MCAT AAMC practice exam Chem Phys
What quantity of Compound 1 (483.5g) must be provided to prepare 100.00 mL of
solution with a concentration equal to Ki (60.3uM)? - ANS-M=mol/v
1 umol=0.000001 moles (1x10^-6)
2.92mg
If only [I] is increased, then [ESI] or [EI] increases. This is an example of:
A. the Bose-Einstein Principle.
B. the Heisenberg Uncertainty Principle.
C. the Le Châtelier's Principle.
D. the Pauli Exclusion Principle. - ANS-Solution: The correct answer is C.
A. The Bose-Einstein Principle states that a collection of atoms cooled close to absolute
zero will coalesce into a single quantum state.
B. The Heisenberg Uncertainty Principle states that one cannot know both the
momentum and position of an object with absolute certainty.
C. Le Châtelier's Principle states that in a reversible process, the application of stress to
the system will cause the system to respond in a way that will relieve this stress. In this
case, the reversible process is E + I forming EI or ES + I forming ESI. In either case,
increasing [I] induces stress of the system, and the system relieves that stress by
converting I to either more EI or ESI.
D. The Pauli Exclusion Principle states that two or more identical fermions, e.g.
electrons, cannot occupy the same quantum state.
Which structural change to Compound 1 would make it more water soluble?
A. Replacing benzene CH with N in the ring
B. Replacing C=O with C=CH2
C. Replacing N-N=N with CH-CH=CH
D. Replacing NH with NCH3 - ANS-Solution: The correct answer is A.
A. Nitrogen in the benzene ring would have a lone pair that could accept a hydrogen
bond from water, thus increasing the solubility of the compound.
B. Replacing C=O with C=CH2 would decrease the polarity of the compound and make
it less water soluble.
C. Replacing N−N=N with CH−CH=CH would decrease the polarity of the compound
and make it less water soluble.
D. Replacing NH with NCH3 removes a hydrogen bond donor, thus decreasing water
solubility.
,In μM•s-1 and μM, what should the approximate values of kcat/KM and Ki be,
respectively, when [I] = 180 μM? - ANS-Neither is affected by a change in I, therefore
they will stay the same (150 and 60.3). Ki is the equilibrium constant and is never
affected by increasing I.
What functional group transformation occurs in the product of the reaction catalyzed by
Na+-NQR (NADH and ubiquinone)?
A. RC(=O)R → RCH(OH)R
B. ROPO32- → ROH + Pi
C. RC(=O)NHR'→ RCOOH + R'NH2
D. RC(=O)OR'→ RCOOH + R'OH - ANS-Solution: The correct answer is A.
A. This is two-electron reduction of a ketone to an alcohol, which is the reaction
catalyzed by Na+-NQR.
A. This is the reaction catalyzed by a phosphatase.
A. This is the reaction catalyzed by a protease or amidase.
A. This is the reaction catalyzed by an esterase.
What is the chemical structure of a component found in four of the five cofactors
(flavins) used by Na+-NQR? - ANS-Solution: The correct answer is B.
A. This is the structure of adenine. It is only found in FAD.
B. This is the structure of flavin, found in four of the five cofactors used by Na+-NQR.
C. This is the structure of ubiquinone. It is a substrate, but not a cofactor.
D. This is the structure of histidine. It is an amino acid, not a cofactor.
What is the ratio of cation (0.150M) to enzyme (0.75mM) in the spectroelectrochemical
experiments described in the passage?
A. 1:2
B. 2:1
C. 20:1
D. 200:1 - ANS-0.150M=150mM
150/0.75= 200: 1 (D)
The reaction between NADH and ubiquinone is exergonic, but the reaction, when
catalyzed by Na+-NQR, does not generate much heat in vivo. What factor accounts for
this difference?
The reaction catalyzed by Na+-NQR in vivo:
A. is more exothermic as a result of the lower activation energy.
B. occurs sequentially in several small steps.
, C. maintains a large separation between the reacting centers.
D. is coupled to the movement of a charged particle against a concentration gradient. -
ANS-Solution: The correct answer is D.
