In radishes, red and white are the pure-breeding colors, and long and round are the pure-breeding shapes, while the hybrids are purple and oval.The cross of a red, long radish and a white, round radish will produce an F₂ generation in which A)the most common phenotype will be oval and purple. B)the purple color will occur with all three shapes of radish. C)the red color will occur with all three shapes of radish. D)all white, long forms produced will be pure-breeding. E)all of these are true.

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The F₂ generation is a result of a dihybrid cross between the two pure-breeding parents. The letters represent the genes and their corresponding alleles for color and shape. F and U represent the alleles for red and white color, respectively, while B and S represent the alleles for long and round shape, respectively. The most common phenotype will be oval and purple (choice A) because these are the traits of the hybrid offspring produced from the cross of the two pure-breeding parents. The purple color will occur with all three shapes of radish (choice B) because the purple trait is dominant over both red and white, and will therefore be expressed in any offspring that inherits at least one copy of the purple allele. The red color will occur with all three shapes of radish (choice C) because the red allele is still present in the F₂ generation, even if it is not expressed in the phenotype. Not all white, long forms produced will be pure-breeding (choice D) because the white and long traits are both recessive, and an offspring must inherit two copies of each allele to be pure-breeding for those traits. It is possible that a white, long offspring could be heterozygous for one or both traits, and therefore not pure-breeding.

In Radishes, Red and White Are the Pure-Breeding Colors, and Long