Question 1

Which of the following best describes a silent mutation?

Accepted Answer

A mutation that changes a codon but does not alter the amino acid sequence due to the wobble effect.

Question 2

A point mutation changes the codon TTT (Phe) to TTA (Leu). What type of mutation is this?

Accepted Answer

Missense mutation

Question 3

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

Accepted Answer

Cell-to-cell contact

Question 4

What is the primary function of the F (fertility) factor in E. coli conjugation?

Accepted Answer

To initiate pilus formation and DNA transfer

Question 5

Which of the following best explains why F+ × F+ matings are much less fertile than F+ × F– matings?

Accepted Answer

Surface exclusion prevents efficient transfer between F+ cells.

Question 6

A bacterial cell undergoes a mutation where two nucleotides are removed from a codon. What is the most likely result?

Accepted Answer

A deletion frameshift mutation

Question 7

Which of the following statements about Hfr strains is correct?

Accepted Answer

Hfr strains can transfer chromosomal genes to the recipient during conjugation.

Question 8

If a segment of DNA is flipped in orientation within the genome, what type of mutation has occurred?

Accepted Answer

Inversion

Question 9

Which of the following best describes the role of the oriT site on the F plasmid?

Accepted Answer

It is the origin of transfer used during DNA conjugation.

Question 10

A bacterial cell with the genotype F+ is mixed with an F– cell. What is the expected outcome after conjugation?

Accepted Answer

Both cells become F+.

Question 11

Which of the following scenarios would most likely result in a nonsense mutation?

Accepted Answer

A codon change from TGG (Trp) to TGA (Stop)

Question 12

Which of the following best explains why conjugation is considered a force in bacterial evolution?

Accepted Answer

It facilitates the spread of genetic traits, such as antibiotic resistance, among bacteria.

Question 13

A mutation changes the reading frame of a gene, resulting in a completely different amino acid sequence downstream. What type of mutation is this?

Accepted Answer

Frameshift mutation

Question 14

In a classic U-tube experiment, why are no recombinants observed when a fine filter separates two bacterial strains?

Accepted Answer

Cell-to-cell contact is required for conjugation, which the filter prevents.

Question 15

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid to another.

Question 16

If a bacterial cell receives a plasmid carrying antibiotic resistance genes via conjugation, what is the most likely outcome?

Accepted Answer

The recipient cell gains resistance to the antibiotics encoded by the plasmid.

Question 17

Which of the following is a key difference between conjugation and transformation in bacteria?

Accepted Answer

Conjugation requires direct cell-to-cell contact, while transformation does not.

Question 18

A mutation reverts a previously mutated codon back to its original sequence. What is this process called?

Accepted Answer

Reversion

Question 19

Which of the following best describes the role of the pilus in bacterial conjugation?

Accepted Answer

It mediates the initial contact and DNA transfer between donor and recipient cells.

Question 20

A bacterial cell undergoes a transition mutation. Which of the following best describes this event?

Accepted Answer

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

Mutations and Genetic Exchange in Bacteria: Study Notes

Study Guide - Practice Questions