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CHSE Odisha Class 12 Biology Important Questions Chapter 8 Evolution

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Odisha State Board CHSE Odisha Class 12 Biology Important Questions Chapter 8 Evolution Important Questions and Answers.

CHSE Odisha 12th Class Biology Important Questions Chapter 8 Evolution

Evolution Class 12 Important Questions CHSE Odisha

Very Short Answer Type Questions

Choose the correct option

Question 1.
The Big-Bang theory applies to the initial formation of
(a) the expanding universe
(b) our solar system
(c) earth and the plants
(d) the first protobionts
Answer:
(a) the expanding universe

Question 2.
Which one of the following gases probably least abundant in the early atmosphere?
(a) H2
(b) O2
(c) NH3
(d) CO
Answer:
(b) O2

Question 3.
The lower invertebrates emerged during the
(a) Palaeozoic
(b) Cenozoic
(c) Mesozoic
(d) Proterozoic
Answer:
(d) Proterozoic

Question 4.
Palaeontological evidences for evolution refer to the
(a) fossils
(b) analogous organs
(c) homologous organs
(d) development of embryo
Answer:
(a) Fossils

Question 5.
Which of the following is a connecting link between annelids and arthropods?
(a) Peripatus
(b) Euglena
(c) Viruses
(d) None of these
Answer:
(a) Peripatus

Question 6.
Miller-Urey’s experiment mixture had the following except
(a) methane
(b) CO2
(c) hydrogen
(d) water vapour
Answer:
(b) CO2

Question 7.
Closely related species differing in various traits express
(a) convergent evolution
(b) divergent evolution
(c) parallel evolution
(d) None of the above
Answer:
(b) divergent evolution

Question 8.
Industrial melanism was highlighted by
(a) Mimosa pudica
(b) Rock python
(c) Triticum aestivum
(d) Biston betularia
Answer:
(d) Biston betularia

Question 9.
The appearance of pesticide resistance in mosquitoes is an example of
(a) adaptive radiation
(b) recapitulation theory
(c) pre-existing variation in the population
(d) transduction
Answer:
(c) pre-existing variation in the population

Question 10.
The most apparent change during the evolutionary history of Homo sapiens is traced in
(a) loss of body hair
(b) walking upright
(c) shortening of jaws
(d) remarkable increase in brain size
Answer:
(d) remarkable increase in brain size

Question 11.
The Primate which existed 15 mya among these was
(a) Homo habilis
(b) Ramapithecus
(c) Homo erectus
(d) Australopithecus
Answer:
(b) Ramapithecus

Question 12.
The tool making ancestor of humans was
(a) Homo erectus
(b) Homo habilis
(c) Ramapithecus
(d) Australopithecus
Answer:
(b) Homo habilis

Question 13.
According to Charles Darwin, evolution is
(a) a slow and discontinuous process
(b) a sudden but discontinuous process
(c) a slow, gradual and continuous process
(d) a slow, sudden and discontinuous process
Answer:
(c) a slow, gradual and continuous process

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

Question 1.
Oxygen releasing prokaryotes first appeared at least 5 billion years ago.
Answer:
2.5 billion years ago

Question 7.
Oparin and Miller independently proposed the origin of life by abiogenic molecular evolution.
Answer:
Oparin and Haldane

Question 8.
Cretaceous period belongs to Palaeozoic era.
Answer:
Mesozoic era

Question 9.
George Cuvier is known as the ‘Father of Palaeontology’.
Answer:
Leonardo da Vinci

Question 10.
The ‘Father of Modem Palaeontology is Leonardo da Vinci.
Answer:
George Cuvier

Question 3.
Amphibians were dominant during Jurassic period.
Answer:
carbinaceous

Question 4.
Haeckel’s biogenetic law is reproductive isolation.
Answer:
ontogeny recapitulates

Question 5.
The phenomenon of development of a new species from pre-existing one is called mutation.
Answer:
speciation

Question 6.
The most accepted theory of evolution known as Modem synthetic theory of evolution, is designated by Miller.
Answer:
Huxley

Question 7.
When gene migration happens multiple times it is called mutation.
Answer:
gene flow

Fill in the blanks

Question 1.
The apparatus used by ……….. was called spark discharge apparatus.
Answer:
Miller

