Class 12 Biology Important Chapter 10 Microbes in Human Welfare

Class 12 Biology Important Chapter 10 Microbes in Human Welfare Solutions English Medium As Per The New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters ASSEB Class 12 Biology Important Solutions in English and select need one. AHSEC Class 12 Biology Additional Notes Download PDF. HS 2nd Year Biology Additional Solutions.

Class 12 Biology Important Chapter 10 Microbes in Human Welfare

Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. ASSEB Class 12 Biology Additional Question Answer are part of All Subject Solutions. Here we have given HS 2nd Year Biology Important Solutions English Medium for All Chapters, You can practice these here.

Microbes in Human Welfare

Chapter: 10

IMPORTANT QUESTION AND ANSWER

Answer the Following Question: 

1. Who discovered penicillin?

Ans: Alexander Fleming.

2. What is activated sludge?

Ans: Sediment of flocs formed during secondary sewage treatment.

3. Which Indian organization developed biogas technology?

Ans: IARI and KVIC.

4. What does Bt-cotton stand for?

Ans: Cotton genetically modified to express Bacillus thuringiensis toxin gene.

5. How do lactic acid bacteria help in curd formation?

Ans: Lactic acid bacteria (LAB), mainly Lactobacillus, convert lactose (milk sugar) into lactic acid. This acid coagulates milk proteins and converts milk into curd. LAB also increase the nutritional quality of curd by synthesizing vitamin B₁₂ and suppress harmful microbes in the gut.

6. Name four fermented food items and the microbes used in them.

Ans: (i) Curd – Lactobacillus.

(ii) Bread – Saccharomyces cerevisiae (baker’s yeast).

(iii) Toddy – Wild yeast and bacteria.

(iv) Swiss cheese – Propionibacterium sharmanii.

7. What is Penicillin? Who discovered it?

Ans: Penicillin is the first antibiotic discovered by Alexander Fleming in 1928. It was obtained from the fungus Penicillium notatum. Later, Chain and Florey developed it for medical use. It kills gram-positive bacteria and was used during WWII to treat wounded soldiers.

8. What is the role of Trichoderma polysporum and Monascus purpureus?

Ans: (i) Trichoderma polysporum produces Cyclosporin A, an immunosuppressant used in organ transplant patients.

(ii) Monascus purpureus produces Statins, which inhibit cholesterol synthesis and are used to lower blood cholesterol.

9. Define BOD. What does a high BOD value indicate?

Ans: BOD (Biochemical Oxygen Demand) is the amount of oxygen required by aerobic microbes to decompose organic matter in a water sample.

A high BOD indicates high organic pollution and greater microbial activity, hence more polluting potential.

10. Write a short note on the primary treatment of sewage.

Ans: Primary treatment involves physical removal of large and small solid particles from sewage by filtration and sedimentation. Floating debris and grit are removed. Solids settle as primary sludge, and the remaining liquid is passed to the secondary treatment stage.

11. What is the role of cyanobacteria in paddy fields?

Ans: Cyanobacteria like Anabaena, Nostoc, and Oscillatoria fix atmospheric nitrogen in paddy fields, increase organic matter, and enhance soil fertility. They act as biofertilisers.

12. Give the advantages of using biocontrol agents in agriculture.

Ans: (i) Eco-friendly and non-toxic.

(ii) Do not harm non-target organisms.

(iii) Maintain ecological balance.

(iv) Prevent resistance buildup unlike chemical pesticides.

(v) Examples: Bt, Trichoderma, Nucleopolyhedrovirus.

13. What are baculoviruses? Mention one of their advantages.

Ans: Baculoviruses are DNA viruses (e.g., Nucleopolyhedrovirus) that infect arthropods. They are species-specific biocontrol agents and do not affect humans, plants, or beneficial insects, making them ideal for integrated pest management.