid cross was
(a) 1
(b) 2
(c) 3
(d) 4
Answer:
(c) 3

Question 5.
In which of the crosses, half of the offsprings show dominant phenotype?
(a) Tt × Tt
(b) TT × tt
(c) Tt × tt
(d) TT × TT
Answer:
(c) Tt × tt

Question 6.
Two allelic genes are located on the
(a) same chromosome
(b) two homologous chromosomes
(c) two non-homologous chromosomes
(d) any two different chromosomes
Answer:
(b) two homologous chromosomes

Question 7.
Red (RR) Antirrhinum is crossed with white (rr) one. The F₁-hybrid is pink. This is an example of
(a) complete dominance
(b) codominance
(c) incomplete dominance
(d) complete recessive
Answer:
(c) incomplete dominance

Question 8.
In a dihybrid cross in F₂-generation, the parental types are far greater in number than the recombinants. This is due to
(a) linkage
(b) incomplete dominance
(c) multiple allelism
(d) complete dominance
Answer:
(a) linkage

Express in one or two word(s)

1. A pair of Mendelian factors (genes) that appear at a particular location on a particular chromosome and control the same characteristic.
Answer:
Alleles

2. Phenomenon where in the heterozygous condition an intermediate phenotype is observed.
Answer:
Incomplete dominance

3. The phenomenon of a single gene contributing to multiple phenotypic traits.
Answer:
Pleiotropy .

4. Genes which move together and do not show independent assortment.
Answer:
Linked gene

5. A cross between the F₁-hybrids with any one of the homozygous parents.
Answer:
Back cross

Correct the sentences, if required, by changing the underlined word (s) only

1. The process of transmission of characters through generations is known as variation.
Answer:
inheritance

2. In Mendel’s monohybrid cross, the dwarf phenotype is always homozygous.
Answer:
Correct statement

3. In Mendel’s dihybrid cross in F₂-generation, nine phenotypes are produced.
Answer:
four

4. The phenomenon of linkage disproved the principle of independent assortment.
Answer:
Correct statement

5. In a test cross, always dominant parent is used.
Answer:
recessive

6. The distance between genes in a constructed gene map is expressed as Mendel unit.
Answer:
Morgan

Fill in the blanks

1. Monohybrid cross in Regeneration yields ____ number of phenotypes.
Answer:
two

2. Monohybrid cross in Regeneration yields ____ number of genotypes.
Answer:
three

3. The name of scientist often coined with linkage is ____ .
Answer:
TH Morgan

4. Genotype of a plant showing the dominant phenotype can be determined by ____ cross.
Answer:
test

5. In a cross between AaBB and aaBB, the genotypic ratio in Ft-generation will be ____ .
Answer:
1 : 1

Short Answer Type Questions

Write notes on the following

Question 1.
Law of independent assortment
Answer:
It states that when two pairs of traits are combined in a hybrid, segregation of one pair of traits is independent to the other pair of traits. As in the dihybrid cross of Mendel the presence of new combinations, i.e. round-green and wrinkled-yellow suggests that the genes for shape of seed and colour of seed are assorted independently. The results (9:3:3:1), indicate that yellow and green seeds appear in the ratio of 9+3 : 3+1 = 3:1.
Similarly, the round and wrinkled seeds appear in the ratio of9 + 3:3+1 = 3:1.

This indicates that each of the two pairs of alternative characters viz yellow-green cotyledon colour is inherited independent of the round-wrinkled characters of the cotyledons. It means that at the time of gamete formation the factor for yellow colour enters the gametes ” independent of R or r, i.e. gene Y can be passed on to the gametes either with gene R or r.

Question 2.
Multiple alleles
Answer:
Multiple allelism and Inheritance of Blood Groups:
Each gene has alternative forms or allelomorphs. For example, the genes for rail and dwarf characters of pea plant arc ailcics or allelomorphs. Here, former is called normal or wild type and Iatcr as mutant type.
Sometimes, there may no be any aiternative form such mutation that results in complete elimination of a gene is known as null mutation. Sometimes silent mutation occurs in which mutation does not have any effect of all.

These mutations occur in wild gene in any direction with a possibility of formation of many alternative alleles. Some genes may occur in more than two allelic forms, i.e. a gene can mutate several times to produce several alternative expressions such genes are called multiple alleles.

Question 3.
Chromosomal basis of inheritance
Answer:
It was proposed independently by Walter Sutton and Theodore Boyen in 1902. They united the knowledge of chromosomal segregation with Mendelian principles and called it chromosornal theory of inheritance.
According to this theory

• All hereditary characters must be with sperms and egg cells as they provide bridge from one generation to the other.
• The hereditary factors must be carried by the nuclear material.
• Chromosomes are also found in pairs like the Mendelian alleles.
• The two alleles of a gene pair are located on homologous sites on the homologous chromosomes.

Question 4.
Codominance
Answer:
Codominance:
It is the phenomenon in which two alleles express themselves independently when present together in an organism. In other words, it is the phenomenon in which offspring shows resemblance to both the parents,
e.g. ABO blood grouping in humans.

Question 5.
Incomplete dominance
Answer:
Incomplete Dominance:
It is a phenomenon in which phenotype of the F₁-hybrid offsprings does not resemble any of the parent, but is an intermediate between the expression of two alleles in their homozygous state. Carl Correns was the one who reported incomplete dominance in plant Mirabilis jalapa. He showed the petal colour inheritance in this plant. Here, the phenotypic ratio deviates from Mendel’s monohybrid ratio but the parental characters reappear in F₂-generation.

Question 6.
Law of segregation
Answer:
This principle states that, though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other, such that a gamete receives only one of the two factors. Hence, the alleles do not show any blending and both the characters are recovered as such in the F₂-generation though one of these is not seen in the F₁-generation.

Question 7.
Linkage
Answer:
The genes of a particular chromosome show the tendency to inherit together. This phenomenon of genic inheritance in which genes of a particular chromosome show their tendency to inherit together, i.e tendency to retain their parental combination even in the offsprings is known as linkage.

Question 8.
Recombination
Answer:
They attributed this due to physical association of the two genes and coined the term ‘linkage’ to describe this physical association of genes on a chromosome and the term ‘recombination’ to describe the generation of non-parental gene combinations. Morgan performed a test cross by crossing heterozygous grey-bodied and long-winged with homozygous recessive black-bodied and vestigial-winged fly

Question 9.
Test cross
Answer:
A special back cross to the recessive parent is known as test cross. This method was devised by Mendel to determine whether the dominant phenotype is homozygous or heterozygous.

For example, in a monohybrid cross between violet colour flower (W) and white colour flower (w), the F₁-hybrid was a violet colour flower. If all the F₁-progenies are of violet colour, then the dominant flower is homozygous and if the progenies are in 1:1 ratio, then the dominant flower is heterozygous.

Question 10.
Back cross
Answer:
Back cross is a cross of F₁ -progeny back to one of their parents. In back cross, there can be two possibilities, i.e. F₁ -hybrid to be crossed with homozygous dominant parent or with homozygous recessive parent.

Differentiate between the following

Question 1.
Homozygous and Heterozygous
Answer:
Differences between homozygous and heterozygous are as follows

Homozygous	Heterozygous
It is a condition when both alleles of a gene are similar.	It is a condition when both alleles of a gene are dissimilar.
The genotype is expressed as TT or tt.	The genotype expressed as Tt.
They are true breeding to purelines.	They are not true breeding.
The gametes produced by them are similar in genotype.	The gametes produced by them are of two types, one with dominant allele and other with recessive allele.

Question 2.
Genotype and Phenotype.
Differences between phenotype and genotype are as follows
Answer:

Phenotype	Genotype
It refers to observable traits or characters.	It refers to the genetic constitution of an individual.
It results from expression of genes.	It constitutes single gene pair or sum total of all the genes.
The phenotypic ratio of Mendel’s monohybrid cross is 3 : 1.	The genotypic ratio of Mendel’s monohybrid cross is 1:2:1.
It may change with age and environment.	It remains the same throughout the life of an individual.

Question 3.
Dominant genes and Recessive genes.
Answer:
Differences between dominant genes and recessive genes are as follows

Dominant genes	Recessive genes
When an allele expresses itself in the presence of its recessive allele, it is called dominant trait.	It can only express in the absence of its dominant allele and remain masked in its presence.
Dominant allele forms a complete functional enzyme due to which complete polyeptide is formed to express.	Recessive allele forms incomplete polypeptide enzyme due to which non-functionai polypetide is formed and fails to express completely.

Question 4.
Back cross and Test cross.
Answer:
Differences between back cross and test cross are as follows

Back cross	Test cross
It is a cross involving F1-progeny and either of the parents.	It is a cross involving
It is used by scientists to improve a breed or variety of plant or animal.	F1-individual and its recessive parent.

Question 5.
Qualitative inheritance and Quantitative inheritance.
Answer:
Differences between qualitative inheritance and quantitative inheritance are as follows

Qualitative inheritance	Quantitative inheritance
It deals with the inheritance of qualitative characters.	It deals with the inheritance of quantitative characters.
Each character is controlled by one pair of contrasting alleles.	Each character is controlled by more than one pair of non-allelic genes (Polygenes).
Each character has two distinct expressions, i.e. exhibits two distinct phenotypes.	Each character has an intergrading range of phenotypes.
The degree of expression remains the same whether the character is controlled by one or both the dominant genes.	The degree of expression depends on the number of the dominant genes.
Phenotypic expression is not affected by the environment.	Phenotypic expression is influenced by environmental factors.
Monogenic inheritance exhibits discontinuous pattern of inheritance.	Polygenic inheritance represents continuous pattern of inheritance.
F1-individuals resemble the dominant parent.	F1-individuals exhibit intermediate expression between the two parents.
F2-individuals exhibit 3:1 ratio. Intermediate expressions are not found.	In F2-generation, individuals with intermediate genotype and phenotype are maximum.
Examples of monogenic or qualitative inheritance are yellow or green coat color or round or wrinkled seed character in pea seeds.	Examples of polygenic or quantitative inheritance are height, weight, intelligence and skin color in human beings, milk yield in cattle and egg production in poultry.

Long Answer Type Questions

Question 1.
Give an account of Mendel’s monohybrid cross. What inference did Mendel draw from this experiment?
Answer:
Monohybrid Cross
The study of inheritance of a single pair of alleles or factors of a trait at a time (monohybrid cross) is called one gene inheritance. When a cross is made between pure tall and pure dwarf plant (for purity, the pureline is taken into consideration) in F₁-generation, all plants will be tall.

When F₁ -plants are self-pollinated, then in F₂-generation both tall and dwarf plants are found in approximate ratio of 3 : 1.

The dwarf plants of F₂ on self-pollination, produce dwarf plants generation after generation, while among tall plants, only 1 /3rd show this character generation after generation (pureline) and rest 2/3rd produce tall and dwarf in 3 : 1 ratio again (F₃ -generation).

Explanation Mendel’s monohybrid cross explained that in each main pair of alternative character one is expressed and other is masked.
The character which is expressed in F₁-generation is called dominant and the one which is not expressed is called recessive.

The monohybrid cross between tail and dwarf

In F₂-generation, the genotypic ratio is 1 : 2 : 1 and phenotypic ratio is 3 : 1. Mendel came to the conclusion that progeny possessing similar factors is called homozygous and the one which is hybrid is called heterozygous.

Mendel used english letters to record his observations of breeding experiments. He assigned capital letters for dominant characters and small letters for recessive characters which tabulated in the given below table

Characters	Dominant	Recessive
Seed shape	Round (R)	Wrinkled (r)
Seed colour	Yellow (Y)	Green (y)
Pod shape	Full (F)	Constricted (f)
Pod colour	Green (G)	Yellow (g)
Flower/Pod position	Axial (A)	Terminal (a)
Seed coat colour/Flower colour	Red/Violet (R/V)	White (r/v)
Plant height	Tall (T)	Dwarf (t)

Based on his observations on monohybrid crosses, Mendel proposed two general rules in order to consolidate his understanding of inheritance in monohybrid crosses.

Based on the Mendel’s observations, the German scientist Carl Correns formulated certain principles of heredity. These now known as Mendel’s laws of inheritance or the principles or laws of inheritance.
These are
Principle of Dominance:
It states that when two contrasting alleles for a character come together in an organism, only one is expressed completely and shows visible effect. This allele is called dominant and the other allele of the pair which does not express and remains hidden is called recessive.

For example, in the monohybrid cross when dwarf plant is crossed with tall plant, the Frgeneration are all tall plants. This shows that allele for tallness is dominant.

Question 2.
State and explain Mendel’s laws of inheritance.
Answer:
Following inferences were made by Mendel based on his observations
1. He proposed that some ‘factors’ passed down from parent to offsprings through the gametes over successive generations. Now-a-days, these factors are known as genes. Genes are hence, the units of inheritance. Genes which code for a pair of contrasting traits are known as alleles or allelomorphs, i.e. they are slightly different forms of the same gene.

2. Genes occur in pairs in which, one dominates the other called as the dominant factor or the gene which expresses itself, while the other remains hidden and is called recessive factor.

3. Allele can be similar in case of homozygous (TT or tt) and dissimilar in case of heterozygous (Tt).

4. In a true-breeding tall or dwarf pea variety, the allelic pair of genes for height are identical or homozygous.

5. TT and tt are called genotype (sum total of heredity or genetic make up) of the plant, while the term tall and dwarf are the phenotype.

6. When tall and dwarf plants produce gametes by process of meiosis, the alleles of the parental pair segregate and only one of the alleles gets transmitted to a gamete. Thus, there is only 50% chance of a gamete containing either allele, as the segregation is a random process.

7. During fertilisation, the two alleles, ‘T’ from one parent and V from other parent are united to produce a zygote, that has one ‘T’ and one allele or the hybrids have Tt.

8. Since, these hybrids contain alleles which express contrasting traits, the plants are heterozygous.

Question 3.
What do you mean by back cross and test cross? Explain test cross through an example.
Answer:
Back cross is a cross of F₁ -progeny back to one of their parents. In back cross, there can be two possibilities, i.e. F₁ -hybrid to be crossed with homozygous dominant parent or with homozygous recessive parent.

A special back cross to the recessive parent is known as test cross. This method was devised by Mendel to determine whether the dominant phenotype is homozygous or heterozygous.

For example, in a monohybrid cross between violet colour flower (W) and white colour flower (w), the F₁-hybrid was a violet colour flower. If all the F₁-progenies are of violet colour, then the dominant flower is homozygous and if the progenies are in 1:1 ratio, then the dominant flower is heterozygous.

Question 4.
Describe Mendel’s dihybrid cross.
Answer:
When two or more than two characters are taken in a cross it is called as polyhybrid cross, e.g. dihybrid cross, trihybrid cross, etc. A dihybrid cross is a cross involving two pairs of contrasting characters. For example, when a cross is made between yellow-round and wrinkled green seeds (both pureline homozygous), plants with only yellow round seeds are seen in F₁-generation but in F₁-generation, four types of combinations are observed.

Two of these combinations are similar to the parental combinations and others are new combinations. These are round green and wrinkled yellow.
The cross can be seen as shown in the figure

Phenotypic Ratio Round yellow : Round green : Wrinkled yellow : Wrinkled green = 9 : 3 : 3 : 1
Genotypic Ratio 1 : 2 :2 : 4 : 1 : 2 : 1 : 2 : 1

The ratio of four combinations in F₂-generation comes out to be 9 (round, yellow) : 3 (round, green) : 3 (wrinkled, yellow) : 1 (wrinkled, green). This ratio is called phenotypic dihybrid ratio. Phenotypic ratio of dihybrid test cross is 1 : 1 : 1 : 1.

Mendel’s Postulate Based on Dihybrid Cross:
Based on the result obtained from dihybrid crosses or two gene interaction, Mendel proposed the fourth postulate, i.e. law of independent assortment.

Question 5.
Give an account of linkage and recombination.
Answer:
Linkage, Crossing Over and Recombination:
According to ‘chromosomal theory of inheritance’, the chromosomes are vehicles of inheritance. Hence, the number of genes per individual for exceed the number of chromosomal pairs, i.e. each chromosome bears many genes. These genes are arranged in linear fashion over the chromosome and cannot show independent assortment.

In other words, we can say that the genes of a particular chromosome show the tendency to inherit together. This phenomenon of genic inheritance in which genes of a particular chromosome show their tendency to inherit together, i.e tendency to retain their parental combination even in the offsprings is known as linkage.

Morgan and his group observed in Drosophila that when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type.

They attributed this due to physical association of the two genes and coined the term ‘linkage’ to describe this physical association of genes on a chromosome and the term ‘recombination’ to describe the generation of non-parental gene combinations. Morgan performed a test cross by crossing heterozygous grey-bodied and long-winged with homozygous recessive black-bodied and vestigial-winged fly. They obtained the following results

Phenotype	Per cent of occurrence
Grey body long wing	41.5
Black body vestigial wing	41.5
Grey body vestigial wing	8.5
Black body long wing	8.5

This result was not in accordance with Mendel’s law of inheritance. Now suppose in order to explain, we assume the alphabets G and g for grey and black body colours and L and 1 for long and vestigial wings, respectively.

Thus, linkage is a phenomenon of genic inheritance in which genes of a particular chromosome show their tendency to inherit together.
Morgan and his group also found that even when genes were grouped on the same chromosome, some genes were tightly linked, i.e. linkage is stronger between two genes, if the frequency of recombination is low (cross-A). Whereas, the frequency of recombination is higher, if genes are loosely linked, i.e. linkage is weak between two genes (cross-B) as given in figure


Linkage : Results of two dihybrid crosses conducted by Morgan. Cross ‘A’ shows crossing between genes y and w ; Cross ‘B’ shows crossing between genes w and m. Here, dominant wild type alleles are represented with (+) sign in superscript

Those traits present on same chromosome, which do not show any production of recombinants are completely linked which is known as complete linkage and it is very rare.

Linkage Groups:
All the genes linked together in a single chromosome constitute a linkage group. The number of linkage group in an organism is equal to their haploid number of chromosomes. This hypothesis was proved by TH Morgan by his experiments on Drosophila.

Morgan and his group hybridised yellow-bodied and white-eyed females with brown-bodied and red-eyed males (wild type) and intercrossed their F₁-progeny (cross A). It was observed that the two genes did not segregate independently of each other and the F₂-ratios deviated significantly from 9:3:3 :1 ratio.

In F₂-generation, parental combinations were 98.7% and the recombinants were 1.3%. In another cross (cross-B), between white-bodied female fly with miniature wing and a male fly with yellow body and normal wing, parental combinations were 62.8% and recombinants were 37.2% in F₂-generation. Thus, it was proved from the crosses that the linkage between genes for yellow body and white eyes is stronger than the linkage between the white body and miniature wing.

Chromosome Maps or Linkage Maps:
Alfred Sturtevant (Morgan’s student) used the frequency of recombination between gene pairs on the same chromosome as a measure of the .distance between genes and ‘mapped’ their position on the chromosome. Genetic maps are now used as a starting point in the sequencing of whole genomes as done in case of human genome sequencing project.

The frequency of recombination Cross Over Value (COV) is calculated by using the formula

A linkage or genetic chromosome map is a linear graphic representation of the sequence and relative distances of the various genes present in a chromosome. 1% crossing over between two linked genes is known as 1 map unit or Morgan (after TH Morgan, who is considered as ‘Father of Experimental Genetics’).

