52) Which of the following statements regarding cancer risk factors is false?
A) Factors that alter DNA and make cells cancerous are called carcinogens.
B) Mutagens are usually not carcinogens.
C) X-rays and ultraviolet radiation are two of the most potent carcinogens.
D) Eating 20-30 grams of plant fiber daily and reducing the intake of animal fat can reduce your
risk of developing colon cancer.
53) E. coli can synthesize the amino acid threonine or absorb it from the environment. In the thr
operon, the repressor is active when it is bound to threonine. If an E. coli bacterium is in an
environment where threonine is absent, will transcription of threonine synthesis genes take
place? Why or why not?
A) Yes, because threonine will not be bound to the repressor, so the repressor will be inactive.
B) No, because threonine will not be bound to the repressor, so the repressor will be inactive.
C) Yes, because threonine will not be bound to the repressor, so the repressor will be active.
D) No, because threonine will not be bound to the repressor, so the repressor will be active.
54) There is a mutation in a promoter next to a gene such that RNA polymerase can never bind.
What steps must occur for the gene to be transcribed?
A) An activator protein must bind an enhancer.
B) The DNA must physically bend so that the activator is close to the promoter.
C) Transcription factors must bind to the activator and promoter.
D) Transcription will never take place in this specific example.
55) A normal muscle cell produces the myosin protein, which allows muscles to contract. You
discover a single muscle cell that has tRNAs that do not bind to amino acids. Will the myosin
gene be expressed in this muscle cell? Why or why not?
A) Yes, because all cells in the body express the myosin gene all of the time.
B) No, because if the tRNAs do not bind amino acids, then translation cannot occur.
C) Yes, because the myosin gene will be transcribed in the muscle cell nucleus.
D) No, because the myosin mRNA will likely get broken down in the cytoplasm.
56) Scientists are attempting to make a chicken look like a dinosaur (“dino-chicken”) by using
drugs or proteins to turn on certain homeotic genes during the development of a chicken embryo.
If the scientists are successful in creating both male and female “dino-chickens,” and then the
“dino-chickens” mate together, what type of offspring would the two “dino-chickens” have?
A) a male or female “dino-chicken”
B) a male or female normal chicken
C) You can’t know for sure because of random fertilization.
D) You can’t know for sure because it depends on whether the modified homeotic genes are
dominant or recessive.
57) A stomach cell is producing pepsin, an enzyme that hydrolyzes proteins. Which of the
following events suggests that gene expression of pepsin has been turned off in the cell?
A) The pepsin protein is folded properly in the cytoplasm.
B) The chromosome with the pepsin gene is tightly coiled.
C) The pepsin mRNA leaves the nucleus and enters the cytoplasm.
D) Activators and RNA polymerases are abundant in the nucleus.
58) In terms of gene regulation, what do eukaryotes and prokaryotes have in common?
A) operons such as the lac operon and the trp operon
B) elaborate packing of DNA into chromosomes
C) activator proteins that bind to DNA
D) promoters that bind RNA polymerases
59) A cell has a mutation in both alleles of its p53 gene that causes the p53 protein to be three
times as effective as normal. What do you predict would happen to this cell?
A) The cell would divide three times as fast and would lead to cancer.
B) The cell would divide into six daughter cells instead of two and would lead to cancer.
C) The cell would divide with mutated DNA and would lead to cancer.
D) The cell would divide normally or possibly not at all.
60) Which of the following molecules are not required to express a gene in eukaryotic cells?
A) RNA polymerase
B) DNA-bending protein
C) activator protein
D) repressor protein
61) There is a mutation in the operator of the lac operon in a cell such that the lac repressor
always stays bound to the operator. If lactose is added to the cell, what will happen?
A) Lactose will bind to the repressor, and lac enzymes will be produced.
B) Lactose will bind to the repressor, and lac enzymes will not be produced.
C) Lactose will not bind to the repressor, and lac enzymes will be produced.
D) Lactose will bind to the operator, and lac enzymes will be produced.
62) Two yeast cells, one of type a and the other type α, are in proximity to each other. The a
yeast cell has a mutation in the gene for the α factor receptor protein such that the receptor does
not translocate to the surface of the a cell. If both cells secrete their respective a and α factors,
which of the following outcomes is most likely to occur?
A) The a and α cells will grow toward each other.
B) The a cell will grow towards the α cell.
C) The α cell will grow toward the a cell.
D) The a and α cells will not grow toward each other at all.
