Printing Guide Use this printing guide as a reference to print selected sections of this practice test To print, click the PRINTER icon located along the top of the window and enter one of the following options in the PRINT RANGE section of the print dialog window: To Print Enter Print Range Options Complete Practice Test Click ALL radio button Physical Sciences Section Click PAGES FROM radio button and enter pages to 25 Verbal Reasoning Section Click PAGES FROM radio button and enter pages 26 to 44 Writing Sample Section Click PAGES FROM radio button and enter pages 45 to 47 Biological Sciences Section Click PAGES FROM radio button and enter pages 48 to 75 Periodic Table Click PAGES FROM radio button and enter page to Answer Sheet Click PAGES FROM radio button and enter page 76 to 76 This document has been encoded to link this download to your member account The AAMC and its Section for the MCAT hold the copyrights to the content of this Practice Test Therefore, there can be no sharing or reproduction of materials from the Practice Test in any form (electronic, voice, or other means) If there are any questions about the use of the material in the Practice Test, please contact the MCAT Information Line (202828-0690) MCAT Practice Test 4R Physical Sciences Time: 100 minutes Questions: 1-77 Most questions in the Physical Sciences test are organized into groups, each containing a descriptive passage After studying the passage, select the one best answer to each question in the group Some questions are not based on a descriptive passage and are also independent of each other If you are not certain of an answer, eliminate the alternatives that you know to be incorrect and then select an answer from the remaining alternatives Indicate your selected answer by marking the corresponding answer on your answer sheet A periodic table is provided for your use You may consult it whenever you wish This document has been encoded to link this download to your member account The AAMC and its Section for the MCAT hold the copyrights to the content of this Practice Test Therefore, there can be no sharing or reproduction of materials from the Practice Test in any form (electronic, voice, or other means) If there are any questions about the use of the material in the Practice Test, please contact the MCAT Information Line (202828-0690) Periodic Table of the Elements H He 4.0 10 1.0 Li Be B C N O F Ne 6.9 9.0 10.8 12.0 14.0 16.0 19.0 20.2 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar 23.0 24.3 27.0 28.1 31.0 32.1 35.5 39.9 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.1 37 40.1 38 45.0 39 47.9 40 50.9 41 52.0 42 54.9 43 55.8 44 58.9 45 58.7 46 63.5 47 65.4 48 69.7 49 72.6 50 74.9 51 79.0 52 79.9 53 83.8 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.5 55 87.6 56 88.9 57 91.2 72 92.9 73 95.9 74 (98) 75 101.1 76 102.9 77 106.4 78 107.9 79 112.4 80 114.8 81 118.7 82 121.8 83 127.6 84 126.9 85 131.3 86 Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9 87 137.3 88 138.9 89 178.5 104 180.9 105 183.9 106 186.2 107 190.2 108 192.2 109 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222) Fr Ra Ac† Unq† Unp Unh Uns Uno Une (223) (226) (227) (261) (262) 58 (263) 59 (262) 60 (265) 61 (267) 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.1 90 140.9 91 144.2 92 (145) 93 150.4 94 152.0 95 157.3 96 158.9 97 162.5 98 164.9 99 167.3 100 168.9 101 173.0 102 175.0 103 * † Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 232.0 (231) 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) Passage I Student researchers conducted an experiment to study static friction between common building materials They used a wooden board and three sets of blocks Each set included one wooden block, one stone block, and one steel block All of the blocks were of equal mass Within each set, all blocks had the same base area A block was placed at rest on the flat wooden board One end of a lightweight string was attached to the block, and the other end of the string was attached to a hook The string passed over a pulley (of negligible mass and friction) at the edge of the board Mass was added to the hook until the block began to slide along the board Table shows the threshold mass, MT, necessary to initiate sliding of each block Table Static Friction Data Block Threshold base area Block mass (m2) material (kg) 0.001 wood 0.049 Set 0.001 stone 0.068 0.001 steel 0.055 0.002 wood 0.049 Set 0.002 stone 0.068 0.002 steel 0.055 0.003 wood 0.048 Set 0.003 stone 0.068 0.003 steel 0.055 The kinetic energy of a sliding block came from the: A) kinetic energy of the string B) kinetic