Question 1

Which of the following best describes the process of gene expression in bacteria?

Accepted Answer

DNA is transcribed into mRNA, which is then translated into protein.

Question 2

In the lac operon of E. coli, what is the role of allolactose?

Accepted Answer

It acts as an inducer, inactivating the repressor and allowing transcription.

Question 3

Which equation correctly represents the central dogma of molecular biology?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 4

A mutation that changes a codon for lysine (AAA) to a stop codon (UAA) is best described as:

Accepted Answer

A nonsense mutation

Question 5

Which of the following is a real-world consequence of improper gene expression in humans?

Accepted Answer

Formation of teratomas containing teeth in ovaries

Question 6

What is the function of the operator region in an operon?

Accepted Answer

It serves as a binding site for repressors to regulate transcription.

Question 7

Which of the following statements about repressible operons is correct?

Accepted Answer

Their default state is on and they are turned off by a corepressor.

Question 8

Which of the following best explains why bacteria use operons to regulate gene expression?

Accepted Answer

To conserve energy and resources by producing proteins only when needed.

Question 9

Which type of mutation is most likely to result from exposure to UV radiation?

Accepted Answer

Thymine dimer formation

Question 10

A bacterium acquires a new trait after taking up naked DNA from its environment. This process is called:

Accepted Answer

Transformation

Question 11

Which of the following is a post-transcriptional control mechanism in bacteria?

Accepted Answer

Riboswitches altering mRNA structure to regulate translation

Question 12

Which of the following best describes the Ames test?

Accepted Answer

It detects mutagenic substances by measuring the reversion rate in mutant bacteria.

Question 13

Which of the following is an example of epigenetic control in bacteria?

Accepted Answer

Methylation of adenine residues to turn genes off

Question 14

Which of the following best explains why populations with low genetic variation are more vulnerable to environmental changes?

Accepted Answer

They lack the diversity needed for natural selection to favor adaptive traits.

Question 15

Which of the following is NOT a possible outcome of a point mutation?

Accepted Answer

Frameshift mutation

Question 16

Which process involves the transfer of genetic material from one bacterium to another via a pilus?

Accepted Answer

Conjugation

Question 17

A chemical mutagen that causes adenine to pair with cytosine instead of thymine is most likely:

Accepted Answer

Nitrous acid

Question 18

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

They base pair with mRNA, leading to its degradation and preventing translation.

Question 19

Which of the following is a correct statement about the effect of ionizing radiation on DNA?

Accepted Answer

It forms ions that can oxidize nucleotides and break DNA strands.

Question 20

Which of the following best explains why the lac operon is considered an inducible operon?

Accepted Answer

It is turned on only in the presence of an inducer such as allolactose.

Microbial Gene Expression, Mutations, and Genetic Exchange: Study Notes

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