Question 1

Which of the following best describes the function of plasmids in prokaryotic cells?

Accepted Answer

They often carry genes that confer survival advantages, such as antibiotic resistance.

Question 2

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in premature termination of translation.

Question 3

Which enzyme is responsible for removing supercoils during bacterial DNA replication?

Accepted Answer

Gyrase

Question 4

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

Accepted Answer

It binds to the repressor, inactivating it and allowing transcription.

Question 5

Which of the following statements about eukaryotic DNA replication is correct?

Accepted Answer

It involves thousands of origins of replication and multiple DNA polymerases.

Question 6

A bacterial cell is exposed to a chemical mutagen that causes the insertion of a single nucleotide into a gene. What is the most likely outcome?

Accepted Answer

A frameshift mutation resulting in a major change in the amino acid sequence.

Question 7

Which process is illustrated by the following equation?

$$	ext{DNA} \xrightarrow{	ext{transcription}} 	ext{RNA} \xrightarrow{	ext{translation}} 	ext{Protein}$$

Accepted Answer

The central dogma of genetics

Question 8

Which of the following is a key difference between prokaryotic and eukaryotic transcription?

Accepted Answer

Eukaryotic mRNA undergoes capping, polyadenylation, and splicing before translation.

Question 9

A scientist uses the Ames test to evaluate a new food additive. What is the test designed to detect?

Accepted Answer

The ability of the additive to induce mutations

Question 10

Which of the following best explains why bacteria can rapidly acquire antibiotic resistance in a hospital setting?

Accepted Answer

They can acquire resistance genes through horizontal gene transfer mechanisms such as conjugation, transformation, and transduction.

Question 11

Which of the following is true about the structure of DNA?

Accepted Answer

The strands are antiparallel, and adenine pairs with thymine via two hydrogen bonds.

Question 12

Which of the following best describes the function of regulatory RNAs such as microRNAs (miRNAs)?

Accepted Answer

They bind complementary mRNA and inhibit its translation.

Question 13

A bacterial cell with a mutation in the gene encoding DNA ligase would have difficulty with which aspect of DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 14

Which of the following is an example of a repressible operon?

Accepted Answer

Trp operon

Question 15

Which of the following DNA repair mechanisms is most likely to fix a thymine dimer caused by UV light?

Accepted Answer

Light repair (photoreactivation)

Question 16

During translation in prokaryotes, what is the first amino acid incorporated into the growing polypeptide chain?

Accepted Answer

Formylmethionine (fMet)

Question 17

Which of the following best describes the outcome of generalized transduction?

Accepted Answer

A phage transfers random DNA segments from the donor to the recipient.

Question 18

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

Accepted Answer

The reading frame is altered, potentially changing every amino acid downstream.

Question 19

Which of the following best explains why mitochondria and chloroplasts have their own DNA?

Accepted Answer

Their DNA resembles prokaryotic chromosomes, supporting the endosymbiotic theory.

Question 20

Which of the following is the best definition of a genotype?

Accepted Answer

The set of genes in the genome of an organism.

Microbial Genetics: Structure, Function, and Regulation of Genetic Material

Guida di studio - Domande di pratica