energy of the board C) gravitational potential energy of the block D) gravitational potential energy of the mass on the hook Based on Table 1, which of the following statements describes the relationship between static friction and base area? A) Static friction is independent of base area B) Static friction is directly proportional to base area C) Static friction is directly proportional to the square of base area D) Static friction is inversely proportional to base area Which of the following force(s) on a sliding block did work on the block? Figure Static friction apparatus A) String tension only B) Kinetic friction only C) String tension and kinetic friction D) String tension and gravity Based on Table 1, attractive molecular forces between surfaces were weakest between: A) metal surfaces B) wood surfaces C) wood and stone surfaces D) wood and steel surfaces Sharing or reproducing this material in any form is a violation of the AAMC copyright 5 If the wooden board is coated with a lubricant, MT will: A) decrease B) decrease only for the wood blocks C) increase D) not change After a block began to slide, how did its speed vary with time? (Note: Assume that the tension and kinetic friction forces on the block were constant in magnitude.) A) It was constant in time B) It increased exponentially with time C) It was first constant, then increased linearly with time D) It increased linearly with time The researchers devised a second procedure to measure static friction They removed the string from a block, placed the block at rest on a board, and raised one end of the board until the block began to slide To determine the static friction force on the block when sliding began, which of the following measurements did they make? A) Time it took for the block to slide down the board B) Distance the block slid down the board before coming to rest C) Mass of the board D) Angle of the board with respect to the horizontal Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage II Four chemicals produced in large quantities in the United States are H2SO4, NH3, N2, and O2 The latter three are gases, and H2SO4 is produced by gaseous reactions The preparation of H2SO4 involves the following Reactions (I–III) S(s) + O2(g) → SO2(g) 2SO3(g) ∆H = –197.8 kJ/mol Reaction II SO3(g) + H2O(ℓ) → H2SO4(aq) ∆H = –132.6 kJ/mol Reaction III NH3 is prepared commercially by the reaction of N2 with H2 (Reaction IV) NH3 has a tendency to form coordination compounds, such as [Co(NH3)6]Cl3, in which NH3 forms covalent bonds with a transition metal ion N2(g) + 3H2(g) A) Addition of H2 B) A decrease in pressure C) An increase in temperature D) Addition of a catalyst ∆H = –296.8 kJ/mol Reaction I 2SO2(g) + O2(g) 10 When Reaction IV is in a state of equilibrium, which of the following changes will cause more NH3 to form? 2NH3(g) Reaction IV ∆H = –92 kJ/mol 11 In the fractional distillation of air, the N2 separates before the O2 because N2: A) is less reactive than O2 B) is less electronegative than O2 C) has a triple bond and O2 has a double bond D) has a lower boiling point than O2 12 If 36 g of S and 32 g of O2 were used in Reaction I, which of the following would be the limiting reagent? A) S B) O2 C) SO2 D) There would not be a limiting reagent N2 and O2 are both prepared by the fractional distillation of air Air samples are first condensed to the liquid state and then passed through a distilling column The N2 separates first, and then the O2 is obtained The ability of NH3 to form coordination compounds with transition metal ions can best be accounted for by the fact that NH3: A) acts as an electron pair donor B) is capable of hydrogen bonding C) is a weak base in aqueous solution D) contains N with a –3 oxidation number N2 has a lower boiling point than O2 Which of the following statements best accounts for this difference? A) N2 is less reactive than is O2 B) N2 is less electronegative than is O2 C) N2 has a lower molecular weight than does O2 D) N2 contains a triple bond, and O2 contains a double bond Sharing or reproducing this material in any form is a violation of the AAMC copyright Table Constant Transmitted f and λ with Different Jet Speeds Away from Receiver Passage III The wavelength of a radio wave measured by a stationary receiver differs from the emitted wavelength when the transmitter is moving The frequency measured by the receiver also changes when the transmitter is moving Three experiments were conducted to determine relationships between the speed of a moving radio transmitter and the changes in wavelength and frequency measured at the receiver In each of the