Reproductive Health — BIOLOGY STD 12 Science — Question

What is the role of ethidium bromide during agarose gel electrophoresis of DNA fragments?

Which one out of Rho factor and sigma factor act as initiation factor during transcription in a prokaryote?

Mention any one major source of variation in a sexually reproduced offspring.

(a) Write an example of a virus biocontrol agent.
(b) Why are they considered desirable for the treatment of an ecologically sensitive area?

Before integrating DNA with bacterial plasmid, bacterial cells are treated with calcium. Why?

Name the main source of air pollution.

What would have happened if antibiotics were not discovered?

Which DNA has importance in DNA fingerprinting?

Name any two threatened animal species of India.

Answer the following questions:
Over the years, it has been observed that some of the lakes are disappearing due to urbanisation. In absence of human interference, depict by making a flow chart, how do the successional series progress from hydric to mesic condition.