Identify A, D, E and F in the diagram of an antibody molecule given below:

Name the two types of immune systems in a human body. Why are cell mediated and humoral immunities so called?

OR

Write the scientific names of the causal organisms of elephantiasis and ringworm in humans. Mention the body parts affected by them.

Justify with the help of an example where a deliberate attempt by humans has led to the extinction of a particular species.

Study the graph given below. Explain how is oxygen concentration affected in the river when sewage is discharged into it.

Explain how a hereditary disease can be corrected. Give an example of first successful attempt made towards correction of such diseases.