Question

If a male parent has two dominant alleles for a

trait and a female parent has two recessive
alleles for the same trait, which phenotype will
their offspring express for that trait? (3.2.2)

Answer 1

If a male parent has two dominant alleles for a trait and the female parent has two recessive alleles for the same trait the phenotype that their offspring will express for the trait is dominant.

Step-by-step explanation:

If a dominant allele and recessive allele appears in combination in a genotype the resulting phenotype will be influenced by the dominant allele. The presence of a dominant allele in a genotype means that the trait expressed will be dominant. Suppose the letter T represents the dominant allele whatever be the trait it expresses.

Let letter t represent the recessive allele. It is given that one parent has two dominant alleles which make that parent’s genotype TT. The other parent has two recessive alleles making that parent’s genotype tt.

The cross can be represented as

`TT * tt`

Tt Tt Tt Tt

All the resulting phenotypes are dominant.

Answer 2

The offsprings will express the dominant trait of the male parent.

To understand this, lets make a punnet square. Let's consider the dominant alleles of the male parent to be DD and the recessive alleles of the female parent to be dd.

d d

D Dd Dd

D Dd Dd

The results from the punnet square depict that all the offsprings will have a heterozygous genotype but ad the dominant allele masks the effect of the recessive allele hence, the offsprings will show the phenotype of the dominant allele.