EVERYDAY SCIENCE

Detailed explanation-1: -A true-breeding organism, sometimes also called a purebred (biology slang: pure line or true-breeding line), is an organism that always passes down certain phenotypic traits (i.e. physically expressed traits) to its offspring of many generations.

Detailed explanation-2: -A purebred refers to offspring resulting from a true breeding. True breeding is a way to produce offspring that would carry the same phenotype as the parents. Thus, a purebred would result when the parents are homozygous for certain traits.

Detailed explanation-3: -A true breeding plant (pureline) has homozygcus genes for a character (e.g. TT for tall or tt for dwarf). It always produces offsprings which are true (pure) for its characters.

Detailed explanation-4: -An example of true breeding is that of the Aberdeen Angus cattle. The cattle have been black for many generations, which is an indication that such trait passed on from many generations remains pure. Another example is the mating between two dogs of the same breed.

Detailed explanation-5: -True bred organisms will have a pure genotype (genetic expression of a trait) and will only produce a certain phenotype. True bred is sometimes also called pure bred. If you take two true breeding pea plants-say, one that is yellow and one that is green-and cross them, you would end up with only yellow offspring.