What determines the phenotype of an organism?

The phenotype of an organism is determined primarily by its genotype, which refers to the genetic makeup of that organism. The genotype consists of the specific alleles or variations of genes that are inherited from the parents. These genes encode for proteins and contribute to the various traits that are observable in the organism, such as physical characteristics, behaviors, and physiological functions.

While the environment can influence how these traits are expressed, it is the underlying genetic code that ultimately provides the blueprint for those traits. The relationship between genotype and phenotype is fundamental in genetics, as it helps explain how inherited traits are passed on and manifested in offspring.

In summary, while other factors can play a role in shaping the final phenotype, the core determinant is the genotype, which provides the basis for the traits that can be observed in an organism.