Final answer:
Genotype and fertility measure the contribution of each genotype to the offspring. During fertilization, the fusion of sperm and egg determines the genotype, which in turn determines the phenotype or physical characteristics of the offspring.
Step-by-step explanation:
Genotype and fertility measure the contribution of each genotype to the offspring of the next generation. When a sperm and egg fuse during fertilization, their chromosomes combine to create a zygote with genetic information from both parents. The resulting genotype determines the physical characteristics or phenotype of the offspring.
For example, in pea plants, the genotype YY or Yy produces yellow-seeded plants, while yy produces green-seeded plants.