A lizard with a striped tail and a normal head is crossed with one having a normal tail and a spotted head. All the F₁ progeny are normal (no stripes or spots). What progeny are expected from a cross of the F₁ progeny? Assume that the genes conferring stripes and spots were on different chromosomes. A) Equal numbers of normal, striped, spotted and striped, and spotted B) 3 striped : 1 spotted C) 9 striped and spotted : 3 spotted : 3 striped : 1 normal D) 9 striped : 3 spotted : 1 striped or spotted E) 9 normal : 3 striped : 3 spotted : 1 striped and spotted

Question

Quizplus · Accepted Answer

The observed pattern of inheritance suggests that both the striped and spotted traits are recessive to the normal phenotype. When F₁ progeny, which are heterozygous for both traits, are crossed, the expected outcome follows a 9:3:3:1 ratio according to Mendelian genetics for a dihybrid cross. This results in 9 normal (neither striped nor spotted), 3 striped only, 3 spotted only, and 1 with both stripes and spots.

A Lizard with a Striped Tail and a Normal Head