The number of pair(s) of sex chromosomes in the zygote of humans is:

The exchange of genetic material takes place in:

A cross between a tall plant (TT) and short plant (tt) resulted in progeny that were all tall plants because :

In peas, a pure tall plant (IT) is crossed with a pure short plant (tt). The ratio of pure tall plants to pure short plants in F₂ generation will be:

The two versions of a trait (character) which are brought in by the male and female gametes are situated on: