AAMC MCAT
In the chromatography of the reaction mixture, water absorbed on cellulose
functioned
as the stationary phase. What was the principal factor determining the
migration of
individual components in the
sample?
A) Hydrogen
bonding
B) Solute
concentration
C) Stationary phase
concentration
D) Thickness of paper correct answersA) Hydrogen
bonding
The answer to this question is A because the relative amount of hydrogen
bonding
the to
stationary phase will determine the relative rate of migration of
the various
components in the
sample.
What assumption is being made if scientists conclude that aspartic acid was
formed
the by
prebiological synthesis in the
passage?
A) Aspartic acid is unstable at temperatures below 150
degrees
B) C. malic acid underwent the dehydration reaction to form
All of the
fumaric/maleic
C) Compound Aacid. and cyanide were available on
primitive
D) Earth. between ammonia and fumaric acid was catalyzed by the
The reaction
presence
water. of answersC) Compound A and cyanide were available on
correct
primitive Earth.
he answer to this question is C since, in order for the experimental reaction
sequence
be relevanttoto the primordial formation of aspartic acid, the starting
materials used
(Compound A and cyanide) are assumed to have been
available.
According to the developed chromatography plate shown below,
what is the Rf value of aspartic
approximate
acid?
aspartic acid =
2 solvent front
= 10
A)
B)
0.20
0.50
C)
5
D) 10 correct answersThe answer to this question is A (0.20) because Rf is
ratio of travelled by the analyte relative to the solvent
the distance
front during a
chromatographic separation. Aspartic acid travelled two units, while the
solvent front
travelled ten units, giving an Rf of 2/10 = 0.20 for
aspartic acid.
,Which of the following statements does NOT correctly describe the
dehydration
acid of malic
to fumaric acid and maleic
acid?
A) The reaction occurs most readily with tertiary
alcohols.
B) The reaction involves the loss of a water
molecule.
C) The reaction has a carbocation
intermediate.
D) The reaction is stereospecific. correct answersD) The reaction is
stereospecific.
The answer to this question is D because the fact that both fumaric and
maleic acid
produced are that the dehydration of malic acid is NOT
means
stereospecific.
What type of functional group is formed when aspartic acid reacts with
another
acid amino
to form a peptide
bond?
A) An amine
group
B) An aldehyde
group
C) An amide
group
D) A carboxyl group correct answersC) An amide
group
The answer to this question is C because the functional group that forms
duringformation
bond peptide is known as an amide
group.
If 2-pentanol replaces 1-pentanol in the reaction shown in Figure 3 (SN2),
the rate of is less
substitution
because:
A) the C-O bond in 2-pentanol is stronger than the C-O bond in 1-
pentanol.
B) there is a competing elimination reaction that slows the rate of
substitution.
C) there is more steric hindrance at the oxygen atom in 2-pentanol than in
1-pentanol,
making protonation less
likely.
D) there is more steric hindrance at the 2-position of 2-pentanol than at the
1-position ofcorrect answersD) there is more steric hindrance at the 2-
1-pentanol.
position of
pentanol than
2- at the 1-position of 1-
pentanol.
The answer to this question is D because the rate of substitution of
protonated
is subject toalcohols
steric hindrance. This inhibits the ability of nucleophiles to
collide with
reacting the
electrophilic center and slows the rate of
reaction.
If a solution containing the compounds shown in Figure 4, is injected into a
gas-liquid
chromatograph, the first peak observed in the gc trace is
attributable to which
compound
?
A) Methyl-2-
butanol
B) Methyl-2-
butene
C) Chloro-2-
methylbutane
D) Bromo-2-mehtylbutane correct answersB) Methyl-2-
butene
The answer to this question is B because 2-methyl-2-butene will exhibit
the lowest weight and also the weakest intermolecular forces of
molecular
attraction. This
,substance will therefore migrate the fastest and be the first peak
in the gas
chromatograph (gc)
trace.
R vs. S stereochemistry* correct answersR =
clockwise
C = counter-
clockwise
Acetic acid and ethanol react to form an ester product as
shown below.
In determining which reactant loses the -OH group, which of the
following isotopic
substitutions would be most
useful?
A) Replace the acidic H of acetic acid
with
B) D
Replace the alcoholic H of ethanol
with
C) D.
Replace the carbonyl oxygen of acetic acid
with
D) O-18. the hydroxyl oxygen of ethanol with O-18. correct answersD)
Replace
Replace the
hydroxyl oxygen of ethanol with
O-18.
The answer to this question is D because this experiment involves
labeling
which a group
does not exchange with other groups present prior to reaction and
will therefore
give information about the true identity of the groups, which are
exchanged during the
reactio
n.
