5R MCAT PREP

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MCAT Practice Test 5R

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.

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Periodic Table of the Elements

1

H

2

He 4.0 10

1.0 3

4

Li

Be

B

C

N

O

F

Ne

6.9

9.0

10.8

12.0

14.0

16.0

19.0

20.2

5

6

7

8

9

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 Ammonia can be prepared by the reversible reaction between H2 and N2 in the presence of a mixture of FeO and Al2K2O4 (Reaction 1) under a variety of conditions (Table 1).

Reaction 1 Table 1 Equilibrium Concentrations of NH3(g) at Several Temperatures and Pressures Equilibrium concentration of NH3(g) Pressure (% by volume) (atm) at 200°C at 400°C at 600°C at 800°C 1 15.3 0.44 0.05 0.01 100 80.6 25.1 4.47 1.15 200 85.8 36.3 8.25 2.24 1,000 98.3 80.0 31.5 — NH3 can also be prepared by reacting a metal nitride, such as Mg3N2, with H2O, as summarized by the following unbalanced equation (Reaction 2).

1. Is Reaction 1 exothermic under standard conditions? A) Yes, because heat must be added to initiate the reaction B) Yes, because the standard enthalpy change is negative C) No, because the percent yield of NH3 is greatest at high pressure D) No, because the standard enthalpy change is negative 2. Which of the following graphs best shows the effect of pressure on the equilibrium percentage yield of NH3(g) at 200°C? A)

B)

→

Mg3N2(s) + H2O(l) Mg(OH)2(s) + NH3(g) Reaction 2 Ammonia and ammonium salts are used as commercial fertilizers. Ammonium salts are prepared by reacting NH3 with HX (an acid) as shown below (Reaction 3).

→

NH3(g) + HX(aq) NH4X(s) Reaction 3

C)

The approximate electronegativities of several elements are given in Table 2. Table 2 Electronegativities of Several Elements Element Elecronegativity H 2.20 I 2.66 N 3.04 O 3.44 F 3.98

D)

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3. The most likely role of the FeO/Al2K2O4 mixture used in Reaction 1 is to: A) increase the rate of the reaction. B) increase the equilibrium constant. C) provide energy to facilitate the reaction. D) lower the pH of the reaction mixture. 4. If excess NH3(g) reacts with H2SO4(aq), which of the following compounds can be produced? A) NH4SO4 B) NH4H2SO4 C) NH4(SO4)2 D) (NH4)2SO4 5. What kind of interactions take place between molecules of the product of Reaction 1? A) Ionic only B) Hydrogen bonding only C) Dipole-dipole only D) Both hydrogen bonding and dipole-dipole 6. Which of the following ions involved in Reaction 2 is the strongest base? A) N3-(aq) B) OH–(aq) C) Mg2+(aq) D) H+(aq)

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Passage II A large amount of energy is released when the nucleus of an atom disintegrates. Nuclear fission of 1 kg of U produces approximately 8.0 × 1013 J, an amount of energy equal to that produced by burning 2.3 × 106 kg of coal. A simple model of nuclear disintegration can be used to explain the source of this large amount of energy. The nucleus of a U atom contains 92 protons and 146 neutrons in a sphere with a radius of approximately 7.6 × 10–15 m. There is a large repulsive force between the positive charges in the nucleus. This force is balanced by a short-range attractive force, the strong nuclear force. By using a simple model, calculations can be done to find the amount of energy released when a uranium atom fissions. The model assumes that the uranium nucleus disintegrates into two spherical fragments, as shown in Figure 1.

The repulsive force between the two nuclei is kQ2/d2, where k is Coulomb’s constant and d is the distance between the centers of the nuclei. The potential energy of the system of charged nuclear fragments is kQ2/(2r), which is the energy available from this disintegration. A value of 3.2 × 10–11 J per atom is obtained by making a calculation for the model uranium atom. This value is very close to the experimentally determined value.

7. According to the passage, the energy released when an atom splits comes from: A) fast-moving electrons. B) the short-range attraction of the nucleons. C) mutual attraction of the fragments. D) mutual repulsion of the fragments. 8. A nucleus splits into two fragments that have equal charge but unequal mass. Which of the following is equal for the two fragments as they move apart? A) Magnitude of the force of one fragment on the other B) Magnitude of acceleration C) Speed D) Kinetic energy 9. Based on the passage, why are there no naturally occurring elements that have more protons in their nucleus than uranium does?