A. This is impossible. Even if it were true, this would make the heat generation larger,
not smaller, for the catalyzed reaction. Catalysis does not change thermodynamics.
B. By Hess's Law, the heat of reaction will sum and be the same. The fact that the
reaction can be broken down into steps will not change the overall thermodynamics.
C. This is also impossible. The reactants ultimately must be close together to react.
D. The movement of a charged particle against its concentration gradient is
energetically costly. Coupling the two processes: the redox reaction between NADH and
ubiquinone and the movement of Na+ up a concentration gradient makes the overall
process less exothermic.
Two open flasks I and II contain different volumes of the same liquid. Suppose that the
pressure is measured at a point 10 cm below the surface of the liquid in each container.
How will the pressures compare?
A. The pressures will be equal.
B. Pressure in flask I will be less.
C. Pressure in flask II will be less.
D. The pressures cannot be compared from the information given. - ANS-Solution: The
correct answer is A.
A. The pressure at a point 10 cm below the surface of the liquid is the same in both
flasks because the pressure is equal to the liquid density multiplied by the gravitational
acceleration multiplied by 10 cm.
B. The pressure at a point 10 cm below the surface of the liquid in flask I is the same as
the pressure in flask II at 10 cm below the surface because the pressure is equal to the
liquid density multiplied by the gravitational acceleration multiplied by 10 cm.
C. The pressure at a point 10 cm below the surface of the liquid in flask II is the same
as the pressure in flask I at 10 cm below the surface because the pressure is equal to
the liquid density multiplied by the gravitational acceleration multiplied by 10 cm.
D. The pressures can be compared because both pressures are calculated according to
the hydrostatic pressure formula p = ρgd, where ρ is the liquid density, g is the
gravitational acceleration, and d is the depth where pressure is measured.
What is the identity of an atom that contains six protons and eight neutrons?
A. Nitrogen
B. Carbon
C. Oxygen
D. Silicon - ANS-Solution: The correct answer is B.
A. The atom cannot be nitrogen because nitrogen contains seven protons.
What quantity of Compound 1 (483.5g) must be provided to prepare 100.00 mL of
solution with a concentration equal to Ki (60.3uM)? - ANS-M=mol/v
1 umol=0.000001 moles (1x10^-6)
2.92mg
If only [I] is increased, then [ESI] or [EI] increases. This is an example of:
A. the Bose-Einstein Principle.
B. the Heisenberg Uncertainty Principle.
C. the Le Châtelier's Principle.
D. the Pauli Exclusion Principle. - ANS-Solution: The correct answer is C.
A. The Bose-Einstein Principle states that a collection of atoms cooled close to absolute
zero will coalesce into a single quantum state.
B. The Heisenberg Uncertainty Principle states that one cannot know both the
momentum and position of an object with absolute certainty.
C. Le Châtelier's Principle states that in a reversible process, the application of stress to
the system will cause the system to respond in a way that will relieve this stress. In this
case, the reversible process is E + I forming EI or ES + I forming ESI. In either case,
increasing [I] induces stress of the system, and the system relieves that stress by
converting I to either more EI or ESI.
D. The Pauli Exclusion Principle states that two or more identical fermions, e.g.
electrons, cannot occupy the same quantum state.
Which structural change to Compound 1 would make it more water soluble?
A. Replacing benzene CH with N in the ring
B. Replacing C=O with C=CH2
C. Replacing N-N=N with CH-CH=CH
D. Replacing NH with NCH3 - ANS-Solution: The correct answer is A.
A. Nitrogen in the benzene ring would have a lone pair that could accept a hydrogen
bond from water, thus increasing the solubility of the compound.
B. Replacing C=O with C=CH2 would decrease the polarity of the compound and make
it less water soluble.
C. Replacing N−N=N with CH−CH=CH would decrease the polarity of the compound
and make it less water soluble.
D. Replacing NH with NCH3 removes a hydrogen bond donor, thus decreasing water
solubility.
