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 cause the disorder.

Question 2

A woman who is a carrier for hemophilia (an X-linked recessive disorder) and a man without hemophilia have a son. What is the probability that their son will have hemophilia?

Accepted Answer

$$0.50$$

Question 3

Which scientist(s) used bacteriophages to demonstrate that DNA, not protein, is the genetic material?

Accepted Answer

Hershey and Chase

Question 4

What is the significance of Chargaff’s rule in understanding DNA structure?

Accepted Answer

It demonstrated that the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Question 5

Which of the following best describes the difference between purines and pyrimidines in DNA?

Accepted Answer

Purines (adenine and guanine) have a double ring structure, while pyrimidines (cytosine and thymine) have a single ring structure.

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 are likely to be inherited together because crossing over is less likely to separate them.

Question 7

Which of the following best describes semiconservative DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 8

A human cell with 47 chromosomes, including three copies of chromosome 21, is an example of which condition?

Accepted Answer

Trisomy

Question 9

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 10

Why is one X chromosome inactivated in each cell of a female mammal?

Accepted Answer

To ensure that females, like males, have only one functional copy of the X chromosome in each cell.

Question 11

Which of the following best describes the structure of double-stranded DNA?

Accepted Answer

Two antiparallel strands held together by hydrogen bonds between complementary bases.

Question 12

Which of the following is a direct result of nondisjunction during meiosis?

Accepted Answer

Some gametes have an abnormal number of chromosomes, leading to aneuploidy.

Question 13

Which of the following is true about telomeres?

Accepted Answer

They are found at the ends of chromosomes and shorten with each cell division, contributing to aging.

Question 14

Which of the following best explains why eukaryotic DNA replication uses multiple origins of replication?

Accepted Answer

Multiple origins allow the large, linear chromosomes to be replicated quickly and efficiently.

Question 15

Which of the following is an example of a viable human trisomy?

Accepted Answer

Trisomy 21 (Down syndrome)

Question 16

Which process is responsible for repairing DNA damage caused by UV light by directly reversing the damage?

Accepted Answer

Photorepair

Question 17

A scientist observes that two genes are inherited together more often than predicted by Mendel’s law of independent assortment. What is the most likely explanation?

Accepted Answer

The genes are linked and located close together on the same chromosome.

Question 18

Which of the following best describes the role of Rosalind Franklin in the discovery of DNA structure?

Accepted Answer

She produced X-ray diffraction images that revealed the helical structure of DNA.

Question 19

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized discontinuously on the lagging strand.

Question 20

If a mutation in DNA is not repaired, what is the most significant potential consequence?

Accepted Answer

The mutation may be passed to daughter cells, potentially leading to diseases such as cancer.

Chromosomal Basis of Inheritance and DNA: Study Guide (Chapters 12 & 13)

Study Guide - Practice Questions

Study Guide - Flashcards