Figure 1 Nuclear disintegration model The fragments each have radius r, mass m, and charge Q. Immediately after separation, their centers are separated by 2r. There is a large electrical repulsion between these two fragments that causes them to move apart and gain kinetic energy.

A) All of the heavier elements have radioactively decayed. B) All of the heavier elements are stable. C) The range of the strong nuclear force is too short to hold them together. D) The heavier elements can be made only in nuclear reactors.

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10. Which of the following graphs best illustrates how the force between fragments from the fission of a uranium nucleus varies as the fragments move away from each other? A)

B)

C)

D)

11. If they are given enough energy, nuclei of lighter atoms can fuse together. Which of the following best explains why this energy is required? A) To overcome the mutual repulsion of the nuclei B) To strip the electrons from the nuclei C) To add electrons to the nuclei D) To overcome the strong nuclear force 12. If a uranium nucleus undergoes fission as shown in Figure 1, as one fragment moves away from the other fragment, it has: A) constant speed. B) constant acceleration. C) decreasing acceleration. D) increasing acceleration.

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Passage III Ozone (O3) is formed in the upper atmosphere by reactions 1 and 2.

→ O+O Reaction 2: O + O → O Reaction 1: O2

2

13. A compound that significantly assists in ozone depletion CANNOT be: A) a gas. B) a radical precursor. C) inert in the lower atmosphere. D) inert in the upper atmosphere.

3

Because reactions 1 and 2 are photochemically reversible, ozone is removed at a rate that is equal to the rate of its formation, and a steady state concentration is reached. Table 1 summarizes the thermodynamic data for the oxygen species involved in ozone formation. Table 1 Thermodynamic Properties of Oxygen Oxygen S ∆Hf ∆Gf Species (J/mol·K) (kJ/mol) (kJ/mol) O 161.0 247.5 230.1 O2 205.0 0 0 O3 238.8 142 163.4 The ozone balance has recently been disturbed, resulting in a net loss of ozone in the upper atmosphere. Scientists believe this is due in part to reactions involving chlorofluorocarbons (CFCs) such as CF3Cl. Although CFCs are typically inert, they can undergo photolysis in the upper atmosphere and subsequently assist in the decomposition of ozone according to reactions 3–5.

→ F C· + Cl· Reaction 4: Cl· + O → ClO· + O Reaction 5: ClO· + O → Cl· + O Reaction 3: F3CCl

14. The chlorine atom in Reaction 4 is very reactive because it has: A) an unpaired electron. B) an extra electron. C) an expanded octet. D) a partial negative charge. 15. Which of the following is the balanced net reaction that is described by reactions 4 and 5? A) O3 + O → O2 B) O3 + O → 2 O2 C) O3 + Cl· → Cl· + O + O2 D) O3 + ClO· → 2 O2 + Cl· 16. Based on Table 1, which of the following graphs most accurately depicts the free energy changes during the course of reactions 1 and 2? A)

3

3

B)

2

2

This mechanism is supported by the fact that periodic increases in ClO· in the upper atmosphere correlate well with times of ozone depletion.

C)

D)

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17. According to Table 1, what is ∆S of the following reaction? 2 O3

→3O

2

A) –33.8 J/(mol·K) B) 33.8 J/(mol·K) C) –137.4 J/(mol·K) D) 137.4 J/(mol·K) 18. From reactions 3–5, what can be determined about the relative concentrations of CFCs and O2? A) One equivalent of CFC is required to produce one equivalent of O2. B) One equivalent of CFC is required to produce two equivalents of O2. C) A catalytic amount of CFC can produce much O2. D) The CFC is produced by a catalytic amount of O2.

