Class 12 VBQs Biology Microbes in Human Welfare

VBQs For Class 12

Very Short Answer Type Questions

Question.  Why does ‘Swiss cheese’ have big holes?
– Thinking Process
Different varieties of bakery like bread and cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.
Answer. The large holes in ‘Swiss cheese’ are due to production of a large amount of CO2 by a bacterium named Propionibacterium sharmanii.

Question. What are fermentors?
Answer. For large scale production of biotechnological products, e.g., antibiotics, beverages) in industries, microbes are grown in very large vessels called fermentors or bioreactors.

Class 12 VBQs Biology Microbes in Human Welfare

Question.  Name a microbe used for statin production. How do statins lower blood cholesterol level?
Answer. Statins are bioactive molecules, produced by the yeast Monascus purpureus. These bioactive molecules have been commercialised as blood-cholesterol lowering agents. It acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol.

Question.  Why do we prefer to call secondary waste water treatment as biological treatment?
Answer. 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.

Question.  What for nucleopolyhedro viruses are being used now a-days?
Answer. Several methods of biological control are being used in the pest management to keep the pollution-free environment and yield clean, non-toxic and good quality products for human consumption.
Baculoviruses are a group of viruses used as biological control agents that occur naturally and are specific to some insects. Most of the baculoviruses belong to the genus Nucleopolyhedro virus.
These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications. They have been shown to have no negative impacts on plants, mammals,birds fish or even on non-target insects.
This is especially desirable when beneficial insects are being conserved to aid in an overall Integrated Pest Management

Question.  How has the discovery of antibiotics helped mankind in the field of medicine?
Answer. Antibiotics produced by microbes are regarded as one of the most significant discoveries of the twentieth century and have greatly contributed towards the welfare of the human society.
Anti is a Gk. word that means ‘against’ and bio means ‘life’, together they mean ‘against life’ (in the context of disease causing organisms); whereas with reference to human beings, they are ‘pro life’ and not against. Antibiotics are chemical substances, which are produced by some microbes and can kill or retard the growth of other (disease-causing) microbes. Antibiotics have greatly improved our capacity to treat deadly diseases such as plague, whooping cough (Kali khansi), diphtheria (Gal ghotu) and leprosy (Kusht rog), which had killed millions all over the globe. Today, we can not imagine a world without antibiotics.

Question.  Why is distillation required for producing certain alcoholic drinks?
Answer. 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 increases the alcohol content in alcoholic drinks. That’s why for producing certain alcoholic drinks, distillation is required.

Question.  Write the most important characteristic that Aspergillus niger, Clostridium butylicum, and Lactobacillus share.
Answer. Their common characteristic is that they produce organic acids as part of their metabolism and are therefore, used for commercial and industrial production of the same.
(i) Aspergillus niger (a fungus) for citric acid.
(ii) Clostridium butylicum (a bacterium) for butyric acid.
(iii) Lactobacillus (a bacterium) for lactic acid.

Question.  What would happen if our intestine harbours microbial flora exactly similar to that found in the rumen of cattle?
Answer. If our intestine harbors microbial flora exactly similar to that found in the rumen of cattle, we would be able to digest the cellulose present in our foods because the microbes present in the rumen (a part of stomach) of cattle, collectively called methanogens, are capable of digesting cellulose as they have cellulase enzyme.

Question.  Give any two microbes that are useful in biotechnology.
Answer. Two microbes that are useful in biotechnology are
(i) Bacillus thuringiensis a gene isolated from this bacterium is introduced in cotton plants to make them able to kill butterfly caterpillars.
(ii) Escherichia coli is a bacterium that is used in many biotechnology procedures. Their plasmid is used as vector to introduce foreign DNA segment in desired organisms.

Question.  What is the source organism for Eco RI, restriction endonuclease?
Answer. Escherichia coli strain RY 13 is the source organism for Eco RI.

Question.  Name any genetically modified crop.
Answer. Bt cotton is a genetically modified plant that has been modified to resist attack by insect pests e.g., cotton ball worm). These are developed by introducing a gene from Bacillus thuringiensis which produces toxin is plants which is lethat to insects.