63) Which of the following statements regarding skin cells and muscle cells in your body is true?
A) Muscle cells contain information about muscle proteins but not about skin color.
B) Skin cells contain information skin color but not about muscle proteins.
C) Muscle cells contain information about skin color but not about muscle proteins.
D) Skin cells and muscle cells each contain information about both muscle proteins and skin
color.
64) What is the proper order of events in the expression of a eukaryotic protein?
A) DNA unpacking, mRNA transport through nucleus, mRNA splicing, protein modification
B) DNA unpacking, mRNA splicing, translation, protein folding
C) transcription, translation, addition of cap and tail to mRNA, DNA unpacking
D) transcription, mRNA splicing, protein modification, translation
65) During an experiment assessing the development of a fly embryo, a scientist artificially turns
on a homeotic gene that controls eye development in somatic cells that develop into the wings.
Which of the following is the most likely outcome of this experiment?
A) A normal adult fly will develop.
B) A mutant adult fly will develop that has eyes on its wings.
C) A mutant adult fly will develop that has legs on its head.
D) A mutant adult fly will develop that has no eyes on its head but has eyes on its wings.
66) In thinking about their role in cell division, oncogenes are like the ________ of a car, while
tumor suppressor genes are like the ________ of a car.
A) gas pedal; brakes
B) steering wheel; brakes
C) gas pedal; headlights
D) brakes; gas pedal
67) Melanoma (skin cancer) can develop after several mutations occur in skin cells. If a woman
is diagnosed with melanoma and becomes pregnant, what are the chances that her offspring will
inherit melanoma?
A) The offspring will certainly be born with melanoma.
B) There is a chance, but it depends on how serious the mother’s melanoma is.
C) There is a chance, but it depends on whether or not the father has melanoma.
D) It is unlikely that the offspring will be born with melanoma.
68) In 2013, an estimated 160,000 people in the United States will die of lung cancer. If the
cancer death rate is expected to increase by 1% per decade, approximately how many people will
die of lung cancer in the United States in 2033?
A) 160,000
B) 163,000
C) 176,000
D) 194,000
69) What is the correct order of structures in a chromosome from smallest to largest?
A) nucleotide, nucleosome, histone, supercoil, tight helical fiber, chromosome
B) nucleosome, nucleotide, histone, tight helical fiber, supercoil, chromosome
C) nucleotide, histone, tight helical fiber, nucleosome, chromosome, supercoil
D) nucleotide, histone, nucleosome, tight helical fiber, supercoil, chromosome
70) A cell is expressing the mutant form of ras, but one of the downstream relay proteins is not
present because of another mutation. How will cell division be affected in this scenario?
A) Cell division will decrease because the mutant form of ras decreases cell division.
B) Cell division will increase because the mutant form of ras increases cell division.
C) The cell will divide normally.
D) The cell will not divide at all unless other proteins that stimulate cell division are present.
71) There is a mutation in the operator of the trp operon in a cell such that the trp repressor is
unable to bind to the operator. If tryptophan is added to the cell, what will happen?
A) Tryptophan will bind to the repressor, and trp enzymes will be produced.
B) Tryptophan will bind to the repressor, and trp enzymes will not be produced.
C) Tryptophan will not bind to the repressor, and trp enzymes will be produced.
D) Tryptophan will bind to the operator, and trp enzymes will be produced.
11.2 Art Questions
1) In this drawing of the lac operon, which molecule is an inactive repressor?
A) molecule A
B) molecule B
C) molecule C
D) molecule D
2) Which structure in this figure shows one complete nucleosome?
A) structure A
B) structure B
C) structure C
D) structure D
3) The figure below shows a normal cell transduction pathway. If the receptor wasn’t there,
which of the following is the most likely outcome?
A) Cell division will occur normally.
B) Cell division will not occur at all.
C) Cell division will be increased.
D) Cell division will be decreased.
11.3 Scenario Questions
After reading the paragraph below, answer the questions that follow.
All apples in the United States, regardless of variety or where they’re purchased, are produced by
cloning. For more than 2,000 years, apple growers around the world have used a type of cloning
called grafting to produce larger, better-tasting apples. Why has cloning become the primary
method of apple growing? Apples grown from seeds usually don’t produce apples with the same
taste and appearance as that of the parent tree because there’s a high degree of genetic variability
among the seeds. Making identical genetic copies of the preferred fruit is the only way to get
reliable apple quality.
