Human Health and Disease — BIOLOGY STD 12 Science — Question

Ankit attended a blood donation camp to donate blood and came to know that he was HIV positive. He lost interest in studies knowing that. He remained absent from school for a long time. The biology teacher visited his house and talked to him. Ankit started coming to school again and showed interest in studies.

1. A person detected to be HIV positive should be isolated by the society. Do you agree? Why/ why not?
2. Write the processes through which, AIDS does not spread.
3. Who are at higher risk of encountering AIDS?
4. What sense of responsibility did the biology teacher exhibit?

What are the properties of an antibiotic?

Draw the next mature stage and label the parts.

Study the graph given below and answer the question that follow:

1. Write the status of food and space in the curves (a) and (b).
2. In the absence of predators, which one of the two curves would appropriately depict the prey population?
3. Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line.

Explain the following.

1. What is the most common example of pleiotropy in humans?
2. How are the pleiotropic genes useful?

In which food would you find lactic acid bacteria? Mention some of their useful applications.

Give an interesting observation of melanic Moth supporting development by natural selection in England.

Study the given pedigree chart and answer the questions that follow:

Is the trait sex–linked or autosomal?

Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.

Study the age pyramids ‘A’, ‘B’ and ‘C’ of the human population given below and answer the questions that follow:

1. Identify pyramids ‘B’ and ‘C’.
2. Write the basis on which the above pyramids are plotted.