Question 1

Which of the following best explains the chromosomal theory of inheritance?

Accepted Answer

Genes are located on chromosomes, and the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 2

A woman who is a carrier for a recessive X-linked disorder and a man who is unaffected have a son. What is the probability that their son will be affected by the disorder?

Accepted Answer

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

Question 3

Which of the following is a direct consequence of the law of independent assortment at the chromosomal level?

Accepted Answer

Each pair of homologous chromosomes orients independently at metaphase I of meiosis.

Question 4

A male with Klinefelter syndrome has which of the following karyotypes?

Accepted Answer

47, XXY

Question 5

Which of the following best describes the genetic mechanism behind Duchenne muscular dystrophy?

Accepted Answer

It is caused by a recessive allele on the X chromosome.

Question 6

If two genes are located very close together on the same chromosome, which of the following is most likely true?

Accepted Answer

They will show a recombination frequency close to $$0\%.$$

Question 7

A woman with normal vision and a man with color blindness (an X-linked recessive trait) have a daughter. What is the probability that the daughter will be color blind?

Accepted Answer

$$0$$

Question 8

Which chromosomal abnormality is most commonly associated with Down syndrome?

Accepted Answer

Trisomy 21

Question 9

Which of the following is an example of genomic imprinting?

Accepted Answer

A gene is expressed only if inherited from the mother, but not if inherited from the father.

Question 10

A geneticist observes that two genes have a recombination frequency of $$12\%. $$What does this indicate about their physical location?

Accepted Answer

They are located close together on the same chromosome.

Question 11

Which of the following chromosomal alterations results in a chromosome with a segment in reverse orientation?

Accepted Answer

Inversion

Question 12

A child is born with Turner syndrome. Which of the following is the most likely karyotype?

Accepted Answer

45, X0

Question 13

Which of the following best explains why females are less likely than males to express X-linked recessive disorders?

Accepted Answer

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

Question 14

Which of the following is a real-world example of a disease caused by a reciprocal translocation?

Accepted Answer

Chronic myelogenous leukemia (CML)

Question 15

Which of the following statements about Barr bodies is correct?

Accepted Answer

A Barr body is an inactivated X chromosome found in the nuclei of female mammalian cells.

Question 16

If a diploid organism has a total of 16 chromosomes, how many chromosomes will be present in each gamete after meiosis?

Accepted Answer

$$8$$

Question 17

Which of the following best describes the effect of nondisjunction during meiosis?

Accepted Answer

It results in gametes with abnormal numbers of chromosomes.

Question 18

A geneticist is mapping two genes and finds a recombination frequency of $$50\%. $$What does this suggest?

Accepted Answer

The genes are likely on different chromosomes or far apart on the same chromosome.

Question 19

Which of the following is an example of aneuploidy?

Accepted Answer

A cell with 45 chromosomes due to loss of one chromosome.

Question 20

Which of the following is true about extranuclear (cytoplasmic) genes?

Accepted Answer

They are located in organelles such as mitochondria and chloroplasts.

Ch. 15: Chromosomal Inheritance

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