Evolution — BIOLOGY STD 12 Science — Question

In snapdragon (Antirrhinum majus), a cross between varieties with red and white flowers produces an all pink progeny.
Explain how it is a case of incomplete dominance and not of blending inheritance.

Gene flow occurs through generations. Gene flow can occur across language barriers in humans. If we have a technique of measuring specific allele frequencies in different population of the world, can we not predict human migratory patterns in pre-history and history? Do you agree or disagree? Provide explanation to your answer.

Name the cells that produce antibodies. Explain the main functions of these compounds.

List the key tools used in recombinant DNA technology.

How does tongue detect the sensation of taste?

A cross was carried out between two pea plants showing the contrasting traits of height of the plant. The result of the cross showed 50% of parental characters.

1. Work out the cross with the help of a Punnet square.
2. Name the type of the cross carried out.

How does spleen act as lymphoid organ? Explain.

Highlight any four areas where genetic modification of plants has been useful.

An infertile couple is advised to adopt test-tube baby programme. Describe two principle procedures adopted for such technologies.

Name the bacterium that causes typhoid. Mention two diagnostic symptoms. How is this disease transmitted to others?