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 15 Ecosystem Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 15 Question Answer Ecosystem

Ecosystem Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
Forests represent …………. ecosystem.
(a) aquatic
(b) terrestrial
(c) estuarian
(d) grassland
Answer:
(b) terrestrial

Question 2.
Decomposers are generally ……………..
(a) green plants
(b) microorganisms
(c) phytoplanktons
(d) insects
Answer:
(b) microorganisms

Question 3.
Man is a ……………..
(a) herbivore
(b) carnivore
(c) omnivore
(d) producer
Answer:
(c) omnivore

Question 4.
Ecological efficiency is less than …………….. per cent.
(a) 1
(b) 10
(c) 5
(d) 0.5
Answer:
(d) 0.5

Question 5.
The efficiency for energy transfer from one trophic level to another is nearly …………….. per cent.
(a) 1
(b) 10
(c) 5
(d) 20
Answer:
(b) 10

Question 6.
Pyramid of …………….. cannot be inverted.
(a) energy
(b) biomass
(c) number
(d) ecosystems
Answer:
(a) energy

Question 7.
Succession that starts at …………….. habitat is called hydrosere.
(a) sandy
(b) rocky
(c) aquatic
(d) xeric
Answer:
(c) aquatic

Question 8.
Succession that starts at sandy habitat is called …………….. .
(a) halosere
(b) lithosere
(c) psammosere
(d) hydrosere
Answer:
(c) psammosere

Express in one or two words

Question 1.
What can be called primary consumers?
Answer:
Herbivores

Question 2.
What is called to decomposers living on dead, decaying substratum?
Answer:
Saprophytes

Question 3.
Through which process is energy lost from living organisms?
Answer:
Respiration

Question 4.
Which type of ecological pyramid is never inverted?
Answer:
Pyramid of energy

Question 5.
What is called to the process of creation of bare area?
Answer:
Nudation

Question 6.
What is the form of climax forest called?
Answer:
Dense climax forest

Correct the statement, in each bit without changing the underlined words

Question 1.
Pond represents a forest ecosystem.
Answer:
Pond represents an aquatic ecosystem.

Question 2.
Ecosystem has structural and energy aspects.
Answer:
Ecosystem has structural and functional aspects.

Question 3.
Biogeochemical cycle may be otherwise called energy cycle.
Answer:
Biogeochemical cycle may be otherwise called nutrient cycle.

Question 4.
All heterotrophs are capable of photosynthesis.
Answer:
All autotrophs are capable of photosynthesis.

Question 5.
Animals are responsible for utilising dead, decaying substances, thereby cycling of materials becomes feasible.
Answer:
Microbes are responsible for utilising dead, decaying substances, thereby degrade detritus into smaller particles.

Question 6.
Flow of nutrients is unidirectional.
Answer:
Flow of energy is unidirectional.

Question 7.
Net primary productivity is calculated by taking into consideration gross primary productivity and photosynthesis.
Answer:
Net primary productivity is calculated by taking into consideration gross primary productivity and respiration loses.

Question 8.
Food-chain shows a complicated net-like inter-relationship in trophic levels.
Answer:
Food web shows a complicated net-like inter-relationship in trophic levels.

Question 9.
Pyramid of biomass takes into consideration the number of organisms in each trophic level.
Answer:
Pyramid of biomass takes into consideration total weight of organisms in each trophic level.

Question 10.
Pyramid of energy is always inverted.
Answer:
Pyramid of energy can never be inverted.

Question 11.
A stable community shows high species dominance.
Answer:
A stable community shows less species dominance.

Question 12.
Primary succession starts where there was living matter previously.
Answer:
Primary succession starts on a substratum where there was no living matter previously.

Fill in the blanks

Question 1.
Green plants are called …………… as they fix CO₂.
Answer:
autotrophs

Question 2.
In forest ecosystem, pyramid of number is ………….. type.
Answer:
inverted

Question 3.
Common decomposers form ………… ecosystem.
Answer:
Detritivorous

Question 4.
Secondary products are called ………… in a food chain.
Answer:
Detritus

Question 5.
The second trophic level in pond is …………….
Answer:
herbivores

Short Answer Type Questions

Write short notes on each of the following

Question 1.
Ecosystem
Answer:
An ecosystem is a basic functional unit that includes the whole community in a given area (biotic component) interacting with the abiotic factors.
Ecosystem is normally an open system because there is a continuous gain and loss of energy and materials from this system.
The term ecosystem’ was first used by AG Tansley in 1935 to describe the whole complex of organisms living together as sociological units and their habitats.
The ecosystem is also called as biocoenosis (Mobius; 1877), microcosm (Forbes; 1887) and biogeocoenosis (Sukachey). It is also known as ecocosm or biosystem.

Question 2.
Ecesis
Answer:
Ecesis It is successful germination of propagules into the bare area. The germination of seeds and spores produces new seedlings or new plants. As a result, some individuals of a species successfully get established in the bare area.

Question 3.
Ecological pyramid
Answer:
These are the diagrammatic illustrations of connection between different trophic levels in terms of energy, biomass and number of organisms. They represent the standing crops at each trophic level.

The base of each pyramid represents the producers or the first trophic Level and its apex represents tertiary or top level consumers. There are three ecological pyramids that are usually studied.

Question 4.
Food web
Answer:
Food web is the network of food chains which become interconnected at various trophic levels. In any complex food web, one can recognise several different trophic levels. In a food web, a given species may occupy more than one trophic level.
The complexity of food web is in direct relation with the stability of the ecosystem. Such type of ecosystem is not destroyed naturally and is sustained for a long time.

Question 5.
Plant succession
Answer:
Plant Succession
The process of changes in the habitat accompanied by the change of vegetation, one after the another is called plant succession. Its basic concept lies in the fact that the interaction between the habitat and the plants colonising the habitat results in some changes in the climate which may not be suitable for the existing plant community.
Thus, new plant community evolves which can survive the changed environment and replace the old ones.

Question 6.
Phytoplankton
Answer:
Phytoplanktons are small aquatic plants that form first stage of hydrosere. They include green flagellates, green algae, blue-green algae, etc. Their death in water bodies build up the amount of organic matter. They contribute about 50% available oxygen in atmosphere.

Question 7.
Nudation
Answer:
This is a process by which a bare area is created. The reasons behind the creation of a bare area may be topographic (soil erosion, land slide, volcanic activity); – climatic (glaciers, storms, frost, fire, etc.) or biotic (anthropogenic activities like industrialisation, agriculture, etc.).

Question 8.
Food chain
Answer:
Types of Food Chain:
There are mainly two types of food chain
(i) Grazing Food Chain (GFC) It begins with the producers, which capture the solar energy and feed the energy into the food chain through
photosynthesis, e.g.

• Grass → Grasshopper → Frog → Snake → Eagle
• Grass (Producer) → Goat (Prirnazy consumer) → Man (Secondary consumer)

In an aquatic ecosystem, the GFC is the major channel for energy flow, e.g.
Phytoplanktons → Crustaceans → Fishes

(ii) Detritus Food Chain (DFC) It begins with dead organic matter and is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria.
Dead leaves (Producer) → Woodlouse (Primary consumer) → Black bird (Secondary consumer)

Question 9.
Climax forest
Answer:
Forest (climax) stage The climax vegetation of trees depends on the climate of the region. If the climate is dry, trees like Acacia grow. In relatively moist and wet climate, mesophytic trees grow and a dense climax forest is formed. Along with the changes in the plant life in a xerosere (as also in a hydrosere), there is also a change in the animal life. The colonisation starts with ants and spiders and goes upto a variety of arthropods, birds and mammals by the fime the climax community is formed.

Question 10.
Species diversity
Answer:
It is the measure of the diversity within an ecological community that incorporates both species richness that is, the number of species in a community and the evenness of the species abundance. A community is more stable when its species diversity is high.

Differentiate the following with at least 3 valid points

Question 1.
Parasite and Saprophyte
Answer:
Differences between parasites and saprophytes are as follows

Parasites	Saprophyte
They derive nutrition from the host body.	They derive nutrition from dead-decaying materials.
Their body is not well-developed with complete-lack of sense organs.	Their body is well-developed.

Question 2.
Producers and Consumers
Answer:
Differences between producers and consumers are as follows

Producers	Consumers
These are green plants who prepare food material in the presence of sunlight.	They are mostly animals who depend on plants or other animals for food.
They are called autotrophs.	They are called heterotrophs.
They form the first trophic level, e.g. green plants.	They form second or third trophic level, e.g. animals.

Question 3.
Food chain and Food web
Answer:
Differences between food chain and food web are as follows

Food chain	Food web
It is a single straight pathway through which food energy travels in the ecosystem.	It consists of number of interconnected food chains through which food energy passes in the ecosystem.
Members of higher trophic level feed upon a single type of organisms of lower trophic level.	Members of higher trophic level can feed upon a number of alternative organisms of the lower trophic levels.
The presence of separate or isolated food chains adds to the instability of the ecosystem.	The presence of food webs increases the stability of the ecosystem.
It does not add to adaptability and competitiveness of the organisms.	Food webs increase the adaptability and competitiveness of the organisms.
Only the members of one trophic level compete for obtaining the same food.	Competition is among members of different species. It is less severe as a number of alternate foods are available.

Question 4.
Herbivores and Predators
Answer:
Differences between herbivores and predators are as follows

Herbivores	Predators
They eat plants.	They eat flesh.
Body is comparatively weak.	Body is strong.
Canine teeth are absent, primolars are well-developed, e.g. cow.	Canines are well-developed for flesh cutting, e.g. lion.

Question 5.
Primary succession and Secondary succession
Answer:
Differences between primary succession and secondary succession are as follows

Primary succession	Secondary succession
It occurs in an area which has been bare from the beginning.	It occurs in an area which has been denuded recently.
Soil is absent at the time of beginning of primary succession.	Soil is present in the area where secondary succession begins.
There is no humus in the beginning.	Humus is present from the very beginning.
Reproductive structures of any previous community are absent.	Reproductive structures of the previous occupants are present in the area.
In the beginning the environment is very hostile.	The environment is favourable from the beginning.
Serai communities are many.	Serai communities are.a few.
It takes a long time for completion, 1000 years or more.	It takes less time for completion, 50-200 years.

Question 6.
Gross primary productivity and Net primary productivity
Answer:
Differences between gross primary productivity and net primary productivity are as follows

Gross primary productivity	Net primary productivity
It is the amount of organic matter synthesised by producers per unit area in unit time.	It is the amount of organic matter stored by producers per unit area in unit time.
It refers to the total productivity including the energy utilised for respiration by the producers.	It refers to the net productivity that is converted to organic matter excluding the energy utilised for respiration by the producers.
GPP=Rate of increase in body weight or rate of organic matter synthesised by producers + the rate of respiration and other damages.	NPP=Rate of organic matter synthesised by photosynthesis by producers= the rate of energy utilised for respiration and other damages.

Question 7.
Pyramid of biomass and Pyramid of numbers
Answer:
Differences between pyramid of biomass and pyramid of numbers are as follows

Pyramid of biomass	Pyramid of numbers
It represents the biomass of producers, consumers, first level carnivores, etc.	It helps to tell about the relative numbers of organisms at each of the 4 trophic levels-producers, consumers and two levels of predators in a forest or lake ecosystem.
It is generally pyramidal in shape, but appears inverted like in a pond ecosystem where phytoplanktons support a large number of zooplankton.	It may become inverted due to existence of parasites or when a single tree supports much smaller organisms.
Difficult to determine because it would be a time consuming job.	It is easy to determine.

Question 8.
Abiotic components and Biotic components
Answer:
Differences between biotic components and abiotic components are as follows

Biotic components	Abiotic components
They represent the living organisms present in an ecosystem.	They represent non-living structures and factors of the ecosystem.
Biotic components include producers, consumers and decomposers.	Abiotic components include inorganic nutrients, organic remains and physical factors.
They build up and utilise chemical energy for their functioning.	Species diversity and Species dominance Differences between species diversity and species dominance are as follows
For their body building, they obtain inorganic nutrients and energy from abiotic components.	They are influenced by physical form of energy as light and heat.

Question 9.
Species diversity and Species dominance
Answer:
Differences between species diversity and species dominance are as follows

Species diversity	Species dominance
It is the presence of different species in an area, hence, species richness is abundant.	It is the presence of single species in an area, hence species richness is negligible.
It forms a stable community.	It forms an unstable community.
Resources of community do not deplete due to the absence or very less competition among different species	Community resources deplete very fast due to competition with same species.

Long Answer Type Questions

Question 1.
What is ecosystem? Describe the different components of ecosystem.
Answer:
Ecosystem is considered as an interactive system, where biotic and abiotic components interact with each other via energy exchange and flow of nutrients. An ecosystem can be either natural or artificial. Natural ecosystems These are capable of maintaining and operating themselves, without the interference of man. They are further classified as

Artificial ecosystems These are maintained and manipulated by man for different purposes, e.g. cropland, aquarium, etc.

Ecosystem Components:
An ecosystem has two major components, abiotic (non-living) and biotic (living), which can be further classified as follows

Biotic Components
In order to survive and maintain themselves, living organisms require various nutrients. On the basis of nutritional requirement of an organism, they can be divided into three types of organisation as follows
(i) Producers
The self-productive (autotrophic) living components that manufacture organic molecules and living protoplasm by using the inorganic compounds from the surrounding are called producers.

These can be further divided into two types

1. Photoautotrophs They obtain energy from the sunlight by the process called photosynthesis, e.g. green plants, photosynthetic bacteria, etc.
2. Chemoautotrophs These are chemosynthetic organisms that utilise hydrogen sulphide (H₂S) and bond energy derived from inorganic components, e.g sulphur oxidizing bacteria (Beggiatoa).

(ii) Consumers
The heterotrophic organisms that directly or indirectly organic materials manufactured by autotrophs are called consumers. These can be further categorised as

1. Primary consumers They directly consume the organic compounds synthesised by autotrophs, e.g. mammalian herbivores (predators), insect herbivores (parasites), etc.
2. Secondary consumers They derive organic compounds by feeding upon herbivores and small carnivores, e.g. mammalian carnivores (predators).

(iii) Decomposers
The saprophytic organisms that breakdown organic waste products into inorganic substances are called decomposers. They play a vital role in nature as they convert complex chemicals to simpler forms, e.g. microorganisms found in rotten and decaying organic materials.

Abiotic Components :
These are the non-living components that are mostly found in the utilisable form. They can be further ‘divided as follows

• Inorganic nutrients They form physical environment, e.g. carbon (C), nitrogen (N), hydrogen (H), etc.
• Organic compounds They provide nutrients, e.g. soil.
• Environmental factors They provide energy, e.g. air, temperature, etc.

Interaction of biotic and abiotic components results in the formation of a functional structure that is an exclusive characteristic of each type of ecosystem.
The two important structural features of an ecosystem are

1. Species composition It is calculated by the identification and enumeration of plant and animal species of an ecosystem.
2. Stratification It is the vertical distribution of different species occupying different levels in an ecosystem, e.g. trees occupy top vertical strata or layer of a forest, shrubs the second and herbs and grasses occupy the bottom (third) layers.

Question 2.
Give an account of energy flow in an ecosystem.
Answer:
Energy Flow Efficiency in an Ecosystem:
Energy transfer from one trophic level to next is governed by Lindemann’s law of trophic efficiency.
Tindeman in 1942 stated that in each step of food chain when food energy is transferred from one trophic level to the next higher trophic level, some energy is lost as heat and only 10% energy of net primary productivity is transferred to the next level.

Energy flow through different trophic levels

Lindemann demonstrated that plants convert solar energy into chemical energy (i.e. carbohydrates). This conversion follows the first law of thermodynamics where one form of energy is converted into another form and it is neither created nor destroyed. But, when this fixed energy is transferred from plants to next trophic level, 90% of it gets lost and only 10% energy is transferred to every successive trophic level.

Question 3.
Write a brief note about ecosystem services.
Answer:
Ecosystem Services
Healthy ecosystems are the base for a wide range of economic, environmental and aesthetic goods and services. Ecosystem services are the products of ecosystem processes, e.g. healthy forest ecosystem purifies air and water, mitigates droughts and floods, cycles nutrients, generates fertile soils, provides wildlife habitat, maintains biodiversity, pollinates crops, provides storage site for carbon and also provides aesthetic, cultural and spiritual values.

Although it is difficult to find out the monitory value of all these services, still it is reasonable to think that biodiversity should carry a hefty price tag.

Robert Constanza and his colleagues recently have tried to put price tag on the nature’s life-support services. Researchers have put a price tag of US $ 33 trillion a year on these fundamental ecosystem services, which we utilise for free. This is almost twice the value of global Gross National Product (GNP), which is of US $ 18 trillion. Out of the total cost of various ecosystem services, soil formation accounts for 50%.

Contribution of other services like recreation and nutrient cycling are less than 10% each. The cost of climate regulation and habitat for wildlife are about 6% each.

The popular definition of ecosystem services was given by United Nation 2005 Millennium Ecosystem Assessment (MEA) after a four year long study involving more than 1300 scientists worldwide. In 2005, MEA defined ecosystem services as benefits people obtain from ecosystem and they distinguished four categories of ecosystem services.
These are described in detail below
1. Provisioning Services
It includes the products that are obtained from ecosystem, e.g. genetic resources, food, fibre and freshwater.

2. Regulating Services
It includes the benefits that are obtained from the regulation of ecosystem processes, e.g.

• Carbon sequestration and climate regulation.
• Waste decomposition and detoxification.
• Purification of water and air.
• Crop-pollination.
• Pest and disease control.

3. Supporting Services
It includes the processes that are necessary for the production of all other ecosystem services, e.g.

• Nutrient dispersal and cycling.
• Seed dispersal.
• Primary production.

4. Cultural Services
It includes non-monetary benefits that we obtain from the ecosystem, e.g.

• Cultural, intellectual and spiritual inspiration.
• Recreational experiences (including ecotourism).
• Scientific discovery.

Study of Ecosystem Services:
The study of ecosystem services includes the following steps

• Identification of Ecosystem Services Providers (ESPs).
• Determination of community structural aspects that influence house ESPs, function.
• Assessment of key environmental (abiotic) factors influencing the provision of services.
• Measurement of spatial and temporal scales ESPs and their services.

Examples of Ecosystem Services:
These include carbon cycle, pollination, oxygen release, etc.
I. Carbon-Fixation
The atmospheric carbon is fixed by the following three means

• Natural carbon-fixation It occurs through biological, chemical and physical processes.
• Artificial carbon-fixation It occurs through saline aquifers, reservoirs, ocean water, ageing oil fields, sea weed cultivation in oceans, etc.
• Biological carbon-fixation It occurs through reforestation, urban forestry, wetland restoration and agriculture.

Carbon-fixation is helpful in following ways

• The long term storge of CO₂ helps to reduce its harmful effects like global warming, climate chage, etc.
• It helps to slow down the accumulation of greenhouse gases in atmosphere and marine bodies.

II. Pollination
It is the process of pollen transfer by different agents so, that a plant can reproduce sexually.
It is helpful in following ways

1. 15-30% of crop plants are pollinated by insects like bees. For this reason, many farmers in USA import non-native bees which ensures proper pollination within 1-2 km radius.
2. In California, wild bees establish behavioural interactions with honeybees so, as to enhance the pollination service.