experiments, a jet flew at constant altitude and emitted a signal that was measured by a receiver on the ground Experiment The jet flew directly away from the receiver at 268 m/s Signals with different frequencies (f) and wavelengths (λ) were transmitted in four trials The transmitted frequencies and wavelengths are listed in Table along with the measured changes in frequency and wavelength Table Changing Transmitted f and λ with Constant Jet Speed Away from Receiver f (10 Hz) 1.20 1.50 2.00 3.00 Change in f (Hz) –1.07 –1.34 –1.79 –2.68 λ (m) 250 200 150 100 Change in λ (10–5m) 22 18 13 Experiment The frequency of the transmitted radio signal was kept constant at 2.0 x 106 Hz, and the transmitted wavelength was kept constant at 150 m as the jet flew directly away from the receiver at the four different speeds listed in Table Speed (m/s) 246 322 447 671 Change in f (Hz) –1.64 –2.15 –2.98 –4.47 Change in λ (10–5m) 12 16 22 34 Experiment The frequency of the radio signal was kept constant at 2.0 x 106 Hz and the wavelength was kept constant at 150 m as the jet flew directly toward the receiver with the two speeds listed in Table Table Constant Transmitted f and λ with Different Jet Speeds toward Receiver Speed (m/s) 300 490 Change in f (Hz) 2.00 3.27 Change in λ (10–5m) –15 –24 13 A stationary receiver detects a change in frequency of the signal from a jet flying directly away from it at 300 m/s Which of the following receivers will detect the same change in frequency from a jet moving away at 600 m/s? A) A receiver moving at 900 m/s in the opposite direction as the jet B) A receiver moving at 300 m/s in the opposite direction as the jet C) A stationary receiver D) A receiver moving at 300 m/s in the same direction as the jet 14 If the jet in Experiment transmits a 2.5 x 106 Hz radio wave, what will be the approximate change in frequency measured at the receiver? A) –1.2 Hz B) –1.5 Hz C) –2.2 Hz D) –3.0 Hz Sharing or reproducing this material in any form is a violation of the AAMC copyright 15 Which of the following graphs best illustrates the relationship between speed of the transmitter away from the receiver and the increase in wavelength of the received signal? 17 Why are the percentages of the change in frequency and wavelength much greater when sound waves are used instead of radio waves in these experiments? A) A) Sound waves travel more slowly B) Sound waves have a much higher frequency C) Sound waves have a much shorter wavelength D) Interference in the atmosphere affects sound waves much more B) 18 A receiver is in a jet flying alongside another jet that is emitting 2.0 x 106 Hz radio waves If the jets fly at 268 m/s, what is the change in frequency detected at the receiver? A) Hz B) 0.90 Hz C) 1.79 Hz D) 3.58 Hz C) 19 An astronomer observes a hydrogen line in the spectrum of a star The wavelength of hydrogen in the laboratory is 6.563 x 10-7m, but the wavelength in the star’s light is measured at 6.56186 x 10-7m Which of the following explains this discrepancy? D) A) The star is moving away from Earth B) The wavelength of light that the star is emitting changes constantly C) The frequency of light that the star is emitting changes constantly D) The star is approaching Earth 16 As the speed of the jet flying away from the receiver increases, what happens to the distance between adjacent peaks of the transmitted waves, as measured at the receiver? A) It decreases B) It remains constant C) It increases D) It changes, but is not dependent on the speed Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage IV Coulometric methods offer a means of monitoring gases For example, Figure shows a schematic diagram of an apparatus that can be used to determine ultrasmall concentrations of oxygen O2(g) + 2H2O + 4e- 4OH- Εo = +0.40 V Equation Ag+ + e- Ag(s) Εo = +0.80 V Equation Cd(s) + 2OH- Cd(OH)2(s) + 2e- Εo = +0.81 V Equation The current produced is measured by recording the potential drop as it passes through a standard resistor (R) The oxygen concentration is proportional to the potential The procedure is reported to be accurate over a range from ppm up to 1% of the gas stream The accuracy of the procedure depends on an adequate flow rate 20 How is the accuracy of the oxygen determination affected by the addition of a gas into the stream that is reduced by a reaction analogous to that of oxygen? A) Increased, because the smaller the amount of oxygen in the stream, the more effective is microanalysis B) Increased, because the larger the sample reduced, the less effect a small variation in measurement will have on results C) Decreased, because the partial