List three techniques that have been developed to prevent pregnancy. Which one of these techniques is not meant for males? How does the use of these techniques have a direct impact on the health and prosperity of a family?

Why does menstruation occur?

Identify A, B and C in the given diagram and write one function of each.

Why is variation beneficial to the species but not necessarily for the individual?

From the internet, gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of organism and answer the following questions.

1. Do larger organisms have more number of chromosomes/ cells?
2. Can organism with fewer chromosomes reproduce more easily than organisms with more number of chromosomes?
3. More the number of chromosomes/ cells greater is the DNA content. Justify.

Give a few characteristics of asexual reproduction.

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.

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

Which is the most commonly used method of birth control.

1. List two sexually transmitted diseases in each of the following cases:

1. Bacterial infections.
2. Viral infections.

2. How may the spread of such diseases be prevented?