Question

What are heterozygous and homozygous??

Answer 1

Homozygous condition means both the alleles are same. Thus, in case of RR both the alleles are dominant and in case of bb both the genes are recessive. Hence, both RR and bb are homozygous.

Heterozygous condition means both the alleles are different. Thus, in case of Rb one is recessive and other is dominant.
Notice that their has to be a dominant and a recessive trait in heterozygous.