31 Years NEET Previous Year Questions: Microbes in Human Welfare Free MCQ

• Alcoholic beverages are classified into two main categories: distilled and non-distilled beverages.
• Depending on the type of 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 whisky, brandy and rum are produced by distillation of the fermented broth.
• Distillation is a crucial process in the production of certain types of alcoholic beverages such as whisky, brandy, and rum. Distillation help to separate alcohol from the fermented broth, increasing its concentration.
• Non-distilled alcoholic beverages are produced through fermentation, a process in which yeast converts sugars into alcohol and carbon dioxide.
• Beer is an example of a non-distilled alcoholic beverage, as it is produced by the fermentation of malted barley and other grains using yeast.

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 infarctio,n leading to a  heart attack.

• Streptokinase is used to remove the blood clots that are formed in the blood vessels i.e acts like a clot buster.
• It is mainly used for people who have undergone a myocardial infarction, leading to a heart attack.
• This helps in restoring the blood flow to the affected tissue.

Other Options:

• Curd production: Curd production involves the activity of lactic acid bacteria like Lactobacillus. The fermentation of lactose into lactic acid by these bacteria gives curd its texture and tangy taste.
• Ethanol production: Ethanol is produced by the fermentation of sugars by yeast, particularly Saccharomyces cerevisiae. 
• Liver disease treatment: This is incorrect. Streptokinase is not used for treating liver diseases. Treatments for liver conditions typically include medications like antivirals, immunosuppressants, or lifestyle changes, depending on the condition (e.g., hepatitis, cirrhosis).

Household products such as bread, curd, alcoholic beverages, and other fermented items are often prepared using specific microbes. These microbes play a vital role in enhancing the quality, flavour, and nutritional value of these products.
Some microbes are industrially used for other purposes, such as the production of antibiotics or enzymes, but they are not involved in the preparation of common household products.

• (A) Aspergillus niger: This fungus is commonly used for the industrial production of citric acid and enzymes, but is not involved in the preparation of household products.
• (B) Lactobacillus: This bacterium is involved in the preparation of household products like curd and yoghurt. It helps in the fermentation of milk, converting lactose into lactic acid.
• (C) Trichoderma polysporum: This fungus is used industrially for the production of cyclosporin, an immunosuppressive drug. It is not involved in the preparation of household products.
• (D) Saccharomyces cerevisiae: Commonly known as baker's yeast, this microbe is widely used in the preparation of bread and alcoholic beverages like beer and wine. It plays a crucial role in fermentation, producing carbon dioxide and ethanol.
• (E) Propionibacterium shermanii: The large holes in ‘Swiss cheese’ are due to the production of a large amount of CO₂ by a bacterium named Propionibacterium shermanii.

Statement I: Bacillus thuringiensis (Bt) produces a toxin that specifically targets and kills certain insect larvae, particularly caterpillar larvae. The toxin is effective against larvae of many species of moths and butterflies, but it does not harm adult insects. This statement is correct.
Statement II: Bacillus thuringiensis toxin primarily affects the larvae of insects, not the adult moths or butterflies. Adult insects do not consume the Bt toxin in sufficient quantities to be affected by it, which means they cannot be killed by the bacterium. This statement is also correct.
Therefore, both statements are correct.

• A. Saccharomyces cerevisiae: This yeast is primarily used in the production of ethanol (III), especially in fermentation processes.
• B. Aspergillus niger: This fungus is widely used to produce citric acid (I) on an industrial scale through fermentation.
• C. Trichoderma polysporum: This fungus is known for the production of cyclosporin-A (IV), an immunosuppressive drug.
• D. Clostridium butylicum: This bacterium is involved in the production of butyric acid (II) during fermentation processes.

Thus, the correct matching is A-III, B-I, C-IV, D-II.

Statement I: Aphids and mosquitoes are indeed considered natural pests. Aphids feed on plants, damaging crops and plants, while mosquitoes are known for spreading diseases, making both of them pests in nature.
Statement II: Ladybird beetles and dragonflies are natural pest controllers. Ladybird beetles feed on aphids, helping to control their populations, while dragonflies prey on mosquitoes, helping to reduce their numbers.
Thus, both statements are correct.

• A. Streptococcus: Streptococcus is known for producing clot busters (II), particularly the enzyme streptokinase, which helps break down blood clots.
• B. Trichoderma polysporum: This fungus is used in the production of Cyclosporin A (III), an immunosuppressive drug.
• C. Monascus purpureus: This fungus is used in the production of statins (IV), a class of drugs used to lower cholesterol levels in the body.
• D. Aspergillus niger: This fungus is widely used for the industrial production of citric acid (I), which is used as a food preservative and flavouring agent.