A person whose eye has a lens-to-retina distance of 2.0 cm, can only
clearly see
objects that are closer than 1.0 m away. What is the strength S of the
person's
lens? eyeUse the thin lens formula 1/O +
(Note:
1/I = S)
A) -50
D
C) 51
B) -10
D) D55 D correct answersC)
51 D
The answer to this question is C because the strength of the eye lens is
equal toofthe
inverse the focal length of the eye lens. Its numerical value is given by (1
m)-1+(0.02
m)-1=1 D+50
D=51 D.
Which statement correctly describes how enzymes affect chemical
Stabilization
reactions?
of:
A) the substrate changes the free energy of the
reaction.
B) the transition state changes the free energy of the
reaction.
C) the substrate changes the activation energy of the
reaction.
D) the transition state changes the activation energy of the reaction. correct
answersD)
the transition state changes the activation energy of the
reaction.
The answer is D because the stabilization of the transition state, not the
substrate,
provides binding energy that is used to lower the
activation energy.
, Which of the following will decrease the percentage ionization of 1.0 M
acetic acid,
CH3CO2H(aq)?
*
A) Chlorinating the CH3
group
B) Diluting the
solution
C) Adding concentrated HCl
(aq)
D) Adding a drop of basic indicator correct answersC) Adding
concentrated HCl (aq)
The answer to this question is C because HCl is a strong acid that will
increaseof
amount theH+ in solution and thus decrease the percentage of CH3CO2H
that ionizes.
When the current in the micro-robot's circuit increases and the resistance
of the circuit
remains constant, the voltage of the
circuit:
A)
decreases
B)
increases
C) is t
constan
D) is zero correct answersB)
increases
V=
IR
The answer to this question is B because according to Ohm's law, current
is equal divided
voltage to by resistance. If current increases and resistance is
constant,
voltage then
increases as
well.
Knowing that the speed of light in the vitreous humor is 2.1 × 108 m/s, what
is the
of index of the vitreous humor? (Note: The speed of light in a vacuum
refraction
is
m/ 3.0 × 108
s.)
A)
0.7
B)
1.4
C)
2.1
D) 3.0 correct answersB)
1.4
n=
c/v
The answer to this question is B because the index of refraction of a medium
is equal
the ratiotoof the speed of light in vacuum to the speed of light in the
medium,
equal thusxit108
to (3.0 is m/s)/(2.1 x 108 m/s)
= 1.4.
The intensity of the radiation emitted by the oxygen sensor is directly
proportional to the:
A) propagation speed of the
radiation
B) wavelength of the
radiation
C) polarization of photons
emitted
D) number of photons emitted correct answersD) number of
photons emitted
In the chromatography of the reaction mixture, water absorbed on cellulose
functioned
as the stationary phase. What was the principal factor determining the
migration of
individual components in the
sample?
A) Hydrogen
bonding
B) Solute
concentration
C) Stationary phase
concentration
D) Thickness of paper correct answersA) Hydrogen
bonding
The answer to this question is A because the relative amount of hydrogen
bonding
the to
stationary phase will determine the relative rate of migration of
the various
components in the
sample.
What assumption is being made if scientists conclude that aspartic acid was
formed
the by
prebiological synthesis in the
passage?
A) Aspartic acid is unstable at temperatures below 150
degrees
B) C. malic acid underwent the dehydration reaction to form
All of the
fumaric/maleic
C) Compound Aacid. and cyanide were available on
primitive
D) Earth. between ammonia and fumaric acid was catalyzed by the
The reaction
presence
water. of answersC) Compound A and cyanide were available on
correct
primitive Earth.
he answer to this question is C since, in order for the experimental reaction
sequence
be relevanttoto the primordial formation of aspartic acid, the starting
materials used
(Compound A and cyanide) are assumed to have been
available.
According to the developed chromatography plate shown below,
what is the Rf value of aspartic
approximate
acid?
aspartic acid =
2 solvent front
= 10
A)
B)
0.20
0.50
C)
5
D) 10 correct answersThe answer to this question is A (0.20) because Rf is
ratio of travelled by the analyte relative to the solvent
the distance
front during a
chromatographic separation. Aspartic acid travelled two units, while the
solvent front
travelled ten units, giving an Rf of 2/10 = 0.20 for
aspartic acid.
,Which of the following statements does NOT correctly describe the
dehydration
acid of malic
to fumaric acid and maleic
acid?
A) The reaction occurs most readily with tertiary
alcohols.
B) The reaction involves the loss of a water
molecule.
C) The reaction has a carbocation
intermediate.
D) The reaction is stereospecific. correct answersD) The reaction is
stereospecific.
The answer to this question is D because the fact that both fumaric and
maleic acid
produced are that the dehydration of malic acid is NOT
means
stereospecific.
What type of functional group is formed when aspartic acid reacts with
another
acid amino
to form a peptide
bond?
A) An amine
group
B) An aldehyde
group
C) An amide
group
D) A carboxyl group correct answersC) An amide
group
The answer to this question is C because the functional group that forms
duringformation
bond peptide is known as an amide
group.