In grafting, the shoots and branches of the desired fruit, called a scion, are attached onto the
trunk and root system of a previously existing tree, called the rootstock. Both components of the
graft are needed because the rootstock controls gene expression in the scion, triggering
production of apples that match the cloned scion.
Grafting research can be used to produce some interesting tree combinations that are beneficial
for intensive agriculture. For example, if you graft the root of a small tree variety, such as the
crab apple, onto the shoot from a larger apple tree, such as the Gala, you can produce Gala
apples on a much smaller tree. Other scientists are trying to create disease-resistant varieties that
would need fewer pesticides. This is beneficial for the environment and also lowers the price of
apples in the grocery store.
1) Why don’t the grafted hybrids produce apples with a blend of traits from the scion and the
rootstock?
A) The rootstock suppresses activation of the scion genes, which alters fruit production.
B) The rootstock is unable to perform photosynthesis and so can’t produce fruit.
C) Transplanted nuclei from scion cells regulate gene expression in the rootstock.
D) The rootstock regulates gene expression in the scion but contributes no genetic information
for fruit production.
24
2) Half the trees in an orchard were derived from rootstock “A” and half from rootstock “B,” but
all the trees had the same scion. If the trees grafted onto rootstock “A” were infected by a
parasite that causes blossom rot, the trees grafted onto rootstock “B”
A) would be less likely to become infected because they’re grafted onto different rootstocks.
B) would be more likely to become infected, since the pathogen would spread through the soil to
the roots of other trees.
C) would be very likely to become infected, because the remaining scions are genetically
identical to those that are already infected.
D) There’s no way to determine the likelihood of infection, since genetic variability gives all the
trees different characteristics.
3) All of the trees in an orchard were derived from the same rootstock, but half had scion “A”
grafted and the other half had a different scion, scion “B,” grafted. The trees that were grafted
with scion “A” developed large fruits. What characteristics do you think the fruit from the trees
that were grafted with scion “B” will have and why?
A) The fruits will be large because the trees share the same rootstock.
B) The fruits will be large because all scions produce the same kind of fruits.
C) The fruits will be small because the trees share the same rootstock.
D) There is not enough information to know what the fruit will look like
After reading the paragraph below, answer the questions that follow.
While DNA microarrays can be used to determine whether or not a gene is expressed in a cell,
quantitative polymerase chain reaction (qPCR) can be used to measure the extent of gene
expression in cells and tissues. To perform qPCR, mRNA is extracted from cells and reverse
transcribed to complementary DNA (cDNA). Using fluorescent DNA molecules that recognize
specific gene sequences and DNA polymerase, copies of the gene sequence of interest are made.
After the copies are made, a fluorescent detector measures the intensity of the fluorescent signal,
which is proportional to the number of mRNA transcripts in the cell and corresponds to the level
of gene expression in the cell.
4) A pancreatic cell normally produces low levels of the protein insulin, but after a meal it
produces large levels of insulin before returning to its initial state. Which of the following figures
would represent qPCR data obtained from a pancreatic cell that went through this cycle?
A)
B)
C)
D)
5) In a muscle cell, the contractile protein myosin is present in larger quantities than the
structural protein actin. Which of the following qPCR results would support this observation?
A) The fluorescent signal for myosin is higher than that of actin.
B) The fluorescent signal for actin is higher than that of myosin.
C) The fluorescent signals for myosin and actin are equal.
D) The fluorescent signal for myosin is large and is zero for actin.
6) A scientist hypothesizes that a new drug turns on a certain gene in a skin cell. Which of the
following experiments would be the best to test her hypothesis?
A) Use qPCR to measure the initial levels of gene expression in skin cells, treat skin cells with
the drug and measure the levels of gene expression, and then compare the two measurements.
B) Use qPCR to measure the levels of gene expression in skin cells after exposure to the drug.
C) Use qPCR to measure the initial levels of gene expression in muscle cells, treat skin cells with
the drug and measure the levels of gene expression, and then compare the two measurements.
D) Use qPCR to measure the levels of gene expression in skin cells after exposure to the drug
and then add another drug to turn off gene expression and use qPCR to measure the levels of
expression.
7) Which of the following statements regarding the comparison of DNA microarrays and qPCR
is false?
A) Both methods use fluorescent DNA molecules and cDNA.
B) Both methods can determine whether a gene has been turned on or not.
C) Both methods use mRNA extracted from cells.
D) Both methods can quantify the levels of gene expression in cells.