Tài liệu ôn thi AAMC MCAT test 6r

Tài liệu ôn thi AAMC MCAT test 6r

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 21 Verbal Reasoning Section Click PAGES FROM radio button and enter pages 22 to 42 Writing Sample Section Click PAGES FROM radio button and enter pages 43 to 45 Biological Sciences Section Click PAGES FROM radio button and enter pages 46 to 69 Periodic Table Click PAGES FROM radio button and enter page to Answer Sheet Click PAGES FROM radio button and enter page 70 to 70 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 6R 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 Archaebacteria are often found in environments that have extreme climatic conditions (e.g., in salt lakes or in very acidic or alkaline hot springs) Most archaebacteria are chemoautotrophs, bacteria that obtain energy by a redox reaction For example, methanogens produce methane by metabolizing CO2 The bond energy of C=O in CO2 is 803 kJ/mol, and the C-H bond energy in CH4 is 414 kJ/mol Table gives some of the chemical species that scientists find in environments where archaebacteria thrive Table Chemicals Name Formula Methane CH4 Glycine H2N-CH2-COOH Potassium hydroxide KOH Sulfuric acid H2SO4 Carbon dioxide CO2 Methanol CH3OH Sodium chloride NaCl Hydrogen sulfide H2S The methane found in swamp gas is a byproduct of methanogens, which are also found in a symbiotic association with a variety of cellulose-digesting organisms, including cows and termites Carbon-14 isotopic analysis even suggests that methane found deep in the earth’s crust might have been produced by archaebacteria Scientists are most likely to find which compound listed in Table in an alkaline lake? A) NaCl B) CH3OH C) H2SO4 D) KOH What pair of compounds found in Table can form extensive networks of intermolecular hydrogen bonds with both participating? A) Methane and methanol B) Methane and glycine C) Glycine and methanol D) Methanol and carbon dioxide How does an atom of carbon-14 differ from the most abundant isotope of carbon? A) By one proton B) By two protons C) By one neutron D) By two neutrons If an archaebacterial species lives in a pool that is 0.01 M HCl(aq), what is the pH of the water? A) 12 B) C) D) 0.01 Which of the following compounds has the same geometry as methane? A) H2S B) CO2 C) XeF4 D) SiCl4 Glycine passes through a very low pH membrane channel in which form? A) H2N-CH2-COOH B) H3N+-CH2-COOH C) H2N-CH2-COOD) H3N+-CH2-COO7 Like oxygen atoms in methanogens, which of the following elements can act as an electron acceptor? A) S B) He C) H2 D) Fe Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage II The periodic table arranges the elements by atomic number, aligning those with similar chemical properties in columns A primitive version of the periodic table was created by a Russian chemist in 1869, long before the electronic configuration of the elements was known Dimitri Mendeleev grouped the elements by their chemical properties and found that the properties varied periodically with the atomic mass Mendeleev left empty spaces for undiscovered elements His genius was confirmed when the elements that filled these blanks were isolated Henry Moseley showed that periodicity is a function not of atomic mass but of atomic number, as stated by today’s periodic law The current periodic table reflects this law In 1985, an international committee numbered the columns in the periodic table from to 18 and abolished the A and B designations for maingroup and transition elements 11 What is the mass number of the isotope of bromine that has 44 neutrons? A) 35 B) 79 C) 80 D) 81 12 According to trends in electronegativity, which of the following pairs of atoms is most likely to form an ionic bond? A) N and O B) C and F C) Ca and I D) Si and Cl Which of the following atoms has the largest atomic radius? A) Sodium B) Aluminum C) Sulfur D) Chlorine Which of the following atoms has the largest first ionization energy? A) Potassium B) Zinc C) Gallium D) Krypton 10 What is the sum of the protons, neutrons, and electrons in strontium-90? A) 90 B) 126 C) 128 D) 218 Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage III The Global Positioning System or “GPS” is based on satellite radio ranging A transmitter aboard each of the 24 satellites sends out a radio signal that specifies the precise position of the satellite and the precise time the signal was sent The position is known from accurate tracking by ground