CHSE Odisha Class 12 Biology Important Questions Chapter 11 Microbes in Human Welfare

Odisha State Board CHSE Odisha Class 12 Biology Important Questions Chapter 11 Microbes in Human Welfare Important Questions and Answers.

CHSE Odisha 12th Class Biology Important Questions Chapter 11 Microbes in Human Welfare

Microbes in Human Welfare Class 12 Important Questions CHSE Odisha

Very Short Answer Type Questions

Choose the correct option

Question 1.
The bacterium that converts milk into curd is ………. .
(a) Lactobacillus
(b) Azotobacter
(c) Rkizobium
(d) Clostridium
Answer:
(a) Lactobacillus

Question 2.
Fermentation of milk sugar, ……… is done by Lactobacillus.
(a) glucose
(b) fructose
(c) sucrose
(d) lactose
Answer:
(d) lactose

Question 3.
The antibiotic chloramphenicol can be obtained from the bacterium ……. .
(a) Streptomyces griseus
(b) S. aureofaciens
(c) S. venezuelae
(d) S. noursei
Answer:
(c) Streptomyces venezuelae

Question 4.
Acetobacter is involved in the production of
(a) citric acid
(b) acetic acid
(c) gluconic acid
(d) fumaric acid
Answer:
(b) acetic acid

Question 5.
Yeast and Acetobacter are both involved in the production of ……… from carbohydrates.
(a) penicillin
(b) citrate
(c) methane
(d) vinegar
Answer:(d) vinegar

Question 6.
Lipase enzyme is produced by the activity of
(a) Trichoderma viride
(b) Rhizopus sp.
(c) Aspergillus sp.
(d) None of these
Answer:
(b) Rhizopus sp.

Question 7.
The secondary treatment of sewage includes
(a) biological treatment
(b) chemical treatment
(c) filtration
(d) All of the above
Answer:
(a) biological treatment

Question 8.
In primary treatment of sewage, non-biodegradable particles are removed through a process of …………. .
(a) sedimentation
(b) sterilisation
(c) chemical treatment
(d) biological treatment
Answer:
(a) sedimentation

Question 9.
In secondary treatment of sewage in open bioreactors, the microorganisms grow and multiply to form ………. .
(a) manure
(b) compost
(c) sludge
(d) sediment
Answer:
(c) sludge

Question 10.
Milk enzyme that coagulates during curd formation is
(a) protease
(b) casein
(c) rennin
(d) pectinase
Answer:
(c) rennin

Question 11.
Name the bacterium, which produces Swiss cheese.
(a) Saccharomyces cerevisiae
(b) Propionibacterium shermanii
(c) Penicillium roqueforti
(d) Lactobacillus
Answer:
(b) Propionibacterium shermanii

Question 12.
Nystatin is obtained from
(a) Penicillium sp.
(b) Streptomyces griseus
(c) Streptomyces noursei
(d) Aspergillus sp.
Answer:
(c) Streptomyces noursei

Question 13.
The raw material used for the production of wine is
(a) grapes
(b) barley grain
(c) vinegar
(d) None of these
Answer:
(a) grapes

Question 14.
During commercial production of vinegar, secondary fermentation occurs under
(a) anaerobic conditions
(b) aerobic conditions
(c) Both (a) and (b)
(d) unfavourable conditions
Answer:
(b) aerobic conditions

Question 15.
The bacterium which acts on bio-waste to produce biogas is
(a) Methanobacterium
(b) Trichoderma
(c) Bacillus thuringiensis
(d) Azotobacter
Answer:
(a) Methanobacterium

Question 16.
The principal component of biogas is ……….. .
(a) hydrogen
(b) carbon dioxide
(c) ozone
(d) methane
Answer:
(d) methane

Question 17.
Which one of the following microbes is used as biocontrol agent?
(a) Papilloma virus
(b) Baculovirus
(c) Herpes virus
(d) Pox virus
Answer:(b) Baculovirus

Question 18.
Biopesticides are preferred over chemical pesticides due to their
(a) high pest specificity
(b) biodegradability
(c) non-biodegradability
(d) Both (a) and (b)
Answer:
(d) high pest specificity and biodegrdability

Question 19.
Which one of the following fungi makes symbiotic association with the plants?
(a) Glomus
(b) Nostoc
(c) BGA
(d) Rhizobium
Answer:
(a) Glomus

