Answer

(c) Microorganisms such as Lactobacillus and others commonly called Lactic Acid Bacteria ( $L A B$ ) grow it milk and convert into curd. During growth, the $L A B$ produce acids that coagulate and partially digest the milk proteins.

A small amount of curd added to the fresh milk as inoculum or starter contain millions of $L A B$, which at suitable temperature multiply, thus, converting milk to curd, which also improves its nutritional quality by increasing vitamin- $\mathrm{B}_{12}$.

Note In our stomach, the LAB play other options are not related with LAB bacteria beneficial role in checking disease causing microbes.

• Vitamin-C: The conversion of milk into curd by lactic acid bacteria does not significantly increase the content of vitamin-C. Vitamin-C is not typically associated with the fermentation process carried out by lactic acid bacteria.

• Vitamin-D: The process of converting milk into curd does not involve any significant increase in vitamin-D content. Vitamin-D is primarily obtained through exposure to sunlight and is not produced by lactic acid bacteria during fermentation.

• Vitamin-E: Similar to vitamin-C and vitamin-D, the content of vitamin-E does not increase as a result of the fermentation process by lactic acid bacteria. Vitamin-E is a fat-soluble vitamin and is not synthesized by these bacteria during the conversion of milk to curd.

Thinking Process

The treatment of waste water is divided into three phases-pre treatment, primary treatment and secondary treatment.

Answer

(a) Sludge is further treated by unaerobic digesters. These are large heated tanks in which its chemical decomposition is catalysed by microorganisms.

The liquid is treated by bacteria which breakdown the organic matter remaining in solution. It is then sent to oxidation ponds where heterotrophic bacteria continue the breakdown of the organics and solar UV light destroys the harmful bacteria. Chemical are not used in fhere treatments.

• Floc: Floc refers to the clumps of bacteria and particulate matter that form during the wastewater treatment process, particularly in the secondary treatment stage. It is not a method for treating sludge but rather a component of the treatment process.

• Chemicals: While chemicals can be used in some stages of wastewater treatment, they are not typically used for the treatment of sludge. The treatment of sludge primarily relies on biological processes rather than chemical ones.

• Oxidation pond: Oxidation ponds are used for the treatment of liquid effluent rather than sludge. They provide a secondary treatment stage where bacteria break down organic matter in the liquid, but they are not designed for the treatment of the solid sludge generated during wastewater treatment.

Answer

(d) 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 digestors 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 $\mathrm{CO}_{2}$ which form the biogas.

• (a) Rumen of cattle: Methanogenic bacteria are found in the rumen of cattle because it is an anaerobic environment where these bacteria help in the digestion process by breaking down cellulose and producing methane as a byproduct.

• (b) Gobar gas plant: Methanogenic bacteria are present in gobar gas plants as they play a crucial role in the anaerobic digestion of organic matter, leading to the production of biogas, which primarily consists of methane.

• (c) Bottom of water-logged paddy fields: Methanogenic bacteria are found at the bottom of water-logged paddy fields because these environments are anaerobic, allowing these bacteria to thrive and produce methane through the decomposition of organic material.

Answer

(c) Following is the list of bacteria and their commercially important products

• Option (a) is incorrect because:

  • Aspergillus niger produces Citric acid, not Butyric acid.
  • Acetobacter aceti produces Acetic acid, not Citric acid.
  • Clostridium butylicum produces Butyric acid, not Citric acid.
  • Lactobacillus produces Lactic acid, which is correctly matched.

• Option (b) is incorrect because:

  • Aspergillus niger produces Citric acid, not Butyric acid.
  • Acetobacter aceti produces Acetic acid, not Citric acid.
  • Clostridium butylicum produces Butyric acid, not Acetic acid.
  • Lactobacillus produces Lactic acid, which is correctly matched.

• Option (d) is incorrect because:

  • Aspergillus niger produces Citric acid, not Butyric acid.
  • Acetobacter aceti produces Acetic acid, not Lactic acid.
  • Clostridium butylicum produces Butyric acid, which is correctly matched.
  • Lactobacillus produces Lactic acid, not Butyric acid.

Answer

(d) Following is the column of bioactive substances and their roles

Statins produced by the yeast Monascus purpureus have been commercialised as blood cholesterol lowering agents.

Cyclosporin A, produced by the fungus Trichoderma polysporum is used as an immunosuppressive agent in organ transplant patients.

Streptokinase produced by the bacterium Streptococcus and modified by genetic engineering is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infaction leading to heart attack.

Lipases are used in detergent formulations and are helpful in removing oily stains from the laundry.

