Download The diagram below shows the arrangement of chromatin (thick black

4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
1.
PROCTOR VERSION
The diagram below shows the arrangement of chromatin (thick black strands) around histones on
a chromosome in the nucleus of a eukaryotic cell.
A signal received by the cell causes the attachment of acetyl groups (–COCH3) to the histones,
and the chromatin-histone complex changes, as shown below.
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4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
PROCTOR VERSION
Which statement best explains how this change will affect cellular activity?
(A) Histone acetylation will reduce gene expression, because the acetyl groups prevent RNA
polymerase from accessing the coding regions.
Distractor Rationale:
This answer suggests the student may understand that RNA polymerase is involved in
transcribing DNA into mRNA, but does not understand that histone acetylation increases
gene expression by exposing DNA in order for transcription to take place, whereas
methylation reduces gene expression by restricting access of transcription factors to DNA.
(B) Histone acetylation will reduce gene expression, because the acetyl groups will bind to
chromatin and prevent proteins from initiating transcription.
Distractor Rationale:
This answer suggests the student may understand that acetylation of histones plays a role in
gene expression, but does not understand that histone acetylation does not repress
genes, and that, instead, it allows for gene transcription.
(C) Histone acetylation will increase gene expression, because the chromatin is no longer tightly
bound to the histones and can be transcribed.
Rationale:
This answer suggests the student understands that histone acetylation allows for gene
expression because it “uncoils” DNA from the histone and allows genes to be exposed to
transcription factors that initiate protein synthesis.
(D) Histone acetylation will increase gene expression, because the acetyl-histone complexes
can bind to promoter regions on the chromatin and activate the transcription of genes.
Distractor Rationale:
This answer suggests the student may understand that gene expression can be initiated
when compounds bind to a promoter, but does not understand that acetylated histone
complexes do not regulate genes by binding to promoter regions and that acetylated
histones instead act by separating from chromatin to expose genes for transcription.
Aligned to: LO 4.7 CA 4.7: Represent Mechanisms of Specialization
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4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
2.
PROCTOR VERSION
A methyl group (CH3) can be attached to a cytosine base on DNA, as shown in the diagram
below. When a methyl group is attached to a base, enhancers and activator proteins are unable
to access the base.
A certain gene is identified that contains many methyl groups, compared to other regions of DNA.
Which statement best explains the significance of methylation to this gene?
(A) The gene will probably not be transcribed into RNA, because transcription factors will not be
able to bind to the gene to initiate transcription.
Rationale:
This answer suggests the student understands that DNA methylation blocks gene
expression by preventing the binding of transcription factors to DNA.
(B) The gene will probably be transcribed into RNA, but not translated into a polypeptide,
because enhancers will be unable to convert the nucleic acid code into amino acids.
Distractor Rationale:
This answer suggests the student may understand that DNA methylation blocks gene
expression, but does not understand that this process prevents transcription because
transcription factors cannot bind to DNA to initiate transcription, and that DNA methylation is
not involved in the translation of RNA into an amino acid sequence.
(C) The gene will probably not be transcribed into mRNA, because the mRNA will have
defective cytosine nucleotides that will be unable to bind with complementary DNA
nucleotides.
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4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
PROCTOR VERSION
Distractor Rationale:
This answer suggests the student may understand that DNA methylation blocks gene
expression, but does not understand that this process prevents transcription and the
formation of mRNA because DNA methylation prevents transcription factors from binding to
DNA and does not affect RNA.
(D) The gene will probably be transcribed and translated into an amino acid sequence, but the
process will continue for a long time and produce excess polypeptides, because the mRNA
cannot be properly degraded.
Distractor Rationale:
This answer suggests the student may understand that methylation of certain regulatory
genes (ribonuclease) may slow the breakdown of mRNA, which would result in greater
production of polypeptides, but does not understand that the methylation of this gene
would prevent expression because transcription factors would not be able to bind to the
DNA to initiate transcription.
