The genetic makeup of an organism refers to which term?

• A. Genotype
• B. Genome
• C. Karyotype
• D. Phenotype

Answer: (A)

Genotype is the genetic makeup—the specific alleles and versions of genes that an organism carries. This is the invisible blueprint that determines inherited traits. It differs from the genome, which is the entire set of genetic material, including noncoding regions. It also differs from the karyotype, which is simply the number and appearance of chromosomes. Finally, phenotype refers to the observable traits that arise from how those genes are expressed in the organism, often influenced by the environment.

For example, a gene with variants A and a can result in genotypes like AA, Aa, or aa. Those genotype combinations represent the organism’s genetic makeup, even if the outward trait (phenotype) might vary depending on environmental factors or gene expression.