Human Reproduction — BIOLOGY STD 12 Science — Question

Explain biodiversity loss due to alien species invasions.###Among the reasons of biodiversity loss, how does extinction of indiginous species is carried out by invation of allian species? Explain.

What is law of dominance. Explain with the help of monohybrid cross. Write the utility in human of law of dominance.

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

Study the graph given below and answer the question that follow:

1. Write the status of food and space in the curves (a) and (b).
2. In the absence of predators, which one of the two curves would appropriately depict the prey population?
3. Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line.

Write any four benefits of using GM plants.

Write a note on the vector relationship for gene cloning in plants and animals.

Enlist the probable causes of infertility.

How does Agrobacterium tumefaciens act as a suitable vector in biotechnology experiments? Cite an example, where it has been successfully used as a vector.

A woman has certain queries as listed below, before starting with contraceptive pills. Answer them.
What do contraceptive pills contain and how do they act as contraceptives?

Differentiate between T-helper cells and T-killer cells.