Question 2.
Direct evidences of organic evolution are provided by …………..
Answer:
fossils

Question 3. The classical example of ………. is the limb skeleton of vertebrates.
Answer:
homology

Question 4.
Recapitualation theory was postulated by ……….. .
Answer:
Ernst Haeckel

Question 5.
The theory of pangenesis was rejected due to the acceptance of ……………… .
Answer:
chemical evolution

Question 6.
Connecting link between plants and animals is …………….. .
Answer:
Euglena

Question 7.
Both …….. and ……… jointly propounded the ‘Theory of Natural Selection’.
Answer:
Darwin, Wallace

Question 8.
Random processes such as …………. and ………… can also affect evolution.
Answer:
mutation, genetic drift

Question 9.
Two populations are said to be isolated if there is no longer any ………… between them.
Answer:
gene flow

Question 10.
Hardy-Weinberg equation is ………..
Answer:
p2 + q2 + 2pq = 1

Express in one or two word(s)

Question 1.
Bacteria-like organisms which evolved about 3.5 billion years ago and possessed chlorophyll pigment
Answer:
Photoautotrophs

Question 2.
The organs which perform similar functions but have different embryological origin.
Answer:
Analogous organs

Question 3.
The connecting like between reptiles and mammals.
Answer:
Platypus

Question 4.
Rocks in which fossils are generally found.
Answer:
Sedimentary rocks

Question 5.
Method used to determine the age of fossils upto one million years old.
Answer:
Radioactive labelling

Question 6.
The diversification of the organisms of a population into a number of new groups.
Answer:
Adaptive radiation

Question 7.
The basis of origin of variations in organisms as described by Hugo de Vries.
Answer:
Mutations

Question 8.
It prevents inbreeding of natural populations present in the same geographical locality.
Answer:
Reproductive isolation

Question 9.
The scientist who proposed theory of pangenesis.
Answer:
Charles Darwin

Short Answer Type Questions

Question 1.
When was earth formed? What was its conditions at that time?
Answer:
The earth was formed approximately 4.5 billion years ago. The atmosphere of primitive earth was much different from today’s atmosphere. It was thick with water vapour along with compounds released by volcanic eruptions. It was formed of simple compounds of carbon, hydrogen, oxygen and nitrogen such as dicarbon, cyanogen, methane, ammonia and water. All of them existed in gaseous form while water formed superheated steam. Such an atmosphere was called as reducing atmosphere.

Question 2.
What does the Big-Bang theory explain to us?
Answer:
The Big-Bang theory attempts to explain to us the origin of universe. It tells us of a single huge the monuclear explosion in a highly condensed super hot cosmic matter. Hydrogen and helium formed some time later. The gases condensed under gravitation and formed the galaxies of the present day universe.

Question 3.
State the theory of abiogenesis. How does Miller’s experiment support this theory?
Answer:
Theory of spontaneous generation It states that life originated from non-living matter automatically. This theory is also known as theory of abiogenesis or autobiogenesis. It was also supported by von Helmont (1642), who claimed that the mice were formed in 21 days from a dirty, sweat-soaked shirt put in a wheat barn in the dark. Abiogenesis was continued to be believed till the 17th century.

Question 4.
Define theory of biogenesis. Who were the scientists to support this theory experimentally?
Answer:
Theory of biogenesis According to this theory, life originated from pre-existing life (Omne vivum vivo). Living beings are neither produced spontaneously nor created. This theory was developed by Francesco Redi (1621-1697), which was subsequently supported by many scientists, including Spallanzani (1729-1799) and Louis Pasteur (1822-1895). It does not explain the origin of life.

Question 5.
List the two main propositions of Oparin and Haldane.
Answer:
This theory was given by AI Oparin (1923) and JBS Haldane (1928). According to them, the first form of life came from pre-existing, non-living organic molecules (like RNA, protein, etc.) and chemical evolution was followed by the formation of life, i.e. formation of diverse organic molecules from inorganic constituents.

The conditions on the earth favouring chemical evolution were high temperature, volcanic storms and reducing atmosphere containing CH4, NH4, etc.