pressure of oxygen will be decreased D) Decreased, because the method cannot distinguish oxygen from the added gas Figure Coulometric determination of oxygen concentration The oxygen is bubbled over a silver electrode where it is reduced according to the reactions represented by Equations and The electrochemical reaction is completed at the cadmium electrode The half reaction is given by Equation 21 If 10 L oxygen at 30oC and 756 mm Hg passes through the apparatus described in the passage, what is the volume at STP? A) (10)(756)(303)/(760)(273) L B) (10)(760)(303)/(756)(273) L C) (10)(756)(273)/(760)(303) L D) (10)(760)(273)/(756)(303) L Sharing or reproducing this material in any form is a violation of the AAMC copyright 10 a skeletal rearrangement, and is stereoselective in both steps Passage VI Three reactions that produce alcohols are shown below Equation shows the hydration of an alkene The reaction is regioselective, not stereoselective, and molecular rearrangements may occur Equation Equation shows an oxymercuration-demercuration reaction sequence Equation 175 Which of the following reactions could be used to prepare the alcohol from the alkene shown in the following equation? Equation An organomercurial alcohol is formed in the first step, followed by removal of the mercury by sodium borohydride Molecular rearrangements not occur in this procedure It is regioselective, and the first step is stereoselective The demercuration step is not stereoselective because the borohydride reduction proceeds through a free-radical mechanism I II III Hydration Hydroboration-oxidation Oxymercuration-demercuration A) I only B) II only C) I and III only D) II and III only Equation shows a hydroboration-oxidation reaction The overall reaction is regioselective, does not involve Sharing or reproducing this material in any form is a violation of the AAMC copyright 62 176 Which compound is the major product of the following sequence of reactions? A) B) C) D) 177 The IR spectra of the alcohols shown in Equations 1-3 all display a broad band centered near a frequency of: A) 1000 cm-1 B) 1500 cm-1 C) 2500 cm-1 D) 3500 cm-1 178 The two isomeric organomercurial alcohols in Equation are: A) constitutional isomers B) diastereomers C) enantiomers D) optical antipoles Sharing or reproducing this material in any form is a violation of the AAMC copyright 63 Passage VII Important discoveries often result from the thoughtful analysis of an incidental observation The main function of endothelial cells that line blood vessels was long thought to be exchange of nutrients and waste products between blood and interstitial fluid In 1980, two scientists noticed that vasodilation of arteries in response to acetylcholine was inhibited if the endothelial layer of the artery was accidentally damaged during experimental preparation Subsequently, the scientists compared the responses of undamaged and deliberately damaged segments of arteries to various signals and showed that endothelial cells release a substance that causes the adjacent arterial smooth muscle to relax, allowing an increase in blood flow Figure shows the results of their initial experiment, in which two rings cut from rabbit aorta were studied in separate saline baths One ring was undamaged, but the endothelium of the other ring had been scraped off Both rings were first contracted by adding norepinephrine to the baths Subsequently, the relaxation of the intact and scraped rings in response to different concentrations of acetylcholine was compared Figure Effect of acetylcholine on tension in rabbit aorta with and without endothelium NE = norepinephrine added; ACH = acetylcholine; at washout, NE and ACH are removed The relaxing substance was found to be nitric oxide (NO), which is derived from the amino acid L-arginine To study the physiological role of NO, competitive inhibitors of the enzyme responsible for NO synthesis (NO synthase) were developed; L-NMMA is one such inhibitor Thus, a serendipitous observation led to the discovery of a new function of vascular endothelium, the regulation of blood flow Sharing or reproducing this material in any form is a violation of the AAMC copyright 64 179 In Figure 1, which of the following observations led to the conclusion that intact endothelium is necessary for the relaxation of smooth muscle when acetylcholine (ACH) is applied? A) The tension initially changes when norepinephrine (NE) is added B) The tension decrease occurs more quickly in the ring without endothelium C) The tension decreases upon addition of 10-7MACH, only in the ring with endothelium D) The tension decreases during