stations and the laws of orbital mechanics, while synchronized cesium clocks aboard each GPS satellite provide very accurate timing Each satellite has a mass of 1000 kg and orbits Earth in a circle = 1.8 x 107 m above the surface of Earth (2.4 x 107 m from the center of Earth) It takes 12.4 hours to complete this orbit The atomic clock is powered with a 5-g radioactive Cs source The transmitter is powered by a 1.32-V nickelcadmium battery A radio receiver on Earth can be used to calculate the distance to the satellite by measuring the time difference between the broadcast and reception because the signal travels at the speed of light (3.0 x 108 m/s) When the distances to several different satellites have been measured–at least four satellites are visible from anywhere on Earth at all times–the receiver position can be determined by triangulation Timing corrections due to atmospheric effects are usually accounted for by broadcasting the GPS signals at two frequencies, one at 102.1 MHz and another at 104.9 MHz o 13 For a GPS satellite that is at an angle of 40 from Earth’s horizon, it takes 0.07 s for the radio signal to reach a receiver The distance between the transmitter and the receiver is: A) 2.1 x 107 sin 40° m B) 2.1 x 107 m C) 2.1 x 1011 cos 40° m D) 2.1 x 1011 m 14 A high-altitude GPS satellite is kept in a circular orbit because Earth’s gravitational force: A) supplies the centrifugal force B) offsets the atmospheric drag force C) offsets the moon’s gravitational force D) supplies the centripetal force 15 If a GPS satellite orbited at six times its present distance from the center of Earth and was four times more massive, by what factor would the gravitational force between Earth and the satellite change? A) Decrease by a factor of B) Increase by a factor of C) Decrease by a factor of 2/3 D) Increase by a factor of 2/3 16 How much current from a Ni-Cd battery is drawn by a radio transmitter that requires 3.96 W? A) 1/9 A B) 1/3 A C) A D) A 17 What beat frequency is detected in a receiver on Earth from the two GPS radio signals used to correct for atmospheric effects? A) 0.7 x 106 Hz B) 1.4 x 106 Hz C) 2.8 x 106 Hz D) 5.6 x 106 Hz 18 A GPS radio signal travels slower through Earth’s atmosphere than it travels through the vacuum of space primarily because: A) the atmosphere is warmer than the vacuum of space B) gravity is stronger in the atmosphere than in space C) the atmosphere steadily decreases the power in the radio signal D) the atmosphere has a larger index of refraction than does the vacuum of space 19 How many years will pass before there are 0.625 grams of Cs remaining in the source, if Cs has a half-life of 175 years? A) 525 years B) 650 years C) 700 years D) 1400 years Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage IV Olestra, a sucrose polyester, is the brand name of an approved dietary fat replacement The large-scale synthesis of Olestra starts with a base-catalyzed cleavage in methanol of the naturally occurring fats (triacylglycerols or triglycerides) found in cottonseed or soybean oils The reaction liberates glycerine and converts the fatty acids into methyl esters (Figure 1) about Cal/g (Note: For water, the heat of fusion is 1.4 kcal/mol, the specific heat is 4.185 J/g•oC or cal/g•oC, and the density is 1.0 g/mL at 15oC One kg equals 2.2 pounds.) 20 According to the passage, which of the following compounds can the worker use to catalyze the cleavage of a triglyceride? A) HCl(aq) B) NaCl(aq) C) NaOH(aq) D) Na2SO4(aq) 21 What is the energy content in kcal of one peanut, if the temperature of kg of water in a calorimeter increases by 50oC upon the combustion of 10 peanuts? A) 0.5 kcal B) kcal C) kcal D) 10 kcal Figure Base-catalyzed cleavage of a triacylglycerol (R = CH3(CH2)n-; n = 8, 10, 12, etc.) As glycerine settles out, a plant worker draws it off and separates the methyl esters from the remaining mixture by distillation A reaction between these esters and sucrose, common table sugar, in the presence of a basic catalyst and emulsifiers at a high temperature liberates methanol and produces crude Olestra The removal of excess fatty acids and emulsifiers produces pure Olestra Normal edible fats contain three fatty acid units, whereas Olestra, also a true fat, contains six to eight fatty acid units bonded to the sugar backbone Olestra is not metabolized because the additional fatty acid units block the approach of digestive enzymes to the cleavage