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Passage IV Fertilizers are substances added to the soil to improve plant growth and productivity. Commonly used fertilizers contain ionic salts of N, P, and K. Because of the complexity of soil chemistry, it is often difficult to predict how soil pH will be affected by the addition of a fertilizer. Ionic salts used as fertilizers can generally be classified chemically as either acidic or basic. Ammonium dihydrogen phosphate (NH4H2PO4), a commonly used fertilizer, can alter soil pH according to Equation 1. 2 NH4H2PO4(s) 2 NH4+(aq) + H2PO4–(aq) + HPO42–(aq) + H+(aq)

Equation 1 Alternatively, the fertilizer ammonium monohydrogen phosphate [(NH4)2HPO4] can alter soil pH according to Equation 2. 2 (NH4)2HPO4(s) + H2O(l) 4 NH4+(aq) + HPO42–(aq) + H2PO4–(aq) + OH–(aq)

Equation 2

If a fertilizer alters the original soil pH too drastically, CaCO3, a standard “liming” material, can be used to raise soil pH, and CaCl2 can be used to lower soil pH. Ammonia is sometimes applied directly to the soil to increase the ammonium ion content by its interaction with water in the soil. The ammonium ions from all these sources can further affect soil pH during the nitrification process. In this process, soil microbes convert ammonium ions to nitrate ions according to Equation 3. NH4+(aq) + 2 O2(g) → NO3–(aq) + H2O(l) + 2 H+(aq)

Equation 3 The nitrate ions are taken up by plants and converted first to nitrite ions, NO2–, then to ammonia for amino acid synthesis in the plant.

19. After adding the fertilizer shown in Equation 2 to the soil, what will be the most likely effect of excessively moist soil conditions? A) The degree of ionization will be greater, releasing more OH–. B) The degree of ionization will be greater, consuming more OH–. C) The degree of ionization will be reduced, releasing more OH–. D) The degree of ionization will be reduced, consuming more OH–. 20. Which of the following is the most likely reason that plants CANNOT utilize nitrogen from the atmosphere? A) N2 is present in very low concentrations in the atmosphere. B) N2 is too polar. C) N2 is very unreactive because it is a noble gas. D) N2 is very unreactive because of the great strength of the N≡N triple bond. 21. In Equation 1, HPO42– is the conjugate: A) acid of NH4+. B) base of NH4+. C) acid of H2PO4–. D) base of H2PO4–. 22. Which of the following equilibria best accounts for the pH-raising effect of CaCO3? Ca2+ + CO32– A) CaCO3 B) CaCO3 + 2 H2O CaH2 + H2CO32– + 2 OH– 2– C) CO3 + H2O HCO3– + OH– D) Ca2+ + H2O CaH2 + OH– 23. In the equilibrium constant expression for Equation 2, [H2O] is omitted because the salt is: A) only weakly basic, and [H2O] is nearly constant. B) strongly basic, and [H2O] is nearly zero. C) only weakly acidic, and [H2O] is nearly constant. D) strongly acidic, and [H2O] is nearly zero.

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11

These questions are not based on a descriptive passage and are independent of each other.

24.

Na2CO3 + HCl

→ CO

2

+ H2O + NaCl

Consider the above unbalanced equation. For this reaction, how many mL of a 2 M solution of Na2CO3 are required to produce 11.2 L of CO2 at STP? A) 125 mL B) 250 mL C) 375 mL D) 500 mL 25. By how much does the oxidation number of manganese in MnO4– differ from that of Mn2+? A) 1 B) 2 C) 5 D) 6 26. If ocean waves strike the shore every 3.0 s and the horizontal distance between adjacent crests and troughs is 1.0 m, what is the average speed of the waves? A) 0.33 m/s B) 0.67 m/s C) 1.5 m/s D) 3.0 m/s 27. A particle is moving on a circular path, whose radius is 4 cm, with a frequency of 4 Hz. How long will it take for the particle to move through a distance of 16π cm along the circle? A) 1/4 s B) 1/2 s C) 1 s D) 4 s

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Passage V A chemist is studying the catalytic effect of the enzyme polynucleotide phosphorylase (PNP) on the polymerization of cytosine 3',5'-diphosphate (CDP). PNP cleaves nucleoside diphosphates with the release of a phosphate species, and the addition of a trace amount of magnesium ion ensures that the catalyst is active. Equation 1 shows a polymerization reaction in which a single polymer macromolecule is made from CDP.