Question.  Why are blue-green algae not popular as biofertilisers?
Answer. Blue-green algae add organic matter to the soil and increase its fertility still these are not popular as biofertilisers. This is due to several constraints that limit the application or
implementation of the biofertiliser technology. The constraints may be environmental, technological, infrastructural, financial, unawareness, quality, marketing etc.

Question.  Which species of Penicillium produces Roquefort cheese?
Answer. Roquefort cheese is formed by ripening of cheese with the fungi Penicillium roqueforti for a particular flavour.

Question. Name the states involved in Ganga Action Plan.
Answer. Ganga runs from Gangotri in the Himalayas to Ganga Sagar in the Bay of Bengal. The Ganga Action Plan (GAP) was a program launched in April 1986 in order to reduce the pollution load on the River Ganga.
The states involved in Ganga Action Plan are— Uttaranchal, UP, Bihar, West Bengal and Jharkhand.

Class 12 VBQs Biology Microbes in Human Welfare

Question.  Name any two industrially important enzymes.
Answer. (i) Lipases are used in detergent formulations and are helpful in removing oily stains from the laundry.
(ii) Pectinases and proteases that are used as clarifying agents in making commercial fruit and vegetable juices.

Question.  Name an immune immunosupressive agent?
Answer. Cyclosporin-A, produced by the fungus Trichoderma polysporum is used as an immunosupressive agent in organ transplant patients.

Question.  Given an example of a rod-shaped virus.
Answer. Tobacco mosaic virus is a rod-shaped virus. This is the first plant virus to be discovered.

Question.  What is the group of bacteria found in both the rumen of cattle and sludge of sewage treatment?
Answer. Methanogens (Methanobacterium), anaerobically break down cellulosic material to
produce CO2 and H2, and are found in
(i) Anaerobic sludge in sewage treatment plants.
(ii) Rumen (a part of stomach) of cattles, thus providing nutrition to cattles.

Question.  Name a microbe used for the production of swiss cheese.
Answer. Cheese is formed by partial degradation of milk by different microorganisms. Swiss cheese is formed by the bacterium Propionibacterium sharmanii. Its characteristic feature is formation of large holes due to production of large amount of CO2.

Short Answer Type Questions

Question. Why are flocs important in biological treatment of waste water?
Answer. Flocs are masses of bacteria associated with fungal filaments that form mesh like structures. These are important in biological treatment of waste water, as they help in digestion of organic matter, remove pathogens and release nutrients in the sewage effluent.

Question.  How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?
Answer. Bacillus thuringiensis produces an are endotoxin which, when ingested and released in the gut of the larvae of insect pest disrupts the insect gut lining thereby killing them.

Question.  How do mycorrhizal fungi help the plants harbouring them?
Answer. The mycorrhizal fungi absorb phosphorus from the soil and transfer them to the host cells.
They also impart resistance to host plants against root pathogens. They also show tolerance to salinity and draught as well as increases overall growth and development of plant.
Hence, fungal hyphae help in synthesising organic food and also recieve/get shelter and nourishment from the higher plant.

Question.  Why are cyanobacteria considered useful in paddy fields?
Answer. Cyanobacteria like Anabaena, Nostoc, Oscillatoria serve as an important biofertiliser in paddy fields as they fix atmospheric nitrogen and add organic matter to the soil and
increase its fertility.

Question.  How was penicillin discovered?
Answer. Penicillin was the first antibiotic to be discovered and it was a chance discovery. Sir,Alexander Fleming observed that in unwashed culture plates of Staphylococcus, a mould
Penicillium was growing.
This mould inhibited the growth of Staphylococcus. Later the antibiotic was isolated from this fungus and named penicillin after the mould Penicillium notatum.

Question.  Name the scientists who were credited for showing the role of penicillin as an antibiotic?
Answer. Penicillin was discovered by Sir Alexander Fleming while, working on Staphylococci bacteria. However, its full potential as an effective antibiotic was established much later by
Ernst Chain and Howard Florey.
This antibiotic was extensively used to treat American soldiers wounded in World War II.
Fleming, Chain and Florey were awarded the Nobel Prize in 1945, for this discovery.