Question 20.
Which one of the following organisms has been commercialised as blood cholesterol lowering agent?
(a) Trichoderma polysporum
(b) Monascus purpureus
(c) Saccharomyces cerevisiae
(d) Aspergillus niger
Answer:
(b) Monascus purpureus

Question 21.
Which one of the following is mainly produced by the activity of anaerobic bacteria on sewage?
(a) Mustard gas
(b) Biogas
(c) Laughing gas
(d) Propane
Answer:
(b) Biogas

Question 22.
Secondary sewage treatment is mainly a
(a) chemical process
(b) biological process
(c) physical process
(d) mechanical process
Answer:
(b) biological process

Question 23.
Organisms called methanogens are most abundant in a
(a) polluted stream
(b) hot spring
(c) sulphur rock
(d) rumen of these
Answer:
(d) rumen of these

Question 24.
A biofertiliser is
(a) Rhizobium
(b) Azotobacter
(c) Nostoc
(d) All of these
Answer:
(d) All of these

Fill in the blanks

Question 1.
Roquefort cheese is ……….. by growing a specific ………… on it.
Answer:
ripened, fungus

Question 2.
The enzyme ……… is used in detergent formulations to remove oily stains from the laundry.
Answer:
lipase

Question 3.
The ……… from secondary treatment of sewage is generally released into ………. water bodies.
Answer:
effluent, natural

Question 4.
During sewage treatement, aerobic microbes are converted into mesh-like structure called ……………. .
Answer:
floes

Question 5.
Species of ………. is used for production of roquefort cheese.
Answer:
Penicillium

Question 6.
………. is an antibiotic that was used to treat soldiers during World War II.
Answer:
Penicillin

Question 7.
………. enzyme produced by Aspergillus niger is used for clarifying bottled juices.
Answer:
Pectinase

Question 8.
…………. is used as a blood cholesterol lowering agent.
Answer:
Statins

Question 9.
During the secondary treatment of primary effluents, the BOD level ……….. .
Answer:
decreases

Question 10.
During sludge digestion, bacteria produce gases like …………. .
Answer:
CH₄,H₂S, CO₂

Question 11.
The technology of biogas production was developed in India by ……….. .
Answer:
Khadi and Village Industries Commision (KVIC)/Indian Agricultural Research Institute (IARI).

Question 12.
The use of biological methods for controlling plant diseases and pests is called ……….. .
Answer:
biocontrol

Question 13.
…………. are used as biocontrol agents to get rid of moquitoes.
Answer:
Dragonflies

Question 14.
Baculovirus is a rod-shaped ………….. DNA virus.
Answer:
double-stranded

Question 15.
Rhizobium is a ………. bacteria that serves as biofertiliser.
Answer:
symbiotic

Question 16.
The first antibiotic was discovered by ………… .
Answer:
Alexander Fleming

Question 17.
……….. are used in biological control of aphids.
Answer:
Ladybirds

Question 18.
Azospirillum and Azotobacter are ………… bacteria.
Answer:
free-living

Question 19.
Plants with mycorrhizal association show tolerance to …………. and ……….. .
Answer:
salinity, drought

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

Question 1.
Antibiotic tetracyclin is obtained from Penicillium notatum.
Answer:
Streptomyces aureofaciens

Question 2.
The first antibiotic to be extracted from bacterial culture was nystatin.
Answer:
streptomycin

Question 3.
In ethyl alcohol production, the unicellular fungus, Penicillium is used.
Answer:
Saccharomyces cerevisiae

Question 4.
Acetic acid is produced by Lactobacillus sp.
Answer:
Acetobacter

Question 5.
In the secondary treatment of sewage, unwanted coarse, non-biodegradable particles are removed.
Answer:
primary treatment

Question 6.
Biogas production technology was developed in India mainly by NBRI and CDRI.
Answer:
KVIC, IARI

Question 7.
Methanogens are present in the liver of cattle.
Answer:
rumen

Question 8.
The major component of biogas is carbon dioxide.
Answer:
methane

Question 9.
Nostoc is present in root nodule of leguminous plants and fixes atmospheric nitrogen.
Answer:
Rhizobium

Question 10.
Biopesticides are non-biodegradable compounds.
Answer:
biodegradable

Question 11.
In paddy fields, blue-green algae fix phosphorus to enrich the soil fertility.
Answer:
nitrogen

