Question 1

Which of the following best describes genetic diversity in a microbial population?

Accepted Answer

The presence of different kinds of genes within a population, supporting species survival.

Question 2

A mutation changes a single nucleotide in a coding sequence, resulting in a different amino acid. What type of mutation is this?

Accepted Answer

Missense mutation

Question 3

Which equation best represents the probability $$P of a $$spontaneous mutation occurring during DNA replication, given a mutation rate per base $$\mu$$ and genome size $$N$$?

Accepted Answer

$$P = \mu 	imes N$$

Question 4

A chemical agent that inserts itself between DNA bases, causing a frameshift mutation, is best classified as:

Accepted Answer

Intercalating agent

Question 5

Which repair mechanism directly reverses thymine dimers using energy from light?

Accepted Answer

Photolyase-mediated light repair

Question 6

In prokaryotes, how do mismatch repair enzymes distinguish the newly synthesized DNA strand from the template strand?

Accepted Answer

The new strand is not yet methylated.

Question 7

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

Accepted Answer

Vertical gene transfer

Question 8

A virus infects a bacterial cell and accidentally packages host DNA, transferring it to another cell. This process is called:

Accepted Answer

Transduction

Question 9

Which of the following best describes a frameshift mutation?

Accepted Answer

Insertion or deletion of one or more nucleotides, shifting the reading frame and altering multiple amino acids.

Question 10

Which enzyme is responsible for directly reversing thymine dimers in light repair?

Accepted Answer

Photolyase

Question 11

During conjugation, what structure connects two bacterial cells to facilitate plasmid transfer?

Accepted Answer

Conjugation pilus

Question 12

Which of the following best explains why antigenic shift in viruses can lead to rapid evolution and new epidemics?

Accepted Answer

It results from recombination between two viruses infecting the same cell, producing new gene combinations.

Question 13

A mutation changes a codon from $$	ext{UGG} ($$tryptophan) to $$	ext{UGA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 14

Which of the following statements about DNA repair is correct?

Accepted Answer

DNA polymerase can proofread and remove mismatched nucleotides during replication.

Question 15

Which process allows a bacterial cell to acquire naked DNA from its environment after another cell dies?

Accepted Answer

Transformation

Question 16

A nucleoside analog is most likely to cause which type of mutation?

Accepted Answer

Point mutation

Question 17

Which of the following is a consequence of antigenic drift in viruses?

Accepted Answer

Gradual accumulation of mutations in genes encoding antigens

Question 18

If a DNA sequence undergoes a frameshift mutation due to the insertion of two nucleotides, how many codons downstream are likely to be affected?

Accepted Answer

All codons downstream of the insertion site

Question 19

Which of the following best describes homologous recombination in bacteria?

Accepted Answer

Integration of new DNA into the genome at regions with similar sequences.

Question 20

A patient is infected with two different strains of influenza virus simultaneously. Which mechanism is most likely to produce a new viral strain capable of reinfecting the host?

Accepted Answer

Antigenic shift

Microbial Genetics and Genetic Variation

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