Question 1

Which experiment provided the strongest evidence that DNA, and not protein, is the genetic material responsible for inheritance in viruses?

Accepted Answer

Hershey and Chase’s experiment using radioactive isotopes to label DNA and protein in bacteriophages

Question 2

According to Chargaff’s rules, which of the following equations is always true for double-stranded DNA?

Accepted Answer

$$A + G = C + T$$

Question 3

What type of chemical bond holds the two strands of the DNA double helix together?

Accepted Answer

Hydrogen bonds

Question 4

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 5

During DNA replication, why is an RNA primer necessary?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3’ end

Question 6

Which of the following best describes the direction in which DNA polymerase synthesizes new DNA?

Accepted Answer

5’ to 3’

Question 7

What is the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together on the lagging strand

Question 8

A mutation in the gene encoding DNA polymerase I results in a loss of its exonuclease activity. What is the most likely consequence?

Accepted Answer

RNA primers will not be removed from Okazaki fragments

Question 9

Which of the following is a direct result of UV-induced thymine dimers in DNA?

Accepted Answer

Disruption of hydrogen bonding between base pairs

Question 10

Why do eukaryotic chromosomes require telomerase for complete replication, but prokaryotic chromosomes do not?

Accepted Answer

Eukaryotic chromosomes are linear, so their ends cannot be fully replicated by DNA polymerase

Question 11

Which of the following best explains why mutations are important for evolution?

Accepted Answer

They are the source of genetic variation upon which natural selection acts

Question 12

Which of the following statements about chromatin structure is correct?

Accepted Answer

Histone modifications can regulate gene expression by altering chromatin structure

Question 13

A bacterial culture is grown in radioactive adenine (A*) and then transferred to nonradioactive adenine (A). After one round of DNA replication, which DNA sequence could be found in the bacteria?

Accepted Answer

Each DNA molecule contains one strand with A* and one with A

Question 14

Which of the following is NOT a function of the sugar-phosphate backbone in DNA?

Accepted Answer

Encoding genetic information

Question 15

Which enzyme is responsible for synthesizing short RNA primers during DNA replication?

Accepted Answer

Primase

Question 16

If a mutation prevents the formation of Okazaki fragments, which process would be directly affected?

Accepted Answer

Synthesis of the lagging strand

Question 17

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental and one new strand

Question 18

Which of the following is a direct consequence of a defect in mismatch repair proteins?

Accepted Answer

Increased rate of mutations in the genome

Question 19

Which of the following statements about nucleosomes is correct?

Accepted Answer

They are composed of DNA wrapped around a core of eight histone proteins

Question 20

Which of the following best explains why dense packing of heterochromatin makes it largely inaccessible to transcription machinery?

Accepted Answer

The tightly packed structure physically blocks access to DNA sequences

The Molecular Basis for Inheritance: DNA Structure and Replication

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