Question 12.
Bacillus thuringiensis is a Gram-negative bacteria.
Answer:
positive

Question 13.
Baculoviruses are single-stranded RNA viruses.
Answer:
double-stranded DNA

Question 14.
Mycorrhizae provide cobalt to the roots of plants.
Answer:
phosphorus

Question 15.
Microorganisms belonging to the genus-Penicillium are used as agents of biological control.
Answer:
Nucleopolyhedrovirus

Express in one or two word (s)

Question 1.
The drink produced by fermentation of sap of palm tree.
Answer:
Toddy

Question 2.
The source of antibiotic streptomycin.
Answer:
Streptomyces griseus

Question 3.
Name the molecules which are used as blood cholesterol lowering agents?
Answer:
Statins

Question 4.
An enzyme used for the clarifying bottled fruit juice.
Answer:
Pectinase

Question 5.
Which organic acid gets converted into methane in the final step of biogas production?
Answer:
Acetate

Question 6.
Name a bacterium used as biopesticide.
Answer:
Bacillus thuringiensis.

Question 7.
Give an example of free-living fungi present in root ecosystem.
Answer:
Trichoderma

Question 8.
Name any two major components of biogas.
Answer:
CH₄ and CO₂

Question 9.
Name any one biocontrol agent.
Answer:
Baculovirus

Question 10.
A cheese with large holes produced by Propionibacterium shermanii.
Answer:
Swiss cheese

Question 11.
Name any two cyanobacteria used as biofertilisers
Answer:
Nostoc and Anabaena

Short Answer Type Questions

Question 1.
Write a note on fermentation by microbes and its two applications.
Or
Write a short note on fermentation.
Answer:
Fermentation is the process of conversion of carbohydrates to alcohol and CO₂ by some microorganisms in the absence of O₂. Microbes via fermentation are utilised for the synthesis of a number of products valuable for human beings.

Some of the applications of microbes are

• Production of bread using baker’s yeast.
• Wine, beer and other alcoholic drinks are produced by fermentation.

Question 2.
Mention a product of human welfare obtained with the help of each one of the following microbes.
(i) LAB
(ii) Saccharomyces cerevisiae
(iii) Propionibacterium shermanii
(iv) Aspergillus niger
Answer:

Microbe	Product of human welfare
(i) LAB	Curd
(ii) Saccharomyces cerevisiae	Bread, cakes, wines, beer
(iii) Propionibacterium shermanii	Swiss cheese
(iv) Aspergillus niger	Citric acid

Question 3.
How are fermented beverages prepared?
Or
Write a note on alcoholic beverages.
Answer:
Fermented beverages include wine, beer, whisky, brandy and rum which are obtained by fermenting malted cereals and fruit juices with Saccharomyces cerevisiae or ‘ brewer’s yeast to produce ethanol.

The production of variety of alcoholic drinks depends on the type of raw material used and the’type of processing, e.g. wine and beer are produced without distillation. Whisky, brandy and rum are produced by the distillation of the fermented broth.

Question 4.
How streptomycin is obtained?
Answer:
Streptomycin is an antibiotic that is obtained from Streptomyces griseus. The bacteria are cultured on medium containing glucose, soyameal and mineral salts. The pH of the medium is maintained at 7.4 -7.5. The fermentation is carried out under submerged condition for 5-7 days. It is done at 25-30° C.

Question 5.
Write a short note on alcoholic fermentation.
Answer:
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

Question 6.
What are anaerobic sludge digesters?
Answer:
Sludge is the remaining part of organic matter after secondary treatment of sewage. In sludge digesters, other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi present in the sludge. During this process, bacteria produce a mixture of gases, such as methane, hydrogen sulphide and carbon dioxide which form biogas. It can be used as a source of energy.

Question 7.
Write a short note on secondary treatment of sewage.
Answer:
Secondary treatment of sewage is as follows
(i) This treatment is also known as biological treatment because it involves the use of microbes or biota for the treatment of sewage. The effluent from primary treatment is passed into large aeration tanks, where it is constantly mechanically agitated and air is pumped into it.

(ii) This air helps in the growth of useful aerobic, microbes into floes (masses of bacteria associated with fungal filament to form mesh like structures). The growth of microbes consumes major part of the organic matter, converting it into microbial biomass and releasing lot of minerals. This significantly reduces the BOD (Biochemical Oxyen Demand) of the water.

