Reproductive Health — BIOLOGY STD 12 Science — Question

How does industrial melanism support Darwin’s theory of Natural Selection? Explain.

Write a short note on extinct species?

In certain seasons we sweat profusely while in some other season we shiver. Explain.

Where is an 'operator' located in a prokaryote DNA? How does an operator regulate gene expression at transcriptional level in a prokaryote? Explain.

A non–haemophilic couple was informed by their doctor that there is possibility of a haemophilic child be born to them. Explain the basis on which the doctor conveyed this information. Give the genotypes and the phenotypes of all the possible children who could be born to them.

Describe with an example the latitudinal gradients of biodiversity.

Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

1. Mention the property that enables the explants to regenerate into a new plant.
2. A banana herb is virus-infected. Describe the method that will help in obtaining healthy banana plants from this diseased plant.

What does 'Hind' and 'III' refer to in the enzyme Hind III?

Explain how and why controlled breeding experiment is carried out in cattle.
OR
Define artificial insemination. What are its advantages over conventional breeding?