Which of the following statements regarding genotypes and phenotypes is false? Alleles are alternate forms of a gene. The expressed physical traits of an organism are called its phenotype. The genetic makeup of an organism constitutes its genotype. An organism with two different alleles for a single trait is said to be homozygous for that trait.

D

Explanation:

Homozygous mean a pair of alleles that are the same. Hence the root word homo - which means same. If the alleles were different, we would call this pairing a heterozygous pair, with the root word hetero - meaning different. An example of a homozygous pair would be AA, two dominant allele, or aa, two recessive alleles, while a heterozygous pair would be Aa, one dominant and one recessive allele.