Question 1

Which of the following best describes an auxotrophic mutant in bacteria?

Accepted Answer

A mutant that requires an additional nutrient not needed by the wild-type strain.

Question 2

A frameshift mutation is most likely to result from which of the following genetic events?

Accepted Answer

An insertion or deletion of one or two nucleotides.

Question 3

Which of the following statements about conjugation in bacteria is TRUE?

Accepted Answer

Conjugation involves direct cell-to-cell contact mediated by a pilus.

Question 4

In a genetic experiment, you observe a mutant strain that cannot synthesize tryptophan. Which method would you use to screen for this auxotrophic mutant?

Accepted Answer

Grow the bacteria on media supplemented with tryptophan and compare to growth on minimal media.

Question 5

Which of the following best explains why frameshift mutations generally have more serious consequences than missense mutations?

Accepted Answer

Frameshift mutations alter the reading frame, potentially changing every amino acid downstream.

Question 6

A bacterium undergoes a point mutation that changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 7

Which of the following is a key difference between generalized and specialized transduction?

Accepted Answer

Specialized transduction transfers only specific portions of the bacterial genome adjacent to prophage integration sites.

Question 8

Which of the following best describes the CRISPR system in bacteria?

Accepted Answer

A prokaryotic adaptive immune system that uses stored DNA sequences to target and destroy invading genetic elements.

Question 9

A bacterial cell is exposed to ionizing radiation. Which of the following best describes the effect of ionizing radiation on DNA?

Accepted Answer

It induces double-strand breaks and large-scale chromosomal rearrangements.

Question 10

Which of the following is TRUE regarding the SOS repair system in bacteria?

Accepted Answer

It is an error-prone repair system activated by extensive DNA damage.

Question 11

A bacterial cell with the genotype $$	ext{trp}^{-} is $$plated on minimal media. What is the expected outcome?

Accepted Answer

The cell will not grow unless tryptophan is supplemented.

Question 12

Which of the following best describes rolling circle replication during bacterial conjugation?

Accepted Answer

DNA is replicated in both donor and recipient simultaneously, allowing both to end up with a complete plasmid copy.

Question 13

Which of the following is a feature shared by insertion sequences and transposons?

Accepted Answer

Both contain genes encoding transposase for movement within the genome.

Question 14

A bacterial cell undergoes a reversion mutation. Which of the following best describes a second-site reversion?

Accepted Answer

A compensatory mutation occurs at a different site, restoring the original phenotype.

Question 15

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

SOS repair system

Question 16

Which of the following best describes a silent mutation?

Accepted Answer

A mutation that does not alter the amino acid sequence due to the redundancy of the genetic code.

Question 17

Which of the following is TRUE about the difference between genotype and phenotype?

Accepted Answer

Phenotype can change without a change in genotype, for example, due to environmental factors.

Question 18

Which of the following best describes the process of transformation in bacteria?

Accepted Answer

Uptake of free DNA from the environment by a competent cell.

Question 19

Which of the following is a plausible outcome of a missense mutation?

Accepted Answer

A change in a single amino acid in the protein sequence.

Question 20

A bacterium is exposed to a mutagen that causes a transition mutation. Which of the following best describes a transition mutation?

Accepted Answer

A purine is replaced by another purine, or a pyrimidine by another pyrimidine.

Study Guide: Genetics of Bacteria and Archaea – Step-by-Step Guidance

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