Biology Regents Practice Exam 2025 - Free Practice Questions and Study Guide

The term that describes the observable physical characteristics of an organism is phenotype. Phenotype refers to the expression of an organism's genes in conjunction with environmental influences, resulting in specific traits such as height, eye color, and leaf shape in plants. Essentially, it encompasses all the observable features of an organism.

Genotype, on the other hand, refers to the genetic makeup of an organism—the specific alleles present at various loci within its DNA. While genotype contributes to the phenotype, it is not directly observable without genetic testing. Alleles are the different forms of a gene that can exist at a specific locus and can influence phenotype, but they are not synonymous with observable traits. A trait refers to a specific characteristic or feature, which is a component of the phenotype but does not encompass the complete set of observable traits. Therefore, phenotype is the most accurate term to represent the observable features of an organism.