III. Oxygen Release
Oxygen is required by various life forms for respiration.
The major sources of oxygen include

1. Planktons and weeds in oceans About 50% of available oxygen is produced by planktons of marine ecosystem.
2. Trees Plants absorb CO₂ for photosynthesis and release oxygen. The net production of O₂ by a healthy tree depends upon its species, size, health and location.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 14 Organisms and Environment Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 14 Question Answer Organisms and Environment

Organisms and Environment Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
A population is a group of
(a) individuals in a species
(b) species’in a community
(c) individuals in a family
(d) communities in an ecosystem
Answer:
(a) individuals in a species

Question 2.
Exponential growth occurs when there is
(a) a great environmental resistance
(b) a fixed carrying capacity
(c) no biotic potential
(d) no environmental resistance
Answer:
(d) no environmental resistance

Question 3.
In a population, unrestricted reproductive capacity is called as
(a) carrying capacity
(b) birth rate
(c) biotic potential
(d) fertility rate
Answer:
(b) birth rate

Question 4.
Two opposite forces operate in the growth and development of a population. One of them is related to the ability to reproduce at a given rate. The force opposite to it is called
(a) environmental resistance
(b) mortality
(c) fecundity
(d) biotic control
Answer:
(b) mortality

Question 5.
The carrying capacity of a population is determined by its
(a) population growth rate
(b) mortality
(c) limiting resources
(d) natality
Answer:
(c) limiting resources

Question 6.
Which of the following at a conduit for energy transfer across trophic levels?
(a) mutualism
(b) parasitism
(c) protocooperation
(d) predation
Answer:
(d) predation

Question 7.
Phenomenon of inhibition of growth of one species by other species through secretion of some chemicals is termed as
(a) commensalism
(b) allelopathy
(b) mutualism
(d) predation
Answer:
(b) allelopathy

Question 8.
Predation performs all, except
(a) transfer of energy
(b) loss of sense organs
(c) keeps prey population under control
(d) maintains species diversity
Answer:
(b) loss of sense organs

Question 9.
Two important factors that influence the life of organisms are
(a) soil, temperature
(b) soil, light
(c) light, water
(d) water, temperature
Answer:
(c) light, water

Question 10.
Ecology describes
(a) interactions between living organisms only
(b) intraspecific competitions only
(c) interactions between members of single species
(d) interactions of organisms and abiotic components around
Answer:
(d) interactions of organisms and abiotic components around

Express in one or two words

Question 1.
Study of interrelationship between the environment and a plant species.
Answer:
Ecology

Question 2.
Amount of water vapours actually present in the air at any given time.
Answer:
Humidity

Question 3.
The total amount of water in the soil, except the gravitational water.
Answer:
Holard

Question 4.
Association of fungi and algae.
Answer:
Lichen

Question 5.
The study of soil.
Answer:
Pedology

Question 6.
Vegetation where the annual rainfall is more than 50 inches.
Answer:
Grassland

Correct the sentences changing the underlined word only

1. Plants those grow in soil and mud are xerophytes.
Answer:
mesophytes

2. Sunken stomata is a characteristic of hydrophytes.
Answer:
xerophytes

3. Air pockets are found in mesophytes.
Answer:
hydrophytes

4. The pre-reproductive mass is found more in urn- shaped pyramid.
Answer:
triangular

5. Population consists of different kinds of species.
Answer:
Community

Fill in the blanks

1. Shallow water region present on the edge of lakes is called …………. .
Answer:
littoral zone

2. The most relevant ecological factor is …………….. .
Answer:
light

3. Mortality and …………. contribute to a decrease in population density.
Answer:
emigration

4. J-shaped curve represents ………… growth.
Answer:
exponential

5. Geometric representation of age structure is a characteristic of ………..
Answer:
population

Short Answer Type Questions

Question 1.
Camouflage
Answer:
Camouflage It is the act of hiding the identify either by colour changes or by making animals or objects hard to see.
Some species of insects and frogs are cryptically coloured (camouflaged) to avoid being detected easily by predators.

Question 2.
Edaphic factor
Answer:
Edaphic factor An edaphic factor relating to physical or chemical composition of the soil found in a particular area, e.g. soil pH, porosity, water holding capacity, etc.

Question 3.
Habitat
Answer:
Environment is termed as sum total of all external conditions which influence the organisms in term of survival and reproduction. Habitat is a natural abode or locality where a plant/ animal grow, based on the environment, the differences in the vegetation and species of different places are observed.

Each organism plays an important role in its surrounding. Niche is the role of an organism plays in its ecosystem. In other words, we can say that niche is how an organism makes a living, interacts with other organisms and helps in cycling of nutrients.

Question 4.
Temperature
Answer:
Temperature
It is the most ecologically significant environmental factor. It varies seasonally on land and decreases progressively from the equator towards the poles and from plains to the mountain tops. It ranges from sub-zero levels in polar areas and high altitudes to > 50°C in tropical deserts in summer. There are also certain unique habitats such as thermal springs, deep sea hydrothermal vents where the average temperature exceeds 100°C.

Question 5.
Biomes
Answer:
Biomes The large unit of ecology which consist of major vegetation type and associated fauna in a particular climatic zone is called biome, e.g. sea coast, deserts. Deciduous forest are the major biomes of India.

Question 6.
Population
Answer:
The term ‘population’ can be defined as a group or assemblage of organisms of the same species living in a particular area at a given time.
For example, the lion population of the Gir forest or the peacock population of India, etc.

The population may be subdivided into demes or local populations, which are a group of interbreeding organisms. It is the smallest collective unit of a plant or animal population.
The other is metapopulation, which consists of whole set of local populations connected by dispersing individuals.

Question 7.
Competition
Answer:
It is generally believed to occur when closely related the two individuals of species compete for the same resources that are limiting. This can happen between the members of the same species, i.e., intraspecific or different species, i.e. interspecific.

Question 8.
Abiotic factors
Answer:
Abiotic factors The non-living factors which influence an ecosystem and the organisms are called abiotic factors. It can determine which species of organism will survive in an given environment.

Question 9.
Population density
Answer:
Population Density
This refers to the size of population to a unit space at a particular time. This can be measured is several ways an mentioned below

• Abundance (absolute number in population).
• Numerical density (number individuals per unit area).
• Biomass density (biomass per unit area).

Question 10.
Necessity of adaptations
Answer:
Necessity of adaptations Adaptations take a lot of time to evolve. They are necessary because they help the organism to fit in to its niches. Also, it is important for’ survival of both, the individual and the species.

Differentiate between the following

Question 1.
Habitat and Niche
Answer:
Differences between habitat and niche are as follows

Habitat	Niche
A place or part of an ecosystem, occupied by a particular organism.	A functiohal description of the role, a species plays in a community.
It can have number of niches.	It does not have any components.
A variety of environmental variables are present in a habitat.	Every niche has its own specific environment.

Question 2.
Mutualism and Parasitism
Answer:
Differences between mutualism and parasitism are as follows

Mutualism	Parasitism
It type of interaction in which both the interacting species gets benefits.	The mode of interaction in two species in which one (parasites) is dependent on another for benefits there by damaging the other one (host).
Mycorrhiza show mutual association between fungi and roots of higher plants.	Human liver-fluke depends on two intermediate hosts to complete its life cycle.

Question 3.
Hydrophytes and Xerophytes
Answer:
Differences between hydrophytes and xerophytes are as follows

Hydorphytes	Xerophytes
The plants which are adapted to live in abundance of water are called hydrophytes.	The plants which are adapted to live in condition of water scarcity and dry habitat are called xerophytes.
Root are poorly developed.	Roots are very well- developed.
Leaves are well-developed.	Leaves are modified in various structure.
Stomata are present abundantly.	Sunken stomata are present.
e.g. Hydrilla, Pistia.	e.g. Opuntia, Asparagus, etc.

Question 4.
Birth rate and Death rate
Answer:
Differences between birth rate and death rate are as follows

Birth rate	Death rate
It is the number of birth of new individuals per unit of population per unit time.	It is the number of loss of individuals per unit of population per unit time.
It increases the size of population.	It decreases the size of population.

Question 5.
Fertility and Fecundity
Answer:
Differences between fertility and fecundity are as follows

Fertility	Fecundity
Fertility is the natural ability to reproduce and is defined as the offspring per couple.	Fecundity is the actual reproductive rate of an organism or population measured by number of gametes, (seed sets or asexual propagules).

Question 6.
Logarithmic and Exponential growth
Answer:
Differences between logarithmic and exponential growth are as follows

Logarithmic growth	Exponential growth
Logistic or Logarithmic occurs rapidly and then slow down.	The kind of growth which is slow initially but, it increases as the population growth takes place.
It considers factors like competition and limited resources.	It requires specific ideal conditions to occur.
It occurs when the resources are limited.	It occurs when the resources are abundant.
It has four phases-lag, log, decelearatlon and steady.	It has two phases-lage and log.
It is more common, in human, etc.	It occurs in algal bloom, etc.

Long Answer Type Questions

Question 1.
Explain, what is population? Describe the different characteristics of population.
Answer:
The term ‘population’ can be defined as a group or assemblage of organisms of the same species living in a particular area at a given time.
For example, the lion population of the Gir forest or the peacock population of India, etc.

The population may be subdivided into demes or local populations, which are a group of interbreeding organisms. It is the smallest collective unit of a plant or animal population.
The other is metapopulation, which consists of whole set of local populations connected by dispersing individuals.

Population Interactions:
In nature, living organisms such as animals, plants and microbes, cannot live in isolation and therefore, interact in various ways to form a biological community. Interspecific interactions occur between the populations of two different species living together within a community.

These interactions could be beneficial (+), detrimental (-) or neutral (0), as shown in table below
Population Interactions and their Effects

Name of interaction	Effect on species-A	Effect on species-B
Mutualism	+	+
Competition	–	–
Predation	+	–
Parasitism	+	–
Commensalism	+	0
Ammensalism	–	0

Mutualism:
It is an interaction that confers benefits to both the interacting species. Some examples of mutualism are
1. Lichens represent an intimate mutualistic relationship between a fungus (mycobiont) and photosynthesising algae (phycobiont) or cyanobacteria. Here, the fungus helps in the absorption of nutrients and provides protection, while algae prepares the food.

2. Mycorrhiza show dose mutual association between fungi and the roots of higher plants. Fungi help the plant in absorption of nutrients, while the plant provides food for the fungus, e.g. many members of genus -Glomus.

3. Plants need help from animals for pollination and dispersal of seeds. In return, plants provide nectar, pollens and fruits to them.

4. Co-evolution to safeguard the mutually beneficial system, plant-animal interactions involve co-evolution of the mutualists, i.e. the evolution of the flower and its pollinator species are tightly linked with one another, e.g.

(i) Fig and its partner wasp species, the female wasp uses the fruit not only as an oviposition (egg-laying) site, but uses the developing seeds from the fruit for nourishing its larvae. In return, the wasp pollinates the fig inflorescence, while searching for suitable egg-laying sites.

(ii) Mediterranean orchid Ophrys employs ‘sexual deceit’ to get pollinated by a species of bee. One petal of its flower bears an uncanny resemblance to the female of the bee in size, colour and markings. The male bee is attracted to what it perceives as a female and ‘pseudocopulates’ with the flower. During this process, pollen are dusted from the flower onto the male bee. When the same bee pseudocopulates with another flower, it transfers pollen to it and thus pollinates the flower.

Competition:
It is generally believed to occur when closely related the two individuals of species compete for the same resources that are limiting. This can happen between the members of the same species, i.e., intraspecific or different species, i.e. interspecific. These are as follows

(i) Intraspecific competition occur for the resources which are short in supply such as food, space or mate. There are of two types

1. Content competition Where each organism claims a part of the resource, but due to competition, some are successful to get, but some fail.
2. Scramble competition In this case, the resource gets divided to many other smaller parts to which all have access. Individual organism scramble for resources. Each individual succeeds to get some of the resource available to survive.

(ii) Interspecific competition It occurs between members of different species, e.g. competition is likely to have two outcomes. These are as follows
1. Competitive exclusion According to Gause’s competitive exclusion principle two closely related species competing for same resources cannot co-exist indefinitely and the competitively inferior species will be eliminated eventually two species of beetles (Tribolium castaneum and T. confusum) feed on stored flour, one species would survive and other will die.

2. Co-existence Species facing competition might evolve a mechanism to live in the same niche by changing the feeding time or foraging pattern. This is called resource partitioning.

Question 2.
What do you understand by population? Explain the different attributes of the population.
Answer:
The term ‘population’ can be defined as a group or assemblage of organisms of the same species living in a particular area at a given time.
For example, the lion population of the Gir forest or the peacock population of India, etc.

The population may be subdivided into demes or local populations, which are a group of interbreeding organisms. It is the smallest collective unit of a plant or animal population.
The other is metapopulation, which consists of whole set of local populations connected by dispersing individuals.

Population Attributes:
Population is a unit of ecosystem through which the energy flows and nutrients get cylced which helps in maintaining its stability. A population has some features such as birth rate, death rate, growth form, age structure, density, etc. which are discussed below

1. Growth
When a few organisms are introduced to a particular unoccupied area, the population show growth (increase in size) in sigmoid or ‘S’-shaped logistic fashion.

The few organisms are introduced to a particular unoccupied area, the growth of population initially is slow (positive acceleration phase). Then suddenly there is sharp increase and growth becomes vary rapid (logarithmic phase). At last stage it finally slow and down because of the increased environmental resistance (negative acceleration phase). It is dipicted in the given [fig. 14.19(a)], The increase of population size does not occure beyond a certain saturation limit. This is known as carrying capacity .

The sigmoid and exponential growth curves

Another kind of population curve in J-shaped this the density of organism increase rapidly, but stops suddenly due to environmental resistance. It is called exponential growth curve.

(i) Growth Rate:
The growth rate of a population can be determined by the following formula

Population size for a given species is not static parameter, but it is ever changing based on different factors including food availability, predation pressure and weather diversity. The population thickness changes because of the following four changes

• Natality It refers to the number of “births during a given period in the population that are added to the initial density.
• Mortality It is the number of deaths in the population during a given period.
  
  Factors influencing population density

2. Birth Rate and Death Rate:
The increased and decreased rate of population depends on birth and death natality is related new homes, i.e. the reproduction capacity of individuals. It is related with two aspects of reproduction.

Thus, natality or birth rate of a population can be expressed as

Where, b = Natality per unit time, d – Changing value of the entity, N = Initial number of individuals in population, Nn – Number of new individuals added and t = Unit time.

Similarly, the death rate or mortality rate is the death or loss of individuals from the population in unit time and can be expressed as

The death rate has a relation with the natality because of over crowding, predation and spread of disease.

3. Sex Ratio:
It represents the ratio of organisms of different sexes of the population. In animals, sex is either male or female which creates difference in the characteristic of the population.

4. Age Distribution:
A population at a given time is composed of individuals of different age groups such as pre-reproductive, reproductive and post-reproductive. The population age distribution is related to the growth rate of the population and this can be used to calculate whether the population is expanding or contracting.

Ordinarily, a rapidly expanding population would have a large proportion of young individuals, a stationary population with even distribution of age groups and declining population contain a large proportion of old individuals.

These age groups of the population can be portrayed through the graphical age pyramid representations.In human population, the age pyramids generally express age distribution of males and females in a combined diagram. The shapes of the pyramids reflect the growth status of the population.

The pyramids can be of three difference types as follows
(i) Expanding (Triangular) This is a type of a growing population representation is like a triangle.
The population carries a high proportion of pre-reproductive individuals followed by reproductive individuals and post-reproductive individuals. Because of the very large number of pre-reproductive individuals, more and more of them enter reproductive phases and rapidily increases the size of the population.

(ii) Stable (Bell-shaped) This type of pyramid will represent a stationary or stable population having an equal number of young and middle aged class of individiuals.

(iii) Declining (Urn-shaped) This group has a small number of pre-reproductive individuals followed by a large number of reproductive individuals. As, there is less number of individuals in pre-reproductive groups.

5. Population Density
This refers to the size of population to a unit space at a particular time. This can be measured is several ways an mentioned below

1. Abundance (absolute number in population).
2. Numerical density (number individuals per unit area).
3. Biomass density (biomass per unit area).

The density of population can be expressed in the following manner
(a) Crude density This is the density of a species population with reference is the total area. It varies according to the season, weather, food supply rate of reproduction, etc.
(b) Ecological density This is the density of a species with reference to the actual area of habitat available to the species.

Question 3.
Explain, how different organisms interact in a population emphasising on the possibilities of various relationships.
Answer:
The term ‘population’ can be defined as a group or assemblage of organisms of the same species living in a particular area at a given time.
For example, the lion population of the Gir forest or the peacock population of India, etc.

The population may be subdivided into demes or local populations, which are a group of interbreeding organisms. It is the smallest collective unit of a plant or animal population.
The other is metapopulation, which consists of whole set of local populations connected by dispersing individuals.

Predation
It is an interspecific interaction, where an animal called predator kills and consumes the other weaker animal called prey. This is a biological control method. It is the nature’s way of transferring energy to higher trophic levels, which is fixed by plants at the first trophic level, e.g. tiger (predator) and deer (prey).

Important roles of predators are as follows
1. In the absence of predators, prey species could achieve very high population densities and cause instability. So, besides acting as ‘conduits’ for energy transfer across trophic levels, predators play very important role in providing population stability.

2. They help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species, e.g. predator starfish Pisaster in the rocky intertidal communities of American Pacific Coast. In a field experiment, when all the starfish were removed from the area, more than 10 species of invertebrates became extinct within a year, because of interspecific competition.

3. When certain exotic species are introduced into a geographical area, they become invasive and start spreading fast because the invaded land does not have natural predators, e.g. prickly pear cactus introduced in Australia in early 1920s was brought under control by introducing its predator (i.e. a moth) in the country.

If a predator is too efficient and over exploits its prey, then the prey might become extinct.
Following it, the predator will also become extinct because of the lack of food. This is why predators in nature are prudent.
Prey species have evolved various defence mechanisms to lessen the impact of predation. These are as follows

In Animals:

1. Camouflage Some species of insects and frogs are cryptically coloured (camouflaged) to avoid being detected easily by the predator. Some are poisonous and therefore, avoided by the predators.
2. Chemical emission Monarch butterfly is highly distasteful to its predators (birds) because of a special chemical present in its body. The butterfly acquires this chemical during its caterpillar stage by feeding on a poisonous weed.
3. Mimicry It refers to the resemblance of an organism to their natural surroundings which hides them from eyes of predators.

In Plants
Nearly 25% of all insects are known to be phytophagous (feeding on plant sap and other parts of plants) apart from other herbivores. So, plants have evolved various defences against them, e.g., thorns of Acacia and cactus are the most common morphological means of defence.

Some plants produce highly poisonous chemicals like cardiac glycosides, e.g., weed Calotropis that makes the herbivore sick, etc.
Chemicals like nicotine, caffeine, quinine, strychnine, opium, etc., are actually defence mechanisms against grazers and browsers.

Parasitism:
It is the mode of interaction between two species in which one species (parasite) depends on the other species (host) for food and shelter and damages the host. In this process, one organism is benefitted (parasite), while the other is being harmed (host).

(i) Adaptation methods of a parasite are
Parasite is host-specific in a way that both host and parasite tend to co-evolve. According to its lifestyle, a parasite, evolved special adaptations as

• Loss of unnecessary sense organs.
• The presence of adhesive organs or suckers for clinging on to host.
• Loss of digestive system.
• High reproductive capacity.

(ii) The life cycles of parasites are often complex, involving one or two intermediate hosts or vectors to facilitate parasitisation of its primary host,, e.g.

• Human liver fluke (a trematode parasite) depends on two intermediate hosts (a snail and a fish) to complete its life cycle.
• Malarial parasite (Plasmodium) needs a vector (mosquito) to spread to other hosts.

(iii) Majority of parasites harm the host. The harm is done in the following ways

• They reduce the survival, growth and reproductive ability of the host.
• They reduce its population density.
• They might render the host more vulnerable to predation by making it physically weak.