Question 8.
Write a short note on biogas.
Ans.
It is a complex mixture of gases, like CH₄, CO₂ and H₂, but its major content is methane gas. It is produced by the microbial activity during anaerobic digestion of biomass. Biogas is used as fuel. The type of gas produced by microbes during their growth and metabolism depends upon the microbes and the organic substrates they utilise. Certain bacteria, which grow anaerobically on cellulosic material, produce large amount of methane gas along with CO₂ and H₂ by the process called methanogenesis.

These bacteria are called methanogens and one such common bacterium is Methanobacterium. Methanogens produce large amount of biogas which contains about 50-70% CH₄, 30-40% CO₂, 1-5% H₂ and 0.01% oxygen.

Question 9.
Write a short note on biocontrol agents.
Answer:
Biocontrol agents involve the use of biological methods for controlling plant diseases and pests. Bacteria, fungi and viruses can act as biocontrol agents.
These microbes reduce the target species population through many ecological mechanisms, including pathogenicity, competition, production of chemicals and other interactions.

Question 10.
Write a short note on Bacillus thuringiensis (Bt).
Answer:
Bacillus thuringiensis is a soil-borne, Gram-positive bacterium. It is used to create a transgenic crop plant having resistance to several diseases. The genes encoding for insecticidal properties in the bacterium are isolated and incorporated into crop plants by using advanced biotechnological methods.

The bacterial spores can also be sprayed on the crops. They are ingested by insects and create pores in their gut wall which leads to their death. Thus Br-toxins work as biocontrol agent.

Question 11.
Why is Rhizobium categorised as a symbiotic bacterium? How does it act as a biofertiliser?
Answer:
Rhizobium lives in the root nodules of leguminous plants and fixes the atmospheric nitrogen by converting them into nitrogenous compounds.
These can be utilised by the plants as nutrients. Since, bacteria make the nitrogen available to plants in utilisable form, therefore, it is known as a biofertiliser.

Question 12.
How do plants benefit from having mycorrhizal symbiotic association?
Answer:

• The fungus absorbs phosphorus from the soil and passes it to the plant.
• Plants with mycorrhizal association show resistance to root borne pathogens.
• They show increased tolerance to salinity and drought.

Question 13.
Write short note on biofertiliser.
Answer:
Nutrients in optimum amount are important for the healthy growth, development and maximum productivity of plants.
Many nutrients required for the same include nitrogen and phosphorus which are the constituents of proteins, nucleic acids, coenzymes and some lipids like important biomolecules.
Phosphorus is present as insoluble phosphate in the soil sediments. On the other hand, nitrogen (80%) is present in atmosphere.

However, plants cannot use this atmospheric nitrogen and insoluble phosphates rather they either depend on microbes or chemical fertilisers to meet this basic necessity but, the continuous use of chemical fertilisers causes soil sickness, environmental pollution, etc. Thus, there is a pressure to shift to organic farming. Biofertilisers enrich the nutrient quality of soil by enhancing the availability of nutrients to the crops.

Differentiate between the following (for complete chapter)

Question 1.
Primary and Secondary sewage treatment.
Answer:
Differences between primary and secondary sewage treatment are as follows

Primary sewage treatment	Secondary sewage treatment
It is a physical process.	It is a biological process.
It involves the removal of grit and large pieces of organic matter.	It involves the digestion of organic matter by microbes.
It is carried out by the sedimentation and filtration process.	It is carried out by aerobic and anaerobic biological units.
It is relatively simple and less time consuming process.	It is relatively complex and takes a long time for its completion.

Question 2.
Primary sludge and Activated sludge.
Answer:
Differences between primary sludge and activated sludge are as follows

Primary sludge	Activated sludge
It is sludge formed during primary sewage treatment.	It is sludge formed during secondary sewage treatment.
It does not possess floes of decomposer microbes.	It possesses floes decomposer microbes.
It does not require aeration.	Formation of activated sludge requires aeration.
Little decomposition occurs during the formation of primary sludge.	A lot of decomposition occurs during the formation of activated sludge.

Question 3.
Swiss cheese and Roquefort cheese.
Answer:
Differences between Swiss cheese and Roquefort cheese are as follows

Swiss cheese	Roquefort cheese
They possess large holes.	They have relatively small holes.
These are made by Propionibacterium shermanii	These are ripened by Penicillium roquefort.

