AP Biology Practice Quiz: Regulation of Gene Expression

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 15 questions to check your progress.

Question 1 of 15

What is the primary function of regulatory sequences in DNA?

A)To code for the amino acid sequence of a protein.B)To interact with regulatory proteins to control transcription.C)To serve as the starting point for DNA replication.D)To provide structural support to the chromosome.

All Questions (15)

What is the primary function of regulatory sequences in DNA?

A) To code for the amino acid sequence of a protein.

B) To interact with regulatory proteins to control transcription.

C) To serve as the starting point for DNA replication.

D) To provide structural support to the chromosome.

Correct Answer: B

According to the provided content, regulatory sequences are stretches of DNA that interact with regulatory proteins to control the process of transcription.

Which of the following is described as an epigenetic change that can affect gene expression?

A) A change in the nucleotide sequence of a gene (mutation).

B) The binding of a ribosome to an mRNA molecule.

C) Reversible modification of histone proteins.

D) The creation of a new allele through sexual reproduction.

Correct Answer: C

The content explicitly states that epigenetic changes, such as reversible modifications of DNA or histones, can affect gene expression without altering the DNA sequence itself.

In prokaryotes, a group of functionally related genes can be coordinately regulated through a structure known as a(n):

A) Operon

B) Histone complex

C) Transcription factor

D) Epigenome

Correct Answer: A

The text specifies that prokaryotes have groups of genes that are coordinately regulated, providing operons as the example of this mechanism.

The observable traits of a cell, or its phenotype, are ultimately determined by which of the following?

A) The total number of chromosomes in the nucleus.

B) The rate of cell division.

C) The combination and expression levels of its genes.

D) The size of the cell's genome.

Correct Answer: C

The content states that the phenotype of a cell is determined by the combination and expression levels of its genes, which leads to cell differentiation.

How does coordinated gene regulation typically differ between prokaryotes and eukaryotes?

A) Only eukaryotes use regulatory proteins to control transcription.

B) Prokaryotes use operons to control gene clusters, while eukaryotes often use shared transcription factors for genes that may be physically distant.

C) Eukaryotes use operons, while prokaryotes rely on epigenetic modifications.

D) Coordinated regulation does not occur in prokaryotes.

Correct Answer: B

The text contrasts the two, noting that prokaryotes use mechanisms like operons, whereas eukaryotes can regulate distant genes together through the use of shared transcription factors.

A muscle cell and a nerve cell in the same individual have different structures and functions. This cell differentiation is primarily caused by:

A) The presence of different genes in each cell type.

B) Different levels of gene expression in each cell type.

C) The muscle cell having more DNA than the nerve cell.

D) A higher rate of mutation in nerve cells.

Correct Answer: B

Based on the content, cell differentiation arises from the specific combination and expression levels of genes, not from having different sets of genes. Both cells have the same DNA, but they express different parts of it.

A scientist discovers a DNA sequence located thousands of base pairs away from a gene it controls. This sequence's function is most likely related to its:

A) Ability to be translated into a small protein.

B) Role as a template for DNA replication.

C) Location, which allows it to interact with specific regulatory proteins to enhance or silence transcription.

D) Function as a stop codon to terminate translation.

Correct Answer: C

The content explains that the location of regulatory sequences relates to their function. Distant sequences, such as enhancers or silencers, interact with regulatory proteins to control transcription from afar.

The fundamental interaction that regulates gene expression at the transcriptional level involves:

A) mRNA binding to a ribosome.

B) A regulatory protein binding to a regulatory sequence of DNA.

C) tRNA delivering an amino acid to a polypeptide chain.

D) DNA polymerase replicating the DNA strand.

Correct Answer: B

The content describes the types of interactions that regulate gene expression, highlighting that regulatory sequences (DNA) interact with regulatory proteins to control transcription.

A gene is found to be silenced in a particular cell line. The DNA sequence of the gene is identical to that of an active version in another cell line. Which of the following is the most plausible explanation for the gene's inactivation?

A) The gene was deleted from the genome of the silenced cell line.

B) An epigenetic modification, such as DNA methylation, has occurred on the regulatory sequence.

C) The gene has been converted into an operon.

D) A frameshift mutation occurred, which is not detectable by sequencing.

Correct Answer: B

Since the DNA sequence is unchanged, the silencing is likely due to an epigenetic mechanism. The content states that reversible modifications of DNA (like methylation) or histones can affect gene expression without altering the sequence.

In eukaryotes, how can multiple genes located on different chromosomes be activated simultaneously by a single signal?

A) They are temporarily moved onto a single chromosome.

B) They are all part of one large, discontinuous operon.

C) They share common regulatory sequences that bind the same transcription factors.

D) The signal causes identical mutations in all the genes at once.

Correct Answer: C

The content explains that eukaryotes can coordinately regulate genes through shared transcription factors. This implies that genes, even if distant, can be controlled together if they have the same regulatory sequences that respond to the same protein signals.

Regulatory proteins are molecules that control transcription by interacting with:

A) Ribosomes

B) Lipids in the cell membrane

C) Stretches of DNA

D) Mitochondria

Correct Answer: C

This is a direct definition from the content. Regulatory sequences are stretches of DNA that interact with regulatory proteins to control transcription.

Which statement best describes the relationship between gene expression and cell differentiation?

A) All genes are expressed equally in all differentiated cells.

B) Cell differentiation is the result of certain genes being permanently deleted from the genome.

C) The selective expression of specific genes determines the final phenotype and function of a differentiated cell.

D) Once a cell is differentiated, gene expression becomes fixed and can no longer be regulated.

Correct Answer: C

The content links gene expression to cell differentiation by stating that the phenotype (and thus the specialized function) of a cell is determined by the unique combination and levels of genes it expresses.

Unlike a change in the DNA sequence, an epigenetic change is characterized by being:

A) Permanent and heritable through many generations.

B) Always caused by viral infections.

C) Reversible and not altering the nucleotide sequence.

D) Only capable of increasing gene expression.

Correct Answer: C

The content explicitly describes epigenetic changes as 'reversible modifications of DNA or histones,' distinguishing them from permanent mutations in the DNA sequence.

A researcher identifies a protein that binds to a specific DNA sequence, preventing RNA polymerase from initiating transcription. This protein is acting as a:

A) Histone

B) Regulatory protein (repressor)

C) Gene

D) Ribosome

Correct Answer: B

Based on the content, regulatory proteins interact with DNA to control transcription. A protein that prevents transcription is a type of regulatory protein known as a repressor, fitting the general description provided.

Both prokaryotes and eukaryotes are capable of:

A) Organizing genes into operons.

B) Modifying histone proteins to regulate transcription.

C) Coordinately regulating groups of genes.

D) Containing their DNA within a nucleus.

Correct Answer: C

The content explicitly states that 'Both prokaryotes and eukaryotes have groups of genes that are coordinately regulated,' although the mechanisms (operons vs. shared transcription factors) differ.