In genetics, what does a monohybrid refer to?

The term "monohybrid" specifically relates to an organism that is heterozygous for a single gene, which means it has two different alleles for that one gene. This concept is rooted in Mendelian genetics, where a monohybrid cross typically focuses on the inheritance pattern of one trait. For example, when a purebred tall pea plant is crossed with a purebred short pea plant, the resulting offspring (F1 generation) would all be heterozygous for the height trait, having one allele for tallness (dominant) and one for shortness (recessive).

In studying monohybrid crosses, scientists predict and analyze the inheritance patterns, such as phenotypic ratios and genotype frequencies, among the offspring. This foundational concept highlights how traits are passed from parents to offspring through alleles, which can be either dominant or recessive.

In contrast, the other choices refer to different genetic concepts. For example, an organism with identical alleles relates to homozygosity, and a cross involving multiple traits refers to dihybrid crosses. Understanding these distinctions helps clarify genetic terminology and the principles of inheritance outlined in Mendel's experiments.