Thus, the correct matching is A-II, B-III, C-IV, D-I.

Statement I: Antibiotics are indeed chemicals produced by microbes (such as bacteria and fungi) that can kill or inhibit the growth of other microbes, including bacteria. Common examples of antibiotics include penicillin and streptomycin.
Statement II: Antibodies are chemicals produced by the immune system in the body. They are proteins that help the body recognise and eliminate harmful microbes (such as bacteria and viruses). Antibodies bind to specific antigens on the surface of pathogens and mark them for destruction by other immune cells.
Thus, both statements are correct.

Trichoderma species are free-living fungi found in the root ecosystem (rhizosphere). The fungus Trichoderma polysporum is responsible for the production of cyclosporin A. It is used as an immunosuppressive drug and is used by organ transplant patients to avoid graft rejection.

Examples of acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid.

Major portion of activated sludge is pumped into large tanks called anaerobic sludge digesters. So, here other kinds of bacteria which grow anaerobically, digest the fungi and bacteria of the sludge.

Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens.

• Lactobacillus bacteria convert milk into curd. It produces acids that coagulate and partially digest the milk proteins. 
• A small amount of curd added to the fresh milk as inoculum or starter contains millions of Lactobacillus which at suitable temperature multiply, thereby converting milk to curd which also improves its nutritional value by increasing vitamin B₁₂ content and a number of organic acids.
  

Primary or physical treatment is the process of removal of small and large, floating and suspended solids from sewage through two processes of filtration and sedimentation.

Maximum nutritional diversity is shown by the members of kingdom - Monera. Some of them are autotrophic (e.g. photosynthetic autotrophic or chemosynthetic autotrophic) while the vast majority are heterotrophs (e.g., saprotrophic or parasitic). Ecologically, these may be producers or decomposers.

All of above

Explanation:

Biological control of pests and diseases using microbes involves the use of microorganisms (bacteria, viruses, and fungi) to control pests and diseases in plants. Here's a brief explanation of each example:

1. Bt-cotton: Bt-cotton is a genetically modified cotton variety that contains genes from the bacterium Bacillus thuringiensis (Bt). This bacterium produces proteins toxic to certain pests, such as bollworms, which are a major threat to cotton crops. By introducing these genes into cotton plants, Bt-cotton provides resistance against these pests, leading to increased cotton yield.

2. Nucleopolyhedrovirus against white rust in Brassica: Nucleopolyhedroviruses are a group of viruses that infect and kill insects, particularly caterpillars. They have been used as biological control agents against various insect pests, including those that cause white rust in Brassica (a genus of plants that includes cabbage, cauliflower, and broccoli). By applying nucleopolyhedroviruses to Brassica crops, the insect pests can be controlled, reducing the incidence of white rust disease.

3. Trichoderma sp. against certain plant pathogens: Trichoderma is a genus of fungi that are known for their ability to antagonize and control various plant pathogens, such as fungi and nematodes. They do this by producing enzymes that break down the cell walls of other fungi

Anabaena azollae resides in the leaf cavities of the fern Anabaena. It fixes nitrogen. A part of the fixed nitrogen is excreted in the cavities and becomes available to the fern. The decaying fern plants release the same for utilization of the rice plants.

Saccharomyces cervisiae is a yeast used in making bread (Baker’s yeast) and commercial production of ethanol. 

Glomus is endomycorrhiza that helps in absorption of nutrition specially phosphorus from soil.

Streptokinase is immediately given to dissolve the thrombus carring myocardial infarction

• Monascus purpureus is a type of yeast known for its ability to produce compounds that can help lower cholesterol.
• It is particularly famous for producing statins, which are medications used to reduce blood cholesterol levels.
• By fermenting this yeast, manufacturers can extract natural statins, making them an alternative to synthetic options.
• This process is significant for people looking to manage cholesterol through dietary means.

c) Clostridium butylicum - lactic acid

This is the wrong matching.

• Clostridium butylicum is not known for producing lactic acid; it is primarily associated with the production of butyric acid during fermentation. It is also known for its role in the production of botulinum toxin.

The other matches are correct:

• Yeast (typically Saccharomyces cerevisiae) is used to produce statins, which are cholesterol-lowering drugs.
• Acetobacter aceti is responsible for producing acetic acid (vinegar) in aerobic fermentation.
• Aspergillus niger is widely used to produce citric acid industrially.

Thus, option (c) is the wrong one.

Glomus aggregatum is a  mycorrhizal fungus used as a soil inoculant in agriculture and horticulture. Its purpose is to increase the surface area of roots for nutrient absorption like phosphorus.

Rhizobium is a nitrogen fixing bacteria, which acts as a biofertilizer in soil to produce soyabean crops.