washout in the ring without endothelium 180 From the data in Figure 1, one can conclude that the sensitivity of aortic smooth muscle to acetylcholine is: A) decreased by the presence of norepinephrine B) increased by the presence of norepinephrine C) increased at least 10 times by the presence of the endothelium D) greatest at 10-8M, with or without endothelium 181 The concentration range within which muscle tension is most sensitive to acetylcholine (Figure 1) is: -8 A) less than 10 M B) near 10-7M C) greater than 10-6M D) much wider in the ring without endothelium than in the ring with endothelium 183 Information in the passage suggests that acetylcholine and norepinephrine are neurotransmitters in the: A) parasympathetic and sympathetic divisions of the autonomic nervous system, respectively B) sympathetic and parasympathetic divisions of the autonomic nervous system, respectively C) motor and sensory pathways of the somatic nervous system, respectively D) sensory and motor pathways of the somatic nervous system, respectively 184 Increased vasoconstriction has an important role in which of the following situations? A) Causing the decrease in blood pressure associated with fainting B) Increasing blood flow to muscle during exercise C) Increasing blood flow to skin during blushing D) Maintaining blood pressure during a hemorrhage 185 Assume that NO is continuously synthesized The addition of a saturating concentration of L-NMMA to a relaxing aortic ring with intact endothelium would probably: A) increase its sensitivity to acetylcholine B) cause the ring to dilate (reduce its tension) C) cause the ring to contract (increase its tension) D) prevent norepinephrine from increasing ring tension 182 Two factors that normally determine the level of blood pressure are: A) the blood concentration of L-NMMA and norepinephrine B) the cardiac output and the resistance to blood flow C) the blood volume and the amount of L-arginine in the diet D) the heart rate (heartbeats/minute) and the cardiac stroke volume Sharing or reproducing this material in any form is a violation of the AAMC copyright 65 Passage VIII Oxiranes (1,2-epoxides) are cyclic ethers that contain one oxygen atom and two carbon atoms in a 3-member ring The strain in the structure makes oxiranes amenable to ring-opening reactions Examples of oxiranes are shown in Figure 186 What is the approximate C-O-C bond angle in (R)-styrene oxide? A) 60o B) 90o C) 109o D) 120o 187 If 1,2-epoxycyclohexane is hydrolyzed under acidic conditions, what is the structure of the predominant conformer of the diol produced? Figure (R)-Styrene oxide and 1,2-epoxycyclohexane A) A trans, diequatorial diol B) A trans, axial and equatorial diol C) A cis, diequatorial diol D) A cis, axial and equatorial diol There are two generally accepted mechanisms for ring opening, which depend on the reaction conditions Ring opening occurs under basic or neutral conditions by Mechanism and under acidic conditions by Mechanism 188 The first step in a reaction that produces its major product by Mechanism (R = tert-butyl and R´ = methyl) is given by which of the following equations? Mechanism A nucleophile attacks an unsymmetrical oxirane predominantly at the least substituted carbon atom, inverting its configuration An alkoxide is produced, which abstracts a proton from the solvent A) B) Mechanism The oxygen atom of the oxirane is protonated in a rapid and reversible first step The second, ratedetermining step is the partial cleavage of a carbonoxygen bond and the partial production of a carbocation, which then bonds with a nucleophile with inversion of stereochemistry C) D) Sharing or reproducing this material in any form is a violation of the AAMC copyright 66 189 If (R)-styrene oxide undergoes ring opening in the presence of NaOH(aq), what is the size of the ring that is formed as a result of intramolecular hydrogen bonding in the product? A) 3-Member B) 4-Member C) 5-Member D) 6-Member 190 What property accounts for diethyl amine reacting more readily with styrene oxide than does ethanol? A) Its volatility B) Its solubility C) Its electrophilicity D) Its nucleophilicity Sharing or reproducing this material in any form is a violation of the AAMC copyright 67 191 Which of the bromomethanes is LEAST polar? 