Types of Parasites
Parasites are broadly divided into following main types

1. Ectoparasites depend on the external surface of the host organism for food and shelter, e.g., lice on humans, ticks on dogs, copepods in marine fishes and Cuscuta, a parasitic plant that grows on hedge plants.
2. Endoparasites live inside the host’s body at different sites like liver, kidney, lungs, etc., for food and shelter, e.g. tapeworm, liver fluke, Plasmodium, etc. The life cycles of endoparasites are more complex because of their extreme specialisation.
3. Brood parasitism is an example of parasitism in which one organism (parasite) lays its eggs in the nest of another organism (host) for the later to incubate them.

The eggs of parasitic birds have evolved to resemble the host’s egg to reduce the chances of host bird from detecting and ejecting the parasitic eggs from nest, e.g., cuckoo (koel, parasite) and crow (host) during breeding season (spring to summer).

Effects of Parasites on Host
There always exist some kind of host parasite relationship which has following characteristics parasites do not kill the host immediately, but they make the host to suffer, they damage their body and in extreme case they may cause their death. These reduce the growth of the host and also afffect their reproductive potential. They also reduce the size of the population of host.

Question 4.
What is habitat? Describe the different types of abiotic factors present in the habitat.
Answer:
Habitat:
Environment is termed as sum total of all external conditions which influence the organisms in term of survival and reproduction. Habitat is a natural abode or locality where a plant/ animal grow, based on the environment, the differences in the vegetation and species of different places are observed.

Abiotic Factors:
These include climatic, edaphic and topographic factors. Climatic factors are light, temperature, precipitation, humidity, wind. Edaphic factors are factors related to soil whereas topographic factors are physical factors related to slope, altitude and others concerned with earth surface. Some of the major abiotic factors are discussed below
1. Light
Sunlight is the primary source of light. It plays an important role in almost all ecosystems. The entire food chain starts with the organisms that are photosynthetic (producers).

So without sunlight, all life excluding some microbes would perish, not just the plants. The total amount of light that falls on the earth varies according to the season, latitude, altitude and conditions of the atmosphere. The significance of light lies in the fact that all autotrophs depend upon light as a source of energy for preparing their food by photosynthesis and release oxygen during the process.

Therefore, it is an important factor for life to exist on earth. Small herbs and shrubs growing in forests are adapted to photosynthesis under very low light intensities, because they are overshadowed by the tall, canopied trees. Most plants depend on sunlight to meet their photoperiodic requirement for flowering also.

The spectral quality of solar radiation as shown in figure is also important for life. The UV component of light is harmful for many organisms. Different components of the visible spectrum are available for marine plants living at different depths of the ocean.

This is why different types of algae, i.e., green, brown and red algae occur at different depths in sea in the upper, middle and deep layers of water respectively.
Plants which grow in bright light are called sun plants or heliophytes while plants growing in shade or low intensity light are called sciophytes.
Depending upon the availability of light aquatic body is divided into the following zones

1. Littoral zone ft adjoins the shore and extends to the point water body when producers (plants) show the light compensation level. The point indicate the rate of photosynthesis equalising with the rate of respiration.
2. Limnetic zone It is the major open area of waterbody next to the littoral zone. The O₂ availability to the organisms living in this area is from the photosynthetic activity of phytoplanktons and in the atmosphere immediately over the water or lake’s surface.
   In the limnetic zone, the region which gets the maximum light above the light compensation point is called euphotic zone.
   The region where light is received less and diffused and is below the light compensation point is disphotic zone.
3. Profundal zone This is the bottom area of the pond, where respiration is greater than production.
4. Benthic zone It is the zone of darkness. No light, penetrate in the deeper layers of waterbody. The organism living here in this zone have poorly developed eye sight. The producers are mainly chemosynthetic bacteria.
   
   Zonation in deep lake showing gradient of light and oxygen

2. Temperature
It is the most ecologically significant environmental factor. It varies seasonally on land and decreases progressively from the equator towards the poles and from plains to the mountain tops. It ranges from sub-zero levels in polar areas and high altitudes to > 50°C in tropical deserts in summer. There are also certain unique habitats such as thermal springs, deep sea hydrothermal vents where the average temperature exceeds 100°C.

Physiological functions as well as geographical distribution of plants and animals are governed by the temperature conditions and their thermal tolerance. Organisms which can tolerate and thrive in a wide range of temperatures are called eurythermal, e.g., most mammals and birds while organisms which can tolerate a narrow range of temperatures are called stenothermal, e.g., polar bear, amphibians.

3. Precipitation
Rainfall and hail storm are two major forms of precipitation. The only available form of water to the plant is the soil water. So, precipitation is indirect form of water which affect the plant life and water content of ‘ the soil. The vegetation of an area is directly or indirectly affected by the precipitation received by that area.

4. Soil
The nature and properties of soil in different places vary significantly. It is dependent mainly on the following factors

1. Climate
2. Weathering process
3. Whether soil is transported or sedimentary
4. Soil development process

Water holding capacity and percolation of the soil is determined by its various characteristics, such as soil composition, soil particle size and aggregation of soil particles.

These characteristics of soil along with its pH, mineral composition, topography, etc., determine the type of plants that can grow in a particular habitat and the type of animals that can feed on them. In aquatic environment also, the bottom sediments and its characteristics determine the type of benthic animals that can live there. Thus, the key abiotic factors affecting the organisms.

Besides these prominent abiotic factors, biotic factors are also forming a habitat and are the part of ecological environment.

Question 5.
What are the various adaptations different plants adapt for their survival in different habitats?
Answer:
Adaptations in Hydrophytes
Adaptations in hydrophytes can be discussed under three headings, i.e. morphological, anatomical and physiological.
1. Morphological Adaptations
Hydrophytes show various kinds of structural adaptations in their roots, stems and leaves.
(i) Root

• Roots may be entirely absent, e.g. Woljfia, Salvinia or poorly developed, e.g. Hydrilla.
• Roots are well-developed with distinct root caps, e.g. Ranunculus (emergent hydrophytes), aerenchymapresent.
• In Eichhornia root caps are replaced by root pockets.
• Some plants, i.e. Jussiaea have two types of roots, one is normal type and other is spongy and negatively geo trophic.

(ii) Stem

• In Hydrilla, Potamogeton, the stems are slender spongy flexible.
• Horizontal stems are found in floating hydrophytes like Azolla, Pistia or Eichhornia.
• In rooted hydrophytes like Sagittaria, Cyperus, Scirpus, the stem is rhizome or stolon.
  
  Stolon stems in marshy plants

(iii) Petioles
Some hydrophytes show special features in the petioles.

• Petioles in submerged plants, with free-floating leaves like Nymphaea and Nelumbium, are long, slender and spongy.
• In the free-floating hydrophyte Eichhornia, stems are long slender and spongy.
• In the free-floating hydrophyte Eichhornia, the petiole is swollen have big air spaces in side tissues and helps in floating.
  
  TS of petiole of Eichhornia

(iv) Leaves
The structural details of hydrophytes show number of variations, which can be summerised as follows

• In Vallisneria the leaves are long and narrow.
• These are finely dissected in Utricularia, Myriophyllum and Ceratophyllum. This helps aquatic plants to provide little resistance against water.
• The free-floating hydrophytes have wax coating on than, these are shiny and smooth. Wax coating present dessication of leaves in water scarce condition.
• In Nelumbium and Nymphaea the leaves remain in touch with water surface and upper layer is exposed to the air.
  

The amphibions hydrophytes exhibit the phenomenon of heterophylly (two types of leaves). The submerged leaves are dissected to go with’water currents while above water are broad, e.g. Sagittaria, Ranunculus, Limnophylla heterophylla.

2. Anatomical Adaptations
Hydrophytes show the following anatomical features
(i) Reduction in Protecting Structures

• Cuticle is absent in submerged portion.
• Epidermis has chloroplast, used as photosynthesising organ.
• Hypodermis is poorly developed.

(ii) Reduction of Mechanical Tissue

• Sclerenchyma is absent or poorly developed in submerged portions.
• Asterosclereids is present that provide mechanical support in case sclerenchyma is absent.
• Sclerenchyma present only in aerial tissues.

(iii) Reduction of Conducting Tissue

• Vascular bundles are reduced to few or even one, e.g Hydrilla.
• Xylem cells are very few.
• Phloem is usually poorly developed, but in some cases it is well-developed.
• Secondary vascular tissue is totally absent.

(iv) Increase in Aeration

• Stomata are totally absent or poorly developed in submerged parts.
• If present, stomata are confined to upper surface leaves.
• In amphibious plants, stomata are scattered on the aerial portions.
• Roots, stems and leaves of most hydrophytes have parenchymatous tissue with air chambers. These chambers store gases like CO₂ and O₂ and help in respiration and photosynthesis. These are hence, called aerenchyma. Besides, the air chambers help in buoyancy and provide mechanical support.
  
  TS of root of Typha

3. Physiological Adaptations
Besides their adaptations in the morphological and anatomical characters, hydrophytes also show physiological adaptations.

• Osmotic concentrations of cell sap is low.
• Photosynthetic and respiratory gases are retained in air chambers for further use.
• No transpiration occurs in submerged plants.
• In hydrophytes, mostly vegetative reproduction.

Xerophytes:
These are the plants which are adapted to drier regions and have high rate of transpiration than absorption of water.

Types of Xerophytes
Xeric habitats are of two types
(i) Physically dry habitats are those in which water cannot be retained (deserts, rock surface).
(ii) Physiologically dry habitats have plants of water, but the water is not available to the plant.

Based on their adaptation to water scarcity or drought conditions, xerophytes are of three types

1. Drought resistant plants are such that they can survive in extreme conditions, drought enduring plants can tolerate drought though they may hot have adaptation.
2. Drought enduring plants these do not have distinct adaptation.
3. Drought escaping plants these are short lived plants, complete the life cycle before the arrival of dry condition, e.g. Artemisia, Astragalus.
   
   Succulents xerophytes

Based on their capacity to store water, xerophytes are classified as succulents and non-succulents. Succulents like Opuntia, have their organs swollen due to accumulation of water, whereas non-succulents are considered as true xerophytes.

Adaptation in Xerophytes:
These show varied adaptions in the morphology, anatomy and physiology which are as follows
1. Morphological Adaptations
Xerophytes exhibit a number of special features in their body organs as given below

(i) Roots

• Roots are very extensive, long tap roots, with branching spread over wide areas.
• Root hairs and root caps are very well-developed.

(ii) Stem

• Stems are stunted, woody, dry, hard and covered with thick waxy cuticle.
• In Opuntia stem becomes green and fleshy (phylloclade).
• On stems and leaves, there are hairs and waxy coatings.
• Succulents have their stem modified into leaf-like structures called cladodes as in Asparagus.

(iii) Leaves
The leaves of xerophytes are reduced to spines to various structures. This helps plants to reduce rate of respiration. The following types of leaf conditions are seen

• Microphyllous when leaves are scaly (Casuarina) and needle-like Pinus.
  
• Trichophyllous when leaves are covered with hairs (.Nerium, Calotropis).
  
• Macrophyllous when leaves are soft and flesh (Begonia).
• Sclerophyllous plants showing leaves which are tough and hard.
• Cadueous when leaves fall early, i.e. plants with no leaves.
• Rolling leaves in ammophilis stomata are directed in words.

Anatomical Adaptations:
These adaptations can be conveniently discussed under the headings, i.e. epidermis, hypodermis and vascular tissue.
(i) Epidermis

• Some xerophytes have multiple epidermis, e.g. Nerium.
• It has thick cuticle and deposition of waxes, resins, etc.
• Epidermal hairs are present in grooves.
• Some leaves have bulliform cells that help in rolling.
• The stomata are present in sunken pits to reduce transpiration rate.
• Stomatal frequency is very low in xerophytes.

(ii) Hypodermis
It is thick and well-developed and is made up of parenchymatous cells.

(iii) Ground Tissue

• In stems, there is abundant mechanical tissue in the form of sclerenchyma, e.g. Casuarina.
• Since, leaves are reduced, the stems usually have chlorenchyma.
• In succulent plants, cortex is filled with water, mucilage, latex, etc.
• In plants that have leaves, palisade parenchyma is well-developed.
• In Pinus, mesophyll cells are modified.
• Intercellular spaces are greatly reduced.

(iv) Conducting Tissue
Vascular tissue (xylem and phloem) .is very well-developed in xerophytes.

3. Physiological Adaptations

• Osmotic concentration of the cell sap is very high.
• Succulents have high pentosan (chemicals derived from polysaccharides) resulting in accumulation of water.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 13 Applications of Biotechnology Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 13 Question Answer Applications of Biotechnology

Applications of Biotechnology Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple Choice Questions

Question 1.
Golden rice is produced by rice plant having a transgene encoding an enzyme in biosynthetic pathway of
(a) P-carotene
(b) luciferin
(c) glyphosate
(d) Bt protein
Answer:
(a) P-carotene

Question 2.
Fruit ripening is delayed by preventing the expression of the enzyme
(a) luciferase
(b) polygalacturonase
(c) nitrogenase
(d) adenosine deaminase
Answer:
(b) polygalacturonase

Question 3.
Humulin is manufactured by
(a) Pfizer
(b) Hoechst
(c) Eli Lilly
(d) Aventis
Answer:
(c) Eli Lilly

Question 4.
Genetic correction of inflicted cells is made in vitro and then reimplanted into its natural environment. This therapy is known as
(a) ex vivo gene therapy
(b) in vivo therapy
(c) in vitro therapy
(d) in toto therapy
Answer:
(a) ex vivo gene therapy

Question 5.
The first genetic disorder treated by gene replacement therapy is
(a) Familial Hypercholesterolemia (FH)
(b) Cystic Fibrosis (CF)
(c) Duchenne Muscular Dystrophy (DMD)
(d) Severe Combined Immunodeficiency (SCID)
Answer:
(d) Severe Combined Immunodeficiency (SCID)

Question 6.
Patent is not granted for
(a) a novel invention
(b) an invention having an industrial application
(c) a discovery made by previously existing knowledge
(d) an invention having an inventive step
Answer:
(c) a discovery made by previously existing knowledge

Question 7.
Which of the following is not related to biosafety?
(a) Convention on Biological Diversity
(b) Cartagena Protocol
(c) World Trade Organisation
(d) UNICEF
Answer:
(d) UNICEF

Question 8.
Which of the following patent cases, India is not directly or indirectly connected with?
(a) Soybean patent case
(b) Neem patent case
(b) Turmeric patent case
(d) Chakraborty patent case
Answer:
(a) Soybean patent case

Question 9.
The supermouse is a genetically modified animal with
(a) insulin transgene
(b) lipid biosynthesis transgene
(c) growth hormone transgene
(d) steroid hormone transgene
Answer:
(c) growth hormone transgene

Question 10.
Which is the nodal centre for Indian biosafety network?
(a) Department of Biotechnology
(b) Department of Science and Technology
(c) Indian Agricultural Research Institute
(d) Department of Forest and Environment
Answer:
(a) Department of Biotechnology

Fill in the blanks

Question 1.
The mass of undifferentiated plant cells in a plant tissue culture media is known as ……………..
Answer:
Callus

Question 2.
Herbicide resistant plants are generated by plant tissue culture technique by transferring …………… gene of a bacterium into a plant protoplast.
Answer:
glyphosate

Question 3.
A bacterium species of ……………. genus is genetically engineered to prevent frost formation in plants.
Answer:.
Pseudomonas

Question 4.
A bioluminescent plant is generated by transferring ………….. gene of a firefly into plant protoplasts.
Answer:
luciferase

Question 5.
Golden rice producing plant is a transgenic plant, whose cells have a transgene encoding …………
Answer:
ß-carotene

Question 6.
Delayed ripening in tomato is due to the inhibition of expression of an enzyme ……………..
Answer:
polygalacturonase

Question 7.
The first recombinant human vaccine produced and marketed is …………. vaccine.
Answer:
hepatitis-B

Question 8.
Recombinant insulin in the trade name of Humulin is manufactured by …………….
Answer:
Eli Lilly Corporation

Question 9.
Monoclonal antibody is synthesised and secreted by a cell known as ……….
Answer:
B-lymphocytes

Question 10.
Severe Combined Immunodeficiency (SCID) is expressed due to the absence of an enzyme, …………… .
Answer:
adenosine deaminase

Question 11.
A forensic analysis of DNA for establishing the identity of a person is known as …………….. .
Answer:
DNA fingerprinting

Question 12.
An immunological technique, applied to detect the presence of very minute quantity of antigen in the serum is known as …………. .
Answer:
ELISA

Question 13.
A biopesticide, known as Bt protein is expressed by a bacterial species, ………… .
Answer:
Bacillus thuringiensis

Question 14.
A legal right, privilege and authority granted to a person for a limited period for an invention is known as …………. .
Answer:
patent

Question 15.
The use of novel biological resource of a sovereign country without its due permission is known as …………….. .
Answer:
biopiracy

Express in one or two word(s)

Question 1.
The tomato plant variety that bears tomatoes exhibiting delayed ripening.
Answer:
Flaw savr

Question 2.
The somatic hybrid cell, which produces monoclonal antibodies.
Answer:
Hybridoma

Question 3.
Genetically engineered rice, rich in vitamin-A.
Answer:
Golden rice

Question 4.
An insecticidal protein, produced by Bacillus thuringiensis.
Answer:
Cry protein

Question 5.
A broad spectrum herbicide that is used world over.
Answer:
Glyphosate

Question 6.
The biotech company, which commercially manufactured the first recombinant human insulin.
Answer:
Genentech

Question 7.
The first genetic disorder that was treated by gene therapy.
Answer:
SCID

Question 8.
The gene transfer into the mammalian fertilised egg with a micropipette.
Answer:
Microinjection

Question 9.
The gene transfer method practiced by passing intermittent pulses of electric current through the medium containing plant protoplasts.
Answer:
Electroporation

Question 10.
The corn was genetically engineered by transferring Bt protein gene into plant protoplasts. The brand was marketed and later was withdrawn due to safety reasons.
Answer:
Star Link corn

Question 11.
The biosafety protocol that was drafted in 1995 and adopted in 2000.
Answer:
Cartagena Protocol

Short Answer Type Questions

Answer each of the following within 50 words

Question 1.
What is golden rice?
Answer:
Golden rice is a transgenic variety of rice with an elevated level of ß-carotene (provitamin-A), a precursor of vitamin-A. The genes encoding the enzymes of the ß-carotene biosynthetic pathway are introduced into rice plant cells in culture. The transgenic rice plants generated produce rice with ß-carotene.

Question 2.
What is Flavr Savr tomato?
Ans.
Fruit ripening in tomato and other fruits and vegetables are delayed by manipulating a gene, involved in softening and ripening. A variety of tomato plant has been successfully engineered, which bears tomatoes, known as Flavr Savr tomatoes. This variety exhibits delayed ripening.

Question 3.
What does the recombinant hepatitis-B vaccine contain?
Answer:
Hepatitis-B vaccine contains surface antigen proteins (HBs Ag) extracted from Hepatitis-B Virus (HBV).

Question 4.
What do you understand by ex vivo gene therapy?
Answer:
Ex vivo gene therapy The affected cells are removed from the body and transformed by the remedial gene in vitro. The transformed cells are grown in a cell culture medium to a sufficient number and then returned to the body by transfusion or transplantation.

Question 5.
What do you mean by a biopesticide? Give an example.
Answer:
Biopesticides are the type of pesticides produced from an organism. They are equally potent but do not inflict a damage on the environment, e.g. a species of bacteria with insecticidal properties is Bacillus thuringiensis. It produces insecticidal cry protein or Bt protein.

