1. In human males, all the chromosomes are paired perfectly except one. This/these unpaired chromosome/s is/are (i) large chromosome (ii) small chromosome (iii) Y-chromosome (iv) X-chromosome (a) (i) and (ii) (b) (iii) only (c) (iii) and (iv) (ii) and (iv)

• Soln:

The answer is (c) (iii) and (iv)

Explanation:

Humans have 22 pairs of autosomes and a sex chromosome. Autosomes make perfect pair. Sex chromosomes, arenot always a perfect pair. Women have a perfect pair of sex chromosomes, i.e. XX. But men have a mismatched pair, i.e. XY in which X is a normal-sized X while Y is short.