Answer: Option B. -> b and c
:
B
Nitrogen fixing microbes are including cyanobacteria, bacteria and fungi have the ability to fix atmospheric nitrogen into its uasable form that can be used by plants. Mycorrhiza is a fungi that is in a symbiotic association with the roots of plants. The fungal symbiont helps in solubalisation of inorganic phosphate in the soil and passes it to the plant. Rhizobia is a symbiotic nitrogen fixing bacterium which fixes nitrogen in roots of leguminous plants. Bacillus thuringiensis is a bacterium with a gene of insecticidal property. This gene has been inserted into the genome of different plants through the process of genetic engineering, most notably into the cotton genome to give rise to Bt-cotton. Now the plant can kill insects on its own without the use of pesticides.

Answer: Option A. -> Both A and R  are correct and R is the correct explanation of A.
:
A
Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen in biogas plants, which can serve as a source of lighting and cooking gas in rural areas. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste etc.  In rural areas animal wastes or cowdung is available in large quatities which are degraded in relatively simple biogas plants that are built next to the houses in rural areas.

Answer: Option D. -> All of the above 
:
D
Fermentation in food processing is the process of converting carbohydrates to alcohols or organic acids using microorganisms (yeasts or bacteria) under anaerobic or aerobic conditions. Example Saccharomyces or yeast is responsible for one of the biggest beverage industries of the world. Lactic acid bacteria are used for converting milk into curd.

Answer: Option D. -> Wood and animal dung
:
D

The common source of energy in villages can be animal dung and wood which can be used to produce biogas in a biogas plant. Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. Biogas plants can be relatively simple structures that are built next to homes in some rural areas, to provide a source of gas for cooking and lighting.

Answer: Option B. -> Fungus Trichoderma polysporum
:
B
Cyclosporin A produced by the fungus Trichoderma polysporum, is used as an immunosuppressive agent in organ-transplant patients to ensure that the new organ is not rejected by the recipient and is integrated into the recipient’s body seamlessly.

Answer: Option C. -> Statement 1 is correct and statement 2 is incorrect.
:
C

Of the millions of microbes that have been categorized, although there exist a large number of microbes that are pathogenic to humans and other species of life, there exist several variants of bacteria that are very useful for life on earth. Hence, it is true that microbes are an important aspect of life on earth yet not all are necessarily pathogenic.

Answer: Option C. -> Rum      
:
A, B, and C
An alcoholic beverage is a drink that contains ethanol, commonly known as alcohol. An undistilled beverage is a hard liquor which can be consumed without distillation such as beer, wine, and cider, vodka, gin, rum, whisky, brandy.

Answer: Option C. -> Rum      
:
Since the sewage is rich in organic nutrients, the microorganism will grow rapidly in the lake and put a strain on the availability of dissolved oxygen in the water. This in turn increases the BOD of the water.

Answer: Option C. -> Microbes
:
C
Antibiotics are usually produced by microbes themselves. When two microbes are fighting for resources in a small area, one of them could produce an antibiotic that might kill the other and capture the resources for itself. Although initially antibiotics were isolated from microbes, today pharma companies synthesize their own antibiotics through artificial methods as well.

Answer: Option D. -> the souring and ripening processes and also providing resistance against spoilage organisms
:
D

In the manufacture of cheese, microbes play an important role in the ripening i.e maturation of cheese and also souring i.e curdling of the milk to produce sour milk cheese.
1.cheese ripening is an important step which is alternatively cheese maturation of affinage.  It is responsible for the distinct flavour of cheese, and through the modification of "ripening agents", ripening determines the features that define many different varieties of cheeses, such as taste, texture, and body. For example, two species of blue mold, P. roqueforti and  P. glaucum give rise to the unique flavour and texture to hundreds of blue cheese which are revered throughout the world.
2. Souring is the initial step in the manufacture of sour milk cheese or acid set cheese that has been curdled (coagulated)  by natural souring or by the addition of lactic acid bacteria. Lactic acid bacteria are often called "starter cultures", as they play the main role in converting the basic milk sugar, lactose, into lactic acid, a step which lowers cheese pH and makes the cheese inhospitable to many spoilage organisms.