Question 6.
What is a supermouse?
Answer:
R L Brinster and R Palmiter (1982) successfully created the first transgenic mouse by transferring the rat growth hormone gene into the fertilised mouse egg by microinjection. This act was carried out in vitro.

Following the transfer, the fertilised egg was implanted into the uterus of a pseudopregnant mouse.
The mouse gave birth to mice that were relatively larger in size, possibly due to an increased synthesis of growth hormone directed by the rat growth homone transgene. This mouse was called supermouse because of its abnormal growth.

Question 7.
Explain biopiracy.
Answer:
Illegal transfer of biological resources has been termed as biopiracy. It describes a practice, in which indigenous knowedge and processes used by indigenous people of a region is used by others for profit without permission from and with little or no compensation or recognition to the indigenous people themselves. This is an illegal practice and enforceable in the court of law.

Question 8.
Ennumerate and explain in brief two biosafety issues, biotechnology is confronted with.
Answer:
Biosafety in a broad sense, refers to the prevention of loss of biological integrity of biological processes and products, harvested by using living organisms. For example, recombinant insulin was manufactured in a complex biological process putting in thought, knowledge, skill and execution method of the inventor. Secondly, a lot of energy and money was spent in the successful execution of the process. Therefore, the right of the inventor needs to be protected by law considering it as a property.

On the other hand, insulin that is manufactured a prescribed trial process to prove that it is suitable for human use. Another potential hazard was the release of Genetically Modified Organisms (GMOs) into the wild. There was a threat that it might sexually reproduce with organisms of its own species and exchange genes, consequently changing the structure of the gene pool.
This might have produced an adverse effect on organic evolution. Thus, normal biological diversity might be destabilised.

Question 9.
Describe the evolution of Indian Patent Act.
Answer:
India enacted the Patent Act in 1970. The Act has undergone amendments in 1999, 2002, 2005 and 2006. The headquarter for the same is in KolKata, West Bengal. The nodal centre for Indian biosafety network is the Department of Biotechnology, Government of India.

Question 10.
Describe the neem patent case.
Answer:
Neem Patent Case:
The multinational agribusiness company, WR Grace of New York and United States Department of Agriculture, Washington DC filed, for a European patent for the fungicidal use of neems oil in the European Patent Office (EPO). It was stated that neem oil controlled fungal growth on plants.

The plea was accepted and a patent was granted. However, following the publication, Dr. Vandana Shiva of Research Foundation for Science and Technology and Natural Resource Policy, New Delhi and others filed a legal opposition to the grant of patent in the EPO.

Write brief notes on the following

Question 1.
Flerbicide resistant plants
Answer:
Herbicide resistant plants Herbicide resistant transgenic plants are generated by transferring bacterial herbicide resistant genes into plant cells grown in culture. Glyphosate is the most widely used broad-spectrum herbicide world over.
A glyphosate resistant gene from Petunia plant is transferred into isolated plant cell§ in culture and glyphosate resistant plants are generated.

Question 2.
Humulin
Answer:
Genentech is the first biotech company to manufacture recombinant human insulin in 1978 using bacteriophage vector and E. coli as the cloning and expression host cell. Later, this technology was licenced to Eli Lilly Corporation of USA.

The recombinant human insulin was termed as Humulin. It was approved as the first recombinant drug by the Food and Drug Administration (FDA), USA for human use. Since then, several companies all over the world have been manufacturing recombinant human insulin on a commercial basis.

Some noteworthy companies are Novo Nordisk of Denmark; Hoechst and Aventis of Germany and Pfizer of USA. Wokhardt Limited, a pharmaceutical company has been manufacturing human insulin in India under the trade name of Wosulin.

Question 3.
Recombinant vaccine
Answer:
Recombinant Vaccines
An antigcnic agent, which after being administered into an animal, generates an active acquired immune response is called as vaccines. The antigenic agent involved in vaccine production varies from vaccine to vaccine.

They generally belong to three classes-attenuated (inactivated) whole organisms isolated antigenic proteins such as coat proteins of viruses and inactivated touns. The latter two fall under the subunit vaccine class, wherein part of the organism possessing antigenic property is used in the vaccine production.

In these vaccines, a DNA insert encoding an antigen (like bacterial surface proteins) is introduced into a less virulanc host. These elicit an immune response expressing the antigens but do cause infection. The expressed antigens are isolated and puri&d and injectedinto the human hosts as a vaccine. It is called recombinant vaccine.

Question 4.
Gene therapy
Answer:
Gene therapy is a therapy or treatment of a gene, which has been mutated. It is a therapy to correct the damage. A genetic disorder is expressed, when a particular gene is mutated.

The mutant gene, as it is known, encodes a different polypeptide other than a normal. This polypeptide is the root cause of the expression of symptoms of a genetic disorder.
Attempts have been made to rectify or replace the mutant gens, so that they express normally. This replacement process is called gene therapy.

Question 5.
Biopesticide
Answer:
Bacillus thuringiensis is known to produce endotoxins or insecticidal crystalline protein or Cry protein or Bt protein.
Bt protein is hydrolysed by an alkali into 250 kD (kilodalton) units, known as protoxins. Each protoxin consists of two 130 kD polypeptides. The 130 kD polypeptide is digested into a 68 kD toxin polypeptide in an alkaline pH. When catepillars eat the leaves of crop plants, on which the bacterial spores are deposited, they ingest the spores.

The spores germinate in the alimentary canal, the bacteria grow in size and produce Bt protein. This protein is digested into 68kD toxin polypeptides in the intestine of the larva. The action of the poypeptide, eventually kills the larva. The alimentary canal of mammals, including human, produces an acid, which degrades the Bt protein. Thus, it is apparently harmless to human and other mammals. Since, this pesticide is produced from an organism, it has been identified as biopesticide.

Question 6.
Transgenic animals
Answer:
Transgenic animals are those which can grow faster, yield more milk, lay bigger eggs and so on. They are produced by combining traditional breeding with gene technology, which yield encouraging results. It involves selecting, isolating, purifying and transferring beneficial genes of one species to another to harvest a beneficial effect. These animals are the transfer of the beneficial gene (genes) developed. The gene that is transferred is known as a transgene. The transgene is transferred by using one of the several methods of gene transfer in practice. Microinjection is found to be most suitable for animal cells.

Question 7.
Patent
Or What is patent?
Answer:
Patent is an open letter granting legal right, privilege and authority by a sovereign state to a person or an institution for a limited period of time. It is given for an invention using scientific and technical knowledge. All sovereign countries have enacted their own Patent Acts to regulate the use of such properties.

An invention involves new knowledge, while a discovery is an application of the knowledge. For example, the double helical model proposed by Watson and Crick was a discovery and hence, does not qualify to be patented, while new forms of DNA, such as recombinant DNAs have been patented.

Question 8.
Biopiracy
Answer:
Biopiracy is theft or robbery or exploitation of biological and genetic resources indigenous to a country. These biological resources are often the main targets of enterprising businessmen because of their many uses in agriculture, healthcare and chemical industries. The process of biopiracy involves collection of samples of biological resources, which then undergo product development for their use on a commercial scale.

Biopiracy begins with biodiversity prospecting, which is exploration of wild plants and animals for commercially viable genetic and biochemical resources. Genetic resources are the genes found in plants and animals that are of actual or potential value to people.

Through the use of new biotechnologies, genes/germplasm from any plant or animal can be transferred to another. Such genetically engineered organisms (plants, animals and microorganisms) are being used for new industrial applications, pharmaceuticals, farming, cattle breeding and poultry farming.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 12 Principles and Processes of Biotechnology Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 12 Question Answer Principles and Processes of Biotechnology

Principles and Processes of Biotechnology Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
The double helical structure of DNA was proposed by
(a) Jacob and Monod
(b) Sanger and Gilbert
(c) Watson and Crick
(d) Beadle and Tatum
Answer:
(c) Watson and Crick

Question 2.
Polymerase chain reaction was discovered by
(a) H G Khorana
(b) K Mullis
(c) R Holley
(d) M Nirenberg
Answer:
(b) K Mullis

Question 3.
Exonuclease is an enzyme that
(a) makes internal cuts in polynucleotide
(b) polymerises nucleotides
(c) joins two polynucleotide fragments
(d) removes nucleotides from the termini one after another
Answer:
(d) removes nucleotides from the termini one after another

Question 4.
DNA ligase is commonly known as
(a) molecular scissors
(b) molecular marker
(c) molecular glue
(d) molecular probe
Answer:
(c) molecular glue

Question 5.
During electrophoresis, DNA fragments move from
(a) anode to cathode
(b) remain static
(c) move randomly
(d) cathode to anode
Answer:
(d) cathode to anode

Question 6.
The blotting of protein molecules to a nylon membrane is known as
(a) Southern blotting
(b) Western blotting
(c) Northern blotting
(d) Eastern blotting
Answer:
(b) Western blotting

Question 7.
Detection of a desired DNA fragment by using radioactive emission is known as
(a) hybridisation
(b) denaturation
(c) autoradiography
(d) electrophoresis
Answer:
(c) autoradiography

Question 8.
Choose the incorrect statement.
(a) A plasmid is small, double-stranded circular DNA
(b) A plasmid contains an origin of replication
(c) A plasmid has several restriction sites
(d) A plasmid has telomeres
Answer:
(d) A plasmid has telomeres

Question 9.
A cosmid is a
(a) plasmid phage hybrid vector
(b) DNA bacteriophage vector
(c) expression vector
(d) viral vector
Answer:
(a) plasmid phage hybrid vector

Question 10.
The example of a plant cell compatible vector is
(a) fertility plasmid
(b) colicinogenic plasmid
(c) tumour inducing plasmid
(d) resistance plasmid
Answer:
(c) tumour inducing plasmid

Question 11.
Amplification of DNA by PCR uses a DNA polymerase called
(a) Taq DNA polymerase
(b) RNA polymerase
(c) DNA polymerase-III
(d) Reverse transcriptase
Answer:
(a) Taq DNA polymerase

Fill in the blanks

Question 1.
The phenomenon of fermentation was demonstrated by ……………
Answer:
Louis Pasteur

Question 2.
The word ‘biotechnology’ was coined by …………..
Answer:
Karl Ereky

Question 3.
Class II restriction endonucleases (enzymes) recognise specific nucleotide sequence in DNA called ……………
Answer:
palindromic sequence

Question 4.
Cohesive ends in the DNA fragments are generated by …………… cutting.
Answer:
staggered

Question 5.
The anionic detergent, used in polyacrylamide gel electrophoresis is known as
Answer:
Sodium Dodecyl Sulphate (SDS)

Question 6.
The transfer of separated protein molecules from the gel into a nylon membrane is known as ………….
Answer:
Western blotting

Question 7.
Detection of desired DNA fragment by the emission of ionising radiation is known as ……….
Answer:
autoradiography

Question 8.
The conjoint structure formed by the joining of the vector DNA and the target DNA fragment is known as …………..
Answer:
recombinant DNA

Question 9.
The uptake of the recombinant DNA by the bacterial host cell is known as ………….
Answer:
transformation

Question 10.
The delivery of a foreign DNA fragment into the fertilised egg with a micropipette is known as …………
Answer:
microinjection

Express in one or two word(s)

1. The technique of separation of DNA fragments based on their molecular weight and electrical charge.
Answer:
Electrophoresis

2. The restriction endonuclease isolated from Escherichia coli.
Answer:
Eco RI

3. The DNA digesting enzyme that removes nucleotides from the termini.
Answer:
Exonucleases

4. The enzyme that catalyses the synthesis of RNA on a DNA template.
Answer:
RNA polymerases

5. The enzyme that catalyses the replication of DNA.
Answer:
DNA polymerases

6. The enzyme that catalyses the synthesis of a complementary DNA strand on an RNA template.
Answer:
Reverse transcriptase

7. The fluorescent dye used in agarose gel electrophoresis.
Answer:
Ethidium bromide

8. Transfer of DNA fragments from the agarose gel to a nylon membrane.
Answer:
Southern blotting

9. Breaking of hydrogen bonds in a duplex so as to make it single-stranded.
Answer:
Denaturation

10. The DNA that helps carry the target DNA fragment to the host cell for cloning.
Answer:
Vector

11. The plasmid phage hybrid cloning vector.
Answer:
Cosmid

12. A plant cell, whose cellulose cell wall is digested.
Answer:
Protoplast

13. The plasmid present in Agrobacterium tumefaciens.
Answer:
Tumour inducing (Ti) plasmid

14. Transfer of a DNA fragment into a host cell in a medium by passing brief pulses of electric current through the medium.
Answer:
Electroporation

15. The instrument used in PCR amplification.
Answer:
Thermocycler

Match the words of group ‘A with those of group ‘B’ to make meaningful pairs

Question 1.

Group-A	Group-B
Restriction endonuclease	End modifying enzyme
DNA ligase	RNA dependent DNA polymerase
Exonuclease	Molecular scissors
Reverse transcriptase	Removes nucleotides from both ends
RNA polymerase	DNA dependent DNA synthesis
DNA polymerase	Molecular glue
Alkaline phosphatase	DNA dependent RNA synthesis

Answer:

Group-A	Group-B
Restriction endonuclease	Molecular scissors
DNA ligase	Molecular glue
Exonuclease	Removes nucleotides from both ends
Reverse transcriptase	RNA dependent DNA polymerase
RNA polymerase	DNA dependent RNA synthesis
DNA polymerase	DNA dependent DNA synthesis
Alkaline phosphatase	End modifying enzymes

Question 2.

Group-A	Group-B
Polyacrylamide	Agrobacterium tumefaciens
Southern blotting	Thermocycler
Plasmid	Protein electrophoresis
Agarose gel	Denaturation
Cos	Taq polymerase
Tumour inducing plasmid	Cloning vehicle
Recombinant DNA	Molecular marker
DNA coated tungsten particles	Nucleic acid electrophoresis
insertional inactivation	Chimeric DNA
Breaking of interchain hydrogen bonds	Particle gun
Equipment for PCR amplification	Screening of clones
Ampicillin resistance gene	Blotting of DNA
Thermophilus aquaticus	Cohesive site

Answer:

Group-A	Group-B
Polyacrylamide	Protein electrophoresis
Southern blotting	Nucleic acid electrophoresis
Plasmid	Cloning vehicle
Agarose gel	Blotting of DNA
Cos	Cohesive site
Tumour inducing plasmid	Agrobacterium tumetaciens
Recombinant DNA	Chimeric DNA
DNA coated tungsten particles	Particle gun
insertional inactivation	Screening of clones
Breaking of interchain hydrogen bonds	Denaturation
Equipment for PCR amplification	Thermocycler
Ampicillin resistance gene	Molecular marker
Thermophilus aquaticus	Taq polymerase

Short Answer Type Questions

Answer each of the following in 50 words

Question 1.
Define biotechnology.
Answer:
‘Biotechnology is an application of knowledge and technique of biochemistry, microbiology, genetics, immunology, tissue and cell culture, molecular biology, chemical engineering and computer science to living systems or parts therefore, for harvesting beneficial products and/or services for mankind.

Question 2.
Define gene cloning.
Answer:
The process of making a number of identical copies of a beneficial gene is known as gene cloning. Microorganisms, especially bacteria are chosen as host cells for this work, which provide a suitable environment for replication (amplification) of genes.

The gene is introduced into a bacterium by a process, known as transformation. For transformation, a gene is delivered into a bacterial host conjointly with a carrier, also DNA, known as a vector.

Question 3.
What is a restriction endonuclease (restriction enzyme)? Why is the word restriction used to designate these?
Answer:
These enzymes recognise specific recognition sequences on DNA and make the cut either within that sequence only or at a variable distance from that sequence. The site where they cleave or cut the DNA is called recognition site.
In rDNA technology, class-II REs are used.

Question 4.
Describe two types of cutting of DNA, executed by restriction endonucleases.
Answer:
Restriction Endonucleases
Each restriction endonuclease functions by ‘inspecting’ the length of a DNA sequence.
Once, it finds its specific recognition sequence, it will bind to the DNA and cut each of the two strands of the double helix at specific points in their sugar phosphate backbones.

Each restriction endonuclease recognises a specific palindromic nucleotide sequences in the DNA. Palindromes are group of letters that form the same words when read both forward and backward, e.g., ‘MALAYALAM’. Therefore, the palindrome in DNA is a base pair sequence that is the same when read forward or background, e.g., the following sequences read the same on the two strands in 5′ → 3′ direction as well as 3′ → 5′ direction.
5′- GAATTC – 3′
3′ – CTTAAG – 5′
Restriction enzymes cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands.

Question 5.
What is electrophoresis? How many types of electrophoresis you have studied?
Answer:
The cutting of DNA by restriction endonucleases results in the generation of DNA fragments which are then separated by a technique known as gel electrophoresis.

The DNA fragments are resolved (separate) according to their size through sieving effect provided by the gel when the potential difference is applied.
Two types of gels used in molecular separation are

• Agarose Used for nucleic acids (RNA and DNA).
• Polyacrylamide Used for proteins.

Question 6.
What is a palindrome? Give an example.
Answer:
Each restriction endonuclease recognises a specific palindromic nucleotide sequences in the DNA. Palindromes are group of letters that form the same words when read both forward and backward, e.gy‘MALAYALAM’. Therefore, the palindrome in DNA is a base pair sequence that is the same when read forward or background, e.g., the following sequences read the same on the two strands in 5′ → 3′ direction as well as 3′ →5′ direction.
5′- GAATTC – 3′
3′ – CTTAAG – 5′

Restriction enzymes cut the strand of DNA a little away from the centre of the palindrome sites, but between the same two bases on the opposite strands.

Question 7.
What is a polymerase? How-many types of polymerases you have studied?
Answer:
Polymerases
These enzymes catalyse the process of copying the nucleic acid molecules. These are of following types
(i) RNA polymerase These are DNA dependent RNA polymerase.
(ii) DNA polymerase They copy DNA strand into another complementary strand through replication. These are also DNA dependent enzymes.
(iii) Reverse transcriptase They catalyse the synthesis of complementary DNA strand on RNA template. These are found in retroviruses and are RNA dependent DNA polymerase.
(iv) RNA polymerase They catalyse the process of strand copying of DNA into RNA through transcription.

Question 8.
Why is DNA ligase called molecular glue?
Answer:
DNA Ligases
These enzymes help to join or seal 3′-OH end of one nucleic acid fragment with the 5′-P end of another nucleic acid fragment by forming a phosphodiester bond. As they are able to stick DNA fragments together, they are known as molecular glue. The widely used ligase enzyme is T₄ DNA ligase. It is purified from E. coli cells that are infected by T₄ bacteriophages.

Question 9.
What is Southern blotting?
Answer:
Southern Blotting:
When the blotting is applied to DNA it is known as Southern blotting (named so after its discover EM Southern in 1975).
Following this, complementary DNA or RNA sequence (probe) labelled with 32 P (radioactive phosphorus) are, hybridised.
The probe binds its complementary target DNA sequence, by forming hydrogen bonds and a duplex is formed. This process is known as molecular hybridisation. The procedure that combines Southern blotting and molecular hybridisation is known as Southern blot hybridisation. After this, the target DNA sequence is identified using autoradiography.

Question 10.
Why is SDS used in polyacrylamide gel electrophoresis?
Answer:
A protein molecule contains many amino acids and all the amino acids do not have similar acid-base properties. Hence, a protein molecule cannot be conferred with uniform negative charges in a buffer solution.
It is therefore, treated with Sodium Dodecyl Sulphate (SDS), an anionic detergent that coats a protein molecule and confers negative charges uniformly.