sites Because a calorie (1 cal = 4.185 J) is a very small unit of energy, food scientists use the Calorie (1 Cal = 4,185 J) with a capital C A 1-ounce bag of potato chips contains about 160 Cal A normal fat contains Cal/g, whereas carbohydrates and proteins provide 22 How many dietary calories does a 1-g sample of Olestra contribute to a human consumer? A) Cal B) Cal C) Cal D) Cal 23 The boiling point of glycerine in comparison with that of isopropyl alcohol, (CH3)2CHOH, is: A) more than 10oC higher B) less than 10oC higher C) less than 10oC lower D) more than 10oC lower 24 How many pounds (lb) of methanol does a worker need if a reaction requires 20 moles of methanol? A) 0.003 lb B) 1.4 lb C) 2.9 x 105 lb D) 1.4 x 106 lb Sharing or reproducing this material in any form is a violation of the AAMC copyright These questions are not based on a descriptive passage and are independent of each other 25 Which of the following elements has the highest electron affinity? A) Carbon B) Fluorine C) Oxygen D) Magnesium 26 Ag+ + e- → Ag Cu+ + e- → Cu Pb2+ + e- → Pb Zn2+ + e- → Zn Eo = +0.80 V Eo = +0.52 V Eo = -0.13 V Eo = -0.76 V With which of the above metals can copper form a galvanic cell in which copper is reduced? A) With silver only B) With lead only C) With lead and zinc D) With silver and zinc 27 Which of the following expressions correctly describes the relationship between the frequency f and the period T of a sinusoidal wave? A) fT = B) f/T = C) f+ T = D) f– T = 28 Suppose that a ball is thrown vertically upward from earth with velocity v, and returns to its original height in a timet If the value of g were reduced to g/6 (as on the moon), then t would: A) increase by a factor of B) increase by a factor of 61/2 C) decrease by a factor of D) decrease by a factor of 61/2 Sharing or reproducing this material in any form is a violation of the AAMC copyright Passage V In 1622, a Spanish ship carrying a cargo of silver crashed on a coral reef near Cuba and sank The ship was laden with hardwood boxes of silver coins The boxes came to rest on the ocean floor and began to decay At first, aerobic microorganisms thrived but, as the concentration of oxygen decreased, these organisms died Subsequently, sulfur-loving bacteria began to flourish These sulfur bacteria consumed sulfate ions in seawater and excreted the weak acid H2S, as shown in Equation SO42-(aq) + H+(aq) + H2(g) → H2S(aq) + H2O(l) Equation The excreted H2S then reacted with silver, which has a standard reduction potential of +0.80 V One of the products was a black precipitate of Ag2S and the other was hydrogen gas, as shown in Equation 2 Ag(s) + H2S(aq) → Ag2S(s) + H2(g) Equation The hydrogen from this reaction provided additional food for the sulfur microorganisms and accelerated the corrosion of the silver coins When the silver coins were completely coated with Ag2S, the corrosive reaction stopped Because the seawater contained small amounts of CO2 (the solubility of CO2 is 0.145 g/100 g H2O at 25oC and 1.00 atm), bicarbonate ions were formed by the reaction shown in Equation H2O(l) + CO2(g) H+(aq) + HCO3-(aq) Equation These bicarbonate ions combined with calcium to form the insoluble CaCO3, which crystallized, encapsulating the coins, sand, and decaying matter into rock-like clumps The explorers who discovered the treasure found these rock-like structures 29 The formation of Ag2S is an example of what kind of reaction? A) A combination reaction B) A decomposition reaction C) A single replacement reaction D) A double replacement reaction 30 What is the maximum number of grams of H2S that can be produced from mol of sulfate ions by the reaction of Equation 1? A) 68 g B) 34 g C) 96 g D) 192 g 31 To a first approximation, the ionization constant of H2S is: A) near zero B) much less than C) about D) much more than 32 Sodium carbonate and calcium chloride are both soluble in water Which of the following equations shows the net ionic reaction between these two compounds? A) Na+(aq) + CO32-(aq) → Na2CO3(s) B) Ca2+(aq) + CO32-(aq) → CaCO3(s) C) Na+(aq) + Cl-(aq) → NaCl(s) D) Ca2+(aq) + Cl-(aq) → CaCl2(s) 33 What species is the reducing agent in Equation 2? A) S2B) H2S C) H+ D) Ag Sharing or reproducing this material in any form is a violation of the AAMC copyright 10 Passage VI Therapeutic alteration of the genome as a treatment for genetic disorders (gene therapy) poses formidable challenges Among them is the problem of targeting