LIFE SCIENCE

Detailed explanation-1: -A dominant allele is denoted by an uppercase letter such as H. A recessive allele is denoted by a lowercase letter such as h. A homozygous genotype contains two identical alleles. An individual can either be homozygous dominant (ex: HH) or homozygous recessive (ex: hh).

Detailed explanation-2: -DD is homozygous dominant, Dd is heterozygous and dd is homozygous recessive. They cannot be heterozygous because the dominant allele will be shown so they will have dimples.

Detailed explanation-3: -DD or Dd is regarded as heterozygous and dd is homozygous recessive. In the heterozygous and homozygous condition, the recessive gene is masked by the dominant gene and not expresses. Therefore, recessive traits are expressed only in the homozygous condition.