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 alternativelycheesematuration of affinage. It is responsible for the distinct flavour ofcheese, and through the modification of "ripeningagents", ripening determines the features thatdefinemany different varieties ofcheeses, such as taste, texture, and body. For example, two species of blue mold,P. roqueforti andP. 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 naturalsouringor 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.

Answer: Option A. -> Both A and R  are correct and R is the correct explanation of A.
:
A
Biogastypically 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.Biogascan 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 inrelatively simple biogas plants that are built next to the houses in rural areas.

Answer: Option D. -> Both A and C
:
D
Yogurt is produced through the fermentation of milk by lactic acid bacteria, usually lactobacillus bulgarius and Streptococcus thermophilus. The milk is firstly heat treated, homogenised and is then cooled to allow the addition of bacteria or starter culture. This yogurt-milk mixture is then left overnight to ferment. The conversion of lactose in milk to lactic acid by the action of these bacteria drops the pH of the solution, causing the milk solids to become trapped in a gel matrix. This gel matrix of milk solids and proteins is called yogurt.

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 bacteriumwitha 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 D. -> Provides specific nutrients in high concentrations
:
D
A biofertiliser improves the nutrient quality of the soil in general in a natural setting. It does not change the chemical nature of soil. It does not cause water pollution like conventional chemical fertilisers do. Hence extensive use of biofertilisers does not result in eutrophication. However, unlike chemical fertilisers, biofertilisers do not provide specific nutrients at high concentrations.

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 A. -> Aspergillus niger 
:
A
Many microbes produce large quantities of a particular small molecule byproduct that can be readily extracted in a large scale using the fermentation technique. For example the yeast Saccharomyces cerevisiae produces ethanol, the fungus Aspergillus niger makes citric acid, Acetobacter aceti makes acetic acid, the bacteria Clostridium butylicum makes butyric acid, and the bacteria Lactobacillus make lactic acid.

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. Biogastypically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen.Biogascan 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 arebuilt next to homes in some rural areas, to provide a source of gas for cooking and lighting.

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.