Question 6.
What was the contribution of Oparin of Russia and Haldane of England regarding evolution ?
Or Write a note on biochemical origin of life.
Answer:
Both Oparin of Russia and Haldane of England proposed that the first form of life could have originated upon our earth spontaneously from non-living organic molecules (RNA, protein, etc.). Thus, formation of life was preceded by chemical evolution, i.e. formation of diverse organic molecules from inorganic constituents which evolved from inorganic compounds, under special environmental conditions prevalent at that time upon the earth.

Question 7.
What is fossil?
Answer:
These are the material remains (bones, teeth, shells) or traces (physical or chemical) of ancient organisms induding plants and animals. According to Charles Lyell, fossil is any body or traces of body of animal or plant buried and preserved by the natural causes.

Fossilisation is the process of formation of fossils. Fossils are generally preserved in sedimentary rocks in which multiple layers are present and the lowermost layer gets harden into rock under pressure. These are formed when parts of dead organisms decay with the passage of time and get replaced by inorganic materials. The hard parts of the body (i.e. bone, teeth, shell, etc.), are preserved more readily than soft parts, into rocks. Both animals as well as plants can be fossilised as additional layers get deposited with time.

Fossils are also formed by processes other than petrification, e.g. an organism may get buried intact in preservatives like resins, snow, oil, tar, volcanic, ash, etc.

Question 8.
Palaeontological evidences support the theory of organic evolution. Explain with an example.
Answer:
The study of fossils is called as palaeontology.
Palaeontological evidences support theory of organic evolution, both in plants and animals. The transitional fossil organisms show evolutionary relationship between two groups and are called connecting links, e.g. Archaeopteryx is a connecting link between reptiles and birds.

Question 9.
What is geological time scale? Discuss geological time scale as evidence of evolution.
Answer:
Geological Time Scale:
It covers the whole span of the earth’s history to correlate the evolutionary events in a proper sequence of ascending order of time. On the basis of time, the geological history of the earth has been divided into five eras namely, Archaeozoic, Proterozoic, Palaeozoic, Mesozoic and Coenozoic.

Each era includes several periods and each period is further divided into epochs.
The most primitive era, i.e. Archaeozoic is placed at the bottom and the most recent era, i.e. Cenozoic is placed at the top.
Geological timescale (starts at the bottom) indicating origin and evolution of important groups of organisms is tabulated below
Img 1

Question 10.
What are homologous organs? Give an example.
Answer:
Homologous Organs:
It is the relation among the organs of different groups of organisms, that show similarity in the basic structure and embryonic development, but have different functions. Homology in organs indicates common ancestry.
It is based on divergent evolution which leads to the formation of homologous organs.

Question 11.
What are analogous organs ? Give two examples.
Answer:
Analogous Organs and Analogy
In contrast to homologous organs, the analogous organs are different in their basic structure and developmental origin, but appear same and perform similar functions.

This relationship between the structures of different groups of animals due to their similar functions is called analogy or convergent evolution.
Examples of analogy are as follows
Wings of an insect a bird, Pterosaur (extinct flying reptile and a bat (flying mammal) show analogy. The wings are modified forelimbs that are adapted for flight.

The internal organisation of vertebrate (reptile, bird and bat) wings is same and they are composed of muscles and bones whereas, the wings of insect do not possess bones and muscles. They are only thin membranous extentions of exoskeleton and are made up of chitin.
Img 2

Question 12.
Explain briefly recapitulation theory.
Answer:
Recapitulation theory (Biogenetic law) This theory was put forward by Von Baer (1828) and Haeckel called it biogenetic law. It states that ontogeny repeats phylogeny, i.e. every organism during its development repeats in abbreviated form, the evolutionary history of its race. However, Haeckel believed that development stages of an embryo show development stage of its ancestral adults.

It is not true. An embryo recapitulates the embryonic stages of its ancestors and not the evolutionary stages of its adults. The frog during its development passes through a fish-like tadpole stage which shows that it descended from a fish-like ancestor.

Question 13.
Name the main critic of Lamarck. Mention the name of his theory.
Answer:
A German Biologist, August Weismann (1834-1914) was the main critic of Lamarck. He proposed the theory ‘The continuity of germplasm’. He cut the tail of mice for 21 generations. There was no difference in the length of the tail in the offspring of 22nd generation as compared to the tail length in the parents of first generation.

