Which term refers to an organism with two identical copies of a gene?

Which term refers to an organism with two identical copies of a gene?

• A. Homozygous
• B. Heterozygous
• C. Carrier
• D. Codominance

Answer: (A)

In a diploid organism, each gene exists in two copies. When those two copies are identical, the organism is homozygous for that gene. For example, having two copies of the same allele (like AA or aa) means you’re homozygous. If the two copies are different, it’s heterozygous (Aa). A carrier typically refers to someone who is heterozygous for a recessive disease allele but shows no symptoms. Codominance is a situation where both alleles are expressed in the phenotype, not about identical copies. So, two identical copies define the homozygous state.

In a diploid organism, each gene exists in two copies. When those two copies are identical, the organism is homozygous for that gene. For example, having two copies of the same allele (like AA or aa) means you’re homozygous. If the two copies are different, it’s heterozygous (Aa). A carrier typically refers to someone who is heterozygous for a recessive disease allele but shows no symptoms. Codominance is a situation where both alleles are expressed in the phenotype, not about identical copies. So, two identical copies define the homozygous state.