During Gregor Mendel’s study of pea plants, he followed the principles of experimental design and only tested one trait at a time. He determined that the pair of alleles separated, or segregated, during the process of meiosis.

Mendel wondered if the segregation of one pair of alleles affected another pair of alleles. For example, Mendel wondered if the pair of alleles that determines seed color would affect the shape of the seeds. To come to a conclusion, Mendel performed many experiments to test this question.

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