Question 11.
What is autoradiography?
Answer:
Autoradiography:
The separated fragments in the gel are treated with an alkali to render the double-stranded fragments into single-stranded. This phenomenon is known as denaturation. These single-stranded fragments are then transferred onto a nitrocellulose filter paper or nylon membrane by a process known as blotting.

Question 12.
Enumerate the features of a suitable cloning plasmid.
Answer:
Plasmids:
These are small, autonomously replicating usually circular, extrachromosomal double-stranded DNA molecules that occur in many bacteria and some yeasts, but naturally occurring plasmids are not suitable for gene cloning. Therefore, they are genetically engineered so to make them compatible for cloning. These are then called as cloning vectors and, they possess the following additional properties other than these found in an ideal vector

• They are non-conjugative.
• They have relaxed replication and a high copy number.
• They should be able to clone a gene in the range of 5-10Kb

The most commonly used cloning vector is pBR322 where p = plasmid; BR = Name of its engineers
[B = Boliver and R= Rodriguez]; 322 = Number of relevant workers who worked out this plasmid. pBR322 has the following features

• It is small, ds circular DNA molecule having ori.
• It has two antibiotic marker genes namely, ampicillin resistance gene amp^R and tetracyclin resistance gene (tet^R). In between these two genes, Eco RI restriction site is present.
• amp^R gene contains Pvu I and Pst I restriction sites.
• tet^R gene contains Bam HI and Sal I restriction sites.
• The target DNA and the vector DNA fragments should be compatible for a successful RDT process.

Question 13.
What is a recombinant DNA?
Answer:
The heterogeneous combination of two different DNAs in which the gene of interest is present is known as recombinant DNA or chimeric DNA and the technology is called recombinant DNA technology.

Question 14.
What is microinjection?
Answer:
Microinjection In this method, foreign DNA is directly injected into the nucleus of animal cell-or plant cell by using microneedles or micropip’ettes without any use of a vector DNA. It is used to v deliver a transgene or foreign DNA into the egg. Microinjection is especially used for transferring the foreign DNA in animal cells. The transgene is injected into the male pronuclei because it is larger and traceable with a dissecting microscope.

The male pronucleus is then fused with female pronucleus to produce zygote in vitro. In plant cells, the cellulose cell wall is first removed by enzymatic digestion before micro injection. This process is very tedious and involves a lot of precision.

Question 15.
Describe briefly electroporation.
Answer:
Electroporation It is the formation of temporary pores in the plasma membrane of host cells by using lysozyme or calcium chloride under high voltage of electric current. These pores are used for introduction of foreign DNA.
It can be used to transform plant protoplast, i.e. the plant cell with removed cell wall.

Question 16.
What is Polymerase Chain Reaction (PCR)?
Answer:
Polymerase Chain Reaction (PCR)
It is one of the important technique that serves the purpose of amplification of nucleic acid without using a host cell. PCR was discovered by Kary B Mullis in 1983.

Write brief notes on the following

Question 1.
Restriction endonuclease
Answer:
Restriction endonuclease These are specific enzymes, which recognise specific sequences called recognition sequences on DNA and make double-stranded cuts either within the recognition sequence or at a variable distance from the recognition sequence.

They act as scissors and therefore, often are referred to as molecular scissors. The point of cleavage is known as a restriction site. There will be as many restriction sites as the number of recognition sites. The REs that are used in the recombinant DNA technology fall under class-II. These make double-stranded symmetrical cuts within recognition sequences, generating cohesive or blunt ends.

Question 2.
DNA Ligases
Answer:
DNA Ligases
These enzymes help to join or seal 3-OH end of one nucleic acid fragment with the 5′-P end of another nucleic acid fragment by forming a phosphodiester bond. As they are able to stick DNA fragments together, they are known as molecular glue. The widely used ligase enzyme is T4 DNA ligase. It is purified from E. coli cells that are infected by T4 bacteriophages.

Question 3.
DNA polymerase
Answer:
DNA polymerase enzyme polymerises the DNA synthesis on DNA template or complementary DNA (cDNA). It was discovered by A. Kornberg and co-workers in E. coli in 1956 in the presence of a preformed DNA template, it produces a parallel strand in the presence of ATP.

Question 4.
Southern blotting
Answer:
When the blotting is applied to DNA it is known as Southern blotting (named so after its discover EM Southern in 1975).
Following this, complementary DNA or RNA sequence (probe) labelled with 32 P (radioactive phosphorus) are, hybridised.
The probe binds its complementary target DNA sequence, by forming hydrogen bonds and a duplex is formed. This process is known as molecular hybridisation. The procedure that combines Southern blotting and molecular hybridisation is known as Southern blot hybridisation. After this, the target DNA sequence is identified using autoradiography.

Question 5.
Agarose gel electrophoresis
Answer:
Agarose Gel Electrophoresis:
The molecules of nucleic acids are given uniform negative charge in alkaline buffer solution. These molecules then migrate towards the anode. The smaller molecules migrate faster than larger molecules because the rate of migration is inversely proportional to the molecular weight of separating molecules and directly proportional to the strength of electric field.

Question 6.
Cloning plasmid
Answer:
Plasmids were discovered by William Hayes and Joshua Lederberg (1952). These are extrachromosomal, self-replicating, usually circular, double-stranded DNA molecules, found naturally in many bacteria and also in some yeast. Although plasmids are usually not essential for normal cell growth and division, they often confer some traits on the host organism. For example, resistance to certain antibiotics or toxins that can be a selective advantage under certain conditions.

The plasmid molecules may be present as 1 or 2 copies or in multiple copies (500-700) inside the host organism. These naturally occurring plasmids have been modified to serve as vectors in the laboratory. The most widely used, versatile, easily manipulated vector pBR 322 is an ideal plasmid vector.

Question 7.
Cosmid
Answer:
Cosmid (cos + plasmid) vectors The term cosmid is a combination of two words. COS + MID. COS is taken from COS site of Lambda phage and MID is taken from plasmid DNA. Cosmid was developed for the first time by Collins and Honn (1978). The simplest cosmid vector contains a plasmid’s origin of replication, a selectable marker, suitable restriction enzyme sites and the lambda ‘cos’ site. Cosmids can be used to clone DNA fragments of upto 45 kb length.

Question 8.
Recombinant DNA
Answer:
Recombinant DNA is the DNA that has formed artificially by genetic engineering. It contain the gene of interest and it becomes the part of host’s genetic makeup where it further replication. The process of constructing recombinant DNA is called Recombinant DNA Technology (RDT).

Question 9.
Polymerase chain reaction
Answer:
A gene can also be cloned or amplified without the assistance of a host cell by a specific reaction, known as Polymerase Chain Reaction (PCR). PCR was discovered by Kary B. Mullis in 1983. The reaction is carried out in a thermocycler having a thermal cycling (heating and cooling) programme.

The target gene is put along with other substrates in the thermocycler. The DNA fragment, doubles at the end of the first cycle and quadruples after the second cycle and so on. In this amplification process, no host cell is used as the supporting system. It is carried out in three steps-denaturation, primer annealing and extension.

Question 10.
Micro injection
Answer:
Microinjection In this method, foreign DNA is directly injected into the nucleus of animal cell-or plant cell by using microneedles or micropip’ettes without any use of a vector DNA. It is used to v deliver a transgene or foreign DNA into the egg. Microinjection is especially used for transferring the foreign DNA in animal cells. The transgene is injected into the male pronuclei because it is larger and traceable with a dissecting microscope.

The male pronucleus is then fused with female pronucleus to produce zygote in vitro. In plant cells, the cellulose cell wall is first removed by enzymatic digestion before micro injection. This process is very tedious and involves a lot of precision.

Long Answer Type Questions

Question 1.
Describe briefly about the making of a recombinant DNA.
Or Describe briefly recombinant DNA technology.
Answer:
Recombinant DNA Technology
Genetic engineering is alternately called as recombinant DNA technology or gene cloning. Paul Berg (1972) was ‘ awarded Nobel Prize in 1980 and is considered as father of genetic engineering. The first recombinant DNA (rDNA) was constructed by Stanley Cohen and Herbert Boyer in 1972. Recombinant DNA technology involves the following steps

1. Isolation of the genetic material (DNA) is carried out as follows
(a) DNA is enclosed within the membranes. To release DNA along with other macromolecules -such as RNA, proteins, polysaccharides and lipids, bacterial cells/plant or animal tissue are treated with enzymes such as lysozyme (bacteria), cellulase (plant cells), chitinase(fungus).
(b) Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out as fine threads in the suspension after the addition of chilled ethanol.

2. Cutting of DNA at specific locations is done by using restriction enzymes. The purified DNA is incubated with the specific restriction enzyme at conditions optimum for the enzyme to act.

3. Isolation of desired DNA fragment is carried out using agarose gel electrophoresis.

4. Amplification of gene of interest using Polymerase Chain Reaction (PCR) is a reaction in which multiple copies of specific DNA (gene of interest) sequence are made (amplification) in-vitro.

5. Ligation of DNA fragment into a vector requires a vector DNA and source DNA.
(a) These are cut with endonuclease to obtain sticky ends.
(b) Both are then ligated by mixing vector DNA, gene of interest and enzyme DNA ligase to form recombinant DNA.

6. Insertion of recombinant DNA into the host cell/organism occurs by several methods, before which the recipient cells are made competent to receive the DNA.
(a) If recombinant DNA carrying antibiotic resistance gene (e.g. ampicillin), is transferred into E. coli cells, the host cell is transformed into ampicillin resistant cell.
(b) The ampicillin resistant gene can be called a selectable marker.
(c) When transformed cells are grown on agar plates containing ampicillin, only transformants will grow and others will die.

7. Culturing the host cells The cell containing the foreign gene is cultured on an appropriate medium at optimal conditions. The DNA gets multiplied.

8. Extraction of desired gene product is carried out in the following steps
(a) A protein encoding gene expressed in a heterologous host is called recombinant protein.
(b) Cells having genes of interest can be grown on a small or on a large scale.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 11 Microbes in Human Welfare Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 11 Question Answer Microbes in Human Welfare

Microbes in Human Welfare Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Multiple choice questions

Question 1.
In curd making, …………. is useful in coagulation of milk protein. (Lactobacillus, Saccharomyces, Penicillium, Aspergillus)
Answer:
Lactobacillus

Question 2.
Antibiotic streptomycin is obtained from ……….. (Streptomyces griseus, S. aureofaciens, S. nouresi, Saccharomyces cerevisiae)
Answer:
Streoptomyces griseus

Question 3.
Citric acid is produced when fermentation is caused by …………. (Lactobacillus, Aspergillus sp., Penicillium sp., Acetobacter sp.)
Answer:
Aspergillus sp.

Question 4.
Lipase enzyme is produced by the activity of …………. (Trichoderma viride, Rhizopus sp., Aspergillus sp., Saccharomyces cerevisiae)
Answer:
Rhizopus sp.

Question 5.
In pest control of crop plants ……………. has pesticidal properties, (baculovirus, papilloma virus, pox virus, Rhizobium)
Answer:
baculovirus

Express in one word only

Question 1.
What is called the process of heating and cooling of milk for inactivation of bacteria?
Answer:
Pasteurisation

Question 2.
What is called the secretions of microorganisms which are toxic to pathogenic bacteria?
Answer:
Antibiotics

Question 3.
What is the commercial name of acetic acid?
Answer:
Vinegar

Question 4.
What is called the accumulated microorganisms and organic matter in the treatment of sewage?
Answer:
Sludge

Question 5.
What is the major component of biogas?
Answer:
Methane

Question 6.
What can be called the natural pest killing agent other than artificial chemical?
Answer:
Biopesticides

Question 7.
What is called the association between Rhizobium in the root system of legumes?
Answer:
Symbiotic association

Correct the sentences, if required, by changing the underlined word(s)

Question 1.
Antibiotic tetracyclin is obtained from Penicillium notatum.
Answer:
penicillin

Question 2.
In biogas, methane is produced due to the activities of nitrogen-fixing bacteria.
Answer:
methanogenic

Question 3.
The first antibiotic extracted from bacterial culture is nystatin.
Answer:
streptomycin

Question 4.
Industrial production of organic acids through microbial cultures is due to the oxidation process by bacteria.
Answer:
fermentation

Question 5.
Acetic acid is produced by Lactobacillus sp.
Answer:
Lactic acid

Fill in the blanks

1. In biogas production ………… bacteria are used.
Answer:
methanogenic

2. BGA used in biological nitrogen-fixation are called ………….. bacteria.
Answer:
cyano

3. Ethanol obtained by ………….. fermentation is used in industry.
Answer:
microbial

4. Acetobacter converts ……………. to vinegar by aerobic fermentation of legumes.
Ans.
ethyl alcohol

Short Answer Type Questions

Write notes on the following with atleast 3 valid points

Question 1.
Biogas
Answer:
It is a complex mixture of gasese like CH₄,CO₂, H₂, etc., that is produced by anaerobic digestion of biomass. It is used as fuel.

Question 2.
Biopesticides
Answer:
These are biodegradable, highly pest specific biological agents that are used to control pest population without harming the environment.

Question 3.
Biofertilisers
Answer:
These are the preparations containing microorganisms that help the plants to uptake various nutrients in utilisable form, e.g. Rhizobium, BGA, etc.

Question 4.
Microbes in industry.
Answer:
Industrial use of microbes includes the production of beverages, antibiotics, etc., that are useful for the human. The large scale production of these products is carried out in bioreactors using the appropriate microbes, e.g. butyric acid is derived from Clostridium and terramycin is derived from Streptomyces rimosus.

Question 5.
Microbes in antibiotics production.
Answer:
The term ‘antibiotics’ was coined by Waksman (1942), and it is derived from the Greek words Anti-against and bios-Yiit, together they mean ‘against life’ (with reference to disease causing organisms). Antibiotics are the chemical substances, produced by some microbes that can kill or retard the growth of other disease causing microbes.

The first antibiotic was obtained from the species of Penicillium notatum in 1928 by Sir Alexander Fleming and it was named Penicillin.

Question 6.
Microbes in sewage treatment.
Answer:
Sewage refers to the municipal waste water generated everyday in cities and towns. Human excreta is the major component of it. It contains large amounts of organic matter and microbes, out of which many are pathogenic. So, it cannot be discharged directly into natural water bodies like rivers, streams, etc.

Differentiate between two words in the following pairs of words

Question 1.
Chemical fertilisers and Biofertilisers.
Answer:
Differences between chemical fertilisers and biofertilisers are as follows

Chemical fertilisers	Biofertilisers
These are industry made products which are used to increase the output of a crop plant.	These are the microorganisms which increase the nutrient level of soil.
These are harmful and cause pollution to water bodies as well as ground water.	These are not harmful as they lead to nutrient enrichment in an organic way.

Question 2.
Synthetic pesticides and Biopesticides.
Answer:
Differences between synthetic pesticides and biopesticides are as follows

Synthetic pesticides	Biopesticides
These are not very specific, so harm non-targeted species.	These are highly specific, so do not harm non-targeted species.
They cause pollution.	They do not cause pollution.
Insects may become resistant, e.g. Heliothis, has become resistant to most insecticides.	Insects are not expected to develop resistance to biopesticides.
Harmful residues may often remain in food, fodder and fibres.	No harmful residues remain in food, fodder and fibres.

Question 3.
Baker’s and Brewer’s yeast.
Answer:
Differences between baker’s and brewer’s yeast are as follows

Baker’s yeast	Brewer’s yeast
Baker’s yeast is Saccharomyces cerevisiae. It is used in fermentation to prepare dough that is used to make bread, idli, dosa, etc.	Brewer’s yeast is also Saccharomyces cerevisiae, but a different strain. It is used to produce various alcoholic drinks by fermenting malted cereals and fruit juices.
In this, CO2 released during the process of fermentation gives the fluffy appearance.	In this, CO2 released does not cause any fluffy appearance.

Question 4.
Symbiotic nitrogen-fixation and Mycorrhizal nitrogen-fixation.
Answer:
Differences between symbiotic nitrogen-fixation and mycorrhizal nitrogen-fixation are as follows

Symbiotic nitrogen-fixation	Mycorrhizal nitrogen-fixation
It is a mutually beneficial association of bacteria with the plants for food and shelter.	It is a mutually beneficial association of fungus with the root of higher plants.
The most common is Rhizobium which resides in root nodules of leguminous plants and fixes nitrogen.	Members of genus Glomus form mycorrhizal association.

Long Answer Type Questions

Question 1.
Give a detailed account of industrial application of microbes.
Answer:
Industrial Products:
A variety of microbes are used to synthesise a number of products in large scale that are valuable to human beings, e.g., beverages, antibiotics, etc.
A microbe should have following characteristics for its application in industrial fermentation.

• It should be non-pathogenic and its raw materials should be cheap and easily available.
• It should have the ability to grow rapidly on suitable nutrients.
• It should have the ability to high yield of desired products consistently in a reasonable time.
• It should possess high levels of enzymes for rapid production of the end products.

Now-a-days a number of products are obtained on commercial level with the help of microbes. To accomplish this, microbes are grown in very large vessels called fermentors or bioreactors.
Some of the industrial products obtained using microbes are as follows

Antibiotics:
The term ‘antibiotics’ was coined by Waksman (1942), and it is derived from the Greek words Anti-against and bios-Yiit, together they mean ‘against life’ (with reference to disease causing organisms). Antibiotics are the chemical substances, produced by some microbes that can kill or retard the growth of other disease causing microbes.

The first antibiotic was obtained from the species of Penicillium notatum in 1928 by Sir Alexander Fleming and it was named Penicillin.

It was obtained at commercial scale by growing the microbe in fermentor. The medium used for growing microbe, contained a carbohydrate as energy source, mineral salts and corn steep liquor. The culture was kept under vigorous aeration to obtain the maximal production of ‘penicillin’. It was called the wonder drug as it was used during second World War to give relief to the wounded soldiers from pain and suffering.
Antibiotics and Their Sources

Antibiotic	Sources	Action
Penicillin	Penicillium chrysogenum, P. notatum.	Tonsilitis, sore throat, gonorrhoea.
Streptomycin	Streptomyces griseus	Pneumonia, tuberculosis and local infections.
Erythromycin	Streptomyces erythreus	Typhoid, diphtheria, whooping cough.
Terramycin	Streptomyces rimosus	Intestinal and urinary infections.
Tetracyclines	Streptomyces aureofaciens	Eye infections.
Chloramphenicol	S. venezuelae	Conjunctivitis.
Nystastin	S. nouresi	Candida infection.
Polymixin	Bacillus polymyxa	Antifungal.

The second antibiotic, streptomycin was obtained from the bacterium Streptomyces griseus. The bacteria were grown on culture medium containing glucose, soyameal and mineral salts at pH 7.4 -7-5.

The fermentation was carried out under submerged condition at 25-30°C for 5-7 days. Now-a-days industrial fermentation is used to produce several antibiotics against diseases which have earlier caused widespred destruction in the form of epidemics.

Alcoholic Beverages:
Earlier, people used to produce alcohol by fermentation. Later, another method was used for the same which included catalytic hydration of ethylene. In modern time, again fermentation process is used for the production of ethanol.

It is used for dual purpose, i.e. as chemical and as fuel. Sugar-beet, potatoes, corn, cassava and sugarcane, etc., are used as substrate for the production of ethanol.

Yeasts (like Saccharomyces cerevisiae, S. uvarum, S. carlsbergensis), Candida brassicae, C. utilis and bacteria (Zymomonas mobilis) are used for the production of ethanol at industrial scale. The type of alcoholic drink depends upon the raw material used for its production.

