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

 

NCERT solutions for class 12 biology chapter 10 microbes in human welfare: Microbes are a very important component of life on earth. Solutions for NCERT class 12 biology chapter 10 microbes in human welfare will tell you a very interesting thing that all microbes are not pathogenic. Even many microbes are very useful to human beings. We use microbes and microbially derived products almost every day. Bacteria called lactic acid bacteria (LAB) grow in milk to convert it into curd. The dough, which is used to make bread, is fermented by a yeast called Saccharomyces cerevisiae. In CBSE NCERT solutions for class 12 biology chapter 10 microbes in human welfare you will see that certain dishes such as idli and dosa, are made from dough fermented by different kinds of microbes only. Bacteria and fungi are used to impart particular texture, taste, and flavor to the cheese. In NCERT solutions for class 12 biology chapter 10 microbes in human welfare, questions and solutions are related to microbes as microbes are used to produce industrial products like lactic acid, acetic acid, and alcohol, which are used in a variety of processes in the industry. If you are looking for the answers of any other class from 6-12 then NCERT solutions are there for you as it's the easiest way to get all the solutions of NCERT.

Here are the important topics of solutions for NCERT class 12 biology chapter 10 microbes in human welfare are given below:

10.1 Microbes in Household Products

10.2 Microbes in Industrial Products

    10.2.1 Fermented Beverages

    10.2.2 Antibiotics

    10.2.3 Chemicals, Enzymes, and other Bioactive Molecules

10.3 Microbes in Sewage Treatment

10.4 Microbes in Production of Biogas

10.5 Microbes as Biocontrol Agents

10.6 Microbes as Bio fertilisers

Antibiotics like penicillins produced by useful microbes are used to kill disease-causing harmful microbes. Antibiotics have played a major role in controlling infectious diseases like:

  1. Diphtheria
  2. Whooping cough and
  3. Pneumonia

NCERT solutions for class 12 biology chapter 10 microbes in human welfare, you will get answers on different uses of microbes. For more than a hundred years, microbes are being used to treat sewage (wastewater) by the process of activated sludge formation and this helps in recycling of water in nature. Methanogens produce methane (biogas) while degrading plant waste. Biogas produced by microbes is used as a source of energy in rural areas. Microbes can also be used to kill harmful pests, a process called as biocontrol. The biocontrol measures help us to avoid the heavy use of toxic pesticides for controlling pests.

CBSE NCERT solutions for class 12 biology chapter 10 microbes in human welfare: Solved Exercise Questions:

Q1. Bacteria cannot be seen with the naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes with the help of a microscope, which sample would you carry and why?

Answer:

If I have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes with the help of a microscope, then in order to demonstrate the presence of microbes, we can take curd from our homes as curd contains millions of bacteria.

 

2. Give examples to prove that microbes release gases during metabolism.

Answer:

When any bacteria grow on any material, it uses that material as the substratum to acquire food and starts metabolising that material to release some products. For example, the puffed appearance of dough of dosa is due to the release of gases like CO2 by the bacteria growing on them. Large holes on Swiss cheeses are also due to the release of gases produced by bacteria growing on them

Q3. In which food would you find lactic acid bacteria? Mention some of their useful applications.

Answer:

Lactic acid bacteria (LAB) is found in curd. The useful applications of LAB are as follows:

1.  These bacteria can convert milk into curd.

2. LAB are also found in our stomach to check the growth of harmful bacteria in our stomach.

3. LAB increases the amount of vitamin B12 in curd. Thus, it makes curd nutritious.

Q4. Name some traditional Indian foods made of wheat, rice and Bengal gram (or their products) which involve the use of microbes.

Answer:

Indian food made of Wheat- Bread, bhatura, cake

Indian food made of rice- Idli, dosa, uttapam

Indian food made of Bengal gram- Dhokla, Khandvi

Q5. In which way have microbes played a major role in controlling diseases caused by harmful bacteria?

