Final answer:
The total composite of heredity instructions coded in the genes at the moment of conception is one's genotype. Genes determine an individual's genotype and phenotype, with the genotype representing the complete genetic makeup and the phenotype referring to the physical characteristics resulting from genetic and environmental influences.
Step-by-step explanation:
The total composite of heredity instructions coded in the genes at the moment of conception is one's genotype. Each human cell has 23 pairs of chromosomes, inherited from the mother and father, that contain thousands of genes responsible for determining an individual's genotype and phenotype. Genes are sequences of DNA that code for functional products. The genotype represents an individual's complete genetic makeup while the phenotype refers to the physical characteristics resulting from the interaction of genetic and environmental factors.