Which statement best distinguishes genotype from phenotype?

• A. Genotype is the observable traits; phenotype is the genetic makeup.
• B. Genotype is the genetic makeup; phenotype is the observable traits resulting from genotype and environment.
• C. Both refer to environmental effects.
• D. Genotype is the set of proteins; phenotype is the set of lipids.

Answer: (C)

Genotype is the genetic makeup—the specific alleles an organism carries. Phenotype is what you can observe—the traits that result from how those genes are expressed, which is influenced by the environment. So the best statement captures that distinction: genotype = genetic information, phenotype = observable traits shaped by both genes and environment. For example, the same genetic potential for height can be realized differently depending on nutrition and health during development. The idea that both refer to environmental effects, or that genotype means observable traits, or that genotype is a set of proteins, doesn’t fit how genotype and phenotype are defined.