Name: ___________________________ NetID: ____________________________ Exam 1 Version 1 September 12, 2017 Dr. A. Pimentel Each question has a value of 4 points and there is a total of 156 points in the exam. However, the maximum score of this exam will be capped at 150 points. Instructions: Select the BEST answer for each question Scientific Method 1- Insulin is a peptide hormone that reduces the amount of sugar in our bodies. What is the general sequence of cell-signaling events upon insulin binding to its receptor? A. 1. Receptor activation, 2. response, 3. signal transduction B. 1. Signal transduction, 2. response, 3. receptor activation C. 1. Response, 2. signal transduction, 3. receptor activation D. 1. Receptor activation, 2. signal transduction, 3. Response E. None of the answer choices are correct. 2- The mitogen-activated protein kinase (MAPK) are enzymes that are involved in a variety of cellular processes ranging from cell growth to cell survival. A scientist has identified MAPK-A, MAPK-B, and MAPK-C that appear to be involved in a cell survival pathway. What should the scientist do in order to determine the order in which these kinases act? A. Design an experiment using control cell lines to determine the order of the kinases. B. Design an experiment using cell lines with random mutations, which may affect a variety of processes in addition to mutating the kinases. C. Design an experiment using cell lines with specific mutations, which either permanently mutates the respective kinases to be either “always on” or “always off.” D. Choices B and C are both correct E. All of the answer choices are correct.
Exam 1 Version 1 September 12, 2017 Dr. A. Pimentel Each question has a value of 4 points and there is a total of 156 points in the exam. However, the maximum score of this exam will be capped at 150 points. Instructions: Select the BEST answer for each question Scientific Method 1- Insulin is a peptide hormone that reduces the amount of sugar in our bodies. What is the
general sequence of cell-signaling events upon insulin binding to its receptor?
A. 1. Receptor activation, 2. response, 3. signal transduction
B. 1. Signal transduction, 2. response, 3. receptor activation
C. 1. Response, 2. signal transduction, 3. receptor activation
D. 1. Receptor activation, 2. signal transduction, 3. Response
E. None of the answer choices are correct.
2- The mitogen-activated protein kinase (MAPK) are enzymes that are involved in a variety of
cellular processes ranging from cell growth to cell survival. A scientist has identified MAPK-A,
MAPK-B, and MAPK-C that appear to be involved in a cell survival pathway. What should the
scientist do in order to determine the order in which these kinases act?
A. Design an experiment using control cell lines to determine the order of the kinases.
B. Design an experiment using cell lines with random mutations, which may affect a variety of
processes in addition to mutating the kinases.
C. Design an experiment using cell lines with specific mutations, which either permanently
mutates the respective kinases to be either “always on” or “always off.”
D. Choices B and C are both correct
E. All of the answer choices are correct.
3- The scientist makes a statement stating, “In order for the cell survival pathway to function
properly, the MAPK-C kinase must function before MAPK-B.” This is an example of a(n)
__________.
A. Observation
B. Hypothesis
C. Prediction
D. Experiment or new observation
E. Theory
4- The scientist performed some initial experiments and she determined that MAPK-C functions
before both MAPK-A and MAPK-B. She still does not know the proper order of MAPK-A and
MAPK-B. These statements are an example of a(n) __________.
A. Observation
B. Hypothesis
C. Prediction
D. New observation
E. Experiment
5- The scientist determines that MAPK-C is present in an “always on” form, MAPK-A in an
“always off” form, and MAPK-B in wild-type (normal) form. She believes that if she replaces the
“always off” MAPK-A with a wild-type MAPK-A in a new experiment, it will result in the activation
of wild-type MAPK-B. These statements are best described as an example of a(n) __________.
A. Observation
B. Hypothesis
C. Prediction
D. Experiment or new observation
E. Theory
6- After much research, the scientist confirmed and concluded that the proper order of the
signaling pathway is MAPK-C → MAPK-A→ MAPK-B. When MAPK-C is mutated to an “always
off” form and MAPK-A is mutated to an “always on” form, what is activity of MAPK-B when the
signal upstream MAPK-C is either present or absent?
