Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Why does the Bt toxin not kill the bacterium that produces it but kills the insect that ingests it?

Explain mechanism of sex-determination in birds.

Differentiate between biodegradable and non biodegradable wastes.

Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop:

1. Recommend two microbes that can enrich the soil with nitrogen.
2. Why do leguminous crops not require such enrichment of the soil?

List the four different human male accessory ducts.

What harm do cancerous cells cause?

What happens when chromatids fail to segregate during cell division cycle? Explain your answer with an example.

The doctor could hear the heartbeats in a foetus. How many days of gestation period must have passed?

Name any two forms of extinct reptiles that evolved from synapsids.

A cross between a normal couple resulted in a son who was haemophilic and a normal daughter. In course of time, when the daughter was married to a normal man, to their surprise, the grandson was also haemophilic.
Represent this cross in the form of a pedigree chart. Give the genotypes of the daughter and her husband.