Q4 of 58 Page 74

Describe the main ideas behind the biological control of pests and diseases.

The main ideas behind the biological control of pests and diseases is that the population of pests is controlled by the introduction of natural predators of these pests in the environment. The natural predators of these diseases causing pests are to keep the population in control and protect the plants or crops from getting harmed.

Some examples are:


i. The Lady bird beetle is used to control the population of insects like Aphids.


ii. Nucleopolyhydro viruses (NPVs) are being used to kill insects such as caterpillars and butterflies which damages the plants and crops. NPVs damages the midguts of the insects to kill them.


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2

(a) Discuss about the major programs that the Ministry of Environment and Forests, Government of India, has initiated for saving major Indian rivers from pollution.

(b) Ganga has recently been declared the national river. Discuss the implication with respect to pollution of this river.


 3

Draw a diagrammatic sketch of biogas plant, and label its various components given below: Gas Holder, Sludge Chamber, Digester, Dung+water chamber.

 5

(a) What would happen if a large volume of untreated sewage is discharged into a river?

(b) In what way anaerobic sludge digestion is important in sewage treatments?


 6

Which type of food would have lactic acid bacteria. Discuss their useful application.