195 Hemophilia, a disease in which the time required for blood to clot is greatly prolonged, is determined by a sex-linked gene Suppose a man with normal blood clotting marries a woman with normal blood clotting whose father was a hemophiliac If this couple has three sons, what is the probability that hemophilia will be transmitted to all three of them? A) CBr4 B) CHBr3 C) CH2Br2 D) CH3Br A) 1/8 B) 1/4 C) 3/8 D) 1/2 These questions are not based on a descriptive passage and are independent of each other 192 The phenomenon exemplified in the equilibrium equation below is called: A) reduction B) resonance C) tautomerism D) mutarotation 193 Most fungal spores are: A) metabolically active and diploid B) metabolically inactive and haploid C) relatively sensitive to environmental changes D) encased in a porous nuclear membrane 194 Which of the following structures is derived from the same germ cell layer as the heart? A) Eye B) Bone C) Spinal cord D) Liver Sharing or reproducing this material in any form is a violation of the AAMC copyright 68 Passage IX Lipopolysaccharide antigens on the surface of gramnegative bacteria are called endotoxins People infected with gram-negative bacteria sometimes develop septic shock syndrome in response to the endotoxins (see Figure 1) To reduce the mortality rate of septic shock two treatment plans were proposed Treatment 1: Administration of a general antiinflammatory drug to block the inflammatory cell response in patients infected with endotoxin Treatment 2: Administration of an antibody that blocks the attachment site for the endotoxin-binding protein complex on macrophages Patients were selected who had signs of septic shock They were treated with either Treatment drug, Treatment drug, or placebo Figure Cascade of events that is important in causing septic shock Sharing or reproducing this material in any form is a violation of the AAMC copyright 69 196 For Treatment to be effective, the antibody must: 199 Fever in septic shock leads to which of the following compensation mechanisms? A) stimulate macrophage activation B) stimulate T-cell production C) inhibit T-cell production D) inhibit macrophage activation A) Dilation of capillary beds in the skin B) Increased skeletal muscle activity C) Decreased respiration rate D) Decreased fluid loss 197 What is a danger of using the drug in Treatment 1? 200 If the anti-inflammatory drug in Treatment interfered with DNA replication, in which phase of the cell cycle would cells tend to be arrested? A) It may decrease endogenous antibacterial activities B) It may increase the platelet count C) It may decrease the red blood cell count D) It may increase the blood pressure A) G0 phase B) G1 phase C) S phase D) G2 phase 198 Which of the following would NOT be predicted as a consequence of venous blood pooling in septic shock? A) An increase in blood lactic acid levels B) A decrease in blood pressure C) A decrease in lymphatic fluid volume D) A decrease in the oxygen content in the blood Sharing or reproducing this material in any form is a violation of the AAMC copyright 70 Passage X Acetoacetic ester (1) and malonic ester (2) serve as synthetic precursors for the preparation of a variety of methyl ketones and carboxylic acids The starting ester is alkylated, saponified, acidified, and pyrolyzed (heated strongly); a typical procedure is shown in Scheme The final product is determined by the alkylating agent Table Target Compounds Product number Name 2-butanone 2-pentanone 4-methyl-2-pentanone 4-methyl-2-hexanone pentanoic acid 3-methylbutanoic acid 4-methylpentanoic acid decanoic acid 10 201 Which of the following alkyl halides can be used in an acetoacetic ester synthesis to make Product 5? A) Methyl chloride B) Ethyl bromide C) Propyl chloride D) Isopropyl iodide 202 The saponification product is acidified to convert: Scheme Acetoacetic ester enolizes regioselectively in sodium ethoxide/ethanol to one of two possible enolate ions, which is stabilized by delocalization of charge to two oxygen atoms The enolate ion is then alkylated by an alkyl halide A second alkylation step may be incorporated into the synthesis, but a different base is sometimes used for the second enolization and alkylation A) an ester into an acid B) an acid into a salt C) a salt into an acid D) an ester into a salt Acetoacetic ester may also be converted into a dianion by successive deprotonation steps with sodium hydride and butyllithium, respectively The alkylation of the dianion results in a substitution at the less substituted enolate ion Table shows eight target compounds that may be synthesized by either an acetoacetic ester or malonic ester synthesis, as appropriate Sharing or reproducing this material in any form is a violation of the AAMC copyright 71 203 How can 3-ethyl-2-pentanone, below, be synthesized starting with acetoacetic ester 1? A) By an alkylation of the enolate with isobutyl iodide B) By successive alkylations with methyl