Aligned to: LO 4.7 CA 4.7: Represent Mechanisms of Specialization
3.
Fur coloration in Himalayan rabbits is determined by genetic and environmental factors. The
pictures below show three genetically identical rabbits reared at three different temperatures.
Which statement best explains why fur coloration in Himalayan rabbits is different at different
temperatures?
(A) Fur coloration is different because cold temperatures cause mutations in genes governing
fur color in certain parts of rabbits.
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4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
PROCTOR VERSION
Distractor Rationale:
This answer suggests the student may understand that some environmental factors can
cause genetic mutations, but does not understand that cold temperatures are not
associated with an increased risk of genetic mutation and that the differential expression of
genes in Himalayan rabbits is caused by a difference in rearing temperature, not mutations.
(B) Fur coloration is different because warm temperatures denature dark-pigmented proteins,
which results in rabbits with only white fur.
Distractor Rationale:
This answer suggests the student may understand that high temperatures can denature
proteins, but does not understand that this outcome is unlikely because the temperature
range affecting Himalayan rabbits is lower than the temperature needed to denature most
biological enzymes, and the temperature is instead affecting gene expression and resulting
in different phenotypes.
(C) Fur coloration is different because different temperatures cause DNA to arrange into
different sequences, and this alters the genes that express fur color in rabbits.
Distractor Rationale:
This answer suggests the student may understand that environmental factors such as
temperature may change gene expression, but does not understand that this explanation
is unlikely because temperature may affect gene expression, but would not affect DNA
arrangement.
(D) Fur coloration is different because different temperatures cause differential expression of
certain genes, which produces different fur colors in rabbits.
Rationale:
This answer suggests the student understands that environmental factors such as
temperature may affect gene expression and that this may result in different phenotypes.
Aligned to: LO 4.7 CA 4.7: Represent Mechanisms of Specialization
Page 5 of 7
4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
4.
PROCTOR VERSION
The diagram below shows a hormone initiating a change in a cell.
Based on the process illustrated in the diagram, which statement best explains how the hormone
initiates a response in the cell?
(A) The hormone initiates a response in the cell by binding to a protein receptor on RNA
polymerase, allowing the enzyme to transcribe a gene.
Distractor Rationale:
This answer suggests the student may understand that gene expression involves initiating
the transcription of DNA by RNA polymerase, but does not understand that the hormone
shown in the diagram does not directly initiate this because the hormone is binding to a
protein receptor, not to RNA polymerase. The protein/hormone complex then binds to a
regulatory region on the gene (DNA), which activates the gene for transcription.
(B) The hormone initiates a response in the cell by binding to a protein receptor, initiating a
series of kinase reactions that result in transcription of a gene in the nucleus.
Distractor Rationale:
This answer suggests the student may understand that many hormones initiate gene
expression via protein kinase reactions, but does not understand that this is not the
pathway illustrated in the diagram because there is no indication that protein kinases are
active in the process; rather, the protein/hormone complex shown in the diagram is binding
to a regulatory region on the gene (DNA), which activates the gene for transcription.
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4.7 A: Factors Affecting Eukaryotic Gene Expression Quiz
PROCTOR VERSION
(C) The hormone initiates a response in the cell by binding to a protein receptor, allowing the
protein/hormone complex to bind to the gene and initiate transcription.
Rationale:
This answer suggests the student understands that the hormone shown in the diagram
controls gene expression by binding to a receptor protein and allowing the protein to activate
a gene for transcription.
(D) The hormone initiates a response in the cell by binding to a protein receptor on a ribosome,
initiating transcription and translation of a gene.
Distractor Rationale:
This answer suggests the student may understand that hormones and ribosomes are both
involved in gene expression, but does not understand that a hormone binding to a receptor
on a ribosome is not the correct description of the pathway shown in the diagram, because
regulatory proteins interact with hormones to regulate gene expression, and ribosomes are
involved with translation of the genetic code into polypeptides.
Aligned to: LO 4.7 CA 4.7: Represent Mechanisms of Specialization
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