Define genotype and phenotype. Describe how they are related and how alleles fit into your definitions.

Genotype refers to an individual organism's unique set of genetic material. This set of genetic material is made up of DNA sequences that code for specific traits, which are then inherited from its parents.

Phenotype is the observable set of characteristics manifested in an individual organism that results from the interaction of its genotype with the environment. This may include physical traits, behaviors, and overall health conditions.

The relationship between genotype and phenotype is strong because an individual's genotype contains the genetic instructions that guide the development of its phenotype. Genotypes are composed of genes, and each gene has a specific location on a chromosome, which may have alternative forms known as alleles. Alleles are responsible for the variations in traits observed in a population. For example, for a given gene that determines eye color, there might be an allele for blue eyes and another one for brown eyes. An individual's genotype is made up of combinations of alleles, which are inherited from both parents. These combinations of alleles will then determine the individual's phenotype. However, it is important to note that the environment also plays a role in an individual's phenotype, as certain traits and characteristics might be influenced by factors external to the genetic makeup of the organism.