Final answer:
A hybrid describes an individual that has one dominant allele and one recessive allele for a gene, making them heterozygous for that gene. Such an individual will express the dominant trait in their phenotype. The genotype of this type of hybrid is typically represented as Aa.
Step-by-step explanation:
The term “hybrid” in genetics refers to an organism with two different alleles for the same trait. Specifically, a hybrid is an individual that has one dominant allele and one recessive allele for a gene. This makes the individual heterozygous for that particular gene (“hetero-” means “different” or “other”). In line with the principles established by Gregor Mendel, such an individual will express the dominant trait in their phenotype, even though they carry a recessive allele. The genotype of a hybrid individual for a single gene would be written as Aa, where “A” represents the dominant allele and “a” represents the recessive allele. It is important to note that while Mendel originally thought only two alleles existed for a gene, we now recognize the possibility of multiple alleles at the population level.