altered genes to the correct cells One method of introducing genes into cells is to coat the DNA with an envelope of cationic (positively charged) amphipathic lipids The packets formed in this way are called liposome-DNA complexes The lipids present their charged surface to the DNA molecules giving them an outer hydrophobic surface coating which enables the DNA to cross the plasma membrane The efficiency of gene therapy depends on the delivery of new genes into cells, the duration of expression of the newly introduced genes, and the ability of the exogenous genes to be transferred from one generation of cells to the next Researchers conducted experiments in which a reporter gene (a gene with an easily visualized product) was introduced into a culture of actively dividing cells using the liposome-DNA complex method The expression of the reporter gene over time in that experiment is shown in Figure Figure Tissue distribution of reporter gene expression 170 According to Figure 2, is the introduced gene spreading widely throughout the fetus? A) No; it is only expressed in tissues in the abdomen B) No; it is only expressed in the largest organs C) Yes; it is expressed throughout tissues of mesodermal origin D) Yes; it is expressed generally throughout the fetus 171 Lipids used to complex with DNA must be cationic because DNA is: A) positively charged and hydrophobic B) positively charged and hydrophilic C) negatively charged and hydrophobic D) negatively charged and hydrophilic Figure Duration of gene expression To study the tissue distribution of the introduced DNA, liposome-DNA complexes containing reporter genes were injected into the abdominal cavities of fetal mice and the expression of the gene was measured in various tissues after a period of days (Figure 2) 172 The liposome-DNA complex crosses a membrane composed of: A) lipids only B) lipids and proteins C) lipids and DNA D) lipids, DNA, and proteins Sharing or reproducing this material in any form is a violation of the AAMC copyright 56 173 Would an exogenous gene introduced into somatic cells be passed from parent to offspring? A) Yes, because the DNA will be localized into the cell’s nuclei B) Yes, because all DNA is passed from parent to offspring during meiosis C) No, because changes to somatic cells are not passed to offspring D) No, because foreign DNA is not passed to offspring 174 Targeting therapeutic genes to specific cells is important because: A) all cells contain, but not express, the same genes B) all cells contain and express the same genes C) different cells contain different genes D) inherited defective genes are only found in some cells of the body Sharing or reproducing this material in any form is a violation of the AAMC copyright 57 Passage VII Joe and Steve were fire fighters Joe was an experienced veteran in the fire department, whereas Steve was a 23-year-old new member Although Joe was 60 years old, he kept his muscles in excellent physical condition and only 8% of his weight was body fat However, his long fire-fighting career had had serious effects on his health At the age of 25, Joe had been trapped in a burning house and had suffered severe burns over 50% of his body, which resulted in massive scarring of his skin As a consequence of long-term inhalation of smoke, Joe also had an earlystage emphysema a disease in which the elastic tissue of the lungs loses its ability to recoil after it is stretched Although Steve weighed only half as much as Joe, Steve had a higher percentage of body fat (15% of his weight) However, he was in excellent physical condition Steve and Joe had identical vital signs: a resting heart rate of 60 beats per minute and blood pressure of 125/70 mmHg Joe and Steve were assigned to a team sent to fight a major fire in an industrial warehouse Fighting a big fire is often a frightening experience Because this was Steve’s first major fire, it was especially frightening for him After the fire was extinguished, an inspection of the building revealed that a chemical storage container had ruptured, possibly exposing Joe and Steve to a hepatotoxic agent, which could damage the liver 175 If the heart rates of Steve and Joe were monitored when they entered the burning warehouse to fight the fire, one would expect: 176 Joe’s body might have a greater tendency to overheat during strenuous work than Steve’s body would, because: A) older males have a higher basal metabolic rate B) Steve