AAMC EXAM 2 CHEMICAL AND PHYSICAL
FOUNDATIONS OF BIOLOGICAL SYSTEMS || ALL
CORRECT ANSWERS
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?
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) Solution: The correct answer is C.
This is a Physics question that falls under the content category "How light and sound interact
with matter." 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. It is a Scientific Reasoning and Problem Solving
question because the question requires determining and using scientific formulas to solve
problems.
Which amino acid is found in greatest abundance in the active site of a laccase?
A.
Phe
B.
Tyr
C.
His
D.
Cys Solution: The correct answer is C.
This is a Biochemistry question that falls under the content category "Structure, function, and
reactivity of biologically-relevant molecules." The answer to this question is C because the five-
membered imidazole rings depicted in Figure 1 are associated with histidine, an amino acid
whose side chain is frequently encountered at the active site of metalloenzymes. It is a
Knowledge of Scientific Concepts and Principles question because you must recognize the
identity of an amino acid based on the graphic depiction of its side chain.
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?
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 Solution: The correct answer is A.
This is a Biochemistry question that falls under the content category "Principles of chemical
thermodynamics and kinetics." 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.
It is a Scientific Reasoning and Problem Solving question because you must determine and then
use a scientific formula to solve a problem.
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 Solution: The correct answer is B.
This is an Organic Chemistry question that falls under the content category "How light and
sound interact with matter." 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. It is a Knowledge of Scientific Concepts and Principles
question because you must recognize a correct scientific principle.
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.
Solution: The correct answer is D.
This is a Physics question that falls under the content category "Atoms, nuclear decay, electronic
structure, and atomic chemical behavior." 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. It is a Knowledge of
Scientific Concepts and Principles question because the question requires recognizing correct
scientific principles and related definitions.
A person is sitting on a chair as shown.
, 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 Solution: The correct answer is D.
This is a Physics question that falls under the content category "Translational motion, forces,
work, energy, and equilibrium in living systems." 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.
It is a Knowledge of Scientific Concepts and Principles question because the question requires
identifying examples of observations that illustrate scientific principles.
Based on the relative energy of the absorbed electromagnetic radiation, which absorber, a
peptide bond or an aromatic side chain, exhibits an electronic excited state that is closer in
energy to the ground state?
A.
An aromatic side chain; the absorbed photon energy is higher.
B.
An aromatic side chain; the absorbed photon energy is lower.
C.
A peptide bond; the absorbed photon energy is higher.
D.
A peptide bond; the absorbed photon energy is lower. Solution: The correct answer is B.
This is a Physics question that falls under the content category "Atoms, nuclear decay, electronic
structure, and atomic chemical behavior." The answer to this question is B because aromatic side
chains absorb in the near UV region of the electromagnetic spectrum, which has longer
wavelengths, and hence lower energy, than peptide bonds. Because the energy of the photon
matches the energy gap between the ground and the excited state, this implies that the aromatic
side chain has more closely spaced energy levels. It is a Knowledge of Scientific Concepts and
Principles question because the question requires identifying the relationships among closely
related concepts.
In designing the experiment, the researchers used which type of 32P labeled ATP?
A.
α32P-ATP
B.
β32P-ATP
C.
γ32P-ATP
FOUNDATIONS OF BIOLOGICAL SYSTEMS || ALL
CORRECT ANSWERS
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?
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) Solution: The correct answer is C.
This is a Physics question that falls under the content category "How light and sound interact
with matter." 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. It is a Scientific Reasoning and Problem Solving
question because the question requires determining and using scientific formulas to solve
problems.
Which amino acid is found in greatest abundance in the active site of a laccase?
A.
Phe
B.
Tyr
C.
His
D.
Cys Solution: The correct answer is C.
This is a Biochemistry question that falls under the content category "Structure, function, and
reactivity of biologically-relevant molecules." The answer to this question is C because the five-
membered imidazole rings depicted in Figure 1 are associated with histidine, an amino acid
whose side chain is frequently encountered at the active site of metalloenzymes. It is a
Knowledge of Scientific Concepts and Principles question because you must recognize the
identity of an amino acid based on the graphic depiction of its side chain.
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?
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 Solution: The correct answer is A.
This is a Biochemistry question that falls under the content category "Principles of chemical
thermodynamics and kinetics." 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.
It is a Scientific Reasoning and Problem Solving question because you must determine and then
use a scientific formula to solve a problem.
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 Solution: The correct answer is B.
This is an Organic Chemistry question that falls under the content category "How light and
sound interact with matter." 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. It is a Knowledge of Scientific Concepts and Principles
question because you must recognize a correct scientific principle.
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.
Solution: The correct answer is D.
This is a Physics question that falls under the content category "Atoms, nuclear decay, electronic
structure, and atomic chemical behavior." 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. It is a Knowledge of
Scientific Concepts and Principles question because the question requires recognizing correct
scientific principles and related definitions.
A person is sitting on a chair as shown.
, 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 Solution: The correct answer is D.
This is a Physics question that falls under the content category "Translational motion, forces,
work, energy, and equilibrium in living systems." 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.
It is a Knowledge of Scientific Concepts and Principles question because the question requires
identifying examples of observations that illustrate scientific principles.
Based on the relative energy of the absorbed electromagnetic radiation, which absorber, a
peptide bond or an aromatic side chain, exhibits an electronic excited state that is closer in
energy to the ground state?
A.
An aromatic side chain; the absorbed photon energy is higher.
B.
An aromatic side chain; the absorbed photon energy is lower.
C.
A peptide bond; the absorbed photon energy is higher.
D.
A peptide bond; the absorbed photon energy is lower. Solution: The correct answer is B.
This is a Physics question that falls under the content category "Atoms, nuclear decay, electronic
structure, and atomic chemical behavior." The answer to this question is B because aromatic side
chains absorb in the near UV region of the electromagnetic spectrum, which has longer
wavelengths, and hence lower energy, than peptide bonds. Because the energy of the photon
matches the energy gap between the ground and the excited state, this implies that the aromatic
side chain has more closely spaced energy levels. It is a Knowledge of Scientific Concepts and
Principles question because the question requires identifying the relationships among closely
related concepts.
In designing the experiment, the researchers used which type of 32P labeled ATP?
A.
α32P-ATP
B.
β32P-ATP
C.
γ32P-ATP
