Question 1

Which of the following best describes the structure of DNA as revealed by Watson and Crick?

Accepted Answer

A double helix with two antiparallel strands, sugar-phosphate backbones on the outside, and nitrogenous bases paired in the interior.

Question 2

In the Hershey-Chase experiment, which molecule was shown to enter the bacterial cell and direct viral reproduction?

Accepted Answer

DNA

Question 3

Which of the following is a purine base found in nucleic acids?

Accepted Answer

Adenine

Question 4

If a double-stranded DNA molecule contains 30% adenine, what percentage of guanine would you expect?

Accepted Answer

$20\%$

Question 5

Which enzyme is responsible for relieving the strain ahead of the replication fork during DNA replication?

Accepted Answer

Topoisomerase

Question 6

During DNA replication, which strand is synthesized continuously in the direction of the replication fork?

Accepted Answer

Leading strand

Question 7

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

The lagging strand is synthesized discontinuously because DNA polymerase can only add nucleotides to the 3' end.

Question 8

A mutation in which enzyme would most directly prevent the joining of Okazaki fragments?

Accepted Answer

DNA ligase

Question 9

Which of the following is NOT a function of DNA polymerase during DNA replication?

Accepted Answer

Joining Okazaki fragments together.

Question 10

Which of the following statements about telomeres is correct?

Accepted Answer

Telomeres are repetitive DNA sequences at the ends of eukaryotic chromosomes that postpone gene erosion.

Question 11

Which enzyme compensates for the replication-associated shortening of linear chromosomes in germ cells?

Accepted Answer

Telomerase

Question 12

Which of the following processes does NOT contribute to the high fidelity of DNA replication?

Accepted Answer

Telomerase

Question 13

Arrange the following terms in order from smallest to largest: nucleosome, looped domain, metaphase chromosome, histone, 30-nm fiber.

Accepted Answer

Histone, nucleosome, 30-nm fiber, looped domain, metaphase chromosome

Question 14

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is loosely packed and transcriptionally active, while heterochromatin is highly condensed and transcriptionally inactive.

Question 15

A scientist is studying a bacterial cell with a mutation in DNA polymerase I. Which process would be most directly affected?

Accepted Answer

Removal of RNA primers and replacement with DNA on the lagging strand

Question 16

Which of the following is a real-world consequence of mutations that escape DNA repair mechanisms?

Accepted Answer

They can be passed to the next generation and contribute to genetic variation.

Question 17

Which of the following statements about the directionality of DNA synthesis is correct?

Accepted Answer

DNA synthesis occurs in the 5' to 3' direction only.

Question 18

Which of the following is a correct pairing of nitrogenous bases in DNA, and how many hydrogen bonds are formed between them?

Accepted Answer

Adenine and thymine; 2 hydrogen bonds

Question 19

A patient is found to have a defect in nucleotide excision repair. Which of the following would most likely result?

Accepted Answer

Accumulation of DNA damage from UV light exposure

Question 20

Which of the following best explains why DNA replication is described as 'semiconservative'?

Accepted Answer

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

DNA Structure, Replication, and Chromosome Organization: Study Notes

Study Guide - Practice Questions