Q: If individual I-2 is heterozygous for the trait, what is the probability that both III-1 and III-2 are carriers, assuming autosomal recessive inheritance?

$$\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$$

Question 1

Based on the pedigree shown, which inheritance pattern is most likely for the trait depicted (filled symbols indicate affected individuals)?

Accepted Answer

Autosomal recessive

Question 2

If individual II-2 is a carrier for the trait, what is the probability that her child with an unaffected male (II-1) will be affected by the trait, assuming autosomal recessive inheritance?

Accepted Answer

$$\frac{1}{4}$$

Question 3

Which of the following best explains why individual III-2 is not affected by the trait, while her sibling III-3 is affected?

Accepted Answer

III-2 inherited one dominant and one recessive allele.

Question 4

If the trait were X-linked recessive, which of the following would be true about the inheritance pattern in this pedigree?

Accepted Answer

Affected females would have affected fathers.

Question 5

Given the pedigree, what is the genotype of individual II-3 if the trait is autosomal recessive? (A = dominant, a = recessive)

Accepted Answer

Aa

Question 6

If individual I-2 is heterozygous for the trait, what is the probability that both III-1 and III-2 are carriers, assuming autosomal recessive inheritance?

Accepted Answer

$$\frac{1}{2} 	imes \frac{1}{2} = \frac{1}{4}$$

Question 7

Which event during meiosis is most responsible for the genetic variation observed among the siblings in generation III?

Accepted Answer

Crossing over during prophase I

Question 8

If the trait is due to a mutation in a mitochondrial gene, which individuals in generation III would be expected to express the trait?

Accepted Answer

All offspring of II-2

Question 9

Which of the following best describes the law of segregation as it applies to this pedigree?

Accepted Answer

Each gamete receives only one allele from each gene pair.

Question 10

If a new mutation causing the trait arose in individual II-4, what is the probability that her child (III-4) will also have the trait, assuming the trait is autosomal dominant?

Accepted Answer

$$\frac{1}{2}$$

AP Biology Unit 5: Heredity – Meiosis, Mendelian & Non-Mendelian Genetics, and Chromosomal Genetics

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