Question

If an organism displays the dominant phenotype, which of the following genotypes is it definitely NOT?

Options

• TT (homozygous dominant)

• tt (homozygous recessive)

• Any of the above could show the dominant phenotype

• Tt (heterozygous)

Answer 1

An organism displaying the dominant tall phenotype must have at least one dominant T allele, so it could be TT or Tt. The only genotype definitively excluded is tt, which produces no functional protein and expresses the recessive dwarf phenotype.