What does genotype refer to in biology?

• A. The organism's genetic makeup, or allele combinations
• B. An organism's physical appearance, or visible traits
• C. The location of a gene on a chromosome
• D. The process of DNA replication

Answer: (A)

Genotype is the organism’s genetic makeup, or the specific alleles it carries. It’s the set of genes inherited from the parents, which can be two identical alleles (homozygous) or two different alleles (heterozygous). This internal genetic information shapes potential traits, even if environmental factors influence whether those traits are expressed as visible characteristics (phenotype). So genotype is about the genetic plan, while phenotype is about the outward appearance you can observe. The other descriptions describe physical appearance (phenotype), the position of a gene on a chromosome (locus), or the process of copying DNA (DNA replication), none of which capture the idea of the organism’s inherited gene set.