Question 1

Which of the following best describes the structure of a DNA molecule?

Accepted Answer

It consists of a double helix with a sugar-phosphate backbone and complementary base pairs joined by hydrogen bonds.

Question 2

During DNA replication, which enzyme is responsible for removing RNA primers and replacing them with DNA nucleotides?

Accepted Answer

DNA polymerase I

Question 3

Which of the following base pairings is correct for DNA, and what type of bond holds these pairs together?

Accepted Answer

A pairs with T, held by hydrogen bonds

Question 4

A mutation occurs in a bacterial cell due to exposure to UV light, resulting in the formation of thymine dimers. Which repair mechanism is most likely to be activated if visible light is present?

Accepted Answer

Photoreactivation

Question 5

Which of the following statements about the semi-conservative model of DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental strand and one new strand.

Question 6

In the process of bacterial transformation, which of the following is essential for the uptake of naked DNA from the environment?

Accepted Answer

Competency of the recipient cell

Question 7

Which of the following best describes the function of the promoter region in transcription?

Accepted Answer

It is the DNA sequence where RNA polymerase binds to start transcription.

Question 8

A scientist is studying a bacterial operon that is only transcribed when an inducer molecule is present. Which type of operon is this, and what is the role of the inducer?

Accepted Answer

It is an inducible operon; the inducer inactivates the repressor.

Question 9

Which of the following processes requires direct cell-to-cell contact for the transfer of genetic material in bacteria?

Accepted Answer

Conjugation

Question 10

During translation, which molecule serves as the template for protein synthesis?

Accepted Answer

mRNA

Question 11

A bacterial cell is exposed to a chemical mutagen that causes base analog incorporation during DNA replication. What type of mutation is most likely to result?

Accepted Answer

Induced mutation

Question 12

Which of the following best explains why using existing DNA strands as templates during replication is important?

Accepted Answer

It allows for accurate base pairing, maintaining genetic consistency between generations.

Question 13

Which of the following is a key similarity between transformation, transduction, and conjugation in bacteria?

Accepted Answer

All involve horizontal gene transfer, increasing genetic diversity.

Question 14

A mutation in a bacterial gene occurs due to a random error during DNA replication, not caused by any external agent. This is best described as:

Accepted Answer

Spontaneous mutation

Question 15

Which of the following correctly outlines the steps in the spread of the F plasmid in a bacterial population?

Accepted Answer

F+ cell forms a sex pilus, transfers the F plasmid to an F- cell, which then becomes F+

Question 16

Which of the following best describes the difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction occurs during the lytic cycle and can transfer any gene; specialized transduction occurs during the lysogenic cycle and transfers specific genes.

Question 17

Which of the following is NOT a function of methylation of bacterial DNA?

Accepted Answer

Facilitation of conjugation

Question 18

A bacterial cell is unable to synthesize tryptophan because the trp operon is permanently repressed. Which of the following best explains this observation?

Accepted Answer

The co-repressor (tryptophan) is always present, keeping the repressor active and bound to the operator.

Question 19

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

Accepted Answer

$A = T, \ C = G$

Question 20

During prokaryotic DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Microbiology Study Guide: DNA Structure, Replication, Mutation, and Gene Transfer

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