Question 1

Which of the following best describes the difference between purines and pyrimidines in nucleic acids?

Accepted Answer

Purines have a double ring structure, while pyrimidines have a single ring structure.

Question 2

Which base is an analog for thymine and pairs with the tautomer of guanine?

Accepted Answer

5-bromouracil

Question 3

A mutation causes the replacement of a thymine with 5-bromouracil in a DNA strand. What is the most likely consequence during DNA replication?

Accepted Answer

5-bromouracil will pair with guanine, potentially causing a transition mutation.

Question 4

Which enzyme is responsible for repairing thymine dimers caused by UV light?

Accepted Answer

Photoreactive enzyme

Question 5

Which DNA repair mechanism is used by humans to remove and replace damaged nucleotides?

Accepted Answer

Nucleotide excision repair

Question 6

Which of the following is true regarding the structure of a DNA polynucleotide strand?

Accepted Answer

It consists of a sugar-phosphate backbone with nitrogenous bases attached.

Question 7

In prokaryotes, which of the following statements about genome structure is correct?

Accepted Answer

The genome is typically a single, circular DNA molecule.

Question 8

Which of the following best describes a nucleotide?

Accepted Answer

A molecule consisting of a nitrogenous base, a sugar, and a phosphate group.

Question 9

Which of the following is a key difference between DNA and RNA polynucleotide strands?

Accepted Answer

DNA contains thymine, while RNA contains uracil.

Question 10

A patient is exposed to UV light, resulting in the formation of thymine dimers. Which repair mechanism is most likely to be activated in human cells?

Accepted Answer

Nucleotide excision repair

Question 11

Which of the following equations correctly represents the complementary base pairing in DNA?

Accepted Answer

$$A = T$$ and $$G = C$$

Question 12

If a DNA sequence contains 30% adenine, what percentage of guanine would you expect to find?

Accepted Answer

$$20\%$$

Question 13

Which of the following is NOT a function of nucleotide excision repair?

Accepted Answer

Directly reversing thymine dimers without removing nucleotides.

Question 14

Which of the following best explains why 5-bromouracil is considered a mutagen?

Accepted Answer

It can mispair with guanine, leading to base substitution mutations.

Question 15

Which of the following is a pyrimidine found in both DNA and RNA?

Accepted Answer

Cytosine

Genome Structure, Mutation, and Cell Division: Key Concepts and Mechanisms

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