Quiz Review Punnett Squares

Quiz Review: Punnett Squares

Multiple Choice

A woman is homozygous dominant for curly hair. Her husband has straight hair, which is a recessive trait. If the woman and her husband decide to have children, what is the probability of them having a child with curly hair?

• 25% chance of having a child with curly hair

• 50% chance of having a child with curly hair

• 75% chance of having a child with curly hair

• 100% chance of having a child with curly hair

Multiple Choice

Two parents, both with freckles (a dominant trait), have four children. One child has freckles, like the parents, while the other three do not. A student, learning about genetics, creates the following Punnett square, assuming the parents are both heterozygous (Ff) for the freckles trait. The student claims that three children should have freckles, and only one should not. However, the observed outcome is one child with freckles and three without. Which explanation BEST describes why the Punnett square does not accurately reflect the observed outcomes?

• The Punnett square represents probabilities, not guaranteed outcomes.

• The parents are homozygous for freckles, not heterozygous.

• Environmental factors influenced the expression of freckles.

• The Punnett square assumes equal probability, but genetic inheritance can vary.

Multiple Choice

In flowers, purple petals are dominant to white petals. If two heterozygous purple-flowered plants are crossed, what percent of the offspring are expected to have white petals? Hint: If you must, do a Punnett Square to show the results.

• 25%
• 50%
• 75%
• 100%

Multiple Choice

In guinea pigs, smooth fur is dominant over rough fur. If two guinea pigs that are both heterozygous for fur texture are mated and produce 40 offspring, which of the following BEST represents the likely outcome from the cross? Hint: Complete a Punnett square of the expected ratio of smooth fur to rough fur when two heterozygous rats are crossed.

• 40 smooth fur, 0 rough fur

• 0 smooth fur, 40 rough fur

• 30 smooth fur, 10 rough fur

• 20 smooth fur, 20 rough fur

Multiple Choice

A farmer is trying to breed a specific flower color in their garden. While red flowers are dominant, purple flowers are more valuable. The farmer aims to produce as many purple-flowered offspring as possible and needs to determine which of their red-flowered plants may carry the gene for purple flowers. The farmer performs test crosses using four different breeding pairs of plants. The results of the test crosses are shown in the table below.

Based on the results of the test cross, the red-flowered parent(s) from which of the pairs can be identified with certainty as heterozygous for flower color?

• Pair 1 and Pair 2

• Pair 2 and Pair 3

• Pair 3 and Pair 4

• Pair 2 and Pair 4