Suggest three contraceptive methods to control the size of human population which is essential for the health and prosperity of a country. State the basic principle involved in each.

Explain the mechanism of sex determination in humans.

List any four methods of contraception used by humans. How does their use have direct effect on the health and prosperity of a family?

Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival – the one reproducing asexually or the one reproducing sexually? Give reason to justify your answer.

Describe the grafting method for the artificial propagation of plants with the help of labelled diagrams.

Describe reproduction by spores in Rhizopus.

What are sexually transmitted diseases. List two example of each diseases caused due to,

1. Bacterial infection.
2. Viral infection.

Which device or devices may be used to prevent the spread of such diseases.

Name the parts A, B and C shown in the following diagram and state one function of each.

What does HIV stand for? Is AIDS an infectious disease? List any four modes of spreading AlDS.

Explain why, more complex multicellular organisms cannot give rise to new organisms through regeneration.