Question.  How do bioactive molecules of fungal origin help in restoring good health of humans?
Answer. Some bioactive molecules of fungal origin have been reported for their role in restoring good health of humAnswer.Cyclosporin-A, that is used as an immuno-suppressive agent in organ transplant patients is produced by the fungus Trichoderma polysporum. Statins produced by yeast Monococcus purpureus have been commercialised as blood cholesterol lowering agents.

Question.  What roles do enzymes play in detergents that we use for washing clothes? Are these enzymes produced from some unique microorganisms?
Answer. Enzymes like lipases are used in detergent which formulations, cause breakdown of oils and thus help in removing oily and greasy stains from the clothes in laundry.
These are obtained from Candida lipolytica and Geotrichum candidum.

Question.  What is the chemical nature of biogas. Name an organism which is involved in biogas production?
Answer. The chemical nature of biogas is CH4, CO2, H2 and a trace amount of H S 2 Methanobacteria, a type of methanogen is employed for biogas production.

Question.  How do microbes reduces the environmental degradation causes by chemicals?
Answer. Chemicals from fertilisers and pesticides are highly toxic to human beings and animals alike, and have been polluting our environment. To reduce the environmental degradation caused by chemicals, microbes can be used both as fertilisers and pesticides and can be called biofertilisers and biopesticides, respectively.Microbes are used as biofertilisers to enrich the soil nutrients, e.g., Rhizobium, Azotobacter,
Azospirillum, etc., which can fix atmospheric nitrogen in the soil. Bacillus thuringiensis
bacteria act as biopesticides to control the growth of insect pests.
Trichoderma, fungal species, is effective bicontrol agent of several plant pathogens.
Baculovirus used as biological control agents in genus Nucleopolyhedrovirus are excellent for species-specific, narrow spectrum insecticidal applications.

Question.  What is a broad spectrum antibiotic? Name one such antibiotic.
Answer. A broad spectrum antibiotic is one which can inhibit the growth of both Gram positive and
Gram negative bacteriae.g.,Tetracyclines, phenicols, fluoroquinolones, third-generation and fourth-generation
antibiotivcs is cephalosporins.

Question. What are viruses parasitising bacteria called? Draw a well labelled diagram of the same.
– Thinking Process
The word phage means ‘to eat’.
Answer. Viruses parasitising bacteria are called bacteriophages. These viruses do not actually eat bacteria. They infect and replicate within the bacteria.

Class 12 VBQs Biology Microbes in Human Welfare

Question.  Which bacterium has been used as a clot buster? What is its mode of action?
Answer. The bacterium Streptococcus that produces streptokinase is used as a ‘clot buster’.
This enzyme has a fibrinolytic action that breaks down the clots formed in the blood vessels of patients who have undergone myocardial infarction. This prevents heart attack in these patients that can otherwise occur because of occlusion by the clots.

Question.  What are biofertilisers? Give two examples.
Answer. Biofertilisers are organisms that enrich the nutrient quality of the soil. The main source of biofertilizers are bacteria, fungi and cyanobacteria. e.g.,
(i) Azospirillum, Rhizobium and Azotobacter can fix atmospheric nitrogen in the soil.
(ii) Blue-green algae like Anabaena, Nostoc, Occilatoria add organic matter to the soil and responsible for increase its fertility.

Long Answer Type Questions

Question.  Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of wastewaters rich in organic matter.
Answer. Aerobic degradation is more important as naturally occurring aerobic and facultative microbes (bacteria, fungi, Protozoa and others) in the waste water can rapidly oxidise soluble organic and nitrogenous compounds.
Mechanical addition of oxygen makes the process faster and most of the pathogenic content of the effluent is removed.