Answer:

Role of microbes in controlling diseases caused by harmful bacteria:

Microbes are used to produce antibiotics. The antibiotics are chemical substances that are obtained from microorganisms and that kill other microorganisms like bacteria. The first antibiotic was penicillin and it was obtained from fungus Penicillium notatum. Penicillin acts by degrading the cell wall of bacteria.

Q6. Name any two species of fungus, which are used in the production of the antibiotics.

Answer:

Penicillium notatum and Penicillium chrysogenum are used for preparing Penicillin.

Q7. What is sewage? In which way can sewage be harmful to us?

Answer:

The municipal wastewater that is drained into sewers and drains is known as sewage. It contains a large amount of organic matter, microbes, human excreta etc. When sewage is not treated properly, it degrades the quality of water and acts as a breeding site for the mosquitoes. This may lead to diseases like dengue, malaria etc in nearby communities. Thus sewage can be harmful to us.

 

Q8. What is the key difference between primary and secondary sewage treatment?

Answer:

The differences between the primary and secondary treatment of sewage are as follows:

Primary sewage treatment                

Secondary sewage treatment

Primary sewage treatment is a mechanical process that removes solid waste materials

Secondary sewage treatment is a biological process in which waste materials are enzymatically treated by bacteria and other microbes

It is a less expensive and simple process

It is an expensive and complicated process

Q9. Do you think microbes can also be used as a source of energy? If yes, how?

Answer:

Yes, microbes can be used as sources of energy. For example, we know that various microbes produce different types of gases as their end products. One such gas is biogas. It is a mixture of gases produced by microbes and is used as a fuel. Similarly, some anaerobic bacteria which grow on cellulosic materials produce gases like methane, hydrogen gas and CO2. Thus, we can say that microbes can be used as a source of energy.

Q10. Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.

Answer:

Generally, farmers use chemical fertilizers and pesticides in their fields. However, these chemical-based fertilizers and pesticides have deleterious effects on us. They tend to pollute the environment including soil and nearby water bodies. The fruits, vegetables and grains grown in fields in chemical fertilizers and pesticides, the chemicals get incorporated in them and they become toxic for animals and humans. Thus, farmers need to find more environmental friendly methods to control pests and fertilize the soil.  Biocontrol agents and biofertilizers are being used now to control pests and fertilize the soil respectively. 

Microbes as biocontrol agents:

These are microbes or other biological organisms that can be used to control pest and parasite populations in fields. For example, the Bt toxins of Bacillus thuringiensis are used to control lepidopteran insects. Trichoderma is free-living fungi that are very common in the root systems and control several plant pathogens. Baculoviruses are also pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications.

Microbes as biofertilizers:

Bio fertilisers are organisms that enrich the nutrient quality of the soil. The main sources include bacteria, fungi and cyanobacteria. The root nodule formed by Rhizobium bacteria on the root of leguminous plants increases the nitrogen level of soil, necessary for various metabolic processes. Azotobacter and Azospirillum are free-living bacteria that live in soil and fix atmospheric nitrogen into organic forms. Cyanobacteria such as Nostoc, Anabaena are autotrophic microbes found in aquatic and terrestrial environment that fix atmospheric nitrogen.

Q11. Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but thelaboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Answer:

BOD means biochemical oxygen demand. It refers to the amount of oxygen consumed if all organic matter in 1 ltr of water is oxidized by bacteria. BOD tests measure the rate of update of oxygen by microorganisms in the water sample. Greater the value of BOD more is the polluting potential. Out of the three samples mentioned above, secondary effluent has the highest BOD value, so it is most polluted. So, the correct labelling will be:

(a) Secondary effluent

(b) River water

(c) Untreated sewage water.

Q12. Find out the name of the microbes from which Cyclosporin A (an immunosuppressive drug) and Statins (blood cholesterol lowering agents) are obtained.

Answer:

Cyclosporin A – Trichoderma polysporum (fungus)

Statins – Monascus purpureus (yeast)

 

Q13. Find out the role of microbes in the following

(a) Single cell protein (SCP)

Answer:

Microorganisms like bacteria, yeast etc can be cultured on a large scale in the fermenters. They can be treated in many ways, dried and used as a food source or animal feed. These microorganisms that can be used as potential sources of proteins for animals and humans are called single cell protein. SCP is rich in proteins and can be produced in laboratories.