A. Signal present: ON, Signal absent: ON
B. Signal present: OFF, Signal absent: OFF
C. Signal present: ON, Signal absent: OFF
D. Signal present: OFF, Signal absent: ON
E. None of the answer choices are correct.
7- How does a scientific theory differ from a scientific hypothesis?
A. Theories are proposed to test scientific hypotheses.
B. A theory is an explanation for a very general phenomenon or observation that has been
tested repeatedly; a hypothesis is an explanation about an observation.
C. A hypothesis is an explanation for a very general phenomenon that has been tested over
and over again; theories pertain to more specific issues.
D. Theories define scientific laws; hypotheses are used to set up experiments.
E. Hypotheses define scientific laws; theories are used to set up experiments.
Amino acids are synthesized in a series of biochemical steps called metabolic pathways. The
pathway to produce the amino acid arginine starts with a basic precursor molecule. The
precursor molecule is processed by “Enzyme 1” and gives rise to the first intermediate molecule
called ornithine. It was also known that the molecule produced after ornithine is citrulline.
Citrulline is finally used by “Enzyme 3” to produce arginine. While the order of the molecules to
produce arginine was clear, scientists knew little about the enzymes that are required to
produce each of the intermediate molecules. They knew that three enzymes were involved in
the pathway and only the position of Arg1 (“Enzyme 1”) was known. The other two enzymes
were ArgY and ArgW. Scientists decided to determine the correct order of enzymes ArgW and
ArgY by mutating cells to produce cell lines in which either ArgY or ArgW was permanently
inactive.
8- In order to inactivate the enzyme certain mutations should be created. This mutation must be
done in which of the following molecules? A. Enzyme
B. Proteins
C. RNA
D. DNA
E. Carbohydrates
9- Which of the following is a plausible hypothesis? A. Ornithine → ArgY → Arginine → ArgW Citrulline
B. Ornithine → ArgW → Citrulline → ArgY → Arginine
C. Precursor → Enzyme 1 → Ornithine → ArgW
D. Precursor → ArgW → Ornithine → Enzyme 1
E. Arginine → ArgY → Citrulline → ArgW → Ornithine
Cell Theory
10- Which of the following statements violate modern cell theory?
A. All known living things are made up of one or more cells.
B. Cells store hereditary information in the form of RNA and this is passed from cell to cell
during cell division.
C. Cells store hereditary information in the form of DNA and this is passed from cell to cell
during cell division.
D. All cells arise from pre-existing cells by division
E. All of the answer choices are correct.
11- Fact: Photosynthesis is the process by which cells synthesize its own food using sunlight.
Assertion Because Reason
Photosynthesis is an example of how energy flows
in a living organism.
All plants have a common
ancestor.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
12-
Assertion Because Reason
All living organism are
composed of cells.
Cell division is the process by which cells divide and
pass their DNA to their offspring.
A. Assertion true, Reason true, Reason is the correct explanation
B. Assertion true, Reason true, Reason is the correct explanation
C. Assertion true, Reason false
D. Assertion false, Reason true
E. Assertion false, Reason true
Theory of Evolution
13- In evolution, a gene pool refers to __________.
A. A group of individuals of the same species living in the same area at the same time.
B. The total amount of gene variants in a population.
C. A trait that increases the fitness of an individual in a given environment.
D. the ability of an individual to produce offspring.
E. None of the answer choices are correct.
14- Which of the following statement(s) is correct?
I. Artificial selection selects traits based on human preference
II. Natural selection chooses traits based on improving an organism’s fitness
III. Artificial selection does not necessarily improve fitness
A. I, II
B. I only
C. III only
D. I, II, III
E. II only
15- The saguaro cactus is a native plant to the Sonoran Desert.
In order to survive water shortage, young saguaro cacti grow
under the shade of a “nurse tree”. This unique characteristic of
saguaro cacti helps to increase their _______________.
A. Natural Selection
B. Adaptation
C. Evolution
D. Fitness
E. Artificial Selection
16-
Assertion Because Reason
Adaptation refers to a trait that
increases the fitness of an
individual in a particular
environment.