Question.  (a) Discuss about the major programs that the Ministry of Environment and Forests, Government of India, has initiated for saving major Indian rivers from pollution.
(b) Ganga has recently been declared the national river. Discuss, the implication with respect to pollution of this river.
Answer. (a) Prior to year 1985, only few cities and towns had sewage treatment plants. Most of the sewage water of urban as well as rural areas was discharged directly into rivers resulting in their pollution. Importance of microbial treatment of sewage was then realised and more sewage treatment plants were established.Still, they are not sufficient due to increasing urbanisation and production of much larger quantities of sewage as compared to earlier days. Realising the importance of microbes in pollution control, the Ministry of Environment and forests has initiated development of sewage treatment plants under the National River Conservation Authority.
e.g., Ganga Action Plan (GAP) and Yamuna Action Plan (YAP) to save these major rivers of our country from pollution.
(b) The Ganga Action Plan (GAP) was a program launched in April, 1986 in order to reduce the pollution load on the river. A steering committee of the National River Conservation
Authority reviewed the progress of the GAP and necessary correction.Scientists and religious leaders have speculated on the causes of the river’s apparent self-purification effect, in which water-borne diseases such as dysentery and cholera are eliminated by killing thin caused organisms. Thus preventing large-scale epidemics.
Some studies have reported that the river retains more oxygen than is typical for comparable rivers; this could be a factor leading to fewer disease agents being present in the water.
National River Ganga Basin Authority (NRGBA) was established by the Central Government of India, on 20th February 2009 Under Section 3(3) of The Environment Protection Act, 1986. It also declared Ganges as the National, river of India.

Question. Draw a diagrammatic sketch of biogas plant and label its various components given below gas holder, sludge chamber, digester, dung + water chamber.
Answer. The raw material for biogas production is excreta (dung) of cattle. The biogas plant has a
concrete tank (10-15 feet deep) in which bio-wastes and slurry of dung is collected.

Class 12 VBQs Biology Microbes in Human Welfare

The tank has a floating cover which rises on production of gas in the tank.Methanobacterium in the dung act on the bio-wastes to produce biogas. The gas produced is supplied to nearby houses by an outlet. Through another outlet, the spent slurry is removed to be used as fertiliser. Biogas is used as fuel for cooking and lighting.

Question.  Describe the main ideas behind the biological control of pests and diseases.
Answer. It’s a natural and eco-friendly concept. If employs the use of organisms to control the population of pathogens and pests in an ecosystem. Classical examples are Trichoderma which is antagonist, i.e., against many soil borne plant pathogens.
Similarly, Penicillium inhibits the growth of Staphylococcus and therefore has been successfully used in the production of penicillin antibiotic to control many human bacterial
pathogens. Bacillus thuringiensis acts as biopesticide to control insect.Baculovirus used as biological control agents in genus Nucleo-polyhedrovirus are excellent for species-specific-narrow spectrum insecticidal application. The overall biological control of pest is considered much more beneficial in an ecological sensitive area.

Question.  (a) What would happen if a large volume of untreated sewage is discharged into a river?
(b) In what way anaerobic sludge diagestion is important in sewage treatments?
Answer. (a) If untreated sewage is discharged directly into rivers it will lead to serious pollution of the waters with organic matter and pathogenic bacteria, Protozoa and many other diseaser.This water, if used, will cause outbreaks of water borne diseases.
(b) In anaerobic sludge digestion, anaerobic bacteria, digest the aerobic bacteria and the fungi in the sludge and the remaining organic matter.
During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide. These gases (biogas) can be used as source of energy as it is inflammable.

Question.  Which type of food would have lactic acid bacteria? Discuss their useful application.
Answer. The most common food item that are curd, and yoghurt contain Lactic Acid Bacteria (LAB) of Lactobacillus species. Curd is formed by adding a small amount of curd to milk, which acts as a starter. Microbes present in starter multiply at suitable temperature and convert milk into curd.
Acids released by LAB during the growth coagulate and partially digest milk protein, casein thus increases the digestibility of milk protein.
Application of LAB
(i) Improves nutritional quality of milk by increasing vitamin-B12.
(ii) Checks disease-causing microbes in stomach.