Equation 1 In practice, the reaction shown in Equation 1 occurs many times, yielding a product composed of many polymeric strands. Experiment 1 The chemist dissolves 16 mmol CDP in 1 L of an aqueous solution containing PNP and Mg2+ and buffers the solution at pH 8.7. The chemist monitors the reaction by measuring the amount of inorganic phosphate produced. No reaction is detected for 30 min, then the reaction appears to proceed at a constant rate until it stops with a final HPO42– concentration of 8 mM. The recovered polymer contains 7.5 mmol of cytosine.

28. What mass of CDP (403 g mol–1) is in 10 mL of the buffered solution at the beginning of Experiment 1? A) 6.4 x 10–4 g B) 6.4 x 10–3 g C) 6.4 x 10–2 g D) 6.4 x 10–1 g 29. As an alternative to Experiment 2, the chemist also can improve the yield of the polymer obtained in Experiment 1 by increasing the amount of: A) H2O. B) PNP. C) Mg2+. D) CDP. 30. Which of the following expressions gives the equilibrium constant (Keq) for the reaction shown in Equation 1? A) B) C) D)

[(CP)n] [HPO42–]n [CDP]n [(CP)n] [HPO42–] [CDP]n [(CP)n] [HPO42–]n [CDP] [CP] [HPO42–]n [CDP]n

Experiment 2

31. According to Equation 1, the concentration of the polymer with respect to [HPO42–] is:

The chemist repeats Experiment 1 but adds enough manganese sulfate to precipitate the slightly soluble manganese hydrogen phosphate as it forms. The recovered polymer contains 11.4 mmol of cytosine.

A) n[HPO42–]. B) n2[HPO42–]. C) (1/n)[HPO42–]. D) (1/n2)[HPO42–]. 32. The pKa for the dissociation of H2PO4– to HPO42– is 6.7. What is the initial ratio of [HPO42–]:[H2PO4–] in the buffer solution of Experiment 1? A) 1:1 B) 2:1 C) 100:1 D) 200:1

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13

Passage VI Carbon dating is a common method for estimating the age of artifacts found by archaeologists. The principle of radioactive dating is based on knowledge of the characteristics of the 14C isotope, which is commonly found in most handmade objects. This isotope is unstable and experiences spontaneous beta decay with a half-life of approximately 6000 years. Archaeologists need only a single radioactive measurement from a found object to estimate the age of the object. Scintillation detectors are often used for measurement of radioactive decay. A scintillator is a substance that produces light as a result of the de-excitation of atoms. The excitation is caused by the absorption of energy, in this case from incident beta radiation. A scintillating material is attached to a photomultiplier tube that collects the light and converts it into electrical pulses, which are measured and counted. The electrical pulses indicate the energy of the radiation produced by the object being measured and the rate at which the decay occurs. The mass of the beta particle is 9 × 10–31 kg. The velocity of electromagnetic radiation in vacuum is 3 × 108 m/s. Planck’s constant is 6.6 × 10–34 J·s.

35. The average velocity of a beta particle ejected from 14C is 3 x 107 m/s. What is the average kinetic energy of this beta particle? A) 1.5 x 10–8 J B) 2.3 x 10–16 J C) 4.0 x 10–16 J D) 1.5 x 10–23 J 36. The best materials to use as scintillators are nearly transparent to the wavelengths of the light that they emit. This characteristic is important because: A) it minimizes the reabsorption of the light. B) it maximizes the reabsorption of the light. C) it maximizes the amount of light produced. D) it increases the wavelength of the light produced. 37. When the wavelength for maximum light emission of a given scintillator is 450 nm, what is the energy of the light photon? A) 4.4 x 10–19 J B) 1.4 x 10–25 J C) 4.4 x 10–28 J D) 2.9 x 10–42 J

33. The 14C atom undergoes beta decay to 14N. What particle is being emitted from the carbon nucleus? A) Electron B) Alpha C) Neutron D) Positron 34. Archaeologists find an object that is known to be created 18,000 years ago. Measurements indicate that 1000 atoms of 14C are present in the object. How many atoms of 14C were present when the object was made? A) 1000 B) 3000 C) 3375 D) 8000