has a greater percentage of body fat C) Joe’s scarred skin would reduce evaporative cooling D) Joe has more skin surface area relative to his body volume 177 Which of the following factors will NOT influence the oxygenation of blood in the pulmonary circulation? A) Rate and depth of breathing B) Hemoglobin concentration of the blood C) Blood pressure in the pulmonary artery D) Surface area of the alveoli 178 If Steve’s blood pressure had increased significantly more than Joe’s increased (other factors being equal) while they worked, what difference in their urinary system function would be expected? A) Joe’s glomerular filtration rate would increase more than Steve’s would B) Steve’s reabsorption rate of glomerular filtrate by the peritubular capillaries would be lower than Joe’s would be C) Steve’s reabsorption rate per milliliter of glomerular filtrate by the peritubular capillaries would be higher than Joe’s would be D) Steve’s glomerular filtration rate would increase more than Joe’s would A) Steve’s heart rate to increase more, because of activation of the sympathetic division of the autonomic nervous system B) Joe’s heart rate to increase more, because of activation of the sympathetic division of the autonomic nervous system C) Joe’s heart rate to increase more, because of activation of the parasympathetic division of the autonomic nervous system D) both heart rates to increase, because of activation of the parasympathetic division of the autonomic nervous system Sharing or reproducing this material in any form is a violation of the AAMC copyright 58 179 If both Steve and Joe performed the same work tasks, which of the following statements would describe their individual energy consumption? A) Steve’s body would consume more energy because of his lesser weight B) Steve’s body would consume less energy because of the greater basal metabolic rate in younger people C) Joe’s body would consume more energy because of his greater weight D) Joe’s body would consume the same amount of energy as Steve’s because the basal metabolic rates are equal 180 Damage to the liver would most directly affect the production of: A) digestive enzymes B) antidiuretic hormone C) new blood cells D) bile salts 181 The blood pressure of these fire fighters was 70 mmHg when: A) their atria and ventricles were contracted B) their atria and ventricles were relaxed C) blood was entering the aorta from the left ventricle D) blood was entering the pulmonary arteries from the right ventricle Sharing or reproducing this material in any form is a violation of the AAMC copyright 59 Compound was a key intermediate compound in the conversion of Compound into Compound Passage VIII A research group synthesized Compound to study how the presence of four adjacent carbonyl groups affects the chemical and physical properties of the novel compound Compound Compound The researchers started their synthesis of Compound with the known dibromide (Compound 6), which they synthesized by the scheme shown in Figure The first step in the synthesis of Compound began with a reaction between Compound and 2methylpropanoic acid in the presence of the strong base lithium diisopropylamide in excess followed by a workup in H+/H2O The synthesis of Compound was completed in several additional steps 182 The basic reagent indicated in Step of Figure was pyridine What was its primary function in the preparation of Compound 3? A) To abstract a proton from the diacid, converting it into a nucleophile B) To neutralize the diacid, converting it into a dicarboxylate C) To serve as a nucleophile and attack the carbonyl carbon atom of the dialdehyde D) To abstract a proton from the dialdehyde so it could undergo an aldol reaction 183 The overall result of Step was an esterification What role did SOCl2 play in the transformation of Compound into Compound 4? Figure (a) Base, 130oC; (b) SOCl2/dimethylformamide (DMF); (c) CH3OH, reflux; (d) H2/Pd/C, tetrahydrofuran (THF), 50oC; (e) LiAlH4, THF, 60oC; (f) HBr, 130oC A) It served as a solvent for DMF B) It converted the diacid into a diacid chloride C) It converted the diacid into a disulfide D) It served as a solvent for CH3OH Sharing or reproducing this material in any form is a violation of the AAMC copyright 60 184 Why did the researchers incorporate the four methyl groups at their specific locations in Compound 1? 