AAMC MCAT Practice Final Exam 1: Chemistry and Physics Questions and Answers, Exams of Biology

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AAMC MCAT Practice Final Exam 1

With 256 Quiz Questions

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 reaction has a carbocation intermediate. D) The reaction is stereospecific. - ✔ ✔ 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. In addition to glucose, what other monosaccharide is part of the UDP- glucose structure?

A) Xylose B) Fructose C) Ribose

D) Arabinose - ✔ ✔ C) Ribose

The answer is C because UDP contains uridine, which is a nucleic acid used in RNA. The structure of RNA contains ribose. Addition of laforin to the reaction mixtures used to generate the data in Figure 2 will result in:

"LBs contain a much larger amount of covalently-linked phosphate compared to normal glycogen."

A) a decrease in the intensity of the band representing WT without glucosidase when visualized with 14C decay. B) an increase in the intensity of the band representing WT without glucosidase when visualized with 14C decay. C) a decrease in the intensity of the band representing WT without glucosidase when visualized with 32P decay. D) an increase in the intensity of the band representing WT without glucosidase when visualized with 32P decay. - ✔ ✔ C) a decrease in the intensity of the band representing WT without glucosidase when visualized with 32P decay.

The answer is C because laforin is an enzyme that removes phosphate from glycogen. Presumably, the removal of phosphate prior to gel

"Lafora disease is a fatal progressive epilepsy that is characterized by the formation of deposits of sparsely branched, insoluble glycogen-like polymers called Lafora bodies"

A) Phosphomonoester B) Phosphodiester C) a-1,4-glycosidic bond D) a-1,6-glycosidic bond - ✔ ✔ D) a-1,6-glycosidic bond

The answer D because it is stated in the passage that the lack of branching is a characteristic of Lafora bodies. Branching occurs through an α-1,6-glycosidic bond in glycogen. Each of the following equations shows the dissociation of an acid in water. Which of the reactions occurs to the LEAST extent?

A) HCl + H2O → H3O+ + Cl− B) HPO42− + H2O → H3O+ + PO43− C) H2SO4 + H2O → H3O+ + HSO4− D) H3PO4 + H2O → H3O+ + H2PO4− - ✔ ✔ B) HPO42− + H2O → H3O+ + PO43−

The answer to this question is B. HPO42− has a high negative charge and so dissociation of it will occur to the least extent. Gamma decay occurs when a nucleus emits: A) a photon B) a proton C) a neutron D) an electron - ✔ ✔ A) a photon

The answer to this question is A because, by definition, gamma decay means the emission of photons by the nucleus. 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 - ✔ ✔ 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.

D) Bromo-2-mehtylbutane - ✔ ✔ 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 intermolecular 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* - ✔ ✔ R = 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 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. - ✔ ✔ D) Replace the hydroxyl oxygen of ethanol with O-18.

The answer to this question is D because 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 - ✔ ✔ C) 51 D

The answer 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 reactions? 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.

C) is constant D) is zero - ✔ ✔ B) increases

V = IR

The answer to this question is B because according to Ohm's law, current is equal to voltage divided by resistance. If current increases and resistance is constant, then voltage increases as well. Knowing that the speed of light in the vitreous humor is 2.1 × 108 m/s, what is the index of refraction of the vitreous humor? (Note: The speed of light in a vacuum is 3.0 × 108 m/s.) A) 0. B) 1. C) 2. D) 3.0 - ✔ ✔ B) 1.

n = c/v

The answer to this question is B because the index of refraction of a medium is equal to the ratio of the speed of light in vacuum to the speed of light in the medium, thus it is equal to (3.0 x 108 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 - ✔ ✔ D) number of photons emitted

The answer to this question is D because the energy of electromagnetic radiation is directly proportional to the number of photons, and the intensity of electromagnetic radiation is defined as energy emitted per unit time. Thus, intensity is directly proportional to the number of photons emitted. What is the energy of the photons emitted by the LED at a frequency of 610 THz? (Note: h = 6.6 × 10-34 J·s)

A) 9.2 × 10-12 J B) 1.6 × 10-16 J C) 1.1 × 10-18 J D) 4.0 × 10-19 J - ✔ ✔ D) 4.0 × 10-19 J

"The location of internal organs where changes in the calcium content occur can be found by placing positron-emitting isotopes such as O- (with a half-life = 2 min) into the patient's bloodstream)

A) 1/ B) 9/ C) 3/ D) 31/32 - ✔ ✔ D) 31/

The answer to this question is D because the half-life of 15O is 2 minutes; thus, 10 minutes = 5 half-lives. Therefore, only (1/2)5 = 1/ of the sample will be left after 10 minutes, while 31/32 of the sample will decay. Compared to micellular Compound 1, Compound 2 is structurally more rigid as a result of what type of interaction?

