Reproductive Health — BIOLOGY STD 12 Science — Question

Given below is the relationship between the HIV levels in the blood and helper T cell count in a person detected with AIDS. Study the relationship and answer the questions that follow.

A. What kind of relationship is observed in the virus levels and the immune response after some days of the initial infection?
B. Does it completely clear the virus from the body permanently? Give reason for your answer.

Differentiate between the roles of B-lymphocytes and T-lymphocytes in generating immune response.

Write benificial activity of following bacteria : (i) Rhizobium (ii) Azotobacter (iii) Streptomyces (iv) Lactobacillus

If the Tropical rainforest would have been from the present 6% areas of earth to 12% areas how would the biodiversity be affected by it? Explain with reason.

Shyam Lal and his wife have been advised by the gynaecologist to go for artificial insemination. What may have been the reason for the doctor to give such an advice? Explain.

In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided ?

Write about the amendment passed by the Indian Parliament regarding patent issues.

Give reason:

1. Antibiotics are sold in combination with Lactobacillus.
2. The insects which are the so called pests are not eradicated in organic farming.

What is bagging technique? How is it helpful in a plant breeding programme?

With the help of a suitable example, explain how cross-breeding is carried out in developing a new breed in animals.