7
practice testMultiple Choice

Practice Test

Question 7 • Biology

The Punnett square predicts the ratio of genotypes in the offspring based on the genotypes of the parents. Which Punnett square represents a cross between a mom who is heterozygous for dimples and a dad who is homozygous for no dimples?

Answer
A
Image with description A Punnett square is shown. The columns are labeled Upper D and Upper D. The rows are labeled Upper D and Upper D. Clockwise from upper left the boxes contain: Upper D Upper D, Upper D Upper D, Upper D Upper D, Upper D Upper D.
B
Image with description A Punnett square is shown. The columns are labeled Upper D and d. The rows are labeled d and d. Clockwise from upper left the boxes contain: Upper D d, d d, d d, Upper D d.
C
Image with description A Punnett square is shown. The columns are labeled Upper D and d. The rows are labeled Upper D and d. Clockwise from upper left the boxes contain: Upper D Upper D, Upper D d, d d, UpperD d.
D
Image with description A Punnett square is shown. The columns are labeled Upper D and Upper D. The rows are labeled d and d. Clockwise from upper left the boxes contain: Upper D d, Upper D d, Upper D d, Upper D d.

Explanation

A heterozygous mom has genotype Dd, so her eggs can carry either D or d. A dad who is homozygous for no dimples has genotype dd, so all his sperm carry d. The offspring combinations are Dd, dd, Dd, and dd, which matches choice A, the Punnett square with columns D and d and both rows d.

AI-written and checked against the verified answer.

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