Question 1

Which of the following best explains why genes located close together on the same chromosome tend to be inherited together?

Accepted Answer

They are linked and less likely to be separated by crossing-over.

Question 2

A woman who is a carrier for hemophilia (an X-linked disorder) and a man who does not have hemophilia have a son. What is the probability that their son will have hemophilia?

Accepted Answer

$$0.50$$

Question 3

Which chromosomal abnormality is caused by the failure of homologous chromosomes to separate during meiosis?

Accepted Answer

Nondisjunction

Question 4

A geneticist observes that two genes are inherited together 90% of the time. What does this suggest about their physical relationship on the chromosome?

Accepted Answer

They are close together on the same chromosome.

Question 5

Which of the following is a result of a chromosomal deletion?

Accepted Answer

Williams syndrome

Question 6

What is the chromosomal composition of a human with Turner syndrome?

Accepted Answer

$$44 + XO$$

Question 7

Which of the following best describes a Barr body?

Accepted Answer

An inactivated X chromosome in females

Question 8

If a segment of a chromosome is reversed end to end, what type of chromosomal mutation has occurred?

Accepted Answer

Inversion

Question 9

A male fruit fly inherits a mutation on the X chromosome. Which of the following is true regarding the expression of this mutation?

Accepted Answer

He will always express the mutation if it is recessive.

Question 10

Which of the following best describes polyploidy?

Accepted Answer

An individual with more than two complete sets of chromosomes

Question 11

Which syndrome is characterized by a male with under-developed testes and some female body characteristics due to an extra X chromosome?

Accepted Answer

Klinefelter syndrome

Question 12

Which of the following is true about the inheritance of X-linked recessive disorders?

Accepted Answer

Males are more likely to express the disorder because they have only one X chromosome.

Question 13

Which of the following is an example of a chromosomal translocation?

Accepted Answer

A segment from chromosome 1 moves to chromosome 5

Question 14

If a person has 47 chromosomes due to an extra chromosome 21, what condition do they have?

Accepted Answer

Down syndrome

Question 15

Which of the following best describes the Law of Independent Assortment?

Accepted Answer

Genes on different chromosomes are inherited independently of each other.

Question 16

A geneticist finds that the recombination frequency between two genes is 12%. What is the approximate distance between these genes on a genetic map?

Accepted Answer

$$12$$ map units

Question 17

Which of the following is NOT a possible result of nondisjunction?

Accepted Answer

Polyploidy in animals

Question 18

Which of the following human syndromes is caused by the loss of a segment of chromosome 5?

Accepted Answer

Cri du chat syndrome

Question 19

Which of the following best describes a duplication mutation?

Accepted Answer

A segment of a chromosome is present more than once

Question 20

Which of the following is true about the Y chromosome in humans?

Accepted Answer

It determines male sex and carries genes for male traits.

Chromosomal Basis of Inheritance and Chromosome Structure

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