Question 1

Which of the following best explains how two cells with identical genomes can have different functions in a multicellular organism?

Accepted Answer

They express different sets of genes due to differential gene expression.

Question 2

In the trp operon of E. coli, what is the role of tryptophan?

Accepted Answer

It functions as a corepressor, activating the repressor to shut off the operon.

Question 3

Which of the following statements about the lac operon is correct?

Accepted Answer

The lac operon is usually off and is induced by allolactose.

Question 4

A mutation in the operator region of the trp operon prevents the repressor from binding. What is the most likely outcome?

Accepted Answer

The operon will be permanently active, and tryptophan synthesis enzymes will always be produced.

Question 5

Which of the following best describes the effect of histone acetylation on gene expression?

Accepted Answer

It loosens chromatin structure, promoting the initiation of transcription.

Question 6

Which mechanism allows eukaryotic cells to produce different proteins from the same gene?

Accepted Answer

Alternative RNA splicing

Question 7

A researcher finds that a gene is heavily methylated in a certain cell type. What is the most likely consequence?

Accepted Answer

The gene will be silenced and not transcribed.

Question 8

Which of the following is an example of epigenetic inheritance?

Accepted Answer

Methylation of DNA that is passed to daughter cells during cell division.

Question 9

In the context of the lac operon, what is the effect of high glucose and high lactose concentrations in the environment?

Accepted Answer

Low transcription of the lac operon because cAMP levels are low and CRP is inactive.

Question 10

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

Accepted Answer

They bind to complementary mRNA sequences and block translation or promote mRNA degradation.

Question 11

A scientist uses RNA interference (RNAi) to study gene function in a model organism. Which molecule is directly responsible for silencing the target gene?

Accepted Answer

Small interfering RNA (siRNA)

Question 12

Which of the following is true about the regulation of gene expression in eukaryotes compared to prokaryotes?

Accepted Answer

Prokaryotic genes are often organized in operons, while eukaryotic co-expressed genes are usually scattered and regulated by shared control elements.

Question 13

Which of the following experimental techniques allows researchers to compare the expression of thousands of genes simultaneously?

Accepted Answer

DNA microarray analysis

Question 14

What is the role of ubiquitin in protein regulation?

Accepted Answer

It marks proteins for degradation by the proteasome.

Question 15

Which of the following best describes the function of an enhancer in eukaryotic gene regulation?

Accepted Answer

A distal control element that binds activators to increase transcription of a gene.

Question 16

A mutation causes a eukaryotic gene's enhancer to be deleted. What is the most likely effect?

Accepted Answer

The gene will be transcribed at a much lower rate or not at all.

Question 17

Which of the following is a real-world example of epigenetic inheritance?

Accepted Answer

Genetically identical mice showing different coat colors due to differences in maternal diet affecting DNA methylation.

Question 18

Which of the following statements about positive gene regulation in the lac operon is correct?

Accepted Answer

CRP (cAMP receptor protein) increases transcription of the lac operon when glucose is scarce and cAMP levels are high.

Question 19

Which of the following best describes combinatorial control of gene activation in eukaryotes?

Accepted Answer

The combination of control elements in an enhancer determines the precise regulation of a gene.

Question 20

A patient’s tumor cells are analyzed using DNA microarray technology. What is the main advantage of this approach?

Accepted Answer

It allows identification of genes that are expressed differently in tumor cells compared to normal cells, suggesting targets for therapy.

Regulation of Gene Expression (Chapter 15) – Campbell Biology in Focus

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