If 2-pentanol replaces 1-pentanol in the reaction shown in Figure 3 (SN2),
the rate of is less
substitution
because:
A) the C-O bond in 2-pentanol is stronger than the C-O bond in 1-
pentanol.
B) there is a competing elimination reaction that slows the rate of
substitution.
C) there is more steric hindrance at the oxygen atom in 2-pentanol than in
1-pentanol,
making protonation less
likely.
D) there is more steric hindrance at the 2-position of 2-pentanol than at the
1-position ofcorrect answersD) there is more steric hindrance at the 2-
1-pentanol.
position of
pentanol than
2- at the 1-position of 1-
pentanol.
The answer to this question is D because the rate of substitution of
protonated
is subject toalcohols
steric hindrance. This inhibits the ability of nucleophiles to
collide with
reacting the
electrophilic center and slows the rate of
reaction.
If a solution containing the compounds shown in Figure 4, is injected into a
gas-liquid
chromatograph, the first peak observed in the gc trace is
attributable to which
compound
?
A) Methyl-2-
butanol
B) Methyl-2-
butene
C) Chloro-2-
methylbutane
D) Bromo-2-mehtylbutane correct answersB) Methyl-2-
butene
The answer to this question is B because 2-methyl-2-butene will exhibit
the lowest weight and also the weakest intermolecular forces of
molecular
attraction. This
,substance will therefore migrate the fastest and be the first peak
in the gas
chromatograph (gc)
trace.
R vs. S stereochemistry* correct answersR =
clockwise
C = counter-
clockwise
Acetic acid and ethanol react to form an ester product as
shown below.
In determining which reactant loses the -OH group, which of the
following isotopic
substitutions would be most
useful?
A) Replace the acidic H of acetic acid
with
B) D
Replace the alcoholic H of ethanol
with
C) D.
Replace the carbonyl oxygen of acetic acid
with
D) O-18. the hydroxyl oxygen of ethanol with O-18. correct answersD)
Replace
Replace the
hydroxyl oxygen of ethanol with
O-18.
The answer to this question is D because this experiment involves
labeling
which a group
does not exchange with other groups present prior to reaction and
will therefore
give information about the true identity of the groups, which are
exchanged during the
reactio
n.
A person whose eye has a lens-to-retina distance of 2.0 cm, can only
clearly see
objects that are closer than 1.0 m away. What is the strength S of the
person's
lens? eyeUse the thin lens formula 1/O +
(Note:
1/I = S)
A) -50
D
C) 51
B) -10
D) D55 D correct answersC)
51 D
The answer to this question is C because the strength of the eye lens is
equal toofthe
inverse the focal length of the eye lens. Its numerical value is given by (1
m)-1+(0.02
m)-1=1 D+50
D=51 D.
Which statement correctly describes how enzymes affect chemical
Stabilization
reactions?
of:
A) the substrate changes the free energy of the
reaction.
B) the transition state changes the free energy of the
reaction.
C) the substrate changes the activation energy of the
reaction.
D) the transition state changes the activation energy of the reaction. correct
answersD)
the transition state changes the activation energy of the
reaction.
The answer is D because the stabilization of the transition state, not the
substrate,
provides binding energy that is used to lower the
activation energy.
, Which of the following will decrease the percentage ionization of 1.0 M
acetic acid,
CH3CO2H(aq)?
*
A) Chlorinating the CH3
group
B) Diluting the
solution
C) Adding concentrated HCl
(aq)
D) Adding a drop of basic indicator correct answersC) Adding
concentrated HCl (aq)
The answer to this question is C because HCl is a strong acid that will
increaseof
amount theH+ in solution and thus decrease the percentage of CH3CO2H
that ionizes.
When the current in the micro-robot's circuit increases and the resistance
of the circuit
remains constant, the voltage of the
circuit:
A)
decreases
B)
increases
C) is t
constan
D) is zero correct answersB)
increases
V=
IR
The answer to this question is B because according to Ohm's law, current
is equal divided
voltage to by resistance. If current increases and resistance is
constant,
voltage then
increases as
well.
Knowing that the speed of light in the vitreous humor is 2.1 × 108 m/s, what
is the
of index of the vitreous humor? (Note: The speed of light in a vacuum
refraction
is
m/ 3.0 × 108
s.)
A)
0.7
B)
1.4
C)
2.1
D) 3.0 correct answersB)
1.4
n=
c/v
The answer to this question is B because the index of refraction of a medium
is equal
the ratiotoof the speed of light in vacuum to the speed of light in the
medium,
equal thusxit108
to (3.0 is m/s)/(2.1 x 108 m/s)
= 1.4.
The intensity of the radiation emitted by the oxygen sensor is directly
proportional to the:
A) propagation speed of the
radiation
B) wavelength of the
radiation
C) polarization of photons
emitted
D) number of photons emitted correct answersD) number of
photons emitted