,In μM•s-1 and μM, what should the approximate values of kcat/KM and Ki be,
respectively, when [I] = 180 μM? - ANS-Neither is affected by a change in I, therefore
they will stay the same (150 and 60.3). Ki is the equilibrium constant and is never
affected by increasing I.
What functional group transformation occurs in the product of the reaction catalyzed by
Na+-NQR (NADH and ubiquinone)?
A. RC(=O)R → RCH(OH)R
B. ROPO32- → ROH + Pi
C. RC(=O)NHR'→ RCOOH + R'NH2
D. RC(=O)OR'→ RCOOH + R'OH - ANS-Solution: The correct answer is A.
A. This is two-electron reduction of a ketone to an alcohol, which is the reaction
catalyzed by Na+-NQR.
A. This is the reaction catalyzed by a phosphatase.
A. This is the reaction catalyzed by a protease or amidase.
A. This is the reaction catalyzed by an esterase.
What is the chemical structure of a component found in four of the five cofactors
(flavins) used by Na+-NQR? - ANS-Solution: The correct answer is B.
A. This is the structure of adenine. It is only found in FAD.
B. This is the structure of flavin, found in four of the five cofactors used by Na+-NQR.
C. This is the structure of ubiquinone. It is a substrate, but not a cofactor.
D. This is the structure of histidine. It is an amino acid, not a cofactor.
What is the ratio of cation (0.150M) to enzyme (0.75mM) in the spectroelectrochemical
experiments described in the passage?
A. 1:2
B. 2:1
C. 20:1
D. 200:1 - ANS-0.150M=150mM
150/0.75= 200: 1 (D)
The reaction between NADH and ubiquinone is exergonic, but the reaction, when
catalyzed by Na+-NQR, does not generate much heat in vivo. What factor accounts for
this difference?
The reaction catalyzed by Na+-NQR in vivo:
A. is more exothermic as a result of the lower activation energy.
B. occurs sequentially in several small steps.
, C. maintains a large separation between the reacting centers.
D. is coupled to the movement of a charged particle against a concentration gradient. -
ANS-Solution: The correct answer is D.
A. This is impossible. Even if it were true, this would make the heat generation larger,
not smaller, for the catalyzed reaction. Catalysis does not change thermodynamics.
B. By Hess's Law, the heat of reaction will sum and be the same. The fact that the
reaction can be broken down into steps will not change the overall thermodynamics.
C. This is also impossible. The reactants ultimately must be close together to react.
D. The movement of a charged particle against its concentration gradient is
energetically costly. Coupling the two processes: the redox reaction between NADH and
ubiquinone and the movement of Na+ up a concentration gradient makes the overall
process less exothermic.
Two open flasks I and II contain different volumes of the same liquid. Suppose that the
pressure is measured at a point 10 cm below the surface of the liquid in each container.
How will the pressures compare?
A. The pressures will be equal.
B. Pressure in flask I will be less.
C. Pressure in flask II will be less.
D. The pressures cannot be compared from the information given. - ANS-Solution: The
correct answer is A.
A. The pressure at a point 10 cm below the surface of the liquid is the same in both
flasks because the pressure is equal to the liquid density multiplied by the gravitational
acceleration multiplied by 10 cm.
B. The pressure at a point 10 cm below the surface of the liquid in flask I is the same as
the pressure in flask II at 10 cm below the surface because the pressure is equal to the
liquid density multiplied by the gravitational acceleration multiplied by 10 cm.
C. The pressure at a point 10 cm below the surface of the liquid in flask II is the same
as the pressure in flask I at 10 cm below the surface because the pressure is equal to
the liquid density multiplied by the gravitational acceleration multiplied by 10 cm.
D. The pressures can be compared because both pressures are calculated according to
the hydrostatic pressure formula p = ρgd, where ρ is the liquid density, g is the
gravitational acceleration, and d is the depth where pressure is measured.
What is the identity of an atom that contains six protons and eight neutrons?
A. Nitrogen
B. Carbon
C. Oxygen
D. Silicon - ANS-Solution: The correct answer is B.
A. The atom cannot be nitrogen because nitrogen contains seven protons.