Under specific environmental pressures,
some genetic traits that increase the fitness
of individuals are more likely to be passed
on.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
Samantha adores cats regularly rescues stray/mud cats from her community and takes them to
the local animal rescue facilities so that they can be properly cared for and a new home can be
found for them. One morning she rescues a litter of kittens and notices that one of them looks
remarkably different from the rest. This kitten had extremely short legs but looks normal
otherwise. The person called it “Munchkin” and decided to keep it because it looks cute. She
was so attached to this munchkin that she decided to mate it and find out whether any offspring
were born with the same trait. After various attempts, she got a couple of additional kittens with
the same characteristic. She decided to keep mating those individuals with shorter legs until she
could develop a new pure breed, which she called Munchkin.
17- She was able to develop the Munchkin breed because:
A. She was persistence
B. Shorter legs in cats increase their fitness
C. The shorter leg trait was encoded in the DNA
D. The shorter leg trait was encoded in the protein
E. The shorter leg trait was encoded in the RNA
18- The description in the paragraph above is an example of ____________.
A. Natural selection
B. Artificial selection
C. Fitness
D. Adaptation
E. Genetic pool
19- The successful establishment of the Munchkin breed was possible because ____________.
A. There are genetic differences between the cat population
B. Cats like to breed a lot
C. There was not a selective pressure
D. The size of the legs increases their fitness
E. The size of their legs increases their adaptation to the city
Molecules
20- Molecules that contain _________ are able to form hydrogen bonds with water and easily
dissolve in water.
A. Non-polar covalent bonds
B. Polar covalent bonds
C. Hydrophobic interactions
D. Dispersion forces
E. None of the answer choices are correct
21- Naturally occurring Uranium is Uranium-238. The number refers to the atomic mass.
However, for nuclear weapons to be the most catastrophic, Uranium-235, an isotope of natural
Uranium, is used. What is the difference between Uranium-238 and Uranium-235?
A. Uranium-238 has 3 more protons than Uranium-235
B. Uranium-238 has 3 more neutrons than Uranium-235
C. Uranium-235 has 3 more electrons than Uranium-238
D. Uranium-238 has 3 more electrical charges than Uranium-235
E. Uranium-235 has 3 more neutrons than Uranium-238
22- Which of the following has the biggest effect on the chemical properties of an atom?
A. The number of neutrons
B. The mass number
C. The number of electrons in the valence shell
D. The number of orbitals the atom contains
E. Whether or not the atom has protons
23-
Assertion
Reason
If atoms of fluoride (F) and radium (Ra)
engaged in a chemical reaction, they will
form a polar covalent bond.
There is a huge difference in the
electronegativity value between fluoride (F)
and radium (Ra).
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
Water
24- In the figure above, all of the molecules are linear monosaccharides. Based on the chemical
structures shown in the figure, determine which monosaccharide will be the least soluble in
water.
25-
Assertion Because Reason
The water molecule
has a neutral pH.
During the dissociation of the water molecule, equal
number of hydrogen ions and hydroxide ions are
produced.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
pH
26- Fact: Human urine has a pH of 6, while the stomach acid has a pH of 2.
Assertion Because Reason
The environment in the stomach is
more acidic than typical human
urine.
Compared to the urine, the stomach acid
has a factor of 10000 more H+ (protons)
than urine.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
27- Industrial emissions contain toxic gases such as sulfur dioxide (SO2) and nitrous oxide (NO).
When these gases react with water in the atmosphere, they form sulfuric and nitric acids. These
chemicals combine with rainwater and fall to the ground as acid rain (pH 4) and cause major
environmental damages. When acid rain falls into ocean water (pH 8), the pH of the ocean
decreases to 6, leading to toxic living conditions for marine life. Which of the following
statements below is correct?
A. The ocean water after acid rain contains approximately two times more [H+] than before
acid rain.
B. The ocean water before acid rain contains approximately two times more [H+] than after
acid rain.