Beer is obtained by the fermentation of barley grains while wine is produced by grapes. This process of alcohol production is known as brewing. In this process, CO₂ is produced as a byproduct which is further used in bakery to provide sponginess to breads, cakes, etc.

Production of Organic Acids:
These are produced by the metabolic actions of microbes, i.e. microbial fermentation. Important organic acids producing organisms are listed below

Organic Acid	Microbes involved
Citric acid	Aspergillus niger and Penicillium sp. (fungi)
Acetic acid	Acetobacter aceti (bacteria)
Butyric acid	Clostridium butylicum (bacteria)
Lactic acid	Lactobacillus (bacteria)
Gluconic acid	Aspergillus niger and P. chrysogenum
Fumaric acid	Penicillium sp.

The methods of production of some organic acids are as follows

1. Acetic acid The production of acetic acid or vinegar occurs in two steps-preliminary fermentation and secondary fermentation. Former involves production of ethyl alcohol while later involves the production of acetic acid under aerobic conditions.
2. Lactic acid It is produced with the help of Lactobacillus. The starchy substances, e.g. corn starch, potato starch, molasses and whey, etc., are initially hydrolysed to obtain simple sugars. It is followed by fermentation under suitable environmental conditions.
3. Citric acid It is produced by the fermentation of beet molasses, sucrose, commercial glucose, starch hydrates, etc. Many fungi, bacteria and yeasts are used for the same.

Use of Organic Adds:
Organic acids are used as preservatives, flavour enhancers and flavouring agent. They are also used to prevent oxidation and turbidity of food products.

Production of Enzymes:
When microbes are grown in culture medium, they release various substances in the medium including enzymes. These substances can be extracted from the medium and can be used for various purposes like enzymes are used in pharmaceutical, food and textile industries. The quality and quantity of enzymes depend upon the microbial strain and cultural conditions.

Some enzymes and their applications have been discussed below

1. Lipase produced by Rhizopus sp., used in detergent formulations and helps in removing oily stains from the laundry due to its digestive application.
2. Pectinase produced by Aspergillus sp., used for clarifying bottled fruit juices.
3. Proteases They are produced by Aspergillus niger and Bacillus subtilis. They are used as clarifying agents for beer, meat tenderizer, etc.
4. Amylase produced by Aspergillus sp., used for digestive purpose and in the preparation of glucose syrup.
5. Cellulase produced by Trichoderma viridie, used for the degradation of cellulose.

Streptokinase produced by Streptococcus and modified by genetic engineering is used as a clot buster for removing clots from blood vessels of patients, who have undergone myocardial infarction leading to heart attack.

Production of Bioactive Molecules:
The bioactive molecules produced by microbes are

1. Cyclosporin-A It is produced by Trichoderma polysporum (fungus). It is used as an immunosuppressive agent for the patients, who have undergone organ transplantation.
2. Statins They are produced by Monascus purpureus (yeast) and are used as blood cholesterol lowering agents.

Question 2.
Explain how microbes are useful in pollution control and also in production of alternative source of energy.
Answer:
Microbes are major component of biological world on this earth. Although they are the causal agents of most of the infectious diseases, still they are of great importance to humans. Now, scientist are working on the ways in which with the use of microorganisms pollution problem can be solved. This can be done by bioremediation. In this technique microorganisms are used to neutralise pollutants from a contaminated site by their oxidation. Pollution can be controlled by microbes in two ways

1. By enhancing the growth and activity of microbes already present an pollutant site.
2. By adding some new microbes to the pollution site. Pollution control by the application of microbes works best when pollutants are a known mixture of organic compounds that are related to each other in structure and when there is no competition from indigenous microorganisms.

Production of Alternative Source of Energy :

Microbes in Biogas Production:
The excreta of cattle, commonly called gobar, is rich in methanogenic bacteria. Thus, cattle dung can be used for the generation of biogas, commonly called gobar gas. As cattle dung is available in large quantities in rural areas this method of biogas production is mostly functional in those areas.

Economically viable biogas is produced in large vessels called bioreactors.
Biogas plant consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and slurry of dung is fed. A floating cover is’placed over the slurry, which keeps on rising, as the gas is produced in the tank due to the microbial activity.

Methanobacterium present in the dung acts on the bio-waste to produce biogas. An outlet is also present which connects to a pipe that supplies biogas to the nearby houses.
Img 1

There is another outlet from which spent slurry is removed that can be used as fertiliser. Biogas production technology was developed in India mainly by Khadi and Village Industries Commission (KVIC) and Indian Agricultural Research Institute (LARI).

The production of biogas occurs in following three steps

Solubilisation: Decomposition of lipids, proteins, cellulose, hemicellulose, etc., present in organic matter to monomers by the action of hydrolytic enzymes like lipases, cellulases, proteases, peptidases, etc., secreted by microorganisms.

Acidogenesis: Conversion of monomers to organic acids with the help of fermentative microbes, e.g. Propionibacterium, Acetovibrio. The most common organic acid produced is acetic acid.

Methanogenesis: Biogas production with the action of methanogens, e.g. Methanococcus Methanobacillus.

Odisha State Board CHSE Odisha Class 12 Biology Solutions Chapter 10 Improvement in Food Production Textbook Questions and Answers.

CHSE Odisha 12th Class Biology Chapter 10 Question Answer Improvement in Food Production

Improvement in Food Production Class 12 Questions and Answers CHSE Odisha

Very Short Answer Type Questions

Fill in the blanks with correct answers from the choices given in the brackets of each bit

1. Physical removal of anthers is done by …………… process.
(introduction, mutation, hybridisation, emasculation)
Answer:
emasculation

2. The cross between two varieties of same crop is called ………… hybridisation. (intervarietal, intravarietal, intrageneric, intergeneric)
Answer:
intervarietal

3. In the process of breeding, genetic makeup of ……….. the concerned organism may be changed, (mutation, interspecific, selection, intraspecific)
Answer:
mutation

4. The plant part used in tissue culture is called …………… .(cells, zygote, explant, gamete)
Answer:
explant

5. To produce haploid plants ………… culture can be made.
(anther, embryo, endosperm, zygote)
Answer:
anther

6. The autotroph ………… is cultured to obtain single cell protein.
(Saccharomyces, Pseudomonas, Spirulina, Chaetomicem)
Answer:
Spirulina

Multiple choice questions

Question 1.
The cross breed milch breed is
(a) Red Sindhi
(b) Tharparkar
(c) Frieswal
(d) Sahiwal
Answer:
(c) Frieswal

Question 2.
The exotic breed of cattle is
Or Which is an exotic breed of cattle?
(a) Jersey
(b) Sahiwal
(c) Gir
(d) Red Sindhi
Answer:
(a) Jersey

Question 3.
An indigenous breed of cattle is
(a) Red Dane
(b) Jersey
(c) Karan Swiss
(d) Rathi
Answer:
(d) Rathi

Question 4.
Sunandini, a cross breed cattle is produced by crossing.
(a) Brown-Swiss bull with Sahiwal cow
(b) Jersey bull with Red Sindhi cow
(c) Red Dane bull with Sahiwal cow
(d) Holstein-Friesian bull with Rathi cow
Answer:
(a) Brown-Swiss bull with Sahiwal cow

Question 5.
An indigenous milch breed of buffalo is
(a) Haryana
(b) Jaffarabadi
(c) Kankrej
(d) Jamunapuri
Answer:
(b) Jaffarabadi

Question 6.
The indigenous breed of poultry is
(a) Nicobari
(b) Rhode Island Red
(b) Barred Plymouth Rock
(d) New Hampshire .
Answer:
(a) Nicobari

Question 7.
Commercial poultry production is done under
(a) free range system
(b) intensive system
(c) semi-intensive system
(d) folding unit system,
Answer:
(b) intensive system

Question 8.
Which of the following is a disease of cattle
(a) Ranikhet disease
(b) Marek’s disease
(c) bacillary white diarrhoea
(d) All of the above
Answer:
(d) All of the above

Express in one or two word(s)

1. What is the nutrient source not required for obtaining single cell protein from autotrophs ?
Answer:
Carbon source

2. What is called to the amorphous mass of loosely arranged thin-walled parenchymatous cells developed in the process of tissue culture?
Answer:
Callus

3. What is called to the remaining part of plant cells when its wall is mechanically or enzymatically removed?
Answer:
Protoplast

4. What is called to the sum total of all the alleles of gene present in a particular species and its allied wild and cultivated varieties?
Answer:
Gene pool

5. What is the process called, where flower buds are artificially enclosed to avoid undesired pollination?
Answer:
Bagging

6. In which process can genetic makeup of concerned organism changed ?
Answer:
Mutation

7. The preservation of semen at ultra low temperature.
Answer:
Cryopreservation

8. The substance the queen bee is fed with.
Answer:
Royal jelly

9. Development of haploid eggs without fertilisation.
Answer:
Parthenogenesis

10. The important monosaccharide present in honey.
Answer:
Levulose

11. The repeated breeding between closely related individuals.
Answer:
Upgrading

12. Breeding between unrelated individuals.
Answer:
Cross-breeding

Correct the sentences, if required by changing the underlined word only

1. The process of aseptic transfer of explant from nutrient medium to culture vessels is called micropropagation.
Answer:
inoculation

2. When cytoplasms are fused and one of the two nuclei lost in formation of new organism, it is called a hybrid.
Answer:
cybrid

3. For nuclear fusion, PEG is used.
Answer:
protoplast fusion

4. Cross between different genotypes of same variety is called intrageneric hybridisation.
Answer:
intravarietal

5. When pollens from selected male parents are transferred to stigma, it is called natural pollination.
Answer:
cross

Fill in the blanks

1. The cross between two species of a genus is called …………. hybridisation.
Answer:
intrageneric

2. In selection and testing of superior recombinants, F₁-generation offsprings are …………… pollinated.
Answer:
self

3. Biofortification is done to enrich crops with micronutrients like minerals and ………. .
Answer:
vitamins

4. Explants sterilised by mercuric chloride or hydrogen peroxide, etc. are known as ………….. sterilisation.
Answer:
surface

5. Through the process of tissue culture, large number of plants raised in a small area and called micropropagation or ……. propagation.
Answer:
clonal

6. Triploids can be raised by ……….. culture.
Answer:
endosperm

7. Milk yielding cattle breeds are known as ………… breeds.
Answer:
milch

8. Foot and mouth disease is a common disease of ………
Answer:
cattle

9. Traditional method of breeding is substituted by artificial ………. .
Answer:
insemination

10. The housing system employed in the commercial poultry farming is known as ……….. farming.
Answer:
intensive system

11. Ranikhet disease is a common disease of …………..
Answer:
poultry

12. Culture of honeybee on a commercial basis is known as ……………
Answer:
apiculture

13. The drones develop from haploid eggs, which are not fertilised. This development is termed as …………….
Answer:
parthenogenesis

14. The deserting of the queen bee is known as ……………… .
Answer:
swarming

15. The characteristic flight of the queen bee during fertilisation is known as …………..
Answer:
nuptial flight

16. The juvenile bees are reared in …………. chamber of the honey comb.
Answer:
brood

17. The worker bees develop from fertilised eggs and hence are diploid ………….. .
Answer:
sterile females

Short Answer Type Questions

Answer the following within 50 words each

Question 1.
Name five indigenous breeds of cattle.
Answer:
Indigenous Milch Breeds of Cattle
The indigenous breeds of cattle are classified into

• Milch breeds These are high milk producers.
• Dual purpose breeds In these breeds, cow yield average quantity of milk, while males are good working bullocks.
• Draught breeds These include poor milkers but superior quality bullocks.

These breeds are the highest milk producing catde. These include Sahiwal, Red Sindhi, Gir, Tharparkar and Rathi.

Question 2.
Name three cross-breeds of cattle.
Answer:
Cross-Breed Strains of Cattle:
Some of the cross-breed cows are as follows
(a) Karan Swiss This breed was developed at National Dairy Research Institute ‘Karnal, by the breeding of Sahiwal cows with Brown Swiss bulls imported from USA.
(b) Karan Fries This breed has got its origin at the National Dairy Research Institute, Karnal by the crossing between Tharparkar and Holstein-Friesian.

(c) Sunandini This breed originated in Kerala by crossing the local non-descript cattle with Jersey, Brown Swiss and Holstein-Friesin breeds.
(d) Frieswal This breed is developed by crossing Holstein-Friesian bulls with Sahiwal cows.

Question 3.
Name three exotic breeds of cattle.
Answer:
Exotic Milch Breeds of Cattle
This breed includes high milk producing cattle breeds of other countries which have been cross breed with indigenous breeds for producing high yielding hybrids which can easily adopt to Indian conditions.
The common exotic breeds which are used in such programme include Holstein-Friesian of Netherlands, Brown-Swiss of Switzerland, Jersey of Europe and America and Red Dane of Denmark.
Img 2

Question 4.
What is cryopreservation?
Answer:
Cryopreservation is the preservation of tissues, embryos gametes, etc., at -196°C (liquid nitrogen), the preserved material is revived through special technique when required. Cryopreservation methods seek to reach low temperatures without causing additional damage caused by the formation of ice during freezing. Traditional cryopreservation has relied on coating the material with cryoprotectants.

Question 5.
Describe organic dairy farming
Answer:
Organic Dairy Farming
Though the milk production has increased by leaps and bounds by the use of synthetic chemicals on cattle and buffaloes, there is a chance of contamination of the harvested milk. It has been found that milk and milk products are contaminated by residue components of harmful chemicals.

Question 6.
What is free-range poultry farming?
Answer:
The term ‘poultry’ means rearing of domesticated fowl (birds) for food (meat) or their eggs, i.e. chicken, ducks, , geese, turkeys and some varieties of pigeons. Poultry farming upto 1960 was considered under free-range condition.

Free-range system In this system, the birds are allowed to move freely to outside. The farmer provides them with food supplements as requird moving outside.

Question 7.
What is intensive housing system in poultry?
Answer:
Intensive system
This system is practiced where there is a need of a large scale production of meat and eggs. The birds do not have access to outside and are kept in a walled house. There are two types of housing system. Cage system is the system, where birds are kept in cages and it also helps in preventing the spread of diseases. In litter system however, birds are kept on a floor covered with rice husk, saw dust, dried leaf, etc.

Question 8.
Describe the protein source in poultry nutrition.
Answer:
These are required for growth and repair of the body tissues. For protein, the feed is supplemented with soyabean meal, groundnut cake, sunflower cake.
The fish meal prepared from the wastes of fish processing industry and meat meal from the wastes of meat processing industry are also used to feed poultry birds. The skimmed milk is highly nutritive for young chicks and should be given in clean vessels. The green foods such as fresh tender grass, garlic lettuce, onions, etc. are important part of the feed.

Fats Only unsaturated fats could be digested by poultry. This requirement is met by providing groundnut, cake, sunflower cake, etc.

Minerals Some minerals are required in large quantity such as calcium, sodium, etc. Minerals such as zinc, iron, copper, are required in lesser quantities and so, are called as trace minerals.

Vitamins fat soluble (A, D, E, K) and water soluble (B,C) all are essential for normal growth of chickens.

Question 9.
Why is inbreeding harmful?
Answer:
Breeding between the animals of the same breed for 4-6 generation is called inbreeding. It increases homozygosity. Thus, inbreeding is necessary to develop pureline. It also helps in accumulation of superior genes and elimination of less desirable genes. But continued inbreeding reduces fertility and even productivity so, it is harmful also.

Question 10.
What is artificial insemination?
Answer:
Artificial Insemination
It is a method in which the semen collected from a superior male parent is injected into the reproductive tract of the selected female parent by the breeder. This results in development of progeny with superior traits like better growth and increased milk production.
The success rate of artificial insemination is fairly low, even then it is carried out because of the following advantages

• The semen collected can be used immediately or stored in frozen form for later use.
• The semen from a desired breed can be easily transported in the frozen form to distant places, where the selected females are present and thus can be used for impregnating the females on a large scale.
• It helps to overcome several problems of normal mating.

Question 11.
What is in vitro fertilisation?
Answer:
In Vitro Fertilisation and Embryo Transfer
In this modern method of animal breeding, eggs of an ovulating livestock animal, e.g. cattle are isolated. Then they are fertilised in- vitro by semen of a bull which possesses desired characters.

This fertilised egg is kept in a suitable medium and is then stimulated to undergo cleavage to a 8-16 called stage embryo which is known as a blastocyst, also in-vitro. This embryo is then finally transferred or implanted into uterus of a surrogate cow and made pseudopregnant.
The cow completes the term and then give birth to calf with the required characters.

Question 12.
What is a transgenic animal?
Answer:
Transgenic Animals:
It involves the transfer of genes intti special cells or embryos. In this method, the unfertilised egg is enucleated by treating with cytochalasin-B and the blastula stage nuclei are obtained from embryo donor. These two are incubated together in’the presence of Polyethylene Glycol (PEG) and transferred into surrogate mother for fusion. The foetus develops into a transgenic animal. Various products like a-antitrypsin, haemoglobin, lacteferrin, iron binding protein, etc., are obtained from transgenic animals. In Japan, gynogenesis is being used to improve fish size.

Question 13.
Describe swarming.
Answer:
Swarming It is the process by which a new honeybee colony is formed when the queen bee leaves the colony with a large group of worker bees.
Swarming is mainly a spring phenomenon, usually within a two or three weeks period depending on the locality but occasional swarms can happen throughout the producing season.

Write notes on with 2/3 valid points

Question 1.
Germplasm collection
Answer:
Collection of Germplasm:
This is the major step acting as the root of any breeding programme. In this step, the pre-existing genetic variability available in purelines, wild varieties, species no longer cultivated and relatives of many crop species are collected and preserved.

Evaluation of their characteristics is a pre-requisite for the effective exploitation of natural genes available in the populations. The entire collection of plants/seeds having all diverse alleles for all genes in a given crop is called germplasm collection. A good germplasm collection is essential for a successful breeding programme.

Question 2.
Emasculation
Answer:
Emasculation
It is the process of removal of stamens of a flower, without affecting the female reproductive organs. Emasculation is usually done in bisexual flowers before the anthers mature and stigma has become receptive. It can be done by various methods, such as, hand emasculation, suction method, hot water emasculation, alcohol treatment, cold treatment and genetic emasculation. Among these methods, hand and suction method are mostly used.

For example, in Triticum (wheat) flowers may be exposed to some chemical like 2,4-dichloro phenoxyacetic acid, maleic hydrozide or a panicle of Sorghum is dipped in lukewarm (50°C) water for 10 minutes, etc. These methods are applied on those cases where the methods of physical nature could not be applied.

Question 3.
Bagging
Answer:
Bagging In this method, the emasculated flower or inflorescence is immediately bagged to avoid . pollination by any foreign pollen. Emasculation bags made up of butter paper, fine cloth or polythene, etc., may be used depending upon the crop.

Question 4.
Artificial pollination
Answer:
Artificial pollination In order to bring about artificial pollination, the collected pollen grains from selected male parents are dusted on the stigma of female plant. The properly labelled flowers are then allowed to cross-pollinate. The crossed flowers are then tagged again.

Question 5.
Breeding for disease resistance
Answer:
Resistance of the host plant is the ability to prevent the pathogen from causing disease and is determined by the genetic constitution of host plant. Crops are required to be disease resistant, as there are a wide range of fungal, bacterial and viral pathogens that affect the yield of cultivated crop species, especially in tropical climates.