A) Intermolecular hydrogen bonding B) Intermolecular covalent bonding C) Intramolecular hydrogen bonding D) Intramolecular covalent bonding - ✔ ✔ B) Intermolecular covalent bonding

The answer to this question is B. It can be reasoned that the interaction described is intermolecular in nature, since multiple molecules of micellular Compound 1 come together to form Compound 2, which is a solid. Multiple pieces of information point to the fact that the interaction is disulfide bond formation, including the fact that an oxidant causes the formation of Compound 2, which can be reversed by the addition of a reducing agent. Which amino acid residues were incorporated into Compound 1 to promote the adhesion of cells on the scaffold surfaces? A) Arg and Gly B) Cys and Gly C) Cys and Asp D) Asp and Arg - ✔ ✔ D) Asp and Arg

The answer to this question is D. The residues that were engineered into the peptide for cell adhesion are arginine and aspartate as can be reasoned based on the structure of the peptide provided, and the description of the roles of the various residues provided in the passage. Which amino acid was incorporated into Compound 1 as a future site of covalent attachment to HA prior to mineralization? A) Ser B) Ala C) Tyr

B) Capillaries have less resistance to blood flow than arteries. C) The total cross-sectional area of capillaries exceeds that of arteries. D) Blood pressure is higher in the capillaries than in arteries. - ✔ ✔ C) The total cross-sectional area of capillaries exceeds that of arteries.

A1v1 = A2v

The answer to this question is C because the high number of capillaries in the body means that the total cross-sectional area of these vessels is larger than any other vessel type in the circulatory system. This causes the velocity of the blood to decrease. Which of the following types of orbitals of the central atom is involved in bonding in octahedral compounds? A) sp B) sp C) p D) d2 sp3 - ✔ ✔ D) d2 sp

The answer to this question is D because octahedral compounds have six σ bonds and no lone pairs. According to valence bond theory, the central atom requires the hybridization of six atomic orbitals, d2sp3.

The term "ideal gas" refers to a gas for which certain assumptions have been made. Which of the following is such an assumption?

A) The law PV = nRT^2 is strictly obeyed. B) Intermolecular forces are infinitely large. C) Individual molecular volume and intermolecular forces are negligible. D) One gram-mole occupies a volume of 22.4 L at 25 degrees C and one atmosphere pressure. - ✔ ✔ C) Individual molecular volume and intermolecular forces are negligible.

The answer to this question is C since a property of an "ideal" gas is that it is composed of particles that have negligible volume and do not exert intermolecular forces. The production of a variety of opsins functions to:

"Additional opsin based receptors are expressed in specialized cone cells"

A) increase sensitivity to low light B) enable the detection of different colors C) ensure fast recovery of 11-cis retinal after exposure

"Wild-type or variant rhodopsin was reconstituted with 11-cis-retinal and phosphorylated by rhodopsin kinase in the presence of ATP before examining arrestin binding"

A) arrestin B) rhodopsin kinase C) ATP D) all-trans-retinol - ✔ ✔ C) ATP

The answer is C because the requirement of ATP for kinase activity implies the phosphate groups come from ATP. What are the hybridization states of the carbon atoms involved in the conversion of trans to cis retinal? A) sp B) sp C) sp D) sp3d - ✔ ✔ B) sp

he answer to this question is B because the reacting carbon atoms are both central to AX3 systems with 3 bonded atoms and no lone pairs. The preferred geometry for such a system is trigonal planar and the hybridization scheme that facilitates this geometry is sp2.

Which reaction is catalyzed by LipA?

A) ATP hydrolysis B) Peptide bond cleavage C) Hydrolysis of triacylglycerides D) Transfer of carboxyl groups - ✔ ✔ C) Hydrolysis of triacylglycerides

The answer is C because the fact that LipA is a lipase, which means it must hydrolyze fatty acids. Compared to the wild-type LipA, what is the change in net charge in variant XI at pH 7?

R33G K112D M134D Y139C I157M

A) + B) +