Question 14.
Describe the mechanism of evolution as explained by Hugo de Vries.
Answer:
Hugo de Vries worked on evening primorse and put forward the idea of mutations, i.e. large difference arising suddenly in population. He believed mutations cause evolution and not the minor heritable continuous variations as proposed by Darwin. Evolution for Darwin was gradual while de Vries believed that mutation caused species formation and hence known as ‘Saltation (Single step large mutation). Thus, evolution is a jerky process.

Question 15.
With the help of any two suitable examples explain the effect of anthropogenic actions on organic evolution.
Answer:
New species evolve in a short time scale months or years due to anthropogenic actions or human activities. This hastens the evolutionary process. For example,

It is another example of natural selection. The excess use of herbicides and pesticides leads to selection of resistant varieties of microbes in very less time. Likewise due to these anthropogenic actions antibiotic resistant bacteria are also appearing now-a-days.

Question 16.
What is reproductive isolation? Give its significance.
Answer:
Prevention of mating between two natural populations of the same or different species due to the presence of barriers to interbreeding is called reproductive isolation. The various barriers to interbreeding or gene exchange are called isolating mechanisms.
Significance

  • It prevents inbreeding of natural populations present in the same geographical locality (sympatric populations).
  • Essential for the formation of new species.
  • Maintaining the distinct identity of different species.

Question 17.
What is gene flow?
Answer:
It is the physical movement of alleles into and out of a population. It can be a powerful agent of variation because the members of two different populations may exchange genetic material.

Sometimes, gene flow is obvious when reproductively fit animal moves from one place to another. If the characteristics of newly arrived animal differ from those of the animals already present there, and if the newcomer is adapted well enough to the new area to survive and mate successfully, the genetic composition of the receiving population may be altered.Gene flow also keeps separated populations genetically similar.

Thus, randon breeding among individuals along with migration changes the gene frequency and gene pool and becomes another driving force of evolution.

Question 18.
How does the process of natural selection affect Hardy-Weinberg equilibrium?
Answer:
This principle states that the allele frequencies in a population are stable and is constant from generation to generation, i.e. gene pool remains constant. This is called genetic equilibrium or Hardy-Weinberg equilibrium.

Sum total of all the allelic frequencies is equal to 1, e.g. in a diploid, if p and q represent the frequency of an allele A and allele a. The frequency of AA individuals in a population is p2, of aa is q2 and of Aa is 2pq.
Hence, it can be expressed by the following reaction
p2 + 2pq + q2 = 1

Question 20.
What does the following equation represent? Explain. p2 + 2pq + q2 = 1
Answer:
This principle states that the allele frequencies in a population are stable and is constant from generation to generation, i.e. gene pool remains constant. This is called genetic equilibrium or Hardy-Weinberg equilibrium.

Sum total of all the allelic frequencies is equal to 1, e.g. in a diploid, if p and q represent the frequency of an allele A and allele a. The frequency of AA individuals in a population is p2, of aa is q2 and of Aa is 2pq.

Hence, it can be expressed by the following reaction
p2 + 2pq + q2 = 1

This is called binomial expansion of (p + q)2. The extent of evolutionary change is the difference between the value of frequency measured (frequency obtained) and the value expected. The disturbance in genetic equilibrium (Hardy-Weinberg equilibrium) would result in evolution.

Long Answer Type Questions

Question 1.
How does the study of comparative anatomy of living organism explain the process of evolution?
Answer:
Evidences from Comparative Anatomy:
These evidences help to identify the similarities and differences among the organisms of today and those that existed years ago. Comparative study of external and internal structure can be used to understand the occurrence of organic evolution.

