What is the phenotype of an organism?

The phenotype of an organism refers to the physical manifestation of a characteristic, encompassing traits such as appearance, behavior, and physiological properties. This concept encapsulates how the genetic makeup of an organism, known as the genotype, interacts with environmental factors to produce observable traits. For example, in plants, the phenotype can include flower color, height, and leaf shape, all of which are expressions of the underlying genetic information influenced by environmental conditions.

The other choices pertain to different genetic concepts: The set of alleles refers to the genotype, which is the actual genetic composition; the location of an allele relates to its specific position on a chromosome; and having two different alleles at a locus describes a condition known as heterozygosity. These aspects play critical roles in genetics but do not define the concept of phenotype, which is strictly about observable traits.