Bihar Board - Class 12 Biology - Chapter 10: Microbes in Human Welfare Short Answer Question

Q.1. Why is secondary wastewater treatment referred to as a biological approach?

A.1. It is because microbes are involved in the breakdown of organic matter in this stage of wastewater management. Primary effluents are passed into aeration tanks where organic matter contained in it is absorbed by aerobic microbes which are later digested by anaerobic fungi and bacteria in sludge digesters.

Q.2. What is the significance of antibiotics in medicine?

A.2. They are chemical substances, produced by a few microbes that have the potential to kill or retard the growth of disease-causing microbes. They have greatly enhanced human capacity to treat deadly diseases such as plague, diphtheria, leprosy, whooping cough etc.

Q.3. List two industrially significant enzymes.

A.3.

(i) Proteases and pectinases are used in making commercial fruit and vegetable juices are clarifying agents

(ii)They are helpful in removing oily stains from the laundry as pauses are used in detergent formulations.

Q.4. The fungi mycorrhizal benefit the plant in which it harbors, How?

A.4. It absorbs phosphorus from the soil and transfers to the host cells. They also provide resistance against root pathogens to the host plants. It promotes the overall development and growth of the plant and shows tolerance to drought and salinity. Thus fungal hyphae aids in producing organic food and also procure nourishment and shelter from higher plants.

Q.5. Write about the discovery of Penicillin.

A.5. It was the first antibiotic to be discovered and is an accidental discovery. Alexander Fleming noted a mold of Penicillium growing in unlaundered culture plates of Staphylococcus. The mould hindered the growth of Staphylococcus. The antibiotic was later isolated from the fungus to be named after the mould Penicillium notatum.

Q.6. How is the restoration of good health in humans brought about by bioactive molecules of fungal origin?

A.6. Cyclosporin-A is utilized as an immunosuppressant in organ transplant patients which is generated by the fungus Trichodermapolysporum. The yeast Monococcuspurpureus produce Statins which are commercially used as agents that lower blood cholesterol levels.

Q.7. Name two alcoholic drinks produced in each of the following ways.

(i) by distillation and (ii) without distillation.

Ans:

(i) Distillation produces whisky, brandy, and rum.

(ii) Wine and beer that has not been distilled.

Q.8. Lactic Acid Bacteria (LAB) is commonly used in the conversion of milk into curd. Mention any two other functions of LAB that are useful to humans.

Ans:

(i) Vitamin B12 is synthesized by LAB in the human gut.

(ii) The presence of LAB in the human stomach inhibits the growth of dangerous microorganisms.

Q.9. How do mycorrhizae function as biofertilizers? Explain with examples.

Ans: Fungi connected with plant roots are known as mycorrhizae. Mycorrhizae are formed by many species of the Glomus genus. These fungal symbionts collect water and minerals such as phosphorus from the soil and pass them on to the plant.

Q.10. Name the bacteria which is used as a clot buster. Mention about its mode of action.

A.8. Bacterium Streptococcus secretes Streptokinase which is used as a clot buster. It has a fibrinolytic action which breaks down the clots that are formed in the blood vessels of patients that undergo myocardial infarction which prevents heart attack in such patients that can otherwise occur because of occlusion by clots.