Question 1

Which of the following best describes the function of the lac operon in E. coli?

Accepted Answer

It enables the cell to metabolize lactose only when lactose is present and glucose is absent.

Question 2

What is the role of the repressor protein in the lac operon system?

Accepted Answer

It binds to the operator to block RNA polymerase from transcribing the operon.

Question 3

Which of the following scenarios would result in constitutive expression of the lac operon?

Accepted Answer

A mutation in the operator that prevents repressor binding.

Question 4

In eukaryotic cells, which process is directly affected by histone acetylation?

Accepted Answer

Chromatin remodeling and increased gene transcription

Question 5

A researcher observes that offspring of rats fed a low-protein diet have abnormal histone modifications and altered gene expression. What is the most likely explanation?

Accepted Answer

Epigenetic changes have been inherited from the mother.

Question 6

Which of the following is NOT a step in the process of gene expression regulation in eukaryotes?

Accepted Answer

DNA methylation of the ribosome

Question 7

Which of the following best explains why alternative splicing increases protein diversity in eukaryotes?

Accepted Answer

It allows different combinations of exons to be included in the final mRNA.

Question 8

A mutation prevents the binding of basal transcription factors to the promoter in a eukaryotic gene. What is the most likely outcome?

Accepted Answer

Transcription will not be initiated.

Question 9

Which of the following statements about the central dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into RNA, which is translated into protein.

Question 10

Which enzyme is responsible for synthesizing the leading strand during DNA replication?

Accepted Answer

DNA polymerase III

Question 11

What is the function of the A site in the ribosome during translation?

Accepted Answer

It is the acceptor site for an incoming aminoacyl-tRNA.

Question 12

Which of the following best describes the effect of histone deacetylase (HDAC) activity on gene expression?

Accepted Answer

It decreases gene expression by condensing chromatin.

Question 13

A mutation in the gene encoding the lac repressor results in a protein that cannot bind lactose. What is the most likely effect on the lac operon?

Accepted Answer

The operon will be permanently repressed, even when lactose is present.

Question 14

Which of the following is a direct result of DNA methylation in eukaryotic cells?

Accepted Answer

Decreased transcription of the methylated gene

Question 15

Which of the following best explains why the offspring of rats with poor maternal nutrition can develop diabetes-like disorders, regardless of their alleles?

Accepted Answer

Epigenetic modifications affecting gene expression are inherited.

Question 16

Which of the following is a function of the mediator complex in eukaryotic transcription?

Accepted Answer

It facilitates the assembly of the transcription initiation complex and DNA looping.

Question 17

Which of the following is true about the structure of a nucleosome?

Accepted Answer

It consists of DNA wrapped around a core of eight histone proteins.

Question 18

Which of the following best describes the difference between prokaryotic and eukaryotic gene regulation?

Accepted Answer

Eukaryotes regulate gene expression at multiple levels, including chromatin structure, transcription, and RNA processing.

Question 19

Which of the following is a real-life example of gene regulation by environmental factors?

Accepted Answer

The lac operon in E. coli is activated in the presence of lactose and absence of glucose.

Gene Expression and Transcriptional Regulation in Prokaryotes and Eukaryotes

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