Question 4.
Methanogenic bacteria and Symbiotic bacteria.
Answer:
Differences between methanogenic bacteria and symbiotic bacteria are as follows

Methanogenic bacteria	Symbiotic bacteria
There bacteria are involved in energy production.	They are used as biofertilisers.
They live in the rumen of cattle.	They live in the root nodules of leguminous plants.
They produce methane gas by converting cellulose components into simple compounds, e.g. Methanobacterium.	They fix atmospheric nitrogen by converting it into nitrogenous compounds, e.g. Rhizobium.

Question 5.
Biopesticides and Biofertilisers.
Differences between biopesticides and biofertilisers are as follows

Biopesticides	Biofertilisers
They inhibit the growth of pests.	They help in the growth of crop plants.
They increase the yield by killing insects and pests, e.g, Bacillus thuringiensis.	They increase the yield by providing nutrients to the plants, e.g. Nostoc.

Long AnswerType Question

Question 1.
Discuss how waste water treatment can be done.
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.

They need to be treated before their disposal. Conventional methods of waste treatment include cell pits, septic tanks, sewage farms, gravel beds percolating filters and activated sludge process with anaerobic digestion. These methods are less effective and sometimes non-productive.

The domestic sewage contains a large amount of degradable organic compounds. These can be degraded into simpler compounds with the help of microbes. The adequate supply of nutrients, oxygen and other essential compounds helps in the growth of microbes. It consequently enhances the rate of chemical degradation of sewage.

Therefore, modern method includes treatment of sewage before its disposal in local water bodies. Sewage is treated in Sewage Treatment Plants (STPs) in order to make it less polluting. The treatment of waste water is done by the heterotrophic microbes, that are naturally present in the sewage.

This treatment is carried out in the following three stages

Primary Treatment:
It is also known as physical treatment because it basically involves the physical removal of small and large, floating and suspended, non-biodegradable solids from sewage through filtration and sedimentation. Initially, floating debris is removed by sequential filtration. Then, the grit (soil and small pebbles) are removed by sedimentation process in settling tanks. Aluminium or iron sulphate is added in certain places for flocculation.

All solids that settle down during this step form the primary sludge. It traps lots of microbes and debris. The supernatant forms the effluent which is then taken from the primary settling tank for secondary treatment.

Secondary Treatment:
This treatment is also known as biological treatment because it involves the use of microbes or microbiota for the treatment of sewage. The effluent from primary treatment is passed into large aeration tanks, where it Is constantly, mechanically agitated and air is pumped into it.

This air helps in the growth of useful aerobic microbes” into floes (masses of bacteria associated with fungal filament to form mesh-like structures). While growing, these microbes consume major part of the organic matter, converting it into microbial biomass and releasing lot of minerals.
This significantly reduces the Biochemical Oxygen Demand (BOD) of water.

When the BOD of effluent is reduced significantly, it is then passed into a settling tank, where the bacterial ‘floes’ are allowed to sediment. This sediment is called activated sludge. A small part of the activated sludge is then pumped back into the aeration tank to serve as the inoculum. The remaining part of the sludge is pumped back into large tanks called anaerobic sludge digesters, in which other anaerobic bacteria (methanogens) are also present.

They digest the organic mass as well as aerobic microbes (bacteria and fungi of the sludge). During the digestion, mixture of gases like methane (CH₄), hydrogen sulphide (H₂S), carbon dioxide (CO₂), etc., are produced. These gases form biogas that is. used as a source of energy because it is inflammable.
The effluents from secondary treatment plant are released into natural water bodies like rivers and streams.

Tertiary Treatment:
It is an optional process including chemical precipitation. Its effectiveness depends on the number of microbes coming in contact with the pollutant organic molecules. Therefore, the secondary and tertiary treatments are performed in a constantly stirred open bioreactor that are supplied with nutrients.

Other Methods:
Sometimes a percolating or trickling fibre bioreactor is also used. In this method, a stone gravel or plastic sheet is used on which microbes have been immobilised. The sewage is allowed to flow on it. Deep shaft fermentation system is another method of waste water treatment.

This system contains a hole (deep shaft) in the ground. It is divided to allow the cycling and mixing of waste water, air and microbes. In some countries where sunlight hours are high, the algae-bacterial bioreactors are used. The biomass is used in the production of biogas and animal feed.