Human Reproduction — BIOLOGY STD 12 Science — Question

List any four characters that are employed in human population census.

Define mutation. State its two types.

Name the type of food chains responsible for the flow of larger fraction of energy in an aquatic and a terrestrial ecosystem respectively. Mention one difference between the two food chains.

Name and mention the events that occur in the cells when HIV gets into blood after gaining entry into the human body.

Why is CuT considered a good contraceptive device to space children?

Name the type of immunity that is present at the time of birth in humans. Explain any two ways by which it is accomplished.

Tribal people from India have a great contribution in production of lac. But it needs certain trees. Name at least two such trees which give food yield of lac. How is lac purified?

Discovery of lobefins is considered very significant by evolutionary biologists. Explain.

1. Name the lymphoid organ in humans where all the blood cells are produced.
2. Where do the lymphocytes produced by the lymphoid organ mentioned above migrate and how do they affect immunity?

Urethra is also called urinogenital duct in males.