Question 1

Which of the following best describes a plasmid in prokaryotic cells?

Accepted Answer

A small, circular DNA molecule that replicates independently and can carry genes for antibiotic resistance.

Question 2

During DNA replication in bacteria, which enzyme is responsible for unzipping the DNA double helix by breaking hydrogen bonds between bases?

Accepted Answer

DNA helicase

Question 3

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The 5’ end of a DNA strand terminates with a phosphate group.

Question 4

Which process is illustrated by the central dogma of genetics: $$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$?

Accepted Answer

Transcription and translation

Question 5

A mutation that results in a premature stop codon is called:

Accepted Answer

Nonsense mutation

Question 6

Which of the following is a function of methylation in bacterial DNA?

Accepted Answer

Protection against viral infection

Question 7

In the lac operon, what is the role of allolactose?

Accepted Answer

It serves as an inducer by inactivating the repressor.

Question 8

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5’ to 3’ direction, so the lagging strand is synthesized discontinuously.

Question 9

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

Accepted Answer

Binary fission

Question 10

A scientist exposes bacteria to UV light, resulting in the formation of thymine dimers. Which DNA repair mechanism is most likely to fix this damage?

Accepted Answer

Light repair (photoreactivation)

Question 11

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It delivers the correct amino acid to the ribosome based on the codon sequence.

Question 12

Which of the following is true about the difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotes have shorter Okazaki fragments and methylate cytosine bases.

Question 13

Which of the following is a likely consequence of a frameshift mutation?

Accepted Answer

A major change in the amino acid sequence downstream of the mutation

Question 14

Which of the following best describes generalized transduction?

Accepted Answer

Transfer of random DNA segments from a donor to a recipient via a phage

Question 15

Which of the following is a function of regulatory RNA molecules such as miRNA?

Accepted Answer

They bind complementary mRNA and inhibit its translation.

Question 16

In the context of the Ames test, what is the purpose of adding liver extract to the experimental setup?

Accepted Answer

To simulate metabolic activation of chemicals as would occur in the body

Question 17

Which of the following best explains why the genetic code is described as 'degenerate'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 18

A bacterium acquires a plasmid carrying a gene for penicillin resistance. Which process most likely led to this genetic change?

Accepted Answer

Horizontal gene transfer via conjugation

Question 19

Which of the following is true about repressible operons such as the trp operon?

Accepted Answer

They are transcribed continually until deactivated by a corepressor.

Question 20

Which of the following best describes the role of the operator in an operon?

Accepted Answer

It controls the movement of RNA polymerase and acts as a regulatory element.

Ch. 7 Genetics and Genetic Processes in Microbiology

Guida di studio - Domande di pratica