Question 1

Which of the following best explains why X-linked recessive disorders are more common in males than in females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will result in the disorder.

Question 2

A woman who is a carrier for hemophilia (X-linked recessive) has children with a normal male. What is the probability that their son will have hemophilia? Use the following genotypes: $$X^H = $$normal allele, $$X^h = $$hemophilia allele.

Accepted Answer

$$0.25$$

Question 3

Which of the following is an example of a sex-influenced trait rather than a sex-linked trait?

Accepted Answer

Male pattern baldness

Question 4

A pedigree shows a trait that appears only in males and is passed from affected fathers to all sons. Which type of inheritance does this pattern most likely represent?

Accepted Answer

Y-linked

Question 5

Which chromosomal abnormality is most commonly associated with Down Syndrome?

Accepted Answer

Trisomy 21

Question 6

A child is born with the genotype $$X^hY. $$What is the phenotype of this child regarding hemophilia?

Accepted Answer

Male with hemophilia

Question 7

Which of the following best describes the result of nondisjunction during meiosis II?

Accepted Answer

Two gametes are normal, one has an extra chromosome, and one is missing a chromosome.

Question 8

Which syndrome is characterized by a female with only one X chromosome (XO), short stature, and infertility?

Accepted Answer

Turner syndrome

Question 9

A deletion of part of chromosome 5 results in which genetic disorder, characterized by intellectual disability and a distinctive cry?

Accepted Answer

Cri-du-chat syndrome

Question 10

Which of the following statements about dominant genetic disorders is correct?

Accepted Answer

Only one defective allele is needed for the disorder to be expressed.

Question 11

A couple has a child with cystic fibrosis, a recessive disorder. Neither parent has the disease. What are the possible genotypes of the parents?

Accepted Answer

Both parents are heterozygous carriers.

Question 12

Which genetic disorder is caused by a mutation on chromosome 1, leading to the accumulation of phenylalanine?

Accepted Answer

Phenylketonuria (PKU)

Question 13

A male with Klinefelter syndrome has which of the following sex chromosome combinations?

Accepted Answer

XXY

Question 14

Which of the following best describes the inheritance pattern of Huntington disease?

Accepted Answer

Autosomal dominant

Question 15

A woman with genotype $$X^H X^h ($$carrier for hemophilia) and a man with genotype $$X^H Y$$ have a daughter. What is the probability that the daughter will be a carrier?

Accepted Answer

$$0.25$$

Question 16

Which of the following is a possible consequence of a chromosomal translocation?

Accepted Answer

Increased risk of certain cancers

Question 17

Which of the following best explains why females are often carriers but rarely affected by X-linked recessive disorders?

Accepted Answer

Females have two X chromosomes, so a normal allele can mask the effect of a recessive allele.

Question 18

Which of the following is NOT a result of nondisjunction during meiosis?

Accepted Answer

Cri-du-chat syndrome

Question 19

A male with genotype $$X^h Y ($$hemophilia) and a female with genotype $$X^H X^H ($$normal) have children. What is the probability that their daughters will be carriers?

Accepted Answer

$$1.00$$

Question 20

Which of the following is a characteristic of Jacob syndrome (XYY)?

Accepted Answer

Tall stature and increased risk of learning disabilities

Genetic Inheritance and Chromosome Abnormalities

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