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

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 yeast used in the production of statins which are used in lowering blood cholestrol.

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.

Organic farming involves use of organic wastes and other biological material along with beneficial microbes to release nutrients to crop to increase the soil fertility in an ecofriendly, and pollution tree environment. Glomus, earthworm and Oscillatoria can be used in organic farming while snail cannot. 

The common nitrogen fixer in paddy field is Azospirillum. It is an anaerobic bacteria that forms loose association with roots of paddy crops.

A common biocontrol agent for control of plant diseases is Trichoderma. Trichoderma is a tree living fungus that exert biocontrol over several plant pathogens for the control of plant diseases. It is the natural method of pest and pathogen control.

Cry I endotoxine obtained from Bacillus thuringiensis are effective against bollworms. A bollworm is a common term for any larva of a moth that attacks the fruiting bodies of certain crops, especially cotton.

Human insulin is being commercially produced from a transgenic species of Escherichia coli. E. coli is a bacterium that is commonly found in the lower intestine of warm blooded animals. The bacteria can also be grown easily and its genetics are comparatively simple and easily manipulated, making it one of the best studied prokaryotic model organisms, and an important species in biotechnology.

Trichoderma harzianum has proved a useful microorganism for biological control of soil borne plant pathogens. Trichoderma harzianum is a fungus that is also used as a fungicide. It is used for foliar application, seed treatment and soil treatment for suppression of various disease causing fungal pathogens. Commercial biotechnological products such as 3 Tac have been useful for treatment of Botrytis, Fusarium, Penicillium sp. It is also used for manufacturing enzymes.

Probiotics are defined as live microorganisms, including Lactobacillus species, Bifidobacterium species and yeasts, that may beneficially affect the host upon ingestion by improving the balance of the intestinal microflora. The dietary use of live microorganisms has a long history.

Escherichia coli is a bacterium found in human colon. On this bacterium scientists have made extensive genetic experiments to make some vital chemicals like insulin. Another bacterium is Agrobacterium tumefaciens which causes crown gall in plants is extensively used for genetic experiments.

Azolla and blue green algae- Anabaena form biofertilizer in rice fields.

Azolla is a freshwater fern harbouring a bluegreen alga - Anabaena in its leaf cavities. The alga fixes atmospheric nitrogen and releases nitrogenous compounds in leaf cavities. This symbiotic system is the main source of algal biofertilizer in rice fields.

Farmers have reported over 50% higher yields of rice by using the biofertilizer Azolla pinnata.

Azotobacter is a free living nitrogen fixing bacterium, Rhizobium is symbiotic and found in the root nodules of leguminous plants, Anabaena occurs in assoction with Azolla. VAM is vesicular arbuscular mycorrhiza.

Gobar gas contains mainly CH₄ + CO₂.

Control of cancer is likely to be achieved in the coming two decades.

'Each antibiotic is effective only against one particular kind of germ' is not correct.