• Option (a) is incorrect:

  • A (Statin) is matched with 2 (Removal of clots from blood vessels) instead of 3 (Lowering of blood cholesterol).
  • B (Cyclosporin A) is matched with 3 (Lowering of blood cholesterol) instead of 4 (Immuno-suppressive agent).
  • C (Streptokinase) is matched with 1 (Removal of oil stains) instead of 2 (Removal of clots from blood vessels).
  • D (Lipase) is matched with 4 (Immuno-suppressive agent) instead of 1 (Removal of oil stains).

• Option (b) is incorrect:

  • A (Statin) is matched with 4 (Immuno-suppressive agent) instead of 3 (Lowering of blood cholesterol).
  • B (Cyclosporin A) is matched with 2 (Removal of clots from blood vessels) instead of 4 (Immuno-suppressive agent).
  • C (Streptokinase) is matched with 1 (Removal of oil stains) instead of 2 (Removal of clots from blood vessels).
  • D (Lipase) is matched with 3 (Lowering of blood cholesterol) instead of 1 (Removal of oil stains).

• Option (c) is incorrect:

  • A (Statin) is matched with 4 (Immuno-suppressive agent) instead of 3 (Lowering of blood cholesterol).
  • B (Cyclosporin A) is matched with 1 (Removal of oil stains) instead of 4 (Immuno-suppressive agent).
  • C (Streptokinase) is matched with 3 (Lowering of blood cholesterol) instead of 2 (Removal of clots from blood vessels).
  • D (Lipase) is matched with 2 (Removal of clots from blood vessels) instead of 1 (Removal of oil stains).

Answer

(b) The primary treatment of waste water involves physical removal of both larger and small particles (stable particles) from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration.

Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent is taken for the secondary treatment.

The primary treatment does not remove the dissolved impurities (a), toxic substances (c) and harmful bacteria (d).

• (a) The primary treatment does not remove dissolved impurities because it focuses on the physical removal of solid particles through filtration and sedimentation, not on the chemical or biological processes needed to eliminate dissolved substances.
• (c) The primary treatment does not remove toxic substances as it is designed to handle physical contaminants. Toxic substances often require advanced treatment processes such as chemical neutralization or biological degradation.
• (d) The primary treatment does not remove harmful bacteria because it does not involve disinfection or biological treatment processes. The removal of harmful bacteria typically occurs during secondary or tertiary treatment stages.

Answer

(d) BOD (Biochemical Oxygen Demand) refers to the amount of the oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.

Other options (a) (b) and (c) are incorrect.

• Option (a) is incorrect because BOD specifically measures the amount of oxygen consumed by bacteria to decompose biodegradable organic matter, not the total organic matter.
• Option (b) is incorrect because while BOD does relate to biodegradable organic matter, it is specifically measured by the oxygen consumption during the decomposition process, not by directly measuring the biodegradable organic matter itself.
• Option (c) is incorrect because BOD measures oxygen consumption, not oxygen evolution. Oxygen evolution refers to the production of oxygen, which is not what BOD quantifies.

Answer

(a) Wine and beer are produced without distillation whereas whisky, brandy and rum are produced by distillation of the fermented broth.

• Whisky is produced by distillation of the fermented broth.
• Rum is produced by distillation of the fermented broth.
• Brandy is produced by distillation of the fermented broth.

Answer

(c) Cattle dung is used for the production of biogas, commonly called gobar gas.

The technology of biogas production from cowdung was developed in India mainly due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC). Other options (a), (b) and (d) did not play any role is this.

• Gas Authority of India (a) is incorrect because it primarily focuses on the distribution and marketing of natural gas and related products, not on the development of biogas technology.
• Oil and Natural Gas Commission (b) is incorrect because its main role is in the exploration and production of oil and natural gas, not in the development of biogas technology.
• Indian Oil Corporation (d) is incorrect because it is mainly involved in the refining, transportation, and marketing of petroleum products, not in the development of biogas technology.

Answer

(b) Trichoderma species are free-living fungi that are very common in soil. They are effective biocontrol agents of several soil borne plant pathogens other options are incorrect

• (a) Trichoderma is not used for killing insects; it is primarily known for its role in controlling plant diseases.
• (c) Trichoderma does not control butterfly caterpillars; it is a fungus that targets soil-borne plant pathogens.
• (d) While some fungi do produce antibiotics, Trichoderma is mainly recognized for its biocontrol properties against plant diseases rather than antibiotic production.

Thinking Process

During secondary treatment, the primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures).

Answer

(b) Activated sludge microorganisms need oxygen as they oxidise wastes to obtain energy for growth. Insufficient oxygen will slow down or kill off aerobic microorganisms, make facultative organisms work less efficiently and ultimately lead to the breakage of flocs.