186 What was the product of the reaction between Compound and 2-methylpropanoic acid? A) A) To enhance the acidity of their α-protons B) To donate electron density to the 16-membered ring C) To prevent enolization adjacent to the carbonyl groups D) To ensure enolization adjacent to the carbonyl groups 185 If methyl propenoate were subjected to the reaction conditions d and e of Step of Figure 1, one product would be: B) A) 2-propen-1-ol B) 1-propen-3-ol C) methyl propanoate D) 1-propanol C) D) Sharing or reproducing this material in any form is a violation of the AAMC copyright 61 These questions are not based on a descriptive passage and are independent of each other 187 A hiker becomes lost and has no drinking water for days At the end of this time, which of the following changes in hormone production would be expected to be significant in this individual? 191 In almost all vertebrates, when the optic cup fails to develop in the embryo, the lens also fails to form This constitutes evidence that: A) the process of neurulation follows gastrulation B) the eye develops early in vertebrate morphogenesis C) cells may induce neighboring cells to differentiate D) cell differentiation is an “all or none” phenomenon A) Decreased glucocorticoid secretion B) Decreased aldosterone secretion C) Increased insulin secretion D) Increased antidiuretic hormone secretion 188 Rates of endocytosis vary from cell type to cell type What cell would be predicted to have the highest rate of endocytosis? A) A macrophage B) An erythrocyte C) An osteoblast D) A neuron 189 Translation of antibody proteins in eukaryotic cells is associated with what organelle? A) Nucleus B) Mitochondrion C) Endoplasmic reticulum D) Golgi apparatus 190 Which of the following changes would NOT interfere with the repeated transmission of an impulse at the vertebrate neuromuscular junction? A) Addition of a cholinesterase blocker B) Addition of a toxin that blocks the release of acetylcholine C) An increase in acetylcholine receptor sites on the motor end plate D) Addition of a substance that binds to acetylcholine receptor sites Sharing or reproducing this material in any form is a violation of the AAMC copyright 62 Passage IX Several species of Drosophila have X-linked e and f genes that affect the sex ratios of individuals’ offspring However, the genes only affect sex ratios if they are brought close together by an inversion of one arm of the X chromosome (Figure 1) Figure Standard and inverted X chromosomes An XsY male is standard: he sires equal numbers of sons and daughters An XiY male expresses the sex ratio trait: he sires only daughters Total reproductive output is not affected; XsY males and XiY males sire equal numbers of offspring If none of the Xi-bearing genotypes (XiY, XiXi, or XiXs) is selected against, then the frequency of Xi is expected to increase to 100%, unless other genes act to suppress expression of e and f Occasionally, XiY males sire viable but sterile sons of normal appearance Genetic analyses show that all these sons are XO, inheriting their X chromosome from their mother and lacking a Y chromosome 192 If all genotypes are equally fit and if there are no genetic modifiers of the sex ratio trait, what will be the ultimate fate of a population in which 50% of the X chromosomes are currently Xi and 50% are Xs? A) Extinction B) Stable population size, with a predominance of females C) Stable population size, with all individuals producing a 50:50 sex ratio D) Stable population size, with some individuals producing an excess of females and some producing an excess of males 193 Which of the following processes is most likely the one disrupted in XiY males? A) Meiosis B) Mate recognition C) Courtship behavior D) Genital development 194 In a laboratory population of Drosophila, all the males are XsY Among the females, 15% are XiXi, 50% are XiXs, and 35% are XsXs Assuming random mating, what proportion of male flies in the next generation will be XiY? A) 12% B) 30% C) 40% D) 65% 195 Which of the following statements best explains why Xi has the potential to increase to 100% frequency in gene pools that contain it? A) XiXs flies have the highest fitness of any genotype B) XiXi flies tend to migrate and introduce the Xi chromosome into new populations C) XiXi flies pass X chromosomes to all their offspring, but XsXs flies pass their X chromosomes to only half their offspring D) XiY flies pass their X chromosome to all their offspring, but XsY flies pass their X chromosome to only half their