What term describes the complete genetic constitution of an individual, representing the set of alleles present in its DNA?

• A. Genome
• B. Chromosome set
• C. Phenotype
• D. Genotype

Answer: (D)

Genotype describes the complete genetic constitution of an individual—the specific alleles present at the loci in its DNA. In diploid organisms, you inherit one allele from each parent for every gene, so the genotype can be homozygous (same allele on both chromosomes) or heterozygous (two different alleles). This is different from the genome, which is the entire sequence of genetic material, and from the phenotype, which is the observable traits resulting from how those alleles interact with each other and the environment. The chromosome set refers to the number and structure of chromosomes, not the particular alleles carried. So, the term that best captures the allelic makeup across the genome is genotype.