The diagram hows a bivalent at prophase -I of meiosis. Which of the four chromatids can cross over?

Name five substages of prophase I of meiosis.

A bivalent of meiosis-I consists of

Observe the diagram and answer the following: Which of these shows a higher water content (i) or (ii)

In an Examination, a candidate has to pass in each of the four subjects. In how many ways can he fail ?

In which phase crossing over occurs?

Mention any four methods by which the vehicular air pollution can be controlled.

Six candidates are called for interview to fill four posts in an office. Assuming that each candidate is fit for each post. determine the number of ways in which : all the four posts can be filled.