MCAT Official Prep Practice Exam
1 Questions and Answers 100%
Accurate
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? - ANSWER - A. The immobilized
water molecules bind to those components in the sample mixture capable of
accepting or donating hydrogen bonds. Those components with stronger hydrogen
bonding migrated more slowly.
What assumption is being made if scientists conclude that aspartic acid was formed
by the prebiological synthesis in the passage? - ANSWER - C. Without Compound A
and cyanide, no aspartic acid can form.
What type of functional group is formed when aspartic acid reacts with another
amino acid to form a peptide bond? - ANSWER - C. The functional group that
represents a peptide bond is called an amide group.
If 2-pentanol replaces 1-pentanol in the reaction shown in Figure 3, the rate of
substitution is less because: - ANSWER - D. At a secondary carbon, there is more
crowding from the adjacent carbon chains, which makes nucleophilic substitution
slower.
If Reaction 2 (Figure 4) is repeated with HCl and the compound shown below, which
of the following compounds is NOT a direct product (without rearrangement)? -
ANSWER - A. The only way that this product can form is by rearrangement, a 1,2-
hydride shift following the initial formation of a tertiary carbocation.
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? - ANSWER - B. In gas-liquid chromatography, the first peak to emerge
will be from the least polar, most volatile compound. 2-Methyl-2-butene is nonpolar
and the most volatile because it only has London forces for intermolecular
attraction.
, What is the product of the reaction of Compound 1 (shown below) with HBr by the
pathway shown in Figure 3? - ANSWER - C. Because this is an SN2 reaction, there
will be inversion of configuration when bromide ion displaces water as a leaving
group, changing the stereochemistry from R to S.
In determining which reactant loses the -OH group, which of the following isotopic
substitutions would be most useful? - ANSWER - D. Labeling the oxygen in ethanol
with O-18 definitely determines which -OH is lost because 100% of the O-18 in
radiolabeled ethanol will be retained in the ester, not the water. Thus, only acetic
acid supplies -OH that is lost to form water.
What percentage of standard atmospheric pressure is the pulse pressure of a
healthy adult? - ANSWER - B. The pulse pressure in a healthy adult is (120 − 75)
mmHg = 45 mmHg, and so the percentage is 45 mmHg/760 mmHg = 6%.
Which amino acid was incorporated into Compound 1 as a future site of covalent
attachment to HA prior to mineralization? - ANSWER - A. Ser is the residue that was
phosphorylated at its primary alcohol side chain for future attachment of
nanocrystals of HA
The graph below shows the relationship between the predominant form of iron as a
function of solution pH and applied potential. Based on the graph, which of the
following statements is true? - ANSWER - B. The Pourbaix diagram for iron is given,
but only one statement correctly conveys information presented by the diagram. At
an applied potential of -0.44V and pH below 6, there is an equilibrium between Fe(s)
and Fe2+(aq), as shown by the line of demarcation. The fact that this line moves
horizontally with increasing pH up until pH = 6 means that this equilibrium is
unaffected by changing the pH.
The term "ideal gas" refers to a gas for which certain assumptions have been made.
Which of the following is such an assumption? - ANSWER - C. A property of an
"ideal" gas is that it is composed of particles that have negligible volume and do not
exert intermolecular forces.
The environment of the retinal binding site is most likely: - ANSWER - D. Retinal is
composed of mainly carbon and hydrogen, making it largely hydrophobic.
1 Questions and Answers 100%
Accurate
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? - ANSWER - A. The immobilized
water molecules bind to those components in the sample mixture capable of
accepting or donating hydrogen bonds. Those components with stronger hydrogen
bonding migrated more slowly.
What assumption is being made if scientists conclude that aspartic acid was formed
by the prebiological synthesis in the passage? - ANSWER - C. Without Compound A
and cyanide, no aspartic acid can form.
What type of functional group is formed when aspartic acid reacts with another
amino acid to form a peptide bond? - ANSWER - C. The functional group that
represents a peptide bond is called an amide group.
If 2-pentanol replaces 1-pentanol in the reaction shown in Figure 3, the rate of
substitution is less because: - ANSWER - D. At a secondary carbon, there is more
crowding from the adjacent carbon chains, which makes nucleophilic substitution
slower.
If Reaction 2 (Figure 4) is repeated with HCl and the compound shown below, which
of the following compounds is NOT a direct product (without rearrangement)? -
ANSWER - A. The only way that this product can form is by rearrangement, a 1,2-
hydride shift following the initial formation of a tertiary carbocation.
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? - ANSWER - B. In gas-liquid chromatography, the first peak to emerge
will be from the least polar, most volatile compound. 2-Methyl-2-butene is nonpolar
and the most volatile because it only has London forces for intermolecular
attraction.
, What is the product of the reaction of Compound 1 (shown below) with HBr by the
pathway shown in Figure 3? - ANSWER - C. Because this is an SN2 reaction, there
will be inversion of configuration when bromide ion displaces water as a leaving
group, changing the stereochemistry from R to S.
In determining which reactant loses the -OH group, which of the following isotopic
substitutions would be most useful? - ANSWER - D. Labeling the oxygen in ethanol
with O-18 definitely determines which -OH is lost because 100% of the O-18 in
radiolabeled ethanol will be retained in the ester, not the water. Thus, only acetic
acid supplies -OH that is lost to form water.
What percentage of standard atmospheric pressure is the pulse pressure of a
healthy adult? - ANSWER - B. The pulse pressure in a healthy adult is (120 − 75)
mmHg = 45 mmHg, and so the percentage is 45 mmHg/760 mmHg = 6%.
Which amino acid was incorporated into Compound 1 as a future site of covalent
attachment to HA prior to mineralization? - ANSWER - A. Ser is the residue that was
phosphorylated at its primary alcohol side chain for future attachment of
nanocrystals of HA
The graph below shows the relationship between the predominant form of iron as a
function of solution pH and applied potential. Based on the graph, which of the
following statements is true? - ANSWER - B. The Pourbaix diagram for iron is given,
but only one statement correctly conveys information presented by the diagram. At
an applied potential of -0.44V and pH below 6, there is an equilibrium between Fe(s)
and Fe2+(aq), as shown by the line of demarcation. The fact that this line moves
horizontally with increasing pH up until pH = 6 means that this equilibrium is
unaffected by changing the pH.
The term "ideal gas" refers to a gas for which certain assumptions have been made.
Which of the following is such an assumption? - ANSWER - C. A property of an
"ideal" gas is that it is composed of particles that have negligible volume and do not
exert intermolecular forces.
The environment of the retinal binding site is most likely: - ANSWER - D. Retinal is
composed of mainly carbon and hydrogen, making it largely hydrophobic.
