Question 1

Which of the following best describes a plasmid in prokaryotic cells?

Accepted Answer

A small, circular DNA molecule that replicates independently and can confer survival advantages.

Question 2

During DNA replication, which enzyme is responsible for removing supercoils in bacterial DNA?

Accepted Answer

Gyrase

Question 3

Which of the following statements about the central dogma of genetics is correct?

Accepted Answer

DNA is transcribed into RNA, which is then translated into polypeptides.

Question 4

A mutation that results in a premature stop codon is called:

Accepted Answer

Nonsense mutation

Question 5

Which of the following is a function of DNA methylation in bacteria?

Accepted Answer

Control of genetic expression

Question 6

In the lac operon, what happens when lactose is present in the environment?

Accepted Answer

The repressor is inactivated by allolactose, allowing transcription to proceed.

Question 7

Which of the following best explains why mutations are usually deleterious?

Accepted Answer

They often disrupt the normal function of proteins encoded by the mutated gene.

Question 8

Which process is illustrated by the following equation? 
$$	ext{DNA} ightarrow 	ext{RNA}$$

Accepted Answer

Transcription

Question 9

A bacterial cell is exposed to a chemical mutagen that causes the insertion of three nucleotides into a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A single amino acid will be added to the protein sequence.

Question 10

Which of the following is a key difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotes have thousands of replication origins, while prokaryotes typically have one.

Question 11

Which of the following best describes generalized transduction?

Accepted Answer

A bacteriophage transfers random DNA segments from a donor to a recipient.

Question 12

Which of the following is NOT a type of RNA involved in gene expression?

Accepted Answer

Deoxyribonucleic acid (DNA)

Question 13

A scientist uses the Ames test to evaluate a chemical. What result would indicate that the chemical is a mutagen?

Accepted Answer

Many colonies of revertant bacteria grow on the medium lacking histidine.

Question 14

Which of the following is true about the structure of double-stranded DNA?

Accepted Answer

The strands are antiparallel and held together by hydrogen bonds between complementary bases.

Question 15

Which of the following best describes the function of the operator in an operon?

Accepted Answer

It is a regulatory sequence where a repressor can bind to block transcription.

Question 16

A mutation changes a codon from UAU (tyrosine) to UAC (also tyrosine). What type of mutation is this?

Accepted Answer

Silent mutation

Question 17

Which of the following is a real-life example of horizontal gene transfer contributing to antibiotic resistance in hospitals?

Accepted Answer

A bacterium acquires a resistance plasmid from another bacterium via conjugation.

Question 18

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5' to 3' direction, so the lagging strand is synthesized discontinuously.

Question 19

Which of the following is a function of microRNAs (miRNAs) in genetic regulation?

Accepted Answer

They bind complementary mRNA and inhibit its translation.

Microbial Genetics: Structure, Function, and Regulation of Genetic Material

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