Question 1

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

Accepted Answer

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

Question 2

A scientist exposes bacterial cells to a chemical that specifically inhibits the activity of DNA ligase. Which of the following processes would be most directly affected?

Accepted Answer

Joining of Okazaki fragments on the lagging strand during DNA replication.

Question 3

Which enzyme is responsible for relieving the strain caused by the unwinding of the DNA double helix ahead of the replication fork?

Accepted Answer

Topoisomerase

Question 4

A mutation causes the loss of function of single-strand binding proteins in a eukaryotic cell. What is the most likely immediate consequence during DNA replication?

Accepted Answer

The separated DNA strands would re-anneal before replication could proceed.

Question 5

Which of the following statements about telomeres is TRUE?

Accepted Answer

They consist of repetitive, non-coding DNA sequences that protect genes from erosion during replication.

Question 6

In the context of DNA replication, what is the primary function of primase?

Accepted Answer

To synthesize short RNA primers complementary to the DNA template strand.

Question 7

A patient is diagnosed with a genetic disorder that results in defective nucleotide excision repair. Which of the following symptoms would you most likely expect?

Accepted Answer

Increased sensitivity to ultraviolet light and higher risk of skin cancer.

Question 8

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

Accepted Answer

It adds nucleotides to the 3' end, synthesizing in the 5' to 3' direction.

Question 9

Which of the following is a direct consequence of the antiparallel structure of DNA during replication?

Accepted Answer

One strand is synthesized continuously while the other is synthesized in fragments.

Question 10

A researcher observes that a certain eukaryotic cell line expresses high levels of telomerase. Which of the following is the most likely explanation for this observation?

Accepted Answer

The cells are cancerous and have acquired the ability to maintain telomere length indefinitely.

Question 11

Which of the following best summarizes Chargaff’s Rules?

Accepted Answer

In any species, the amount of adenine equals thymine and the amount of guanine equals cytosine.

Question 12

Rosalind Franklin’s X-ray crystallography images provided critical evidence for which of the following features of DNA?

Accepted Answer

The helical structure and uniform width of the DNA molecule.

Question 13

Which of the following is the correct sequence of events during the initiation of DNA replication in prokaryotes?

Accepted Answer

Origin recognition, helicase unwinding, single-strand binding protein stabilization, primase primer synthesis.

Question 14

A DNA molecule has 30% adenine. According to Chargaff’s rules, what percentage of guanine would you expect?

Accepted Answer

$$20\%$$

Question 15

Which of the following best explains why repeated rounds of DNA replication in eukaryotic somatic cells lead to shorter chromosomes?

Accepted Answer

The replication machinery cannot fully replicate the 5' ends of linear DNA molecules.

Question 16

Which of the following is a function of DNA polymerase during DNA replication?

Accepted Answer

Proofreading newly synthesized DNA and replacing incorrect nucleotides.

Question 17

A patient is found to have a mutation that inactivates the gene encoding for the enzyme nuclease. Which DNA repair process would be most directly impaired?

Accepted Answer

Excision repair of damaged DNA segments.

Question 18

Which of the following best describes the role of telomerase in germ cells?

Accepted Answer

It catalyzes the lengthening of telomeres, preventing the loss of essential genetic information.

Question 19

Which of the following is a real-life example of nucleotide excision repair in action?

Accepted Answer

Repair of thymine dimers in skin cells caused by ultraviolet light exposure.

Question 20

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

Accepted Answer

The two strands of DNA run antiparallel, with one running 5' to 3' and the other 3' to 5'.

Molecular Basis of Inheritance: DNA Structure, Replication, and Repair

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