offspring 196 A virgin female Drosophila mates and produces 34 daughters and 38 sons Eighteen of these sons sire only daughters, while the remainder sire approximately equal numbers of daughters and sons What are the genotypes of the original female and the male with whom she mated? A) XiXs and XsY B) XiXs and XiY C) XiXi and XsY D) XsXs and XiY Sharing or reproducing this material in any form is a violation of the AAMC copyright 63 197 The characteristics of the occasional sons sired by XiY ales show that the Y chromosome is essential for: A) survival to adulthood B) development of somatic tissues C) production of functional gametes D) production of normal external morphology 198 If the e and f genes are expressed, the Xi chromosome will be prevented from reaching 100% frequency if selection pressures cause which of the following to be true? A) XsXs flies have the lowest fitness of any genotype B) XsXs flies have the highest fitness of any genotype C) XiY flies and XsY flies have equal fitness D) XiXs flies and XsXs flies have equal fitness Sharing or reproducing this material in any form is a violation of the AAMC copyright 64 Passage X The study of human disease has revealed many details and raised many questions about the genetic basis of cellular physiology The study of neurofibromatosis type I (NF1) suggests that defects in a single gene cause the various clinical features that characterize this disease, which include skeletal abnormalities, learning disabilities, and benign and malignant tumors This array of clinical features is difficult to reconcile with the idea of defects in a single gene Studies of DNA mutations in NF1 patients have revealed few mutations–too few to explain all the features of this genetically dominant disease At least four alternative mRNA transcripts are expressed from the single NF1 gene Each mRNA transcript is expressed differently in different tissues and at different developmental stages Some investigators propose that changes in the types of NF1 transcript may drive cellular differentiation, whereas others propose that cellular differentiation causes changes in the type of NF1 transcript expressed In either case, epigenetic (developmental) events evidently affect the expression of the NF1 gene Mistakes in RNA processing might contribute to the disease phenotype The events involved in NF1 gene expression probably are not unique to this gene Many genes may undergo a similarly complex series of events, which ultimately regulate the amount and composition of protein expressed from a particular DNA sequence 199 The passage suggests that the expression of disease genes probably is important in regulating normal cellular physiology because: A) altered expression of disease genes leads to disease B) the expression of disease genes leads to disease C) disease genes are frequent targets for mutation D) gene mutations frequently lead to disease 200 The most likely shared feature of the clinical manifestations of NF1 is that they all: A) affect the same tissues B) arise from the same cell type C) arise from one genetic defect D) arise from defects in gene expression 201 Changes in the type of NF1 transcript expressed will cause changes in the type of NF1: A) protein synthesized by the ribosomes B) protein transcribed by the ribosomes C) gene passed to the offspring of those affected D) gene within cells of those affected 202 The mechanisms that regulate gene expression are: A) simple because they are contained within the cell B) complex and occur at many levels within the cell C) complex and affect only DNA D) simple because all genes are regulated in the same way 203 Which of the following statements best explains why the type of NF1 mRNA transcript that is expressed changes as cells differentiate? A) Cellular differentiation is a continuous process B) Differentiated cells may express the same proteins as undifferentiated cells C) Differentiated cells express different proteins than undifferentiated cells D) Differentiated cells may lose the ability to divide Sharing or reproducing this material in any form is a violation of the AAMC copyright 65 204 Epigenetic modulation of gene expression is most likely to be important in evolutionary terms because it allows: A) multiple proteins to be encoded by a single gene B) multiple genes to encode the same protein C) the posttranslational modification of defective proteins D) more variation at the DNA level 205 If