A person who is heterozygous for a gene is called a

• A. Allele
• B. Chromosome
• C. Carrier
• D. Codon

Answer: (C)

Having two different versions of a gene, one on each chromosome, means you’re heterozygous for that gene. The term used for a person who carries one normal allele and one recessive allele is a carrier. They typically show the normal trait because the dominant allele masks the recessive one, but they can pass the recessive allele to their offspring, which is important for understanding genetic inheritance and risk. The other terms aren’t describing a person: an allele is a variant form of a gene, a chromosome is the structure that holds DNA, and a codon is a three-nucleotide sequence in mRNA that codes for an amino acid.