What does true-breeding refer to?

True-breeding refers to organisms that consistently produce offspring with specific traits when they are bred together. This means that if true-breeding plants or animals are crossed, they will yield progeny that display the same traits as the parent generation. This consistency occurs because true-breeding individuals are homozygous for the traits in question; they possess two identical alleles for those traits.

In plants, for instance, a true-breeding pea plant that exhibits yellow seeds will only produce offspring with yellow seeds when self-pollinated, proving that its genetic makeup is stable and uniform regarding that trait. This concept is significant in the study of genetics and breeding, as it helps establish reliable lines for research, farming, and practice in both agriculture and animal husbandry.

In contrast, the other choices involve hybridization or variability, which do not align with the definition of true-breeding. True-breeding organisms are characterized by their uniformity rather than the production of varied offspring or hybrids.