NF1 is a genetically dominant disease, what relationship between NF1 genes on homologous chromosomes and phenotype is expected? A) A defect in both genes is necessary for the disease to occur B) A defect in both genes will not lead to the disease C) A defect in only one allele will not lead to the disease D) A defect in only one allele is necessary for the disease to occur Sharing or reproducing this material in any form is a violation of the AAMC copyright 66 Passage XI The synthesis of some ethers can be accomplished by the reaction of a metal alkoxide or phenoxide with an alkyl halide, a reaction known as the Williamson ether synthesis An alkoxide is prepared by treating an alcohol with an active metal such as potassium, and a phenoxide is prepared by the reaction of a phenol with NaOH(aq) instead of potassium In the synthesis, a halide ion is displaced by an alkoxide or phenoxide ion An organic chemistry instructor asked two students to propose reaction schemes for the synthesis of tert-butyl methyl ether (TBME), a compound that has some advantages over diethyl ether as a solvent Students and proposed the reaction schemes shown in figures and 2, respectively 206 If such factors as competing side reactions and recovery of the product are considered, which of the following compounds is the best solvent for the synthesis? A) Methanol B) Ethanol C) t-Butanol D) n-Butanol 207 Which of the following 1H NMR spectra represents the synthetic product desired by the instructor? A) B) Figure Student 1’s proposal C) Figure Student 2’s proposal The class evaluated the reaction schemes proposed by the two students and concluded that Student 2’s synthesis would give the desired product and Student 1’s synthesis would yield an alcohol and an alkene instead of the desired product D) 208 The reaction shown in Step of Student 2’s scheme occurs by what reaction mechanism? A) SN1 B) SN2 C) E1 D) E2 Sharing or reproducing this material in any form is a violation of the AAMC copyright 67 209 An active halide such as Ar3CX reacts directly with an alcohol with no need for an alkoxide ion, because the halide undergoes solvolysis to form: A) a carbanion B) a carbene C) a free radical D) a carbocation 210 If a geminal dihalide reacts with two equivalents of alkoxide, the product is: A) an acetal B) a 1,3-diether C) an ortho ester D) a cyclic ether Sharing or reproducing this material in any form is a violation of the AAMC copyright 68 These questions are not based on a descriptive passage and are independent of each other 211 Antidiuretic hormone (ADH) acts to decrease urine output by increasing the water permeability of the walls of: A) the glomerulus B) Bowman’s capsule C) the loop of Henle D) the distal tubule and collecting duct 214 Table shows the average composition of the fatty acids obtained by hydrolysis of four oils Table Weight % of Acids Oil Coconut Palm Olive Tung Saturated 92 47 Enoic 43 86 Dienoic + Trienoic 10 92 If equal weights of oils are hydrolyzed, which oil will decolorize the largest volume of bromine in carbon tetrachloride? 212 A) Coconut B) Palm C) Olive D) Tung 215 Which of the following hormones is LEAST directly regulated by the anterior pituitary? The diagram above shows the pattern of inheritance of a certain disease Females are represented by circles, males by squares Individuals that exhibit the disease are represented by shaded circles or squares What is the most likely method of inheritance of this disease? A) Autosomal dominant B) Autosomal recessive C) Sex-linked dominant D) Sex-linked recessive 213 Suppose that an extract from a muscle cell contains only the following: all the enzymes of the glycolytic pathway, including the enzyme that converts pyruvate to lactate; phosphate and other salts; NAD+and ADP When the extract is incubated anaerobically and glucose is introduced, neither pyruvate nor lactate is produced What must be added in order for pyruvate to be made? A) Cortisone B) Epinephrine C) Progesterone D) Thyroxin 216 The mineral component of human bone is a salt that consists primarily of all of the following EXCEPT: A) calcium B) phosphate C) potassium D) hydroxyl groups A) O2 B) ATP C) NADH D) Acetyl-coenzyme A Sharing or reproducing this material in any form is a violation of the AAMC copyright 69 MCAT Practice Test 6R 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) 70 .. .MCAT Practice Test 6R 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