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NCERT Exemplar Class 12 Biology Solutions Chapter 10 Microbes in Human Welfare

NCERT Exemplar Class 12 Biology Solutions Chapter 10 Microbes in Human Welfare

#CBSE Class 12th
author
Irshad AnwarUpdated on 27 Jun 2025, 12:13 PM IST

Do you know that microbes, though invisible, make up more than 90% of the total biomass on Earth and play an important role in human survival? The NCERT Exemplar Class 12 Biology Solutions Chapter 10 Microbes in Human Welfare has different types of questions like multiple choice, very short, short and long answer with proper answers. These NCERT exemplar solutions help students to learn the chapter in an organised way and make their concepts stronger.

This Story also Contains

  1. Get the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Multiple Choice Questions)
  2. Access the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Very Short Answer Type Questions)
  3. Find the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Short Answer Type Questions)
  4. NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Long Answer type Questions)
  5. Approach to Solve Questions of Class 12 Biology Chapter 10
  6. Important Topics and Subtopics Covered in NCERT Class 12 Biology Chapter 10
  7. Important Question for Class 12 Biology Chapter 10
  8. NCERT Exemplar Class 12 Biology Chapter Wise
NCERT Exemplar Class 12 Biology Solutions Chapter 10 Microbes in Human Welfare
NCERT Exemplar Class 12 Biology Solutions of Chapter 10 Microbes in Human Welfare

The topics covered in the NCERT Exemplar Solutions for Class 12 Biology are about role of microbes in medicine, industries, environmental safety and also how they support evolution and daily human life. If students do these questions regularly, they can remember the important facts and small terms better and also improve their problem-solving skills. Regular revision with these resources helps to build confidence and makes the Microbes in Human Welfare chapter easy enough to face the exam with help of the NCERT Exemplar Solutions for Class 12.

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Get the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Multiple Choice Questions)

A set of question formats, like MCQs, short answers, and long answers, is provided to help students strengthen their understanding and perform better in exams.

Question:1

The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is
a. Vitamin C
b. Vitamin D
c. Vitamin B12
d. Vitamin E

Answer:

Milk, when converted into curd by lactic acid bacteria, sees an increase in the content of vitamin B12. This vitamin is crucial for red blood cell formation and neurological function. The fermentation process enhances its bioavailability.

Hence, the correct answer is option (c) Vitamin B12.

Question:2

Wastewater treatment generates a large quantity of sludge, which can be treated by:
a. anaerobic digesters
b. floc
c. chemicals
d. oxidation pond

Answer:

The sludge formed during wastewater treatment is biologically degraded in anaerobic digesters. These digesters use anaerobic microbes that break down the organic matter, producing biogas.

Hence, the correct answer is option (a) Anaerobic digesters.

Question:3

Methanogenic bacteria are not found in:
a. rumen of cattle
b. gobar gas plant
c. bottom of water-logged paddy fields
d. activated sludge

Answer:

Methanogenic bacteria are obligate anaerobes and are found in oxygen-free environments like the rumen of cattle, gobar gas plants, and paddy fields. Activated sludge, however, contains aerobic microbes.

Hence, the correct answer is option (d) Activated sludge.

Question:4

Match the following list of bacteria and their commercially important products:

BacteriumProduct
A. Aspergillus nigeri. Lactic acid
B. Acetobacter aceticii. Butyric acid
C. Clostridium bretyliumiii. Acetic acid
D. Lactobacillusiv. Citric acid
Choose the correct match:
a. A-ii, B-iii, C-iv, D-i
b. A-ii, B-iv, C-iii, D-i
c. A-iv, B-iii, C-ii, D-i
d. A-iv, B-i, C-iii, D-ii

Answer:

Aspergillus niger produces citric acid, Acetobacter aceti produces acetic acid, Clostridium butylicum produces butyric acid, and Lactobacillus produces lactic acid. These are used in commercial fermentation processes.

Hence, the correct answer is option (c) A-iv, B-iii, C-ii, D-i.