iodide C) By successive alkylations with ethyl iodide D) By alkylation of the dianion with isopropyl iodide 204 Why is a different base often used for a second alkylation of acetoacetic ester? A) Because the active hydrogen of the monoalkylated product is less acidic, making a stronger base more effective B) Because the active hydrogen of the monoalkylated product is more acidic, making a weaker base more effective C) Because the monalkylated product is sterically hindered, making a larger base more effective D) Because the monoalkylated product is more soluble in ethanol, requiring a different solvent and base Sharing or reproducing this material in any form is a violation of the AAMC copyright 72 Passage XI Researchers have isolated G proteins, a new family of membrane-associated proteins These proteins are believed to regulate all or most of the intracellular signaling systems operating across the plasma membrane, including those involving hormones and action potentials Figure depicts how this mechanism is hypothesized to function According to this hypothesis, extracellular signals such as some hormones bind to specific receptors on the surface of the plasma membrane This binding activates the receptor that then binds to a G protein embedded in the lipid bilayer of the plasma membrane This, in turn, causes the G protein to release guanosine diphosphate (GDP) and bind guanosine triphosphate (GTP) The G protein with bound GTP interacts with various enzymes or proteins in the plasma membrane The end result is either activation or inactivation of the enzyme, depending on the specific system The G protein is then inactivated, which “turns off” the initial steps of the signaling system Adenylate cyclase, the enzyme that synthesizes the intracellular signal cyclic AMP (cAMP), is believed to be activated by this mechanism Figure Intracellular signaling by G proteins Sharing or reproducing this material in any form is a violation of the AAMC copyright 73 205 Which of the following observations best supports the hypothesis that G proteins regulate intracellular signaling? A) Membrane-bound receptors for extracellular signals directly activate the intracellular signaling systems B) The absence of G proteins in a mutant cell line results in the cells’ inability to operate signaling systems C) All cells are found to contain varying ratios of G protein to adenylate cyclase D) Adenylate cyclase is found to be activated without the aid of G proteins 206 According to the passage, all of the following events must occur in order to activate a G protein EXCEPT: A) binding of the G protein to the receptor B) binding of the extracellular signal to the receptor C) displacement of GDP by GTP on the G protein D) phosphorylation of GTP 207 Binding an activated G protein to an inactive enzyme changes which of the following? A) Primary structure of the G protein B) Primary structure of the enzyme C) Secondary structure of the G protein D) Tertiary structure of the enzyme 209 Which of the following best explains the role of GTP in controlling the function of G proteins? A) GTP is required for binding the G protein to the hormone receptor B) GTP alters the conformation of the G protein allowing interaction with the enzyme C) Hydrolysis of GTP acts as a source of energy to activate the G protein D) Hydrolysis of GTP is required for activation of the membrane-bound enzyme 210 Binding of G proteins to a membrane-bound enzyme was observed to inactivate the signaling system Is this observation consistent with the information presented in the passage? A) No, because G proteins are believed to activate signaling systems B) No, because G proteins should have been activated by binding to the signal-receptor complex C) Yes, because the effect of G proteins is dependent upon the specific signaling system involved D) Yes, because binding of G proteins to the membrane-bound enzyme results in the hydrolysis of GDP, which inactivates the signaling system 208 Which of the following, if found to be true, would best refute the hypothesis that a membrane-bound enzyme is activated by a G protein? A) The enzyme can be activated in the absence of bound GTP B) The enzyme is activated only when hormone is present C) The enzyme cannot be activated when GDP is bound to a G protein D) The enzyme is always found in the activated state Sharing or reproducing this material in any form is a violation of the AAMC copyright 74 These questions are not based on a descriptive passage and are independent of each other 211 Inflation of the lungs in mammals is accomplished by: A) diffusion of gases B) active