These can be determined by the following types
Homologous Organs and Homology
It is the relation among the organs of different groups of organisms, that show similarity in the basic structure and embryonic development, but have different functions. Homology in organs indicates common ancestry.
It is based on divergent evolution which leads to the formation of homologous organs
In divergent evolution, a same basic organ gets specialisation to perform different functions, in order to ‘ adapt to the different environmental conditions prevailing in the habitat, e.g. forelimbs of vertebrates. Examples of homology are as follows
(i) Structural organisation of vertebrate’s heart, brain, kidney, muscles, skull, etc.
(ii) Different mouthparts of some insects.
(iii) Forelimbs of animals like – whales, bats, cheetah and mammals (e.g. humans).
Img 3
Flomologous organs as exhibited by the forelimbs of vertebrates; (a) Fluman, (b) Bat, (c) Whale, (d) Horse

Adaptive Radiation (Divergent Evolution)
It is the diversification of the organisms of a population into a number of new groups with adaptive characters suiting their need for survival.
Thus, it can be concluded that adaptive radiation and divergent evolution are interrelated and based on the modification of homologous structures. This can be proved studying the basic pattern of the pentadactyl limb which has undergone adaptive modifications in vertebrates.

All these animals have five digits (pentadactyl) in their forelimbs. All these digits possess the same number of skeletal elements that are arranged in same order (i.e. proximal to distal) along with similar muscle, nerve fibres, blood vessels, etc. These limbs have undergone adaptive modifications so as to perform the required funtions to adapt to their environment.
Similar adaptive modification rule also applies to mammals. In figure, a typical pentadactyl limb is seen in a terrestrial mammal.
Img 4
Adaptive radiation in the limb structure of mammals

This pattern has been modified for different functions like running (cursorial), swimming (aquatic), flying (aerial), climbing (arboreal) and burrowing (fussorial). Thus, all mammals have originated from an ancestral terestrial mammal through adaptive modifications of the basic pentadactyl limb plan.

Analogous Organs and Analogy:
In contrast to homologous organs, the analogous organs are different in their basic structure and developmental origin, but appear same and perform similar functions.
This relationship between the structures of different groups of animals due to their similar functions is called analogy or convergent evolution.
Examples of analogy are as follows
(i) Wings of an insect a bird, Pterosaur (extinct flying reptile and a bat (flying mammal) show analogy. The wings are modified forelimbs that are adapted for flight.
The internal organisation of vertebrate (reptile, bird and bat) wings is same and they are composed of muscles and bones whereas, the wings of insect do not possess bones and muscles. They are only thin membranous extentions of exoskeleton and are made up of chitin.
Img 2
Analogy in the wings
(ii) Flippers of dolphin and penguin.
(iii) Fins of fishes and flippers of whales.
(iv) Tracheae of an insect and lungs of the vertebrates are adapted for respiration, but are not homologous, as tracheae are ectodermal in origin, whereas the lungs are endodermal in origin.

Question 2.
(i) Explain Darwinian theory of evolution with the help of one suitable example. State the two key concepts of the theory.
Or Describe the Darwin’s theory of nature selection.
(ii) Why was Darwin’s theory of evolution criticised? Explain.
Answer:
(i) Darwinian theory of evolution states that as a result of struggle for existence only those organisms survive which have favourable variations.

Darwinism (Natural Selection Theory):
Charles Robert Darwin was born in 1809. In 1831, he accepted an unpaid post of naturalist on the survey ship, called HMS Beagle. In his voyage, he spent five years in sea charting the East Coast of South America. During a five week stay on the Galapagos Archipelago Islands, he was struck by the similarities shown by the flora and fauna of the islands and mainland. In particular, he was intrigued by the characteristic distribution of species of tortoises and finches.

Darwin observed different types of beaks in the same population of finches. He termed this phenomenon as adaptive radiation which explains that the changes in beak structure were the result of adaptations to the available food to the native finches. Over the years, the ancestral beak evolved into diverse types of beaks. Thus, Darwin realised the importance of competition and adaptation in the evolution of finches.

After his return, Darwin formulated his concept of organic evolution. He was also influenced by a paper published by Robert Malthus (1838) on populations, which states that the population increases in a geometric progression, while the food supply increases more slowly. Therefore, the ‘food supply becomes a limiting factor. In the meantime, another naturalist Alfred Russel Wallace, came to the same’ conclusions as Darwin regarding natural selection. The content of Wallace’s write-up was similar to Darwin’s thinking.

Darwin and Wallace presented papers on their ideas which were published in the ‘Journal of the Proceedings of The Linnaean Society of London’ in 1858. Darwin published a book entitled ‘On the Origin of Species by Means of Natural Selection (later changed to ‘Origin of Species’ In its 6th edition in 1872), embodying his observations and conclusions in 1859.

