(i) No doubt such practice helps in the management of pest and diseases but at the same time have some adverse side effects too. Therefore such practices should be used judiciously after proper scrutinisation so that harm to the environment is minimum and agricultural output is maximum.
(ii) Biocontrolmethods of pest and disease management should be preferred. It is a natural method of pest and pathogen control. It involves the use of microorganisms or other natural predaters or their product for controlling the plant diseases. e.g. the fungus Trichoderma exerts biocontrol over several plant pathogens. Their biocontrol agents are specific and unlike chemical pesticides do not harm the useful non target organisms and keep the pest and ecological balance managable.
(iii) Ethical values with regard to the safety of environment have been neglected in this case.

(a) Leguminous plant and nitrogen-fixing bacteria, e.g., chickpea and Rhizobium of Leguminosae or Fabaceae plants and nitrogen fixing-bacteria
(b) Steps in the formation of root nodules:
(i) Root hair of the leguminous plant curls upon contact with nitrogen fixing bacterium, which secretes chemicals.
(ii) Nitrogen-fixing bacteria proliferate withincurled root hair.
(iii)The plant responds by forming an infection thread of the plasma membrane, which grows inward from the infected cell of the host, separating it from the rest of the plant.
(iv) Cell division is stimulated in the infected tissue and more bacteria invade the newly formed cells, and a nodule is formed. Auxin from leguminous plant cells and cytokinin from bacteria help in this cell division.
Physiological processes : Photosynthesis and respiration provide FAD and ATP for fixation of atmospheric nitrogen.

(ii) Cyanobacteria
(iii) Rahul is helpful in nature. He uses his knowledge for the benefit of society. Moreover, he is concerned to protect the environment from pollution as discouraged the use of chemical fertilisers.

(i) It would be helpful to humans as microorganisms are fast growing, the food is rich in nutrients and it reduces pollution.
(ii) Initially, there can be very low response, but it is expected to have high response (as of mushroom culture in the recent years).
(iii) Recycling nutrients and minimising pollution for the betterment of the environment.

(i) SCP refers to the large-scale production of protein obtained from unicellular or filamentous microorganisms.
(ii) Spirulina, Chlorella.
(iii) He was concerned about the welfare of the society.

1. Aeration to prevent alcohol formation.
2. Optimum pH = 5.
3. Ammonium phosphate that stimulates then growth of yeast.

(a) Untreated sewage contains large amounts of organic matter and microbes. Many microbes are pathogenic. So the consumption of such water by humans and useful animals increases the chances of spread of a number of water-borne diseases like cholera, typhoid and diarrhea diseases.
The presence of high amounts of organic wastes in water increases the biochemical oxygen demand (BOD) while decreases the Dissolved Oxygen(DO) which causes the death of aquatic animals like fishes.
(b) Major part of activated sludge is pumped into anaerobic sludge digesters where anaerobic bacteria digest the bacteria and fungi during which a mixture of gases like methane, \({ Co }_{ 2 }\) and \({ H }_{ 2 }S\) is produced which can be used as biogas as source of energy. It also produces manure. 

MOEF of Government of India has initiated the Yamuna Action Plan and Ganga Action plan for saving Yamuna and Ganga rivers respectively.
Ganga Action Plan:
1.Due to increased urbanisation and industrialisation there is a huge quantity of sewage produced; but there are not enough sewage treatments plants and hence the untreated sewage is let into major rivers.
2. The government has planned to build a number of sewage treatment plants, because the sewage and effluents from the areas nearby Ganga rivers can be treated before they are let into the river.
3. The objective of Ganga Action Plan is to save the river from pollution.
Yamuna Action plan :
In order to protect the major rivers of India from sewage pollution, the Ministry of Environment and Forests has initiated development of sewage treatment plants under the National River Conservation Authority, e.g., Ganga Action Plan and Yamuna Action Plan. Industries contribute chemical effluents to the river's pollution load and the toxicity kills aquatic animals in large sections of the river.

MOEF of Government of India has initiated the Yamuna Action Plan and Ganga Action plan for saving Yamuna and Ganga rivers respectively.
Ganga Action Plan:
1.Due to increased urbanisation and industrialisation there is a huge quantity of sewage produced; but there are not enough sewage treatments plants and hence the untreated sewage is let into major rivers.
2. The government has planned to build a number of sewage treatment plants, because the sewage and effluents from the areas nearby Ganga rivers can be treated before they are let into the river.
3. The objective of Ganga Action Plan is to save the river from pollution.
Yamuna Action plan :
In order to protect the major rivers of India from sewage pollution, the Ministry of Environment and Forests has initiated development of sewage treatment plants under the National River Conservation Authority, e.g., Ganga Action Plan and Yamuna Action Plan. Industries contribute chemical effluents to the river's pollution load and the toxicity kills aquatic animals in large sections of the river.

Biofertilisers are those organisms which enrich the soil fertility.
Categories of organisms:
(i) Bacteria, e.g. Rhizobium, Azotobacter
(ii) Cyanobacteria, e.g. Nostoc, Aulosira
(iii) Mycorrhizae/fungi, e.g. Glomus
Functions:
1. Bacteria and Cyanobacteria fix atmospheric nitrogen and increase the nitrogen content of the soil.
2. Cyanobacteria also add organic matter to the soil through their photosynthesis.
3. The fungi decompose the organic matter of the soil and make the nutrients available to the roots.
4. Mycorrhizae help in absorption and storage of some mineral nutrients like phosphorus for the plants.