transport of gases C) positive pressure pumping action D) negative pressure pumping action 212 An organism is a bacterium rather than a virus if it: A) reproduces via fission B) has a rigid cell wall C) lacks a nuclear membrane D) contains both RNA and protein 213 Would an increase in the level of plasma aldosterone be expected to follow ingestion of excessive quantities of NaCl? A) No; aldosterone causes Na+ reabsorption by kidney tubules B) No; aldosterone causes Na+ secretion by kidney tubules C) Yes; aldosterone causes Na+ reabsorption by kidney tubules D) Yes; aldosterone causes Na+ secretion by kidney tubules 215 The sequence of events in the human menstrual cycle involves close interaction among which organs? A) Hypothalamus-thyroid-ovary B) Hypothalamus-pituitary-ovary C) Pituitary-thyroid-ovary D) Pituitary-adrenal glands-ovary 216 In a certain plant, the gene for red flowers is incompletely dominant to the gene for white; hence, heterozygotes are pink In the same plant species, long leaf is dominant to short leaf and the single gene controlling leaf length is not linked to the gene for flower color Homozygous long, white plants are crossed with homozygous short, red plants (P1 generation) The resulting offspring (F1) are bred randomly among themselves How many different color and leaflength phenotypes will occur in the F2 generation? A) B) C) D) 214 HIV (human immunodeficiency virus) is a retrovirus, an RNA virus that can insert itself into the human genome This virus can reproduce in host cells because it contains: A) enzymes that destroy T cells B) viral DNA that is compatible with human DNA C) core proteins rather than DNA D) reverse transcriptase Sharing or reproducing this material in any form is a violation of the AAMC copyright 75 MCAT Practice Test 4R Answer Sheet Physical Sciences (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) (A) (B) (C) 10 (A) (B) (C) 11 (A) (B) (C) 12 (A) (B) (C) 13 (A) (B) (C) 14 (A) (B) (C) 15 (A) (B) (C) 16 (A) (B) (C) 17 (A) (B) (C) 18 (A) (B) (C) 19 (A) (B) (C) 20 (A) (B) (C) 21 (A) (B) (C) 22 (A) (B) (C) 23 (A) (B) (C) 24 (A) (B) (C) 25 (A) (B) (C) 26 (A) (B) (C) 27 (A) (B) (C) 28 (A) (B) (C) 29 (A) (B) (C) 30 (A) (B) (C) 31 (A) (B) (C) 32 (A) (B) (C) 33 (A) (B) (C) 34 (A) (B) (C) 35 (A) (B) (C) 36 (A) (B) (C) 37 (A) (B) (C) 38 (A) (B) (C) 39 (A) (B) (C) 40 (A) (B) (C) 41 (A) (B) (C) 42 (A) (B) (C) 43 (A) (B) (C) 44 (A) (B) (C) 45 (A) (B) (C) 46 (A) (B) (C) 47 (A) (B) (C) 48 (A) (B) (C) 49 (A) (B) (C) 50 (A) (B) (C) 51 (A) (B) (C) 52 (A) (B) (C) 53 (A) (B) (C) 54 (A) (B) (C) 55 (A) (B) (C) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) Verbal Reasoning 78 (A) (B) (C) (D) 79 (A) (B) (C) (D) 80 (A) (B) (C) (D) 81 (A) (B) (C) (D) 82 (A) (B) (C) (D) 83 (A) (B) (C) (D) 84 (A) (B) (C) (D) 85 (A) (B) (C) (D) 86 (A) (B) (C) (D) 87 (A) (B) (C) (D) 88 (A) (B) (C) (D) 89 (A) (B) (C) (D) 90 (A) (B) (C) (D) 91 (A) (B) (C) (D) 92 (A) (B) (C) (D) 93 (A) (B) (C) (D) 94 (A) (B) (C) (D) 95 (A) (B) (C) (D) 96 (A) (B) (C) (D) 97 (A) (B) (C) (D) 98 (A) (B) (C) (D) 99 (A) (B) (C) (D) 100 (A) (B) (C) (D) 101 (A) (B) (C) (D) 102 (A) (B) (C) (D) 103 (A) (B) (C) (D) 104 (A) (B) (C) (D) 105 (A) (B) (C) (D) 106 (A) (B) (C) (D) 107 (A) (B) (C) (D) 108 (A) (B) (C) (D) 109 (A) (B) (C) (D) 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) Writing Sample 138 139 Biological Sciences 140 (A) (B) (C) (D) 141 (A) (B) (C) (D) 142 (A) (B) (C) (D) 143 (A) (B) (C) (D) 144 (A) (B) (C) (D) 145 (A) (B) (C) (D) 146 (A) (B) (C) (D) 147 (A) (B) (C) (D) 148 (A) (B) (C) (D) 149 (A) (B) (C) (D) 150 (A) (B) (C) (D) 151 (A) (B) (C) (D) 152 (A) (B) (C) (D) 153 (A) (B) (C) (D) 154 (A) (B) (C) (D) 155 (A) (B) (C) (D) 156 (A) (B) (C) (D) 157 (A) (B) (C) (D) 158 (A) (B) (C) (D) 159 (A) (B) (C) (D) 160 (A) (B) (C) (D) 161 (A) (B) (C) (D) Sharing or reproducing this material in any form is a violation of the AAMC copyright 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (B) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (C) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) (D) 76 .. .MCAT Practice Test 4R Physical Sciences Time: 100 minutes Questions: 1-77 Most questions in the Physical Sciences test are organized into groups, each containing... account The AAMC and its Section for the MCAT hold the copyrights to the content of this Practice Test Therefore, there can be no sharing or reproduction of materials from the Practice Test in any... account The AAMC and its Section for the MCAT hold the copyrights to the content of this Practice Test Therefore, there can be no sharing or reproduction of materials from the Practice Test in any