Question 1

Which experiment provided the first direct evidence that DNA, and not protein, is the genetic material responsible for heredity?

Accepted Answer

Hershey-Chase Experiment

Question 2

A scientist isolates a DNA sample and finds it contains 32% cytosine. According to Chargaff's rules, what percentage of the sample is adenine?

Accepted Answer

$$18\%$$

Question 3

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

Accepted Answer

Topoisomerase

Question 4

If a DNA strand has the sequence $$5'-GCTA-3'$$, what is the sequence of the complementary strand?

Accepted Answer

$$3'-CGAT-5'$$

Question 5

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously toward the replication fork, while the lagging strand is synthesized discontinuously away from the fork in Okazaki fragments.

Question 6

A mutation causes a cell to lose the function of DNA ligase. What is the most likely consequence during DNA replication?

Accepted Answer

Okazaki fragments on the lagging strand will not be joined together.

Question 7

Which of the following is a direct result of UV radiation on DNA?

Accepted Answer

Formation of thymine dimers

Question 8

Why do eukaryotic chromosomes require telomeres, but prokaryotic chromosomes do not?

Accepted Answer

Eukaryotic chromosomes are linear and lose DNA at the ends during replication, while prokaryotic chromosomes are circular and do not.

Question 9

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

Accepted Answer

Primase

Question 10

A cell is exposed to a chemical mutagen that causes errors during DNA replication. Which cellular process is most likely to correct these errors?

Accepted Answer

Nucleotide excision repair

Question 11

Which of the following best explains why DNA is packaged with histones in eukaryotic cells?

Accepted Answer

To compact the DNA so it fits in the nucleus and regulate gene accessibility

Question 12

Which of the following statements about euchromatin and heterochromatin is correct?

Accepted Answer

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

Question 13

Which enzyme is responsible for removing RNA primers and replacing them with DNA nucleotides during replication?

Accepted Answer

DNA Polymerase I

Question 14

A patient has a mutation that causes telomerase to be active in all somatic cells. What is a likely consequence?

Accepted Answer

Cells may divide indefinitely, increasing the risk of cancer.

Question 15

Which of the following best describes the role of single-strand binding proteins during DNA replication?

Accepted Answer

They prevent separated DNA strands from re-annealing.

Question 16

If a DNA molecule is replicated in a semi-conservative manner, what will be the composition of the two resulting DNA molecules?

Accepted Answer

Each will have one parental strand and one newly synthesized strand.

Question 17

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

Accepted Answer

Removing RNA primers

Question 18

A mutation in the gene encoding histone proteins would most likely affect which cellular process?

Accepted Answer

DNA packaging and gene regulation

Question 19

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

Accepted Answer

They are the ultimate source of genetic variation.

Question 20

In the Hershey-Chase experiment, why was radioactive phosphorus used to label DNA?

Accepted Answer

Because phosphorus is present in DNA but not in protein

DNA as the Genetic Material: Structure, Replication, and Packaging

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