Question:5

Match the following list of bioactive substances and their roles:

Bioactive SubstanceRole
A. Statini. Removal of oil stains
B. Cyclosporin Aii. Removal of clots from blood vessels
C. Streptokinaseiii. Lowering of blood cholesterol
D. Lipaseiv. Immunosuppressive agent
Choose the correct match:
a. A-ii, B-iii, C-i, D-iv
b. A-iv, B-ii, C-i, D-iii
c. A-iv, B-i, C-ii, D-iii
d. A-iii, B-iv, C-ii, D-i

Answer:

Statins (from Monascus purpureus) lower cholesterol, Cyclosporin A is an immuno-suppressant, Streptokinase helps dissolve blood clots, and Lipases remove oil stains. Each has a bioactive industrial or therapeutic application.

Hence, the correct answer is option (d) A-iii, B-iv, C-ii, D-i.

Question:6

The primary treatment of wastewater involves the removal of:
a. dissolved impurities
b. stable particles
c. toxic substances
d. harmful bacteria

Answer:

Primary wastewater treatment is physical. It removes solid and stable particles through filtration and sedimentation. Chemical and biological impurities are handled in later stages.

Hence, the correct answer is option (b) Stable particles.

Question:7

BOD of wastewater is estimated by measuring the amount of:
a. total organic matter
b. biodegradable organic matter
c. oxygen evolution
d. oxygen consumption

Answer:

BOD or biochemical oxygen demand is the amount of oxygen required by microbes to break down biodegradable organic matter in water. It indirectly measures pollution.

Hence, the correct answer is option (d) Oxygen consumption.

Question:8

Which one of the following alcoholic drinks is produced without distillation?
a. Wine
b. Whisky
c. Rum
d. Brandy

Answer:

Wine is prepared by fermentation of fruit juices like grapes and is not distilled. Whisky, rum, and brandy are distilled alcoholic drinks.

Hence, the correct answer is option (a) Wine.

Question:9

The technology of biogas production from cow dung was developed in India largely due to the efforts of:
a. Gas Authority of India
b. Oil and Natural Gas Commission
c. Indian Agricultural Research Institute and Khadi & Village Industries Commission
d. Indian Oil Corporation

Answer:

Biogas technology in India was pioneered by the Indian Agricultural Research Institute and KVIC. They promoted the use of cow dung as a renewable energy source.

Hence, the correct answer is option (c) Indian Agricultural Research Institute and KVIC.

Question:10

The free-living fungus Trichoderma can be used for:
a. killing insects
b. biological control of plant diseases
c. controlling butterfly caterpillars
d. producing antibiotics

Answer:

Trichoderma is a fungus used as a biocontrol agent against plant pathogens. It inhibits harmful fungi and promotes plant growth.

Hence, the correct answer is option (b) Biological control of plant diseases.

Question:11

What would happen if oxygen availability to activated sludge flocs is reduced?
a. It will slow down the rate of degradation of organic matter
b. The centre of flocs will become anoxic, which would cause the death of bacteria and eventually the breakage of flocs.
c. Flocs would increase in size as anaerobic bacteria would grow around flocs.
d. Protozoa would grow in large numbers

Answer:

Activated sludge flocs require oxygen for the aerobic bacteria within them. If oxygen is limited, anoxic conditions kill bacteria and break down the floc structure.

Hence, the correct answer is option (b) Centre of flocs becomes anoxic, causing breakdown.

Question:12

Mycorrhiza does not help the host plant in:
a. Enhancing its phosphorus uptake capacity
b. Increasing its tolerance to drought
c. Enhancing its resistance to root pathogens
d. Increasing its resistance to insects

Answer:

Mycorrhiza helps in nutrient and water absorption and disease resistance, but not in fighting insect pests.

Hence, the correct answer is option (d) Increasing resistance to insects.

Question:13

Which one of the following is not a nitrogen-fixing organism?
a. Anabaena
b. Nostoc
c. Azotobacter
d. Pseudomonas

Answer:

Pseudomonas is generally non-nitrogen-fixing. It includes pathogenic species. Anabaena, Nostoc, and Azotobacter fix nitrogen.