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14

Passage VII A group of students performed two experiments to study several transition metals. Experiment 1 The students reacted four transition metals with nonmetals and observed the products formed (Table 1). Table 1 Products of Reacting Transition Metals with Nonmetals Transition Metal Ni Cu

O2(g) NiO Cu2O, CuO ZnO Ag2O

Zn Ag

S(s) NiS Cu2S ZnS Ag2S

Nonmetal Cl2(g) Br2(l) NiCl2 NiBr2 CuCl2 CuBr2 ZnCl2 AgCl

ZnBr2 AgBr

I2(s) NiI2 CuI ZnI2 AgI

Experiment 2 The students prepared solutions of 0.1 M X(NO3)n(aq), where X represents a transition metal. Then they prepared the following three reagents. • • •

0.1 M NaCl(aq) 0.1 M (NH4)2C2O4(aq) 0.1 M Na2CO3(aq)

The students put 2.0 mL of X(NO3)n(aq) into each of three test tubes. They added 2.0 mL of NaCl(aq) to the first tube, 2.0 mL of (NH4)2C2O4(aq) to the next tube, and 2.0 mL of Na2CO3(aq) to the third tube. They observed whether a precipitate formed and noted its color (Table 2). Table 2 Results of Adding Reagents to Transition Metal Solutions Transition Color of precipitate Metal NaCl(aq) (NH4)2C2O4(aq) Na2CO3(aq) Ni(NO3)2(aq) * * green Cu(NO3)2(aq) * aqua blue Zn(NO3)2(aq) * white white Cd(NO3)2(aq) white white white AgNO3(aq) white colorless yellow

Note: * indicates that no precipitate formed. Finally, the students added 2.0 mL of 1.0 M HNO3(aq) to each tube containing a precipitate. In all but two cases, the precipitate disappeared when HNO3(aq) was added. The precipitate remained in the tube that contained AgNO3(aq) and NaCl(aq) and in the tube that contained AgNO3(aq) and (NH4)2C2O4(aq).

38. Cu attains a different oxidation state when it reacts with Cl2(g) than when it reacts with I2(s) because Cl2(g): A) has a higher boiling point than does I2(s). B) has a lower boiling point than does I2(s). C) attracts electrons more strongly than does I2(s). D) attracts electrons less strongly than does I2(s). 39. What was the most likely identity of the precipitate that formed when NaCl(aq) was added to Cd(NO3)2(aq)? A) Cd2Cl(s) B) CdCl(s) C) CdCl2(s) D) CdCl3(s)

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40. If Cd is reacted with S, what is the most likely oxidation state of Cd in the product? A) +1 B) +2 C) +4 D) +6 41. When a strip of Cu is placed into H2O(l), no change is observed. However, when a strip of Cu is placed into a solution of HNO3(aq), a gas evolves. What is the most likely identity of the gas? A) NO(g) B) CO2(g) C) H2(g) D) O3(g) 42. In Experiment 2, is the boiling point of Zn(NO3)2(aq) higher than that of AgNO3(aq)? A) Yes, because the solute in Zn(NO3)2(aq) is ionic, whereas the solute in AgNO3(aq) is not B) Yes, because the solute in Zn(NO3)2(aq) dissociates into three ions, and the solute in AgNO3(aq) dissociates into two ions C) No, because the solute in Zn(NO3)2(aq) has a higher molecular weight than does the solute in AgNO3(aq) D) No, because Zn(NO3)2(aq) contains fewer grams of solute than does AgNO3(aq) 43. When a strip of Cu is placed in AgNO3(aq), a new metal forms on the surface of the Cu strip. This occurs because Cu is: A) reduced and Ag is oxidized. B) reduced and Ag+ is oxidized. C) oxidized and Ag is reduced. D) oxidized and Ag+ is reduced.

