Question

When a test cross produces all offspring with the dominant phenotype, what can be concluded about the dominant parent's genotype?

Options

• The parent's genotype cannot be determined from this result

• The parent is heterozygous (Tt)

• The parent is homozygous recessive (tt)

• The parent is homozygous dominant (TT)

Answer 1

If all offspring exhibit the dominant phenotype when crossed with a homozygous recessive (tt) parent, the dominant parent must be homozygous dominant (TT). This is because TT × tt produces only Tt offspring, all showing the dominant phenotype.