Hence, the correct answer is option (d) Pseudomonas.



Question:14

Big holes in Swiss cheese are made by a:
a. A machine
b. A bacterium that produces methane gas
c. A bacterium producing a large amount of carbon dioxide
d. A fungus that releases a lot of gases during its metabolic activities

Answer:

Swiss cheese holes are due to carbon dioxide production by Propionibacterium shermanii during fermentation. Methane and other gases are not involved.

Hence, the correct answer is option (c) Bacterium producing carbon dioxide.

Question:15

The residue left after methane production from cattle dung is:
b. buried in landfills
c. used as manure
d. used in civil construction

Answer:

The leftover slurry after biogas production is rich in nutrients and is used as organic manure in agriculture.

Hence, the correct answer is option (c) used as manure.

Question:16

Methanogens do not produce:
a. Oxygen
b. Methane
c. Hydrogen sulfide
d. Carbon dioxide

Answer:

Methanogens produce methane, CO2, and H2S but not oxygen. They are anaerobic organisms.

Hence, the correct answer is option (a) Oxygen.

Question:17

Activated sludge should have the ability to settle quickly so that it can:
a. be rapidly pumped back from the sedimentation tank to the aeration tank
b. absorb pathogenic bacteria present in wastewater while sinking to the bottom of the settling tank
c. be discarded and anaerobically digested
d. absorb colloidal organic matter

Answer:

Activated sludge must settle quickly to allow proper separation from treated water and enable anaerobic digestion of the sludge.

Hence, the correct answer is option (c) Be discarded and anaerobically digested.

Question:18

Match the following:

Column IColumn II
A. Ladybirdi. Methane bacterium
B. Mycorrhizaii. Trichoderma
C. Biological controliii. Aphids
D. Biogasiv. Glomus

Answer:

Ladybird controls aphids (iii), Mycorrhiza involves Glomus (iv), Trichoderma (ii) is a biocontrol agent, and biogas involves methane bacteria (i).

Hence, the correct answer is option (b) A-iii, B-iv, C-ii, D-i.

Access the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Very Short Answer Type Questions)

To make the basic concepts strong students can go through the very short answers provided here:

Question:1

Why does ‘Swiss cheese’ have big holes?

Answer:

A bacterium called Propionibacterium sharmanii produces a large amount of carbon dioxide during fermentation. This is the reason for the big holes in Swiss cheese.

Question:2

What are fermentors?

Answer:

Exceptionally large vessels, which are used for industrial-scale fermentation, are called fermenters.

Question:3

Name a microbe used for statin production. How do statins lower blood cholesterol levels?

Answer:

The yeast Monascus purpureus is used for the commercial production of stains. Stain competitively inhibits the enzyme responsible for cholesterol formation and thus helps in lowering the blood cholesterol level.

Question:4

Why do we prefer to call secondary wastewater treatment a biological treatment?

Answer:

Secondary treatment of wastewater involves action by microbes. Due to this, secondary treatment is called biological treatment.

Question:5

What Nucleopolyhydro viruses are being used nowadays?

Answer:

Nucleopolyhydro viruses are used for controlling pests and other arthropods in farms. These are narrow-spectrum viruses and do not harm plants, cattle humans or even non-target insects.

Question:6

How has the discovery of antibiotics helped mankind in the field of medicine?

Answer:

Antibiotics have created a revolution in the treatment of diseases.
Many infectious diseases which were incurable earlier can now be treated with antibiotics. Antibiotics have helped in saving millions of lives.

Question:7

Why is distillation required for producing certain alcoholic drinks?

Answer:

Distillation is done to remove most of the water and impurities from certain alcoholic drinks.

Question:8

Write the most important characteristic that Aspergillus niger, Clostridium bretylium, and Lactobacillus share.

Answer:

All of them produce organic acids. Aspergillus niger produces citric acid, Clostridium butylicum produces butyric acid, and Lactobacillus produces lactic acid.

