Answer
The genotype of an individual is his/her genetic makeup ; more specifically, it is combination of alleles (genes) for a trait at the locus for that trait in homologous chromosomes
Phenotype. The phenotype is the expression ( physical, biochemica, psychological)) of a genotype. Phenotypes are usually influenced/affected by environmental factors--internal and external.
"Dominant" describes the relationships between alleles in which one --the dominant allele-- masks or suppresses the expression of the recessive variant allele for the specific locus. In a dominant--recessive relationship ( between one pair of alleles), the recessive trait is not expressed as a phenotype, unless the genotype is double recessive.
Work Step by Step
Homozygote:
A homozygote is an individual with two copies of one variant of a pair of alleles ( e.g. P and p)-- the same variant being present at the specific locus for the given trait on homologous chromosomes. The genotype P/P and p/p are homozygous for alleles at the phenylthiocarbamide taster trait (PTC trait) alleles. Since the taster gene, "p," is recessive , only the individual who is double recessive is a PTC taster. P/P is a nontaster.
Heterozygote:,
A heterozygote, in contrast to a homozygote, has one of each of the pair of variant alleles (for the trait) at the specific locus on each of the pair of homologous chromosomes. The genotype P/p is heterozygous for PTC taster, and the phenotype is PTC nontaster
Note. The gene for the ability to taste PTC is a recessive gene.
