Question 1

Which of the following best describes a spontaneous mutation?

Accepted Answer

A mutation that arises from normal biological or chemical processes without external influence.

Question 2

Replication slippage is most likely to occur in which type of DNA sequence, and what is a potential consequence?

Accepted Answer

In repeat sequences, leading to small insertions or deletions.

Question 3

Tautomeric shifts in DNA bases can result in which of the following outcomes?

Accepted Answer

Noncomplementary base pairing during replication.

Question 4

Depurination of DNA most commonly leads to which type of mutation during replication?

Accepted Answer

A deletion of a nucleotide pair.

Question 5

Which chemical change converts cytosine to uracil in DNA, and what is the mutational consequence?

Accepted Answer

Deamination; leads to a G=C to A=T transition.

Question 6

Which of the following is a real-life example of a disease caused by replication slippage?

Accepted Answer

Huntington disease

Question 7

Which of the following statements about free radicals is TRUE?

Accepted Answer

Free radicals can break phosphodiester bonds and cause chromosomal fragmentation.

Question 8

Base analogs such as 5-bromouracil increase mutation rates by which mechanism?

Accepted Answer

They mimic normal bases but increase tautomeric shifts, leading to mispairing.

Question 9

Which DNA repair mechanism is defective in individuals with xeroderma pigmentosum (XP)?

Accepted Answer

Nucleotide excision repair (NER)

Question 10

A researcher exposes E. coli to ethylmethanesulfonate (EMS). What type of mutation is most likely to result?

Accepted Answer

A transition mutation due to alkylation of guanine.

Question 11

Which of the following best explains why eating a diet high in antioxidants may reduce mutation rates?

Accepted Answer

Antioxidants neutralize free radicals, reducing oxidative DNA damage.

Question 12

Which repair system is activated if DNA polymerase proofreading fails to correct a replication error?

Accepted Answer

Mismatch repair

Question 13

What is the primary difference between homologous recombination repair and nonhomologous end joining in double-strand break repair?

Accepted Answer

Homologous recombination repair uses a sister chromatid as a template, while nonhomologous end joining does not.

Question 14

Which of the following is a consequence of a transposable element inserting into the promoter region of a gene?

Accepted Answer

It can prevent the gene from being expressed.

Question 15

Which of the following best describes the function of DNA glycosylase in base excision repair (BER)?

Accepted Answer

It recognizes and removes altered bases from DNA.

Question 16

A patient with a defect in the gene encoding a protein involved in nonhomologous end joining would be most sensitive to which type of DNA damage?

Accepted Answer

Double-strand breaks

Question 17

Which of the following is a plausible outcome if a transposable element inserts into an exon of a protein-coding gene?

Accepted Answer

The protein may be disrupted, resulting in a null mutation.

Question 18

Which of the following best explains why the E. coli SOS repair system is considered a 'last resort'?

Accepted Answer

It allows replication to continue past DNA damage but is highly error-prone.

Question 19

Which of the following statements about P elements in Drosophila is TRUE?

Accepted Answer

P elements can cause hybrid dysgenesis when wild males are crossed with lab females.

Question 20

Which of the following is a real-world application of transposable elements in genetics research?

Accepted Answer

They are used as vectors to introduce genes into Drosophila.

Mutation and DNA Repair: Mechanisms, Causes, and Consequences

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