Question 1

Which of the following best describes the 'end replication problem' in eukaryotic cells?

Accepted Answer

The lagging strand cannot be fully replicated at the chromosome ends, leading to progressive telomere shortening.

Question 2

What is the sequence most commonly repeated in human telomeres?

Accepted Answer

$$	ext{TTAGGG}$$

Question 3

Which enzyme solves the end replication problem by extending the 3’ end of chromosomes?

Accepted Answer

Telomerase

Question 4

Telomerase is classified as which type of enzyme?

Accepted Answer

RNA-dependent DNA polymerase

Question 5

What is the fate of most human somatic cells when their telomeres become critically short?

Accepted Answer

They enter a state called senescence and stop dividing.

Question 6

Which of the following cell types typically maintain active telomerase expression throughout life?

Accepted Answer

Germ cells

Question 7

A scientist observes that a certain cancer cell line has reactivated telomerase. What is the most likely consequence?

Accepted Answer

The cells will become immortal and continue dividing indefinitely.

Question 8

Which of the following best explains why telomerase inhibitors are being explored as cancer therapies?

Accepted Answer

They selectively shorten telomeres in cancer cells, limiting their ability to divide.

Question 9

Which of the following is the correct order of events in the mismatch repair (MMR) pathway?

Accepted Answer

Identify, nick, digest, replace, ligate

Question 10

In bacteria, how does the mismatch repair system distinguish the newly synthesized DNA strand from the template strand?

Accepted Answer

By the absence of methylation on the new strand

Question 11

Which DNA repair mechanism is primarily responsible for correcting errors that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair (MMR)

Question 12

A patient is exposed to UV light, resulting in thymine dimers in their DNA. Which repair pathway is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair (NER)

Question 13

Which of the following best describes the function of the 3’-5’ exonuclease activity of DNA polymerase?

Accepted Answer

It removes mismatched nucleotides during proofreading.

Question 14

If a mutation disables the MutS protein in E. coli, which process will be most directly affected?

Accepted Answer

Mismatch repair

Question 15

A 100-year-old person’s lymphocytes have telomeres that are, on average, how much shorter than those of a 20-year-old?

Accepted Answer

About 2-3 kilobases shorter

Question 16

Which of the following is a real-world consequence of telomere shortening in human tissues?

Accepted Answer

Reduced regenerative capacity and onset of age-related tissue dysfunction

Question 17

Which of the following best explains why mutations are both beneficial and harmful?

Accepted Answer

They fuel evolution but can also cause disease.

Question 18

Which of the following is NOT a source of DNA damage?

Accepted Answer

Telomerase activity

Question 19

Which repair pathway is most likely to fix a double-strand break in DNA?

Accepted Answer

Homologous recombination (HR)

Telomeres, Telomerase, and DNA Repair Mechanisms

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