It will also result in the production of the foul-smelling byproducts of anaerobic decomposition. So, sufficient oxygen must always be maintained in the aeration tank to ensure complete waste stabilisation.

• (a) I will slow down the rate of degradation of organic matter: While it is true that reduced oxygen availability will slow down the rate of degradation of organic matter, this option does not fully capture the more severe consequences such as the death of bacteria and breakage of flocs, which are critical aspects of the process.

• (c) Flocs would increase in size as anaerobic bacterial would grow around flocs: This is incorrect because anaerobic bacteria do not typically grow around flocs in a way that would increase their size. Instead, the lack of oxygen would lead to the death of aerobic bacteria and the eventual breakage of flocs, not their growth.

• (d) Protozoa would grow in large numbers: Protozoa generally thrive in well-oxygenated environments. Reduced oxygen availability would not support the growth of protozoa; instead, it would lead to conditions that favor anaerobic bacteria, which do not support protozoa proliferation.

Answer

(d) Fungi form symbiotic association with the roots of higher plants called mycorrhiza (VAM) e.g, Glomus.

The fungal hyphae symbiont in these associations absorb phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and draught, and an overall increase in plant growth and development. Mycorrhiza does not help the host plant in increasing its resistance to insects.

• (a) Mycorrhiza enhances the host plant’s phosphorus uptake capacity because the fungal hyphae absorb phosphorus from the soil and pass it to the plant.
• (b) Mycorrhiza increases the host plant’s tolerance to drought by improving water absorption and retention through the extensive network of fungal hyphae.
• (c) Mycorrhiza enhances the host plant’s resistance to root pathogens by forming a protective barrier around the roots and producing antimicrobial compounds.

Answer

(d) Pseudomonas is a dentrifying bacteria, which convert ammonia and nitrates into free nitrogen, i.e., these denitrifying bacteria are responsible to liberate free nitrogen in the environment through nitrogen in the environment through nitrogen cycle.

Other options (a), (b) and (c) show nitrogen fixing organisms.

Azospirillum and Azotobacter are free-living bacteria, which absorb free nitrogen from soil, air and convert it into salts of nitrogen like amino acids and enrich soil nutrients

Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments, many of which can fix atmospheric nitrogen, e.g., Nostoc, Anabaena Oscillatoria, etc.

• Anabaena is a nitrogen-fixing organism because it is a type of cyanobacteria that can fix atmospheric nitrogen.
• Nostoc is a nitrogen-fixing organism because it is also a type of cyanobacteria that can fix atmospheric nitrogen.
• Azotobacter is a nitrogen-fixing organism because it is a free-living bacterium that absorbs free nitrogen from the soil and air and converts it into nitrogen compounds that enrich soil nutrients.

Thinking Process

Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.

Answer

(c) The large holes in ‘Swiss cheese’ are due to production of a large amount of $\mathrm{CO}_{2}$ by a bacterium named Propionibacterium sharmanii. Other options are in correct.

• (a) A machine: Swiss cheese holes are not made by a machine; they are a natural result of bacterial activity during the cheese fermentation process.
• (b) A bacterium that produces methane gas: The bacterium involved in making Swiss cheese holes produces carbon dioxide, not methane gas.
• (d) A fungus that releases a lot of gases during its metabolic activities: The holes in Swiss cheese are not caused by a fungus but by a specific bacterium, Propionibacterium sharmanii, which produces carbon dioxide.

Answer

(c) The raw material for biogas production is excreta (dung) of cattle. The biogas plant consists of a concrete tank (10-15 feet deep) in which bio-wastes are collected and a slurry of dung is fed.

A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to the microbial activity. Methanobacterium in the dung act on the bio-wastes to produce bio-gas. The gas produced is supplied to nearby houses by an outlet. Through another outlet, the spent slurry is removed to be used as manure.

• (a) burnt: Burning the residue would waste valuable nutrients that can be used to enrich soil. Additionally, burning can contribute to air pollution and is not an environmentally sustainable practice.

• (b) burried in land fills: Burying the residue in landfills would not utilize its potential as a nutrient-rich fertilizer. It would also contribute to landfill waste, which is not an efficient or sustainable waste management practice.

• (d) used in civil construction: The residue from methane production is primarily organic and nutrient-rich, making it unsuitable for use in civil construction. It lacks the structural properties required for construction materials.

Answer

(a) In the digesters (during secondary treatment of waste water), heterotrophic microbes (methanogens) anaerobically digest bacteria and fungi in sludge producing mixture of gases such as methane, hydrogen sulphide and $CO_{2}$ which form the biogas. The $O_{2}$ is not produced by methanogens.

• Methanogens produce methane as a byproduct of their metabolic processes, making option (b) incorrect.
• Methanogens produce hydrogen sulphide during the anaerobic digestion process, making option (c) incorrect.
• Methanogens produce carbon dioxide as part of the biogas mixture during the digestion process, making option (d) incorrect.

