Control of Gene Expression Practice Questions
A-Levels · A-Level Biology · 150 free MCQs with instant results and detailed explanations.
150
Total
45
Easy
75
Medium
30
Hard
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Sample Questions from Control of Gene Expression
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Q1
Easy
What is the primary function of a promoter in gene expression?
A.
To enhance the stability of mRNA
B.
To serve as a binding site for RNA polymerase
C.
To degrade unwanted RNA
D.
To add methyl groups to DNA
Show Answer & Explanation
Correct Answer: B
A promoter is a specific region of DNA where RNA polymerase binds to initiate transcription. Hence, its primary function is to serve as a binding site for RNA polymerase.
Q2
Easy
Which of the following is an example of post-transcriptional regulation of gene expression?
A.
DNA methylation
B.
Alternative splicing of mRNA
C.
Transcription factor binding
D.
Chromatin remodeling
Show Answer & Explanation
Correct Answer: B
Alternative splicing of mRNA is a process that occurs after transcription and can result in different protein variants being produced from the same gene, thus it is a form of post-transcriptional regulation.
Q3
Easy
In the control of gene expression, what role do transcription factors play?
A.
They directly synthesize proteins.
B.
They modify DNA structure.
C.
They bind to specific DNA sequences to regulate transcription.
D.
They transport RNA out of the nucleus.
Show Answer & Explanation
Correct Answer: C
Transcription factors are proteins that bind to specific DNA sequences, thereby influencing the transcription of genes. They can either promote or inhibit the transcription process.
Q4
Medium
Which of the following processes is primarily involved in the regulation of gene expression at the transcriptional level?
A.
RNA splicing
B.
Transcription factor binding
C.
Translation initiation
D.
Post-translational modification
Show Answer & Explanation
Correct Answer: B
Transcription factor binding is crucial for the regulation of gene expression at the transcriptional level as it facilitates or inhibits the transcription of specific genes by binding to their promoter regions.
Q5
Medium
In eukaryotes, the presence of which of the following elements can enhance the transcription of a gene?
A.
Silencer
B.
Promoter
C.
Enhancer
D.
Intron
Show Answer & Explanation
Correct Answer: C
Enhancers are regulatory DNA sequences that can significantly increase the likelihood of transcription of particular genes by binding to transcription factors, thus promoting gene expression.
Q6
Medium
A researcher is studying a mutation in a gene that causes a premature stop codon. What is likely to be the consequence of this mutation?
A.
Increased protein function
B.
No change in protein structure
C.
A truncated protein
D.
Enhanced transcription
Show Answer & Explanation
Correct Answer: C
A mutation that introduces a premature stop codon results in the production of a truncated protein, which is usually nonfunctional or has significantly altered function compared to the normal protein.
Q7
Medium
Which of the following statements about epigenetic modifications is true?
A.
They involve changes to the DNA sequence.
B.
They can be inherited across generations.
C.
They always result in gene activation.
D.
They are permanent and unchangeable.
Show Answer & Explanation
Correct Answer: B
Epigenetic modifications, such as DNA methylation and histone modification, can influence gene expression without altering the DNA sequence and can be inherited across generations, impacting traits.
Q8
Hard
Which of the following mechanisms is primarily responsible for the regulation of gene expression at the transcriptional level in eukaryotic cells?
A.
Histone acetylation
B.
mRNA splicing
C.
Translation initiation
D.
Proteolytic cleavage
Show Answer & Explanation
Correct Answer: A
Histone acetylation modifies histones, reducing their affinity for DNA and allowing greater access for transcription factors, thus regulating gene expression at the transcriptional level.
Q9
Hard
A researcher is studying the effects of a specific transcription factor on the expression of a gene that codes for a growth factor. Which experimental approach would best provide evidence for the direct involvement of this transcription factor in regulating the gene?
A.
Chromatin immunoprecipitation sequencing (ChIP-seq)
B.
Quantitative polymerase chain reaction (qPCR)
C.
Western blot analysis
D.
RNA interference (RNAi)
Show Answer & Explanation
Correct Answer: A
ChIP-seq allows the researcher to determine whether the transcription factor directly binds to the gene's promoter region, thus providing direct evidence of its role in regulating gene expression.
Q10
Hard
In eukaryotic cells, which mechanism of gene regulation most directly influences the accessibility of DNA to transcription factors?
A.
Histone acetylation
B.
mRNA degradation
C.
Transcription factor binding
D.
RNA splicing
Show Answer & Explanation
Correct Answer: A
Histone acetylation adds acetyl groups to histone proteins, which reduces their positive charge and decreases their affinity for negatively charged DNA. This results in a more relaxed chromatin structure, making the DNA more accessible to transcription factors, thereby promoting gene expression.
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Control of Gene Expression — A-Levels A-Level Biology Practice Questions Online
This page contains 150 practice MCQs for the chapter Control of Gene Expression in A-Levels A-Level Biology. The questions are organized by difficulty — 45 easy, 75 medium, 30 hard — so you can choose the right level for your preparation.
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