Question:9

What would happen if our intestine harbours microbial flora exactly similar to that found in the rumen of cattle?

Answer:

The microbial flora in the rumen of cattle facilitates the digestion of cellulose. If such microbial flora is present in our intestines, then humans will also be able to digest cellulose.

Question:10

Give any two microbes that are useful in biotechnology.

Answer:

Streptococcus, Bacillus thuringiensis

Question:11

What is the source organism for EcoRI restriction endonuclease?

Answer:

The source organism for the EcoRI restriction endonuclease is Escherichia coli (E. coli).


Question:12

Name any genetically modified crop.

Answer:

BT cotton is a GM crop and contains a gene from Bacillus thuringiensis which helps in killing pests.


Question:13

Why are blue-green algae not popular as biofertilisers?

Answer:

Blue-green algae can proliferate in water and can carry out nitrogen fixation. However, paddy is the only crop which grows in stagnant water. Most of the other crops do not need stagnant water to grow. This is the main reason for the low popularity of blue-green algae as biofertiliser.

Question:14

Which species of Penicillium produces Roquefort cheese?

Answer:

The species of Penicillium that produces Roquefort cheese is Penicillium roqueforti.

Question:15

Name the states involved in the Ganga action plan.

Answer:

Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal

Question:16

Name any two industrially important enzymes.

Answer:

Lipase and pectinase

Question:17

Name an immune immunosuppressive agent.

Answer:

Cyclosporin A

Question:18

Give an example of a rod-shaped virus.

Answer:

Tobacco Mosaic Virus (TMV)

Question:19

What is the group of bacteria found in both the rumen of cattle and the stage of sewage treatment?

Answer:

The group of bacteria found in both the rumen of cattle and the stage of sewage treatment is Methanogen.

Question:20

Name a microbe used for the production of Swiss cheese.

Answer:

A microbe used for the production of Swiss cheese is Propionibacterium sharmanii.

Find the NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Short Answer Type Questions)

Students can go through the short answers for a better understanding of concepts:

Question:1

Why are flocs important in the biological treatment of wastewater?

Answer:

Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures. Flocs digest most of the organic material from the sludge. Thus, floc helps in reducing the BOD (Biochemical Oxygen Demand) of the effluent. This helps in the further treatment of sludge.

Question:2

How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?

Answer:

Bacillus thuringiensis produces an endotoxin which when ingested and released in the gut of the larvae of insect pest disrupts its gut lining, and thus caterpillars are killed. By killing the caterpillars, it helps in pest control.

Question:3

How do mycorrhizal fungi help the plants harbouring them?

Answer:

Mycorrhizal fungi absorb phosphorus from soil and pass it to the plant. These fungi also help the plant to develop resistance against root-borne pathogens and develop sustainability against salinity and drought.

Question:4

Why are cyanobacteria considered useful in paddy fields?

Answer:

Cyanobacteria are important biofertilisers in paddy fields. They add organic matter to the soil and enhance soil fertility. Hence, they are considered useful in paddy fields.

Question:5

How was Penicillin discovered?

Answer:

Penicillin was discovered accidentally. Alexander Fleming was working on Staphylococci when he observed that in one of the unwashed culture plates, bacteria did not grow around a mould. He could observe that it was because of a chemical released by the mould. He named it Penicillin after the mould Penicillium notatum.

Question:6

Name the scientists who were credited for showing the role of Penicillin as an antibiotic.

Answer:

Alexander Fleming first discovered penicillin in 1928. Later, Howard Florey and Ernst Boris Chain worked out how to purify and produce it on a large scale. Together, their work proved penicillin’s role as an antibiotic that could treat bacterial infections. Their discovery saved millions of lives.

Question:7

How do bioactive molecules of fungal origin help in restoring the good health of humans?

Answer:

Following are some bioactive molecules of fungal origin which help in restoring good health in humans:
Cyclosporin A is produced by Trichoderma polysporum and is used as an immunosuppressive agent. Penicillin is a major antibiotic which is produced from Penicillium notatum.

