Problem 1: Explain briefly the reason why blood groups A and B in humans can exist both in the heterozygous and homozygous forms while blood group O can only exist in homozygous form.
Problem 2:
(a) Name the Classes of vertebrates in order of their evolutionary trend.
(b) Give one example each of the Classes of vertebrates-named in above
Problem 3: Explain briefly independent assortment of genes.