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

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Nicole Leisy · Accepted Answer

Final Answer : E, Explanation :  The observed pattern of inheritance suggests that both the striped and spotted traits are recessive to the normal phenotype. When F 1  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.

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