Question:8

What roles do enzymes play in detergents that we use for washing clothes? Are these enzymes produced from some unique microorganisms?

Answer:

Lipase is used in detergent formulations because it helps in removing oily stains from laundry. Lipases are prepared from the yeast Saccharomyces cerevisiae.

Question:9

What is the chemical nature of biogas? Name an organism which is involved in biogas production.

Answer:

Biogas is mainly composed of methane; other gases are CO2 and H2. It is highly inflammable and is used as fuel, especially in rural areas. Methanogen bacteria are involved in the production of biogas.

Question:10

How do microbes reduce the environmental degradation caused by chemicals?

Answer:

Many harmful chemicals are produced as a byproduct of modern lifestyle. These chemicals are finally dumped in the soil and end up contaminating the soil. Soil contamination can be removed with the help of microbes.
The removal of soil contamination with the help of microbes is called bioremediation. This is usually achieved by bio-augmentation of soil flora.

Question:11

What is a broad-spectrum antibiotic? Name one such antibiotic.

Answer:

An antibiotic which is effective against most of the common pathogenic bacteria is called a broad-spectrum antibiotic. Cefoperazone and Ceftazidime are examples of broad-spectrum antibiotics.

Question:12

What are viruses parasitising bacteria called? Draw a well-labelled diagram of the same.

Answer:

Virus
A virus which attacks bacteria is called bacteriophage. The virus enters a bacterial cell and controls the genetic material of bacteria in order to produce more viruses.

Question:13

Which bacterium has been used as a clot-buster? What is its mode of action?

Answer:

Streptococcus is genetically modified to make streptokinase which is used as a clot buster. Streptokinase carries out thrombolysis which breaks the clot into smaller fragments, and thus, the clot is dissolved.

Question:

What are biofertilisers? Give two examples.

Answer:

Organisms which enrich nutrients in the soil are called bio-fertilisers. Azotobacter and Rhizobium are examples of biofertilizers.
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NCERT Exemplar Class 12 Biology Solutions Chapter 10 (Long Answer type Questions)

The long answers will help the students understand the complex concepts very well to secure good marks in any examination:

Question:1

Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of wastewater rich in organic matter? Discuss.

Answer:

Organic matter in wastewater consumes a lot of oxygen to carry on various biological processes. It results in a reduction of oxygen levels in the surrounding air and thus can increase air pollution. Consumption of oxygen by organic matter in wastewater is measured by BOD (Biochemical Oxygen Demand). A higher level of BOD indicates a higher polluting potential of wastewater. It is important to reduce the BOD so that pollution can be reduced. Hence, aerobic degradation is more important than anaerobic degradation for the treatment of large volumes of wastewater rich in organic matter.
BOD level is reduced by aerobic degradation, which is carried out by floc. Flocs are associations of bacteria and fungi which form mesh-like structures. Flocs eat away most of the organic matter in wastewater and thus help in reducing BOD. The sludge is ready for anaerobic degradation once BOD is pulled down below a threshold level.

Question:2

(a) Discuss the major programs that the Ministry of Environment and Forests, Government of India, has initiated to save major Indian rivers from pollution.

(b) Ganga has recently been declared the national river. Discuss the implications with respect to the pollution of this river.

Answer:

(a) The Government has launched the Ganga Action Plan and Yamuna Action Plan to reduce pollution levels in these rivers. Under the Ganga Action Plan, dredging and cleaning of the riverbed are being carried out. These activities are especially intensified at places where the river passes through a major urban centre. The current government has named the Ganga Action Plan Namami Gange.

(b) The Ganga is probably the most important river in India. It is important from a religious perspective as well as from an economic perspective. The Gangetic Plain is one of the most densely populated areas in the world and supports the livelihood of billions of people. A high level of pollution in this river will jeopardise the very existence of people who have lived in the Gangetic Plain for thousands of years. High levels of pollution will do irreparable damage to the ecosystem in our country.

