What is the difference between phenotype and genotype?

• A. Genotype is the genetic makeup; Phenotype is the observable expression influenced by environment
• B. Genotype is environmental influence; Phenotype is genetic makeup
• C. Genotype is brain structure; Phenotype is neurotransmitter levels
• D. Genotype is behaviour; Phenotype is mood

Answer: (A)

Genotype is the genetic makeup—the specific genes you carry. Phenotype is the observable traits that result from how those genes are expressed in a particular environment. Because the environment can influence how genes are turned on or off, the phenotype can vary even with similar genotypes. For example, eye color is mostly determined by genetics, so the phenotype is usually predictable from the genotype, while height is strongly influenced by nutrition and health during development, so the phenotype reflects both genetic potential and environmental input. A classic illustration is PKU, where diet can significantly alter outcomes despite the underlying genotype. So this description best captures how genetic makeup relates to observable traits and how environment shapes their expression.