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Passage VIII A student performed an experiment to investigate thermal and electrical properties of an iron wire. At room temperature the wire had a length (L) of 4 m, a diameter (D) of 4 × 10–4 m, and a mass (M) of 4 × 10–3 kg. The wire was connected in series with an ammeter, a power supply, and a switch. The student selected a voltage (V) and closed the switch so current (I) flowed through the circuit, raising the wire’s temperature (T). The values in Table 1 were measured in five trials with different wire temperatures. (Note: The initial value of R, the circuit’s resistance, was measured at a temperature of 293 K with an ohmmeter. The other values of R were calculated from the values of V and I.) Table 1 Data for Thermal and Electrical Properties of Iron Wire R T L I V Trial (K) (m) (A) (V) (Ω) 1 293 4.000 4.0 0 0 2 373 4.004 6.1 0.75 4.6 3 473 4.009 8.7 1.18 10 4 573 4.014 11.3 1.60 18 5 673 4.019 13.9 2.00 28 The change in wire length (∆L) is related to the change in temperature (∆T) by the relationship ∆L = αL∆T, where α , the coefficient of thermal expansion, is a constant. A similar relationship, ∆D = αD∆T, describes how the diameter of a wire changes when it is heated. The constant has the same value in both equations. The energy radiated from a heated wire each second is AσT 4, where A is the surface area of the wire, and σ = 5.67 × 10–8 J/m2·s·K4 is the Stefan-Boltzmann constant.

44. What is the electrical power through the wire when T is 673 K? A) 24 W B) 40 W C) 56 W D) 72 W 45. What is the approximate density of the wire at 473 K? (Note: The volume of the wire is 5 x 10–7 m3.) A) 2,000 kg/m3 B) 3,600 kg/m3 C) 6,400 kg/m3 D) 8,000 kg/m3 46. Which of the following graphs best illustrates the relationship between T and R? A)

B)

C)

D)

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47. The ratio of T in Trial 5 to T in Trial 3 is approximately . What is the ratio of the energy radiated each second for Trial 5 to that of Trial 3? A) B) 2:1 C) 2 D) 4:1 48. What is the minimum amount of heat energy required to increase T from 373 K to 573 K? (Note: The heat capacity of iron is 460 J/kg·K.) A) 368 J B) 550 J C) 1,840 J D) 3,680 J 49. During Trial 5, the wire was heated from 293 K to 673 K while V was held constant at 28 V. How did the current through the circuit change during this time? A) It remained constant at 2 A. B) It remained constant at 7 A. C) It increased from 2 A to 7 A. D) It decreased from 7 A to 2 A.

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18

These questions are not based on a descriptive passage and are independent of each other.

53. Below is a phase diagram for water.

50. The initial decay activity of a given quantity of a radioactive element is 240 counts/min. After 24 min, the activity is 60 counts/min. What is the half-life of the element? A) 4 min B) 12 min C) 24 min D) 48 min 51. Which of the following describes the entropy change for the sublimation of iodine I2(s) → I2(g)? A) ∆S < 0 B) ∆S = 0 C) ∆S > 0 D) Cannot be determined from the given information. 52. When a sound source moves away from an observer, the observer has the impression that the sound source is: A) rotating. B) louder than it actually is. C) lower in frequency than it actually is. D) higher in frequency than it actually is.

As the pressure applied to a sample of water at – 0.1°C is increased from 1.0 torr to 200 atm at constant temperature, the: A) vapor will become a solid and then a liquid. B) vapor will become a liquid and then a solid. C) vapor will become and remain a solid. D) solid will become a liquid. 54. A small negatively charged particle is placed near a fixed positively charged particle (Q). Which of the following describes the motion of the negatively charged particle? A) It accelerates away from Q. B) It accelerates toward Q. C) It moves with constant speed away from Q. D) It moves with constant speed toward Q.

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Passage IX A chemist reacted Substance X with various quantities of Ti and then performed two experiments to study the properties of the resulting samples. The samples contained 0%, 1%, 3%, and 5% Ti (and were referred to as XT-0, XT-1, XT-3, and XT-5, respectively.) Experiment 1 The solubilities of the XTs were determined by adding a fixed amount of each to two different solvents, tetrahydrofuran (THF) and toluene (Figure 1). The results are shown in Table 1.

Table 2 Effects of Temperature Change on the Mass of XT Samples Temperature Mass of Sample (g) (°C) XT-0 XT-1, 3, & 5* 20° 1.0 1.0 700° 0.8 0.8 1,200° 0.8 0.8 1,500° 0.8 1.1 20° 0.8 0.8 1,200° 0.8 0.8 1,500° 0.8 1.1 * XT-1, 3, and 5 responded the same way.