Question:3

Draw a diagrammatic sketch of the biogas plant, and label its various components given below:
Gas Holder, Sludge Chamber, Digester, Dung + water chamber.

Answer:

Biogas plant

Question:4

Describe the main ideas behind the biological control of pests and diseases.

Answer:

Biological control of pests and diseases is based on the interdependency among various components of an ecosystem. This approach is also based on the acknowledgement of potential harm caused by chemical control of pests and diseases.
Checks and Balances in the Ecosystem: In any given ecosystem; various organisms are dependent on each other and on abiotic factors. Pests are also part of the ecosystem. They turn problematic for farmers only when their population goes beyond a certain level. If the system of natural checks and balances can be understood, then it would be pretty easy for farmers to control the pests without harming useful insects.
Drawbacks of Chemical Control: Synthetic pesticides are highly effective in pest control, but their use leads to collateral damage. Many useful insects are killed in the process. This problem can be removed by using biological control.
Minimising Pollution: The use of pesticides has another drawback, i.e. creating soil pollution and groundwater pollution. If biological control is applied, then the chances of soil pollution and groundwater pollution can be minimised.

Question:5

(a) What would happen if a large volume of untreated sewage is discharged into a river?

(b) In what way anaerobic sludge digestion is important in sewage treatments?

Answer:

(a) The following are the harmful effects of untreated sewage being discharged into a river:
  1. It will contaminate water, making it unfit for drinking.
  2. It will alter the pH level of water, which can be detrimental to aquatic plants and animals.
  3. This will also pollute groundwater.
  4. Fish from contaminated water will become unfit for human consumption.
(b) Anaerobic sludge digestion is important from the following angles:
(i) It helps in the production of biogas which can be used as fuel. Biogas from sewage treatment plants is being used for electricity generation in many places in the world.
(ii) The slurry can be used as manure. This will help in improving soil fertility.
(iii) This also helps in reducing soil pollution and water pollution.

Question:6

Which type of food would have lactic acid bacteria? Discuss their useful application.

Answer:

Lactic acid bacteria are present in milk products which are prepared by fermentation. They are also found in pickled vegetables and wines. The following are some useful applications of lactic acid bacteria:
  1. They are used for making curd and cheese.
  2. They are used for making pickled vegetables. Kimchi is a popular South Korean dish, and it contains lactic acid.
  3. Lactic acid and bacteria are used to make probiotics. Probiotics are taken as supplements in order to restore the gut flora. Probiotics can help in getting rid of diarrhoea, irritable bowel syndrome, etc.
  4. Many types of bread are made with the help of lactic acid bacteria.

NCERT Exemplar Class 12 Solutions Subject Wise

CBSE Class 12th Syllabus: Subjects & Chapters
Select your preferred subject to view the chapters

Approach to Solve Questions of Class 12 Biology Chapter 10

Some points to understand before solving the questions of the chapter are given below:

  • The students should begin by categorising the role of microbes into different types- agriculture, industries, household products, sewage treatment and bio control.
  • They should pay attention to examples like Rhizobium, Lactobacillus, Methanogens and Trichoderma, as questions generally ask about the specific uses.
  • They should understand the processes such as fermentation, biogas production and integrated waste management, as they are frequently asked in both MCQ and short answer formats.
  • They should highlight the key terms and flowchart for revision and practice to answer them in a step-by-step manner, by first naming the microbes, then the function, and finally, it's application.

Also, read the NCERT Solution subject-wise

NEET Highest Scoring Chapters & Topics
Most Scoring concepts For NEET (Based On Previous Year Analysis)
Download EBook

Important Topics and Subtopics Covered in NCERT Class 12 Biology Chapter 10

The important topics of the Microbes in Welfare Chapter are given below-

  • Microbes In Household Products
  • Microbes In Industrial Products
  • Microbes In Sewage Treatment
  • Microbes In the Production Of Biogas
  • Microbes As Biocontrol Agents
  • Microbes As Biofertilizers

Also Check NCERT Books and NCERT Syllabus here

Important Question for Class 12 Biology Chapter 10

Below is an important question of the chapter:

