Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

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

Question 2

A bacterial cell is exposed to a chemical mutagen that causes the insertion of a single nucleotide into a gene. What type of mutation is most likely to occur?

Accepted Answer

Frameshift mutation

Question 3

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 4

In the semiconservative model of DNA replication, what is the composition of the daughter DNA molecules after one round of replication?

Accepted Answer

Each daughter molecule contains one original and one new strand.

Question 5

Which of the following statements about plasmids is TRUE?

Accepted Answer

Plasmids replicate independently of the bacterial chromosome.

Question 6

A mutation changes a codon from UAU (tyrosine) to UAA. What is the most likely effect of this mutation?

Accepted Answer

It will result in a nonsense mutation.

Question 7

Which of the following best explains why DNA replication requires a large amount of energy, but does not use ATP from the cell’s energy supply?

Accepted Answer

The energy comes from the hydrolysis of triphosphate groups on the deoxyribonucleotides themselves.

Question 8

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

Accepted Answer

Protection against viral infection

Question 9

During transcription in prokaryotes, which of the following events occurs first?

Accepted Answer

RNA polymerase binds to the promoter region of DNA.

Question 10

Which of the following is a characteristic of the lagging strand during DNA replication?

Accepted Answer

It is synthesized discontinuously, forming Okazaki fragments.

Question 11

A bacterium is exposed to UV light, resulting in the formation of thymine dimers. Which enzyme is directly involved in repairing this type of DNA damage using visible light?

Accepted Answer

Photolyase

Question 12

Which of the following best describes an inducible operon?

Accepted Answer

It is transcribed only when an inducer is present.

Question 13

Which of the following is a real-life example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquiring antibiotic resistance genes from a plasmid during conjugation.

Question 14

Which of the following statements about the genetic code is correct?

Accepted Answer

The genetic code is degenerate, meaning most amino acids are coded by more than one codon.

Question 15

A scientist discovers a bacterial strain that can no longer synthesize tryptophan due to a mutation. Which method would best allow the scientist to isolate this mutant from a population of wild-type bacteria?

Accepted Answer

Negative (indirect) selection

Question 16

Which of the following best explains why translation can begin before transcription is complete in prokaryotes, but not in eukaryotes?

Accepted Answer

Prokaryotic mRNA is not processed and both processes occur in the cytoplasm.

Question 17

Which of the following is a function of the enzyme DNA ligase during DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 18

Which of the following is a likely consequence of a frameshift mutation in a gene encoding an essential enzyme?

Accepted Answer

The enzyme will have a completely altered amino acid sequence downstream of the mutation.

Question 19

Which of the following best describes the role of transposons in bacterial genomes?

Accepted Answer

They are segments of DNA that can move from one location to another, sometimes carrying antibiotic resistance genes.

Question 20

Which of the following processes increases genetic diversity in bacterial populations and provides material for natural selection?

Accepted Answer

Genetic recombination and mutation

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

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