Answer

(a) In the secondary treatment of waste water, when BOD of sewage has reduced, the effluent is passed into setting tank. Here, the bacterial flocs settle and the sediment is called activated sludge.

A small part of the sludge is used as an inoculum in the aeration tank and the remaining part is passed into large tanks called anaerobic sludge digesters. That’s why activated sludge should have the ability to settle quickly.

• (b) absorb pathogenic bacteria present in waste water while sinking to the bottom of the settling tank: Activated sludge is primarily used to reduce organic matter and BOD in wastewater. While it may incidentally capture some pathogens, its primary function is not to absorb pathogenic bacteria.

• (c) be discarded and anaerobically digested: Only a portion of the activated sludge is discarded and sent for anaerobic digestion. The main purpose of activated sludge is to be recycled back into the aeration tank to maintain the microbial population necessary for the treatment process.

• (d) absorb colloidal organic matter: The primary role of activated sludge is to break down organic matter through microbial activity, not merely to absorb it. The settling ability is crucial for separating the biomass from the treated water, not for absorbing colloidal organic matter.

Answer

(b)

Ladybird is the very familiar beetle with red and black markings, used to get rid of Aphids.

Fungi form symbiotic association, with the roots of higher plants called mycorrhiza, e.g., Glomus.

A biological control being developed for use in the treatment of plant disease is the fungus Trichoderma.

Methanogens, particularly Methanobacterium, are found in cowdung. These bacteria grow anaerobically on cellulosic material and produce large amount of methane along with $CO_{2}$ and $H_{2}$.

• Option (a) is incorrect:

  • A. Lady bird (2. Trichoderma): Ladybirds are not associated with Trichoderma; they are known for controlling aphids.
  • C. Biological control (3. Aphids): Biological control refers to using natural predators or agents like Trichoderma, not aphids.
  • D. Biogas (1. Methanobacterium): This is correct, but the other mismatches make the option incorrect.

• Option (c) is incorrect:

  • A. Lady bird (4. Glomus): Ladybirds are not associated with Glomus; they are known for controlling aphids.
  • B. Mycorrhiza (1. Methanobacterium): Mycorrhiza is associated with Glomus, not Methanobacterium.
  • C. Biological control (2. Trichoderma): This is correct, but the other mismatches make the option incorrect.
  • D. Biogas (3. Aphids): Biogas production is associated with Methanobacterium, not aphids.

• Option (d) is incorrect:

  • A. Lady bird (3. Aphids): This is correct.
  • B. Mycorrhiza (2. Trichoderma): Mycorrhiza is associated with Glomus, not Trichoderma.
  • C. Biological control (1. Methanobacterium): Biological control is associated with Trichoderma, not Methanobacterium.
  • D. Biogas (4. Glomus): Biogas production is associated with Methanobacterium, not Glomus.

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 $\mathrm{CO}_{2}$ by a bacterium named Propionibacterium sharmanii.

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.

Fermentors

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.

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.

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 (IPM) Programme or when an ecologically sensitive area is being treated.

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.

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.

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.

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.

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.

Answer

Escherichia coli strain RY 13 is the source organism for Eco RI.

Answer

$B t$ 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.

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.

Answer

Roquefort cheese is formed by ripening of cheese with the fungi Penicillium roqueforti for a particular flavour.

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.

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.

Answer

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

Answer

Tobacco mosaic virus is a rod-shaped virus. This is the first plant virus to be discovered.

Answer

Methanogens (Methanobacterium), anaerobically break down cellulosic material to produce $CO_{2}$ and $H_{2}$, and are found in

(i) Anaerobic sludge in sewage treatment plants.

(ii) Rumen (a part of stomach) of cattles, thus providing nutrition to cattles.

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 $\mathrm{CO}_{2}$.

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.

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.

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.

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.

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.

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.

Answer

Some bioactive molecules of fungal origin have been reported for their role in restoring good health of humans.

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.

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.

Answer

The chemical nature of biogas is $CH_{4}, CO_{2}, H_{2}$ and a trace amount of $H_{2} ~S$ Methanobacteria, a type of methanogen is employed for biogas production.

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.

Answer

A broad spectrum antibiotic is one which can inhibit the growth of both Gram positive and Gram negative bacteria

e.g.,Tetracyclines, phenicols, fluoroquinolones, third-generation and fourth-generation antibiotivcs is cephalosporins.

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.

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.

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.

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.

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.

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.

A typical biogas plant

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.

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.

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.

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 $L A B$ 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- $B_{12}$.

(ii) Checks disease-causing microbes in stomach.