Question:

Which of the following is used as a bioinsecticide to control caterpillar pests in crops?

a) Rhizobium leguminosarum

b) Trichoderma harzianum

c) Bacillus thuringiensis

d) Azotobacter chroococcum

Answer:

Bacillus thuringiensis Bt acts as a natural pest controller in crops as it produces a protein crystal that disrupts the gut of caterpillar larvae leading to their death without harming humans or beneficial insects farmers prefer Bt because it is eco friendly and safe for the environment the other options listed work for nitrogen fixation or fungal control but Bt remains the most effective for managing caterpillar pests

Hence, the correct answer is option (c) Bacillus thuringiensis.

Must Read NCERT Notes subject-wise

NCERT Exemplar Class 12 Biology Chapter Wise

The chapter-wise solutions for all chapters of Class 12 Biology are given below:-

NCERT Exemplar Class 12 Biology Chapter 1 Reproduction In Organisms

NCERT Exemplar Class 12 Biology Chapter 2 Sexual Reproduction In Flowering Plants

NCERT Exemplar Class 12 Biology Chapter 3 Human Reproduction

NCERT Exemplar Class 12 Biology Chapter 4 Reproductive Health

NCERT Exemplar Class 12 Biology Chapter 5 Principles of Inheritance And Variation

NCERT Exemplar Class 12 Biology Chapter 6 Molecular Basis of Inheritance

NCERT Exemplar Class 12 Biology Chapter 7 Evolution

NCERT Exemplar Class 12 Biology Chapter 8 Human Health and Disease

NCERT Exemplar Class 12 Biology Chapter 9 Strategies For Enhancement in Food Reproduction

NCERT Exemplar Class 12 Biology Chapter 10 Microbes in Human Welfare

NCERT Exemplar Class 12 Biology Chapter 11 Biotechnology: Principles and Processes

NCERT Exemplar Class 12 Biology Chapter 12 Biotechnology and Its Applications

NCERT Exemplar Class 12 Biology Chapter 13 Organisms and Populations

NCERT Exemplar Class 12 Biology Chapter 14 Ecosystems

NCERT Exemplar Class 12 Biology Chapter 15 Biodiversity and Conservation

NCERT Exemplar Class 12 Biology Chapter 16 Environmental Issues


Frequently Asked Questions (FAQs)

Q: How are microbes used in industrial production according to NCERT Exemplar?
A:

Microbes are vital in industrial production, used in processes like fermentation to create food, biofuels, enzymes, and pharmaceuticals, as well as in bioremediation and single-cell protein production. 

Q: What are biofertilizers and their role in agriculture as per Chapter 10?
A:

Biofertilizers are substances containing living microorganisms that, when applied to soil or plants, promote plant growth by increasing nutrient availability and improving soil health, making agriculture more sustainable.

Q: How do microbes help in sewage treatment as per NCERT Class 12 Biology?
A:

In sewage treatment, microbes, particularly bacteria, play a crucial role in breaking down organic matter, reducing pollution, and producing biogas, as outlined in NCERT Class 12 Biology.

Q: What is the best way to solve various questions in the Class 12 Biology NCERT exemplar solutions chapter 10?
A:

The students can study each section of the chapter completely and attempt the question bank given with the NCERT exemplar Class 12 Biology solutions to study and get the answer format completely.

Q: What are the main points covered in the NCERT exemplar Class 12 Biology solutions chapter 10?
A:

The topics included in the NCERT exemplar solutions for Class 12 Biology Chapter 10 are -

1. Microbes in Household Products

2. Microbes in Industrial Products

3. Microbes in Sewage Treatment

4. Microbes in the Production of Biogas

5. Microbes as Biocontrol Agents

6. Microbes as Biofertilizers

And other detailed explanations of related topics too are mentioned.

Q: Is the NCERT exemplar Class 12 Biology chapter 10 solutions enough for the students to clear the exams?
A:

Yes, along with the textbooks the student can rely on NCERT Exemplar Class 12 Biology solutions chapter 10, for any reference and guidance.