C. The ocean water after acid rain contains approximately one hundred times more [H+] than
before acid rain.
D. The ocean water before acid rain contains approximately one hundred times more [H+]
than after acid rain.
E. The ocean water after acid rain contains approximately one thousand times more [H+]
than before acid rain.
Proteins
28- Which of the following functional groups are found in nucleotide above?
I.Phosphate group
II. Hydroxyl group
III.Carboxyl group
IV. Amino group
V.Carbonyl group
A. I, II
B. II, IV, V
C. III, IV, V
D. I, III, V
E. I, II, IV
29- Which of the following best summarizes the relationship between dehydration reactions and
hydrolysis?
A. Dehydration reactions break down polymers and hydrolysis reactions create polymers.
B. Macromolecular synthesis occurs through the addition of water and digestion occurs
through the removal of water.
C. Dehydration reactions can occur only after hydrolysis.
D. Hydrolysis creates monomers, and dehydration reactions break down polymers.
E. Dehydration reactions assemble polymers and hydrolysis reactions break down polymers.
Nucleic Acids
30-
Assertion Because Reason
During RNA polymerization, RNA
polymerase facilitates the formation
of a phosphodiester bond.
In the RNA sequence 5’-AAUGC-3’, the 3’
hydroxyl group of guanine forms a
phosphodiester bond with 5’ phosphate
group of uracil.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
31- Which of the following statements about DNA and RNA is false?
A. DNA is more stable relative to RNA
B. The nucleotides in DNA and RNA can both form hydrogen bonding interactions
C. DNA and RNA are both synthesized in the 5’ to 3’ direction
D. Nucleic acids in the DNA contain deoxyribose sugars and nucleic acids in RNA contain
ribose sugars
E. All of the answer choices are correct.
32- If 30% of a double-stranded DNA molecule is composed of Guanine, what percent of
Thymine is present in the DNA?
A. 20%
B. 30%
C. 40%
D. 50%
E. 60%
Transcription
33- What is the proper order of events in which a pre-mRNA is converted into a mature mRNA? 1. 3’ poly(A) tail
2. Splicing of introns and exons
3. 5’ cap
A. 1, 2, 3
B. 1, 3, 2
C. 3, 2, 1
D. 3, 1, 2
E. 2, 1, 3
34- Evolutionarily, alternative splicing has enabled eukaryotic cells to?
A. Create more unique protein coding messages from a given gene
B. Create less unique protein coding messages from a given gene
C. Maintain the same amount of protein coding messages for a given gene
D. Reduce the size of their genome as more proteins can now be encoded for with less
physical genes
E. Both A and D are correct
35-
Assertion Because Reason
In prokaryotes, transcription stops when
RNA polymerase encounters a
transcription termination signal.
Formation of RNA hairpin structure
causes RNA polymerase to dissociate
from DNA in prokaryotes.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
36-
Assertion Because Reason
During transcription, the template is read
from the 3’ to 5’ but the mRNA is
synthesized in the 5’ to 3’ direction.
During transcription, the growing
nucleic acid contains a ribose sugar
and uracil nucleotide.
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
37-
Assertion Because Reason
If a RNA molecule contains 30% cytosine then this
molecule must contain 30% guanine, 20% uracil and
20% adenine
The RNA molecule
contains uracil instead of
thymine
A. Assertion is true; Reason is true; Reason is the correct explanation
B. Assertion is true; Reason true; Reason is NOT the correct explanation
C. Assertion is true; Reason is false
D. Assertion is false; Reason is true
E. Assertion is false; Reason is false
38- A mutation caused by radiation in a prokaryotic organism destroys the -10 box of the
promoter. Select the statement that correctly describes the most likely consequence of this
mutation.
A. The general transcription factor will no longer bind to the promoter.
B. The transcriptional activator proteins will no longer bind to the promoter.
C. The mediator protein will no longer bind to the promoter.
D. The DNA will not bend to bring the enhancers closer to the promoter.
E. The sigma subunit will no longer bind to the promoter.
Extra Credit:
39- What is the correct mRNA sequence synthesized based on the following template DNA