Question 6.
Biofortification
Answer:
It is a method of breeding crops with higher levels of vitamins, minerals, healthier fats to improve public health. The objective of breeding for improved nutritional quality is to enhance
(i) Protein, oil content and quality.
(ii) Vitamin content.
(iii) Micronutrients and mineral content

Question 7.
Explant
Answer:
It is the technique of maintaining and growing plant cells, tissues or organs in nutrient media under controlled environmental conditions. The plant part taken out to be grown in a test tube in special nutrient media is called explant.

Explant Selection:
It is the tissue obtained from the plant for the purpose of tissue culture. The most commonly used explant tissues are the meristematic ends of the plants. These include stem tip, auxiliary bud tip and root tip. Meristematic tissues have high rate of cell division. Before the procedure starts, explants are cleaned and surface sterilised with the help of disinfectants and detergents to remove germs.

Question 8.
Tissue culture medium
Answer:
Tissue Culture Techniques and Steps
Plant tissue culture involves producing entire plants from a few plant cells or tissues by growing them in an artificial medium.

1. Explant Selection
2. Sterilisation
3. Preparation of Nutrient or Culture Medium
4. Inoculation
5. Callus Formation and its Culture
6. Organogenesis
7. Somatic Embryogenesis

Question 9.
Totipotency .
Answer:
Totipotency The capacity to generate a whole plant from any cell/ explant is called cellular totipotency in fact, the whole plant can be regenerated from any plant part or cells.

Question 10.
Micropropagation
Answer:
Micropropagation or Clonal Propagation
By the process of plant tissue culture which requires lesser space and lesser time, a large population of plants could be raised. Also since the plants produced are genetically identical, this process is also called as clonal propagation. Examples of plants cutlivated micropropagation include grapes, bamboo, coffee, banana, cardamoms, etc.

Question 11.
Anther culture
Answer:
This technique was developed by Guha and Maheshwari (1946) in Datura innoxia. In this technique, floral buds are opened to remove anthers. These anthers are then cultured for the production of haploid embryoids. The plants produced by haploid culture are sterile. These haploids could be subjected to colchicine treatment in order to double their chromosome number.

Question 12.
Somaclonal variation
Answer:
Somaclonal variation Genetic variation present among plant cells of a culture is called somaclonal variation.
The term somaclonal variation is also used for the genetic variation present in plants regenerated from a single culture.

Question 13.
Synthetic seeds
Answer:
Synthetic Seeds/Artificial Seeds:
Artificial seeds are those seeds in which somatic embryos or plantlets are encapsulated by calcium alginates. This can put a stop to desiccation and they could be used by farmers like normal seeds and are also used for rapid propagation of crop plants.

Question 14.
Secondary metabolites
Answer:
Secondary Metabolites Production:
Cell suspension culture has been employed for commercial production of secondary metabolites like tannin, latex, resin. These cost of secondary metabolites production would be very high if manufactured chemically. So, the plant tissue culture comprising of large scale cell suspension culture has been used.

For example, taxol which is an anticancer drug is obtained from Taxus. The cells of Taxus are cultured which produce a similar chemical which is later chemically modified to taxol. Another example includes Digitalis lantana which is being employed to modify digoxin, to digitoxin, a drug used in cardiac treatment.

Question 15.
Embryo rescue
Answer:
Endosperm Culture:
It is used to produce triploids. Endosperm culture is helpful in producing seedless apple, Citrus which are of better commercial values.

Differentiate between the following

Question 1.
Bagging and Tagging.
Answer:
Differences between bagging and tagging are as follows

Bagging	Tagging
It is the step involved in hybridisation.	It is also a step of hybridisation.
Emasculated flowers are immediately covered by paper, plastic or polythene bags.	Bapqed flowers tagged by writing date, time, male and female, parents.

Question 2.
Chemical pest control and Biological pest control.
Answer:
Differences between chemical pest control and biological pest control are as follows

Chemical pest control	Biological pest control
In this method chemicals are used for pest control.	In this method biological organisms, i.e predator, parasitoids are used for pest control.
Various types of chemicals are used, i.e herbicides, insecticides, pesticides, etc.	Various predators, i.e Trichoderma, B. thuringiensis, etc. are used.
These are expensive.	These are cost effective methods.

Question 3.
Callus and Protoplast.
Answer:
Differences between callus and protoplast are as follows

Callus	Protoplast
It is a growing mass of unorganised plant parenchyma cells.	It refers to entire cell excluding cell wall.
Explants are supplemented with auxin, cytokinin, etc to initiate callus.	It is used to study membrane biology, protoplast fusion, etc.

Question 4.
Synthetic seeds and Embryo.
Answer:
Differences between synthetic seeds and embryo are as follows

Synthetic seeds	Embryo
These are encapsulated somatic embryo, shoot buds or aggregates of cell or any tissues which has the ability to form a plant in in vitro.	It is the part of seed, consisting of precursor tissues for the leaves, stem and roots.
Hybrid plants can be easily propagated using synthetic seeds.	Embryo culture is used for the culturing of embryo.

Question 5.
Endosperm culture and Anther culture
Answer:
Differences between endosperm culture and anther culture are as follows

Endosperm culture	Anther culture
Endosperm is used for culturing.	Anther is used for culturing.
Triploid plants are formed.	Haploid plants are formed.
Used in production of seedless fruits.	It is useful for the improvement of crop plants.

Question 6.
Hybrid and Cybrid.
Answer:
Differences between hybrid and cybrid are as follows

Hybrid	Cybrid
It is the result of combining the qualities of two organisms of different breeds, varieties, species through hybridisation.	It is a eukaryotic cell produced by the fusion of two protoplast.
Hybrids are produced through hybridisation.	These are produced through somatic hybridisation.

Long Answer Type Questions

Question 1.
Describe the main steps of breeding to develop genetic variability in crop plants.
Answer:
Steps in Plant Breeding:
The major steps in breeding a new genetic variety of a crop are
(i) Collection of Germplasm:
This is the major step acting as the root of any breeding programme. In this step, the pre-existing genetic variability available in purelines, wild varieties, species no longer cultivated and relatives of many crop species are collected and preserved.

Evaluation of their characteristics is a pre-requisite for the effective exploitation of natural genes available in the populations. The entire collection of plants/seeds having all diverse alleles for all genes in a given crop is called germplasm collection. A good germplasm collection is essential for a successful breeding programme.

(ii) Evaluation and Selection of Parents:
It is carried out by evaluating germplasm, to identify plants with desirable combination of characters.
The selected plants are multiplied and hybridised by self-pollination. Purelines are created, whenever desired and possible.

(iii) Cross Hybridisation among Selected Parents
It is possible by cross hybridising the two parents to produce hybrids that genetically combine the desired characters in a single plant. It is known to be a time consuming and tedious process as it involves collection of pollen grains from the desired plants (male parent) and have to be placed on the stigma of the selected flower (female parent) to incorporate desired traits.

It is also not necessary that the hybrids do combine desired characters. The chances of desirable combination is usually only one in few hundred to a thousand crosses carried out.

Some of the objectives of hybridisation are as follows
(a) To produce variations in progeny which are useful. It is achieved by recombination of characters.
(b) To make the use of hybrid vigour which is the superiority of progeny over its parents.
(c) To develop high yielding varieties which are also resistant to diseases.

Depending on the nature of plants involved in the cross, there may be different types of hybridisation such as
(a) Inter-varietal Cross between two varieties of same crop.
(b) Intra-varietal Cross between different genotypes of the same variety.
(c) Intra-generic Cross between two species of a genus.
(d) Inter-generic Cross between two genera.

Techniques of Hybridisation:
The first step in hybridisation is to ensure that pollination can not occur before the intended artificial process. This can be achieved by
(a) Emasculation It is the process of removal of stamens of a flower, without affecting the female reproductive organs. Emasculation is usually done in bisexual flowers before the anthers mature and stigma has become receptive. It can be done by various methods, such as, hand emasculation, suction method, hot water emasculation, alcohol treatment, cold treatment and genetic emasculation. Among these methods, hand and suction method are mostly used. For example, in Triticum (wheat) flowers may be exposed to some chemical like 2,4-dichloro phenoxyacetic acid, maleic hydrozide or a panicle of Sorghum is dipped in lukewarm (50°C) water for 10 minutes, etc. These methods are applied on those cases where the methods of physical nature could not be applied.

(b) Bagging In this method, the emasculated flower or inflorescence is immediately bagged to avoid pollination by any foreign pollen. Emasculation bags made up of butter paper, fine cloth or polythene, etc., may be used depending upon the crop.

(c) Tagging In this process, the emasculated and bagged inflorescence or flowers are tagged and properly labelled.
The labels contain following information

1 Date of emasculation
2 Date of pollination
3 Name of female and male plants. The name of the female parent plant is written first and that of the male parent plant is written later.

(d) Artificial pollination In order to bring about artificial pollination, the collected pollen grains from selected male parents are dusted on the stigma of female plant. The properly labelled flowers are then allowed to cross-pollinate. The crossed flowers are then tagged again.

(e) Selection and testing of superior recombinants:
This step consists of selection of plants among the progeny of the hybrids with desired combination of characters. It yields plants that are superior than both the parents. This is known as hybrid vigour/heterosis. These are self-pollinated for several generations, till they reach a state of uniformity or homozygosity, so that the characters will not segregate in the progeny.

(f) Testing, release and commercialisation of new varieties Evaluation is done for newly selected lines for their yield and other agronomic traits of quality, disease resistance, etc. Selected plants are grown in research fields and their performance is recorded under ideal fertiliser applications, irrigation and other crop management practices.

Testing of hybrid line is done in farmer’s field after evaluation. After testing, the crop is grown at different locations in the country with different agroclimatic zones for atleast three growing seasons. The tested material is evaluated in comparison to the best available local crop cultivar used as reference cultivar. Release of tested material is finally done in bulk after selection and certification.

Examples of Some Improved Varieties
(i) Wheat Kalyan Sona and Sonalika are semi-dwarf, high yielding and resistant to root disease, introduced to wheat growing belt of India.
(ii) Rice Along with the above wheat varieties, rice varieties such as IR – 8 and Taichung and their derivatives Jaya and Ratna varieties were introduced around the same time in India. All these varieties contributed to the quantum jump in food production which is called green revolution.

Question 2.
Describe the techniques of hybridisation.
Answer:
Techniques of Hybridisation:
The first step in hybridisation is to ensure that pollination can not occur before the intended artificial process. This can be achieved by
(a) Emasculation It is the process of removal of stamens of a flower, without affecting the female reproductive organs. Emasculation is usually done in bisexual flowers before the anthers mature and stigma has become receptive. It can be done by various methods, such as, hand emasculation, suction method, hot water emasculation, alcohol treatment, cold treatment and genetic emasculation. Among these methods, hand and suction method are mostly used. For example, in Triticum (wheat) flowers may be exposed to some chemical like 2,4-dichloro phenoxyacetic acid, maleic hydrozide or a panicle of Sorghum is dipped in lukewarm (50°C) water for 10 minutes, etc. These methods are applied on those cases where the methods of physical nature could not be applied.

(b) Bagging In this method, the emasculated flower or inflorescence is immediately bagged to avoid pollination by any foreign pollen. Emasculation bags made up of butter paper, fine cloth or polythene, etc., may be used depending upon the crop.

(c) Tagging In this process, the emasculated and bagged inflorescence or flowers are tagged and properly labelled.
The labels contain following information

1 Date of emasculation
2 Date of pollination
3 Name of female and male plants. The name of the female parent plant is written first and that of the male parent plant is written later.

(d) Artificial pollination In order to bring about artificial pollination, the collected pollen grains from selected male parents are dusted on the stigma of female plant. The properly labelled flowers are then allowed to cross-pollinate. The crossed flowers are then tagged again.

(e) Selection and testing of superior recombinants:
This step consists of selection of plants among the progeny of the hybrids with desired combination of characters. It yields plants that are superior than both the parents. This is known as hybrid vigour/heterosis. These are self-pollinated for several generations, till they reach a state of uniformity or homozygosity, so that the characters will not segregate in the progeny.

(f) Testing, release and commercialisation of new varieties Evaluation is done for newly selected lines for their yield and other agronomic traits of quality, disease resistance, etc. Selected plants are grown in research fields and their performance is recorded under ideal fertiliser applications, irrigation and other crop management practices.

Testing of hybrid line is done in farmer’s field after evaluation. After testing, the crop is grown at different locations in the country with different agroclimatic zones for atleast three growing seasons. The tested material is evaluated in comparison to the best available local crop cultivar used as reference cultivar. Release of tested material is finally done in bulk after selection and certification.

Question 3.
Give an account of techniques and steps of plant tissue culture.
Answer:
Tissue Culture:
It is the technique of maintaining and growing plant cells, tissues or organs in nutrient media under controlled environmental conditions. The plant part taken out to be grown in a test tube in special nutrient media is called explant.
The capacity of producing a whole plant from this explant is called totipotency.

It was Gottilieb Haberlandt (1902) who discovered totipotency. Haberlandt also attempted to cultivate plant leaf cells for the first time in simple nutrient medium. Plant tissue culture technique is a major tool in various areas of crop improvement, experimental biology and fundamental or applied research.

Tissue Culture Techniques and Steps:
Plant tissue culture involves producing entire plants from a few plant cells or tissues by growing them in an artificial medium.

1. Explant Selection
It is the tissue obtained from the plant for the purpose of tissue culture. The most commonly used explant tissues are the meristematic ends of the plants. These include stem tip, auxiliary bud tip and root tip. Meristematic tissues have high rate of cell division. Before the procedure starts, explants are cleaned and surface sterilised with the help of disinfectants and detergents to remove germs.

2. Sterilisation
For plant tissue culture, it is essential that the explants, culture vessel, media and instruments, etc. are free from microbes. For this purpose, explants are treated with specific antimicrobial chemicals like mercury chloride, hydrogen peroxide, etc.
This procedure is called surface sterilisation. The vessels, media and instruments, are suitably treated with steam (in autoclave), dry heat or alcohol or subjected to filtration to make them free from microbes. This is complete sterilisation.

3. Preparation of Nutrient or Culture Medium
The medium on which explants are cultured is known nutrient medium or culture medium or simply medium. The culture media may be solid or liquid. The optimum pFl of the media should be 5.7.
The basic components of culture media are
(i) Inorgnic nutrients These include salts, providing all essential macro and microelements. Macronutrients include salts of calcium, magnesium, nitrogen, phosphorus and potassium. Micronutrients include iron, chloride, copper, zinc, boron and molybdenum.
(ii) Source of carbon These are the sources of energy in the form of sucrose, glucose, fructose or carbohydrates, amino acids, etc.
(iii) Growth hormones and vitamins Auxin (2, 4 -D) and cytokinins (benzyl amino purine), vitamins (Pyridoxine HCL) are commonly used in tissue culture. A media without growth hormones is known as base media. High auxins result in root formation while high cytokinins may yield shoots. After the preparation of medium, agar-agar is added in order to obtain a solid medium. In some cases liquid medium is required, for example in root culture where no agar-agar is added.

4. Inoculation
The process of transfer of explant to suitable nutrient medium contained in culture vessels is called inoculation. It is done under sterile conditions, achieved in an inoculation chamber or under laminar air flow. After the process, temperature and light of vessels is kept at controlled range. The temperature ranges between 18-25°C.

5. Callus Formation and its Culture
In callus culture, cell division in the explant forms a callus. It is an amorphous mass of’loosely arranged thin-walled parenchymatous cells developing frome proliferating cells of the parent tissue (Dodos and Roberts; 1985). This is usually maintained on a medium gelled with agar. If nutrient medium contains auxins cell division occurs and the upper surface of explant gets covered by callus. This callus later develops into normal roots, shoots and finally lead to the formation of plant. The development of callus occurs through three stages, i. e. induction, cell division and differentiation.

The callus formation is affected by the composition of medium, the source from which explant has been taken and the surrounding environmental factors. The first stage (induction) involves stimulation of metabolic rate of cells. With the increase in the metabolic rate, these cells enter the cell division stage. Finally in differentiation stage, the cells produce secondary products by the expression of certain metabolic pathways. It is necessary to subculture the callus in fresh media when the callus is being grbwn for a long time on the nutrient media.

6. Organogenesis
It involves the formation of plant organs, i.e. roots and shoots directly from cultured tissues. Organogenesis begins from the stimulation provided by the chemicals of medium, endogenous compounds produced by the culture and substances that have been carried over from the original explants. The process of formation of roots is known as rhizogenesis while that of shoots is caulogenesis. Organogenesis is highly controlled by the ‘ melatin concentrations of auxin and cytokinin in medium.

It was Skoog and Miller (1957) who demonstrated that a high concentration of auxin promotes rhizogenesis while high concentration of cytokinin promotes caulogenesis.

7. Somatic Embryogenesis
A Somatic Embryo (SE) is an embryo derived from a somatic cell, other than zygote. SEs are obtained usually on culture of the somatic cells in vitro. So, this process is called somatic embryogenesis. The embryo formed is known as embryoids. SEs are bipolar structures, i.e. they have a radicle and a plumule.

It is induced by a relatively high concentration of an auxin, like 2, 4-D. There are two different media for the formation of embryoids. The first medium comprises of auxin that initiates embryogenic cells.

The second medium either lacks or has decreased level of auxins. For the further development of embryonic cells into embryoids and plantlets the embryogenic cells undergo three developmental stages such as globular, heart-shaped and torpedo stage. Examples of plants undergoing embryogenesis in vitro include Nicotiana tabaccum, Loffea arabica, Atropa belladona, Brassica oleracea, etc.
The method used for tissue culture is as given below
Major Methodology of plant Tissue Culture

Events of somatic embryogenesis

Question 4.
Elaborate the application of plant tissue culture.
Answer:
Applications of Plant Tissue Culture
(i) Micropropagation or Clonal Propagation:
By the process of plant tissue culture which requires lesser space and lesser time, a large population of plants could be raised. Also since the plants produced are genetically identical, this process is also called as clonal propagation. Examples of plants cutlivated micropropagation include grapes, bamboo, coffee, banana, cardamoms, etc.

(ii) Production of Virus-Free Plants:
Crop plants that reproduce asexually are susceptible to viral infections which advances through the vegetative organs for propagation like stem, tuber, rhizome, etc. The cambium culture in some plants produces virus-free plants.

(iii) Synthetic Seeds/Artificial Seeds:
Artificial seeds are those seeds in which somatic embryos or plantlets are encapsulated by calcium alginates. This can put a stop to desiccation and they could be used by farmers like normal seeds and are also used for rapid propagation of crop plants.

(iv) Embryo Rescue:
It is a technique in which immature embryos are dissected out from the fruit (seeds). They are then grown in nutrient medium which lead to the formation of plantlets. Embryo rescue technique is done in conditions where the embryo does not develop after initial divisions though the pollination and fertilisation had been successfully completed.
This technique is being used to improve chick-pea, groundnut, etc. at International Crop Research Institute for Semi Arid Tropics (ICRISAT), Hyderabad.

(v) Endosperm Culture:
It is used to produce triploids. Endosperm culture is helpful in producing seedless apple, Citrus which are of better commercial values.

(vi) Secondary Metabolites Production:
Cell suspension culture has been employed for commercial production of secondary metabolites like tannin, latex, resin. These cost of secondary metabolites production would be very high if manufactured chemically. So, the plant tissue culture comprising of large scale cell suspension culture has been used.

For example, taxol which is an anticancer drug is obtained from Taxus. The cells of Taxus are cultured which produce a similar chemical which is later chemically modified to taxol. Another example includes Digitalis lantana which is being employed to modify digoxin, to digitoxin, a drug used in cardiac treatment.