Campbell Biology (10th Edition)

Published by Pearson
ISBN 10: 0321775651
ISBN 13: 978-0-32177-565-8

Chapter 15 - 15.3 - Concept Check: 2

Answer

In a testcross, the progeny directly show the unknown parental genotype. In this case, where the female parent has a dominant allele, that determines the phenotype in the offspring. Where the female has a recessive allele, that works with the identical allele in the recessive (known) parent) to produce the phenotype.

Work Step by Step

The recessive parent in a testcross is like a white canvas. If the unknown parent as a dominant allele, think of that like a strong color which masks the white and is obvious. A recessive allele in the unknown parent is like white paint which blends in with the canvas--you know it by what you don't see.
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