PSEB 12th Class Biology Important Questions Chapter 10 Microbes in Human Welfare

Punjab State Board PSEB 12th Class Biology Important Questions Chapter 10 Microbes in Human Welfare Important Questions and Answers.

PSEB 12th Class Biology Important Questions Chapter 10 Microbes in Human Welfare

Very short answer type questions

Question 1.
Give an example of a rod-shaped virus,
Answer:
Tobacco mosaic virus.

Question 2.
Which one of the following is the baker’s yeast used in fermentation?
Saccharum barberi, Saccharomyces cerevisiae, Sonalika.
Answer:
Saccharomyces cerevisiae.

Question 3.
Why is distillation required for producing certain alcoholic drinks? [NCERT Exemplar]
Answer:
Distillation increases the alcohol content in alcoholic drinks.

Question 4.
What would have happened if antibiotics were not discovered? s [NCERT Exemplar]
Answer:
If antibiotics were not discovered, bacterial and fungal diseases would , not have been controllable.

Question 5.
Give the scientific name of the source organism from which the first antibiotic was produced.
Answer:
Penicillium notatum.

Question 6.
Write the scientific name of the microbe used for fermenting
malted cereals and fruit juices.
Answer:
Saccharomyces cerevisiae.

Question 7.
Name a microbe used for statin production. How do statins lower blood cholesterol level? [NCERT Exemplar]
Answer:
Monascus purpureus is used for statin production. Statins lower blood cholesterol level by competitively inhibiting the enzyme responsible for . synthesis of cholesterol.

Question 8.
Name the group of organisms and the substrate they act on to produce biogas.
Answer:
Name of the group of organisms – Methanogens.
Substrate – Cellulosic material/cow dung/agriculture waste.

Question 9.
Name any genetically modified crop. [NCERT Exemplar]
Answer:
Bt. cotton.

Question 10.
What are Nucleopolyhedroviruses being used for nowadays? [NCERT Exemplar]
Answer:
Nucleopolyhedroviruses are used for the biological control of insect pests.

Question 11.
Which of the following is a free-living bacteria that can fix nitrogen in the soil?
Answer:
Spirulina, Azospirillum, Sonalika Ans. Azospirillum.

Question 12.
Mention the role of cyanobacteria as a biofertiliser.
Answer:
It is a biological organism that fixes atmospheric nitrogen.

Short answer type questions

Question 1.
Name the source of streptokinase. How does this bioactive molecule function in our body?
Answer:
Source: Streptococcus.
Streptokinase is a clot buster, i.e., it removes clot from the blood vessels of patients who had a heart attack.

Question 2.
Why are some molecules called bioactive molecules? Give two examples of such molecules.
Answer:
This is because microbes like bacteria or fungi are used in their production, e.g.,
Citric acid – Acetic acid
Butyric acid – Lactic acid
Ethanol – Lipases
Streptokinase – Cyclosporin A (Any two)

Question 3.
Given below is a list of six microorganisms. State their usefulness to humans.
(a) Nucleopolyhedrovirus
(b) Saccharomyces eerevisiae
(c) Monascus purpureus
(d) Trichoderma polysporum
(e) Penicillium notatum
(f) Propionibacterium sharmanii
Answer:
(a) Nucleopolyhedrovirus: Biocontrol agents for pest.
(b) Saccharomyces eerevisiae: Bread making and alcohol/wine production.
(c) Monascus purpureus: Statins-blood cholesterol lowering agents.
(d) Trichoderma polysporum: Cyclosporin-A, immune suppressing medicine in organ transplant patients.
(e) Penicillium notation: Penicillin, a anti-bacterial antibiotic.
(f) Propionibacterium sharmanii: Preparation of Swiss cheese with large holes.

Question 4.
What are methanogens? How do they help to generate biogas?
Or What are methanogens? Nameanimals they are present in and the role they play there?
Answer:
Methanogens are the bacteria which are grown anaerobically on cellulose material and produce large amount of methane along with CO₂ and H₂S.

Methanobacterium is the common methanogen found in the anaerobic sludge during sewage treatment. These bacteria are also present in the rumen (a part of the stomach) of cattle. In rumen, these bacteria help in the breakdown of cellulose present in the food of cattle. Hence, they play an important role in the nutrition of cattle.

The excreta (dung) of cattle commonly called gobar is rich in cellulosic material and these bacteria. Dung can be used for generation of biogas commonly called Gobar gas.
Note: Human beings are unable to digest cellulose in the vegetable food because the enzyme cellulose is not secreted. Cellulose forms the roughage in the body.

Question 5.
(a) How do organic fanners control pests? Give two examples, (b) State the difference in their approach from that of conventional pest control methods.
Answer:
(a) Organic farmers control pests by use of biological methods (biocontrol). They use natural enemy of the pest such as predator or parasite, by introducing these biocontrol agents in the field.
Example:
(i) Ladybird – a beetle and dragonflies are used to get rid of aphids and mosquitoes.
(ii) Bacillus thuringiensis, a bacterium is introduced into crop plants to control butterflies and caterpillars.

(b) In conventional pest control, toxic chemical pesticides are used which are expensive, persist, pollute the environment and kill both the target and non-target pests (beneficiary and parasitic insects which depend upon pests).

Long answer type questions

Question 1.
Explain the process of sewage water treatment before it can be discharged into natural water bodies. Why is this treatment essential?
Or Explain the different steps involved in sewage treatment before it can be released into natural water bodies.
Or Secondary treatment of the sewage can also called biological treatment. Justify this statement and explain the process.
Or Explain the different steps involved during primary treatment phase of sewage.
Or Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) in it.
Answer:
Sewage water treatment involves two steps:
(i) Primary treatment and
(ii) Secondary treatment.

(i) Primary Treatment: It is a physical process of removing small and large particles through filtration and sedimentation. Firstly, the sewage is passed through the wire mesh of screens of sequentially smaller pore sizes to remove floating objects (like polythene bags etc). Then the grit is sedimented by passing the sewage into a grit chamber. The sewage is then kept in settling tanks, where the suspended materials settle down to form the primary sludge. The effluent is then taken for secondary treatment.

(ii) Secondary Treatment: It is a biological process by the heterotrophic bacteria naturally present in the sewage. The primary effluent is passed into large aeration tanks where it is constantly agitated and air is pumped out. This causes the rapid growth of aerobic microbes into ‘floes’ which consume the organic matter of sewage leading to the reduction in biochemical oxygen demand (BOD). After the significant reduction in BOD of sewage, the effluent is passed into settling tanks where floes are sedimented leading to the formation of activated sludge. A part of this activated sludge is used as inoculum which is pumped back into the aeration tanks. The major part of this sludge is pumped into anaerobic sludge digesters, where its digestion occurs by the anaerobic bacteria producing methane, hydrogen sulphide and carbon dioxide. These gases form biogas. After secondary treatment the effluent is released into natural water bodies like streams and rivers.