Question 1

Which of the following statements best describes autosomal recessive inheritance?

Accepted Answer

Affected individuals must have two mutant alleles, one from each parent.

Question 2

A couple, both of whom are carriers for an autosomal recessive disorder, have a child. What is the probability that their child will be affected by the disorder? Use a Punnett square to justify your answer.

Accepted Answer

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

Question 3

Which of the following is a key characteristic of autosomal recessive diseases compared to autosomal dominant diseases?

Accepted Answer

Phenotypes are more uniform in autosomal recessive diseases.

Question 4

A woman with cystic fibrosis (an autosomal recessive disorder) marries a man who is not a carrier. What is the probability that their child will be a carrier?

Accepted Answer

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

Question 5

Which of the following best explains why autosomal recessive diseases are more common in certain ethnic populations?

Accepted Answer

Founder effects and genetic drift can increase the frequency of specific mutant alleles in isolated populations.

Question 6

If two first cousins, both carriers for a rare autosomal recessive disease, have a child, what is the risk that their child will be affected?

Accepted Answer

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

Question 7

Which of the following is NOT a typical feature of autosomal recessive inheritance?

Accepted Answer

The disease is usually present in every generation.

Question 8

A child is diagnosed with Gaucher disease, an autosomal recessive disorder. Neither parent is affected. What is the most likely genotype of the parents?

Accepted Answer

Both parents are heterozygous carriers.

Question 9

Which of the following best describes the genotype and phenotype relationship in autosomal recessive inheritance?

Accepted Answer

Homozygous recessive individuals express the disease phenotype.

Question 10

In a population where the carrier frequency for cystic fibrosis is $$\frac{1}{25}$$, what is the expected frequency of affected individuals, assuming Hardy-Weinberg equilibrium?

Accepted Answer

$$\frac{1}{625}$$

Question 11

Which of the following statements about consanguinity and autosomal recessive diseases is correct?

Accepted Answer

Consanguinity increases the risk for rare autosomal recessive diseases.

Question 12

A pedigree shows a disease skipping generations and affecting both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 13

Which of the following is a common mutation in the CFTR gene causing cystic fibrosis?

Accepted Answer

Delta F508 deletion

Question 14

A healthy couple has a child with an autosomal recessive disorder. What is the probability that their next child will also be affected?

Accepted Answer

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

Question 15

Which of the following best explains why new mutations are rarely detected clinically in autosomal recessive diseases?

Accepted Answer

A single new mutation is not sufficient to cause disease; both alleles must be mutated.

Question 16

A man with a family history of Gaucher disease (autosomal recessive) marries a woman with no family history. What is the chance their child will be affected if the man is a carrier and the woman is not?

Accepted Answer

$$0$$

Question 17

Which of the following is true regarding the clinical expression (phenotype) of autosomal recessive diseases?

Accepted Answer

Affected individuals have two mutant alleles and usually show complete penetrance.

Question 18

In a family with a history of cystic fibrosis, a child is born to two carrier parents. What is the probability that the child is a carrier but not affected?

Accepted Answer

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

Question 19

Which of the following best describes the effect of loss-of-function mutations in autosomal recessive diseases?

Accepted Answer

They usually cause disease only when both alleles are mutated.

Question 20

A population has a carrier frequency for a certain autosomal recessive disease of $$q = 0.1. $$Using Hardy-Weinberg equilibrium, what is the expected frequency of affected individuals ($$q^2$$)?

Accepted Answer

$$0.01$$

Patterns of Single Gene Inheritance: Autosomal Recessive Inheritance

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