The major advantage of SCP is as follows:

1. The production of SCP do not depend upon climatic factors,

2. The microorganism grows at a very fast rate and requires very less space

3. The cost of production of SCP is very less.

4. Microorganisms used as substrates are otherwise pollutants so it also reduces pollution.

Q13. Find out the role of microbes in the following

(b) Soil

Answer:

Microbes decompose complex organic debris into a dark amorphous substance called humus and degradation products which can be used as manure to increase the fertility of soil. The manure can loosen the soil and increases aeration in the soil. It contains many organic substances which are easily assimilated by plants. Some microbes are used for enriching soil fertility. Microorganisms like Azatobacter and Rhizobium can be used as nitrogen fertilisers. Thus, it can be said that microbes play an important role in improving the quality of the soil.

Q14. Arrange the following in the decreasing order (most important first) of their importance, for the welfare ofhuman society. Give reasons for your answer.

Biogas, Citric acid, Penicillin and Curd

Answer:

These can be arranged as Penicillin - Biogas- Curd- Citric acid.

Penicillin is an antibiotic which is used to cure many diseases like pneumonia. Thus it should be the most important.

Biogas serves as a source of clean fuel, so it is the second most important.

Curd comes next which is a nutritious milk product.

Citric acid is used in food processing industries. Thus, it is last in the list

Q15. How do biofertilisers enrich the fertility of the soil?

Answer:

The term biofertilizer is used for microorganisms that bring nutrient enrichment and minimize the environmental hazards of chemical fertilizers. These biofertilizers increase the physical and chemical structure of soil like buffer capacity and water holding capacity of the soil. Biofertilizers can be introduced into seeds, roots or soil in order to mobilize the desired nutrient. Rhizobium is a biofertilizer, that is introduced in roots and it fixes nitrogen for the plants. Similarly, Cyanobacteria like Nostoc, Anabaena are also used for fixing nitrogen.

NCERT Solutions class 12 – Biology

Chapter 1

NCERT solutions for class 12 biology chapter 1 Reproduction in organisms

Chapter 2

Solutions of NCERT class 12 biology chapter 2 Sexual Reproduction in Flowering Plants

Chapter 3

CBSE NCERT solutions for class 12 biology chapter 3 Human Reproduction

Chapter 4

NCERT solutions for class 12 biology chapter 4 Reproductive Health

Chapter 5

Solutions of NCERT class 12 biology chapter 5 Principles of Inheritance and Variation

Chapter 6

CBSE NCERT solutions for class 12 biology chapter 6 Molecular basis of inheritance

Chapter 7

NCERT solutions for class 12 biology chapter 7 Evolution

Chapter 8

Solutions of NCERT class 12 biology chapter 8 Human health and disease

Chapter 9 

CBSE NCERT solutions for class 12 biology chapter 9 Strategies for Enhancement in Food Production

Chapter 10

NCERT solutions for class 12 biology chapter 10 Microbes in Human Welfare

Chapter 11

Solutions of NCERT class 12 biology chapter 11 Biotechnology: Principles and Processes

Chapter 12

CBSE NCERT solutions for class 12 biology chapter 12 Biotechnology and its Applications

Chapter 13

NCERT solutions for class 12 biology chapter 13 Organisms and Populations

Chapter 14

Solutions of NCERT class 12 biology chapter 14 Ecosystem

Chapter 15

CBSE NCERT solutions for class 12 biology chapter 15 Biodiversity and Conservation

Chapter 16

NCERT solutions for class 12 biology chapter 16 Environmental Issues

NCERT Solutions for Class 12- Subject wise

Solutions for NCERT Class 12 Maths

CBSE NCERT solutions for Class 12 Chemistry

NCERT solutions for  Class 12 Biology

Solutions for NCERT Class 12 Physics

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