AAMC MCAT Practice Exam 1 Questions and Answers 2024
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AAMC FL
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AAMC FL
AAMC MCAT Practice Exam 1 Questions and Answers 2024
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 conc...
AAMC MCAT Practice Exam 1 Questions and Answers 2024 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 -Answer -A) Hydrogen bonding The answer to this question is A because the relative amount of hydrogen bonding to the stationary phase will determine the relative rate of migra tion of the various components in the sample. What assumption is being made if scientists conclude that aspartic acid was formed by the prebiological synthesis in the passage? A) Aspartic acid is unstable at temperatures below 150 degrees C. B) All of th e malic acid underwent the dehydration reaction to form fumaric/maleic acid. C) Compound A and cyanide were available on primitive Earth. D) The reaction between ammonia and fumaric acid was catalyzed by the presence of water. -
Answer -C) Compound A and c yanide were available on primitive Earth. he answer to this question is C since, in order for the experimental reaction sequence to be relevant to 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 approximate Rf value of aspartic acid? aspartic acid = 2 solvent front = 10 A) 0.20 B) 0.50 C) 5 D) 10 -Answer -The answer to this question is A (0.20) beca use Rf is the ratio of the distance travelled by the analyte relative to the solvent 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 of malic acid 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 reacti on has a carbocation intermediate. D) The reaction is stereospecific. -Answer -D) The reaction is stereospecific. The answer to this question is D because the fact that both fumaric and maleic acid are produced means that the dehydration of malic acid is NOT stereospecific. What type of functional group is formed when aspartic acid reacts with another amino acid to form a peptide bond? A) An amine group B) An aldehyde group C) An amide group D) A carboxyl group -Answer -C) An amide group The answer to this question is C because the functional group that forms during peptide bond formation is known as an amide group. If 2-pentanol replaces 1 -pentanol in the reaction shown in Figure 3 (SN2), the rate of substitution is less 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 ra te 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 of 1 -
pentanol. -Answer -D) th ere is more steric hindrance at the 2 -position of 2 -pentanol than at the 1 -
position of 1 -pentanol. The answer to this question is D because the rate of substitution of protonated alcohols is subject to steric hindrance. This inhibits the ability of nucleo philes to collide with the reacting 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 -Answer -B) Methyl -2-butene The answer to this question is B because 2 -methyl -2-butene will exhibit the lowest molecular weight and also the weakest intermol ecular forces of attraction. This substance will therefore migrate the fastest and be the first peak in the gas chromatograph (gc) trace. R vs. S stereochemistry* -Answer -R = clockwise C = counter -clockwise Acetic acid and ethanol react to form an ester pr oduct 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 D B) Replace the alcoholic H of ethanol with D. C) Replace the carbonyl oxygen of acetic acid with O -18. D) Replace the hydroxyl oxygen of ethanol with O -18. -Answer -D) Replace the hydroxyl oxygen of ethanol with O -18. The answer to this question is D bec ause this experiment involves labeling a group which 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 reaction. 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 eye lens? (Note: Use the thin lens formula 1/O + 1/I = S) A) -50 D B) -10 D C) 51 D D) 55 D -Answer -C) 51 D The answ er to this question is C because the strength of the eye lens is equal to the inverse of 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 rea ctions? Stabilization 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 activ ation energy of the reaction. -Answer -D) 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
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