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Questions related to CBSE Class 12th

On Question asked by student community

Have a question related to CBSE Class 12th ?
I'm studying scince in karnatakastate board, can i take commerce in cbse for 12th next year?

Yes, you can switch from Science in Karnataka State Board to Commerce in CBSE for 12th. You will need a Transfer Certificate from your current school and meet the CBSE school’s admission requirements. Since you haven’t studied Commerce subjects like Accountancy, Economics, and Business Studies, you may need to catch up before or during 12th. Not all CBSE schools accept direct admission to 12th from another board, so some may ask you to join Class 11 first. Make sure to check the school’s rules and plan your subject preparation.



Read Complete Answer
A
Abhilasha Agrawal
18 Sep'25
12th class cbse boards most important que ans ans in hindi midum subject hindi impotent question jo exam main aaynge wo btai

Hello

For the 12th CBSE Hindi Medium board exam, important questions usually come from core chapters like “Madhushala”, “Jhansi ki Rani”, and “Bharat ki Khoj”.
Questions often include essay writing, letter writing, and comprehension passages. Grammar topics like Tenses, Voice Change, and Direct-Indirect Speech are frequently asked.
Students should practice poetry questions on themes and meanings. Important questions also cover summary writing and translation from Hindi to English or vice versa.
Previous years’ question papers help identify commonly asked questions.
Focus on writing practice to improve handwriting and presentation. Time management during exams is key to answering all questions effectively.

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S
SEJAL JAIN
17 Sep'25
Can i improve my 12 result this year in PCM

Hello,

If you want to improve the Class 12 PCM results, you can appear in the improvement exam. This exam will help you to retake one or more subjects to achieve a better score. You should check the official website for details and the deadline of this exam.

I hope it will clear your query!!

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R
Rahul Mandal
8 Sep'25
what will be tha CBSE Exam Date?

For the 2025-2026 academic session, the CBSE plans to conduct board exams from 17 February 2026 to 20 May 2026.

You can download it in pdf form from below link

CBSE DATE SHEET 2026

all the best for your exam!!

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A
Afreen
13 Sep'25
registration no. 12th class cbse

Hii neeraj!

You can check CBSE class 12th registration number in:

  • Your class 12th board exam admit card. Please do check admit card for registration number, it must be there.
  • You can also check the registration number in your class 12th marksheet in case you have got it.
  • Alternatively you can also visit your school and ask for the same in the administration office they may tell you the registration number.

Hope it helps!

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S
Shivani Chaurasia
15 Sep'25
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Popular CBSE Class 12th Questions

A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

 Option 2)

0.16\; J
Option 3)

1.00\; J

 Option 4)

0.67\; J
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A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

 Option 2)

 6.45×10−3 kg
Option 3)

 9.89×10−3 kg

 Option 4)

12.89×10−3 kg

 
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An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

 Option 2)

200 \, \, J - 500 \, \, J
Option 3)

2\times 10^{5}J-3\times 10^{5}J

 Option 4)

20,000 \, \, J - 50,000 \, \, J
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A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

 Option 2)

\; K\;
Option 3)

zero\;

 Option 4)

K/4
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In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

 Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced
Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

 Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .
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How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

 Option 2)

3.125 × 10-2
Option 3)

1.25 × 10-2

 Option 4)

2.5 × 10-2
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If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

 Option 2)

increase two fold
Option 3)

remain unchanged

 Option 4)

be a function of the molecular mass of the substance.
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With increase of temperature, which of these changes?

Option 1)

Molality

 Option 2)

Weight fraction of solute
Option 3)

Fraction of solute present in water

 Option 4)

Mole fraction.
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Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

 Option 2)

6.023 × 1022
Option 3)

half that in 8 g He

 Option 4)

558.5 × 6.023 × 1023
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A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

 Option 2)

more than 3 but less than 6
Option 3)

more than 6 but less than 9

 Option 4)

more than 9
Read Complete Answer

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