An allele is dominant and heterzygote (Pp) when a dominant allele (P) is crossed with a recessive allele (p).
Explanation:
A dominant allele is the one with a particular dominant character or phenotype which dominates even though there are other alleles found.
A heterozygous allele results from two different alleles coding for a gene.
A heterozygous dominant allele (Pp) results from the crossing of a dominant allele (P) with a recessive allele due to complete masking of the recessive allele (p).
For example, when dominant brown eyes are crossed with recessive blue eyes, in a heterozygous dominant allele results in brown eyes and masks the recessive blue eyes.
