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In this article we are providing the NCERT Solutions for CBSE Class 12 Biology chapter 10, Microbes in Human Welfare. All the questions have been solved in the most appropriate and simple way so as to help students access the right study material for the exam preparation.
All the class 12 Biology NCERT Exemplar solutions have been collated in PDF format which students may easily download totally free.
Few problems along with their solutions from this chapter are given follows:
Q. Methanogenic bacteria are not found in
(a) rumen of cattle (b) gobar gas plant
(c) bottom of water-logged paddy fields (d) activated sludge
Ans. (d) activated sludge
Methanogenic bacteria (that produce methane) are not found in activated sludge. The microbes present in the activated sludge are aerobic bacteria that grow rapidly and form flocs.
During secondary treatment of wastewater it is in the digesters where other kinds of bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge producing mixture of gases such as methane, hydrogen sulphide and CO2 which form the biogas.
Q. Why do we prefer to call secondary waste water treatment as biological treatment?
Ans. Secondary waste water treatment is called biological treatment because microorganisms are involved in the breakdown of organic matter in this phase of waste water treatment.
The primary effluent is passed into large aeration tanks where the organic matter in it is consumed by aerobic microbes which are later themselves digested by anaerobic bacteria and fungi in anaerobic sludge digesters.
Q. Why is distillation required for producing certain alcoholic drinks?
Ans. Depending on the type of the raw material used for fermentation and the type of processing (with or without distillation) different types of alcoholic drinks are obtained.
Wine and beer are produced without distillation whereas whiskey, brandy and rum are produced by distillation of the fermented broth.
Distillation removes most of the water and impurities from certain alcoholic drinks. That's why for producing certain alcoholic drinks, distillation is required.
Question. 14 What are biofertiilisers? Give two examples.
Answer. Biofertiilisers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilisers are bacteria, fungi and cyanobacteria. e.g.,
- Azospihllum, Rhizobium and Azotobacter can fix atmospheric nitrogen in the soil.
- Blue-green algae like Anabaena, Nostoc, Occilatoria add organic matter to the soil and are responsible for increasing its fertility.
Find below the links to download Class 12 Biology NCERT Exemplar Solutions for chapter 10 - Microbes in Human Welfare:
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Class 12 Biology NCERT Exemplar Problems:
NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. Every year, many questions from the NCERT Exemplar are directly asked in the board exams. Also, these are the kind of questions asked in the various competitive exams and Olympiad level tests. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the boards and the competitive exams.
Here, we are providing the NCERT Exemplar Problems for Class 12 Biology chapter - Microbes in Human Welfare, in the PDF form which students may download and solve them to analyse their preparedness for the exams.
Main topics discussed in Class 12 Biology, Chapter 10- Microbes in Human Welfare, are:
- Microbes in household products
- Microbes in industrial products
- Microbes in sewage treatment
- Microbes in production of biogas
- Microbes as biocontrol agents
- Microbes as biofertilisers
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Note: Once you are done with all the NCERT Exemplar problems, refer the solutions given above in this article to check the correctness of your own solutions and know the right way to get the perfect answers.