What term describes having two different alleles at the loci for a gene on a pair of homologous chromosomes?

What term describes having two different alleles at the loci for a gene on a pair of homologous chromosomes?

• A. Locus
• B. Zygote
• C. Heterozygous
• D. Homozygous

Answer: (C)

Having two different alleles at the same gene locus on homologous chromosomes is heterozygosity. In diploid organisms, each gene sits at a specific location on each chromosome of a homologous pair. If the two copies differ—one allele on one chromosome and a different allele on the other—the genotype is heterozygous. If the two copies are identical, the genotype is homozygous (both copies the same). Locus simply means the gene’s position on the chromosome, and zygote is the fertilized cell, not a description of the alleles present.

Having two different alleles at the same gene locus on homologous chromosomes is heterozygosity. In diploid organisms, each gene sits at a specific location on each chromosome of a homologous pair. If the two copies differ—one allele on one chromosome and a different allele on the other—the genotype is heterozygous. If the two copies are identical, the genotype is homozygous (both copies the same). Locus simply means the gene’s position on the chromosome, and zygote is the fertilized cell, not a description of the alleles present.