Question 1

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

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

Question 2

A mutation changes the codon UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in early termination of translation.

Question 3

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

Accepted Answer

DNA helicase

Question 4

In prokaryotes, what is the function of the F plasmid during conjugation?

Accepted Answer

It carries genes required for the formation of sex pili and DNA transfer.

Question 5

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

Accepted Answer

There are 64 possible codons, including three stop codons.

Question 6

A bacterium is exposed to a chemical mutagen that causes the insertion of a single nucleotide into a gene. What is the most likely result?

Accepted Answer

A frameshift mutation

Question 7

Which of the following best explains why antibiotics like erythromycin can target bacterial cells without harming human cells?

Accepted Answer

Bacterial and human ribosomes have different structures.

Question 8

Which process involves the uptake of free DNA from the environment by a competent bacterial cell?

Accepted Answer

Transformation

Question 9

What is the role of DNA methylation in prokaryotes?

Accepted Answer

It helps control gene expression and protects against viral infection.

Question 10

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

Accepted Answer

Eukaryotic mRNA undergoes capping, polyadenylation, and splicing.

Question 11

A scientist discovers a bacterial strain that can survive in the presence of ampicillin, tetracycline, and kanamycin. Which genetic element most likely confers this trait?

Accepted Answer

Resistance plasmid

Question 12

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid in the protein sequence.

Question 13

Which of the following is a function of regulatory RNA in eukaryotes?

Accepted Answer

It can bind to mRNA and prevent translation.

Question 14

Which of the following is TRUE about the lac operon in E. coli?

Accepted Answer

It is an inducible operon activated by the presence of lactose.

Question 15

Which of the following is a real-world consequence of horizontal gene transfer among bacteria?

Accepted Answer

Spread of antibiotic resistance genes

Question 16

A scientist uses the Ames test to evaluate a new chemical. What is the underlying assumption of this test?

Accepted Answer

A substance that is mutagenic for bacteria may be carcinogenic for humans.

Question 17

Which of the following best describes a transposon?

Accepted Answer

A segment of DNA that can move from one location to another within a genome.

Question 18

Which of the following is required for bacterial conjugation to occur?

Accepted Answer

Physical contact between donor and recipient cells

Question 19

Which of the following is a likely result of a frameshift mutation in a gene?

Accepted Answer

The reading frame is altered, affecting all downstream amino acids.

Question 20

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

Accepted Answer

Joining Okazaki fragments on the lagging strand

Microbial Genetics: Structure, Function, Mutation, and Genetic Transfer

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