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AAMC MCAT Practice Exam 2 (Updated 2022 With Explanations)
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AAMC MCAT Practice Exam 2 (Updated 2022 With Explanations)
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AAMC MCAT Practice Exam 2 (Updated2022 With Explanations)
C/P: What expression gives the amount of light energy (in J per photon) that is converted to other
forms between the fluorescence excitation and emission events?
"intensity of fluorescence emission at 440 nm excitation at 360 nm) was monitored for 20 minutes"
A) (6.62 × 10-34) × (3.0 × 108)
B) (6.62 × 10-34) × (3.0 × 108) × (360 × 10-9)
C) (6.62 × 10-34) × (3.0 × 108) × [1 / (360 × 10-9) - 1 / (440 × 10-9)]
D) (6.62 × 10-34) × (3.0 × 108) / (440 × 10-9) - C) (6.62 × 10-34) × (3.0 × 108) × [1 / (360 × 10-9) -
1 / (440 × 10-9)]
The answer to this question is C because the equation of interest is E = hf = hc/λ, where h = 6.62 ×
10 −34 J ∙ s and c = 3 × 10 8 m/s. Excitation occurs at λe = 360 nm, but fluorescence is observed at λf
= 440 nm. This implies that an energy of E = (6.62 × 10 −34) × (3 × 10 8) × [1 / (360 × 10 −9) − 1 /
(440 × 10 −9)] J per photon is converted to other forms between the excitation and fluorescence
events.
C/P: Compared to the concentration of the proteasome, the concentration of the substrate is larger
by what factor?
"purified rabbit proteasome (2 nM) was incubated in the presence of porphyrin...the reaction was
initiated by addition of the peptide (100 uM)"
A) 5 × 101
B) 5 × 102
,C) 5 × 103
D) 5 × 104 - D) 5 × 104
The answer to this question is D. The proteasome was present at a concentration of 2 × 10-9 M,
while the substrate was present at 100 × 10-6 M. The ratio of these two numbers is 5 × 104.
sp2 hybridized - possess exactly one doubly bonded atom
C/P: The concentration of enzyme for each experiment was 5.0 μM. What is kcat for the reaction at
pH 4.5 with NO chloride added when Compound 3 is the substrate?
Rate of reaction = 125 nM/s
A) 2.5 × 10-2 s-1
B) 1.3 × 102 s-1
C) 5.3 × 103 s-1
D) 7.0 × 105 s-1 - A) 2.5 × 10-2 s-1
The answer to this question is A. The fact that the rate of product formation did not vary over time
for the first 5 minutes implies that the enzyme was saturated with substrate. Under these
conditions, kcat = Vmax/[E] = (125 nM/s)/5.0 μM = 2.5 × 10-2 s-1.
kcat, Vmax, [E] - kcat = Vmax/[E]
C/P: Absorption of ultraviolet light by organic molecules always results in what process?
A) Bond breaking
B) Excitation of bound electrons
C) Vibration of atoms in polar bonds
,D) Ejection of bound electrons - B) Excitation of bound electrons
The answer to this question is B. The absorption of ultraviolet light by organic molecules always
results in electronic excitation. Bond breaking can subsequently result, as can ionization or bond
vibration, but none of these processes are guaranteed to result from the absorption of ultraviolet
light.
C/P: Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a
mixture, are separated by column chromatography using silica gel with benzene as the eluent. What
is the expected order of elution of these four organic compounds from first to last?
A) n-Pentane → 2-butanone → n-butanol → propanoic acid
B) n-Pentane → n-butanol → 2-butanone → propanoic acid
C) Propanoic acid → n-butanol → 2-butanone → n-pentane
D) Propanoic acid → 2-butanone → n-butanol → n-pentane - A) n-Pentane → 2-butanone → n-
butanol → propanoic acid
The answer to this question is A. The four compounds have comparable molecular weights, so the
order of elution will depend on the polarity of the molecule. Since silica gel serves as the stationary
phase for the experiment, increasing the polarity of the eluting molecule will increase its affinity for
the stationary phase and increase the elution time (decreased Rf).
C/P: The half-life of a radioactive material is:
A) half the time it takes for all of the radioactive nuclei to decay into radioactive nuclei.
B) half the time it takes for all of the radioactive nuclei to decay into their daughter nuclei.
C) the time it takes for half of all the radioactive nuclei to decay into radioactive nuclei.
D) the time it takes for half of all the radioactive nuclei to decay into their daughter nuclei. - D) the
time it takes for half of all the radioactive nuclei to decay into their daughter nuclei.
, The answer to this question is D because the half-life of a radioactive material is defined as the time
it takes for half of all the radioactive nuclei to decay into their daughter nuclei, which may or may
not also be radioactive.
C/P: A person is sitting in a chair. Why must the person either lean forward or slide their feet under
the chair in order to stand up?
A) to increase the force required to stand up
B) to use the friction with the ground
C) to reduce the energy required to stand up
D) to keep the body in equilibrium while rising - D) to keep the body in equilibrium while rising
The answer to this question is D because as the person is attempting to stand, the only support
comes from the feet on the ground. The person is in equilibrium only when the center of mass is
directly above their feet. Otherwise, if the person did not lean forward or slide the feet under the
chair, the person would fall backward due to the large torque created by the combination of the
weight of the body (applied at the person's center of mass) and the distance along the horizontal
between the center of mass and the support point.
C/P: The side chain of tryptophan will give rise to the largest CD signal in the near UV region when:
A) present as a free amino acid
B) part of an a-helix
C) part of a B-sheet
D) part of a fully folded protein - D) part of a fully folded protein
The answer to this question is D because tryptophan has an aromatic side chain that will give rise to
a significant CD signal in the near UV region if it is found in a fully folded protein.
C/P: Which amino acid will contribute to the CD signal in the far UV region, but NOT the near UV
region, when part of a fully folded protein?
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