Postulates of Darwinism:
The main postulates, which formed the basis of Darwin’s theory of natural selection are as follows
1. Prodigality of Reproduction (Overproduction)
All organisms possess enormous fertility. They multiply in a geometric proportion with some organisms producing very large number of species. Despite of this high rate of reproduction of a species, its number remains constant under fairly stable environment. The production of more offsprings by some organisms and fewer by others is termed as differential reproduction.

2. Limiting Factors
The resources like food, space, etc., remain limited inspite of rapid multiplication of the individuals of all the species. It helps to check the increased number of animals and plants.

3. Struggle for Existence
The limited amount of resources and overproduction of organisms are the main causes of struggle for existence. Various types of struggle help an organism to cope up with unfavourable environmental conditions.
The three types of struggles are as follows

  • Intraspecific struggle It is the struggle among the individuals of same species for their common requirements like food, shelter, mate, breeding places, etc.
  • Interspecific struggle It is the struggle between the individuals of different species for their similar requirements like food and space.
  • Environmental struggle It is the struggle of living forms against the environmental conditions like extreme heat, cold, drought, earthquakes, storms, disease, volcanic eruption, etc.

4. Variations and Heredity:
All individuals are dissimilar in some of their characters except the identical twins. This dissimilarities are mainly due to the variations. These are the small or large differences among the individuals. Variations allow some individuals to better adjust with their environment. Variations can be categorised into the following types

(a) Somatic variations These variations affect the somatic cells of an organism. They are also called modifications or acquired characters because they are aquired by an individual during its lifetime. These are caused by various environmental factors, use and disuse of organs and conscious efforts, etc.
(b) Germinal variations These are inheritable variations recognised by Darwin but he had no idea of inheritance of characters. They are formed mostly in germinal cells.
They are further of two types

  • Continuous (gradual) variations These are fluctuating variations, which oscillate due to race, variety and species.
  • Discontinuous (sudden) variations These appear suddenly and show no ‘spots’ gradation. These variations were termed as ‘spots’ by Darwin and ‘mutation’ by Hugo de Vries. Darwin regarded continuous variations to be more important because the discontinuous variations being mostly harmful would not be selected again.

5. Survival of the Fittest and Natural Selection:
The organisms, which have inherited favourable variations generally survive. This is termed as ‘survival of the fittest’ (the phrase being originally used by Herbert Spencer). Whereas, the organisms without such variations appear unfit and get eliminated. Nature plays a decisive role in selecting the fit organisms.

Natural selection is based on merit and is without any prejudice or bias. It eliminates the unfit ones and selects those organisms that are most fit to survive in a particular environment and to produce offsprings. Survival alone does not make any sense from evolution point of view.
The fit organisms must reproduce to contribute to the next generation. Lerner (1959) says, ‘Individuals having more offsprings are the fit ones’.

6. Origin of New Species (Speciation)
Darwin considered that as a result of struggle for existence, variability (continuous variations) and inheritance, species became better adapted to their environment. These beneficial adaptations are preserved and accumulated in the individuals of species generation after generation. This results into the origin of new species or speciation and the resultant offsprings become visibly distinct from their ancestors.

(ii) Criticism to Darwinism:

Darwin’s theory was widely accepted, but Sir Richard Owen and Adam Sedgewick criticised it due to following reasons

  1. Darwin emphasised on inheritance of useful variations,. However, sometimes inheritance of small variations, which are not useful to individuals are also seen.
  2. He could not explain the presence of vestigial organs and concept of use and disuse of organs.
  3. Darwinism failed to explain the arrival of the fittest.
  4. Darwinism failed to differentiate between the somatic and germinal variations and considered all types of variations as heritable.
  5. Darwin’s natural selection theory was based on the mistaken concept of artificial selection. He wrongly believed that changes brought on by domestication of animal were also heritable.
  6. Darwin failed to recognise the large fluctuating variations (occurring due to mutation). He only believed in the occurrence of small continuous variations.

Darwin proposed ‘theory of pangenesis’ explaining that pangenes or gemmules are transmitted from one generation to next. However, this theory was refuted by Weismann’s germplasm theory.