What attribute of an organism is determined by genes or alleles?

The attribute of an organism that is determined by genes or alleles is referred to as a phenotype. The phenotype encompasses all observable traits and characteristics of an organism, such as physical appearance, development, and behavior, which result from the expression of the organism’s genotype in combination with environmental influences.

Genes provide the coded information that dictates the potential traits of an organism, while alleles are different versions of these genes. The way these alleles interact with one another and the environment ultimately shapes the phenotype. For example, a plant's height, flower color, or disease resistance are all phenotypic traits determined by its genetic makeup.

Genotype refers specifically to the genetic constitution of an organism—essentially, the alleles it possesses—but does not include the external manifestation of these traits. The locus is the specific location of a gene on a chromosome, and while characteristics is a broad terms referring to traits, it does not specifically denote the expression of those traits as phenotypes do. Therefore, the correct understanding is that the observable attributes that result from genetic factors are encapsulated in the concept of phenotype.