Question 1

Which of the following best describes a point mutation?

Accepted Answer

A change in a single base pair in the DNA sequence.

Question 2

A silent mutation is best defined as:

Accepted Answer

A mutation that does not change the amino acid sequence of a protein.

Question 3

Which of the following mutations would most likely result in a nonfunctional protein?

Accepted Answer

A nonsense mutation that introduces a stop codon early in the coding sequence.

Question 4

Which DNA repair mechanism specifically recognizes and removes thymine dimers caused by UV light?

Accepted Answer

Nucleotide excision repair (UvrAB complex)

Question 5

The Ames test is used to:

Accepted Answer

Determine whether a chemical is a mutagen by measuring reversion mutations in bacteria.

Question 6

Which of the following is an example of horizontal gene transfer in bacteria?

Accepted Answer

Transfer of DNA from one bacterium to another via a pilus (conjugation).

Question 7

A frameshift mutation can be caused by:

Accepted Answer

A single base pair insertion or deletion.

Question 8

Which enzyme is responsible for catalyzing homologous recombination during DNA repair?

Accepted Answer

RecA recombinase

Question 9

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 10

A bacterial cell is exposed to nitrous acid, which causes deamination of cytosine. What is the likely result?

Accepted Answer

Cytosine is converted to uracil, leading to a point mutation.

Question 11

Which of the following is a consequence of gene duplication in genome evolution?

Accepted Answer

Creation of new gene functions while maintaining the original function.

Question 12

Which of the following best explains why most mutations do not affect the phenotype of an organism?

Accepted Answer

Many mutations occur in non-coding regions or result in synonymous codons.

Question 13

Which of the following is true about the SOS repair system in bacteria?

Accepted Answer

It is activated by extensive DNA damage and is error-prone.

Question 14

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

Accepted Answer

Spread of antibiotic resistance genes in hospitals and farms.

Question 15

A bacterium with an integrated F factor in its chromosome is called:

Accepted Answer

Hfr cell

Question 16

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid to another.

Question 17

Which process involves the packaging of bacterial DNA into a viral capsid and transfer to a new host?

Accepted Answer

Transduction

Question 18

Which of the following is a direct result of a frameshift mutation?

Accepted Answer

All downstream amino acids are altered.

Question 19

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

Accepted Answer

Base excision repair

Question 20

Which of the following best describes the role of RecA in bacterial cells?

Accepted Answer

It catalyzes homologous recombination and DNA repair.

Gene Transfer, Mutations, and Genome Evolution in Microbiology

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