55. Which of the following conclusions about XT solubility is most consistent with the data in Table 1? A) The solubility of XTs in THF decreases as the percentage of Ti increases. B) The solubility of XTs in toluene decreases as the percentage of Ti increases. C) XTs are more soluble in THF than in toluene. D) XTs are more soluble in toluene than in THF. Figure 1 Chemical structures of the solvents Table 1 Percent Solubility of XT Samples Amount of sample that dissolves (%) Compound THF Toluene XT-0 32 35 XT-1 35 38 XT-3 50 53 XT-5 60 65 Experiment 2 The XTs were placed under N2(g), then heated to 1,500°C, cooled, and reheated. The mass of each sample was recorded at various temperatures during the process (Table 2).

56. The loss in weight as XTs are heated from 20°C to 700°C most likely occurs because: A) hydrogen bonds are formed. B) XTs are ionized. C) nuclei emit protons. D) volatile components are released. 57. Electrons in which of the following orbitals of Ti can form bonds with Substance X? A) 2s B) 3d C) 4p D) 5f

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58. Which of the following elements, if reacted with Substance X, will most likely yield compounds with the same properties as the XTs described in the passage? A) Sc B) Cu C) Zr D) Nb 59. Which of the following is the orbital hybridization of O in THF? A) sp2 B) sp3 C) sp3d2 D) s2p2 60. Which of the two solvents in Figure 1 is most soluble in H2O? A) THF, because THF forms hydrogen bonds with H2O but toluene does not B) THF, because THF forms stronger hydrogen bonds with water than does toluene C) Toluene, because toluene contains double bonds but THF does not D) Toluene, because toluene has a higher molecular weight than does THF

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Passage X A 47-kg child with a 3-kg sled and a 54-kg child with a 6-kg toboggan slide down the ice-covered hill illustrated in the figure below. Points A and B are at the top and bottom of the hill, respectively, and are a distance l apart along the slope. Between points A and B the sled and rider slide free of friction, but the toboggan and rider are opposed by a constant 60-N frictional force. To the right of Point B the sled and rider are opposed by a 50-N frictional force, and the toboggan and rider are opposed by a 120-N frictional force. (Note: Assume that air resistance is negligible. Use g = 10 m/s2.)

63. The sled and rider are traveling at 10 m/s when they have a completely inelastic collision with the stationary toboggan and rider. How fast do the sled and toboggan travel immediately after the collision? A) 4.6 m/s B) 5.0 m/s C) 8.3 m/s D) 10 m/s 64. What is the coefficient of friction between the sled and the ground when the sled and rider are to the right of Point B? A) 0.1 B) 0.2 C) 0.5 D) 1.0 65. From ground level, a person at Point A throws a snowball horizontally to the right at 25 m/s. Where does the snowball land?

61. Which of the following best describes the energy conversion that is taking place when the toboggan is sliding from Point A to Point B? A) Kinetic to potential and thermal B) Kinetic and potential to thermal C) Potential to kinetic and thermal D) Potential and kinetic to thermal 62. Which of the following expressions gives the amount of energy lost to friction by the toboggan and rider between points A and B? A) (60 N)(20 m) B) (60 N)(l) C) (60 kg)(g)(20 m) D) (60 kg)(g)(l)

A) 10 m to the left of Point B B) At Point B C) 12.5 m to the right of Point B D) 50 m to the right of Point B 66. The sled and rider start from a location on the hill that is 10 m lower than Point A. How does the speed of the sled and rider at Point B, starting from this location, compare to the speed of the sled and rider at Point B when starting from the top of the hill? A) It is slower by a factor of 4. B) It is slower by a factor of 2 . C) It is slower by a factor of 2. D) It is slower by a factor of .

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Passage XI Lasers produce extremely coherent light due to the long-term stability of the standing-wave pattern established within a laser cavity. A standing-wave pattern in a laser cavity is illustrated in the figure below.

Standing-wave patterns are characterized by nodes and antinodes. There are five nodes in the figure with three of them labeled. Antinodes are located midway between adjacent nodes. The amplitude is always zero at a node, but the wave amplitude oscillates sinusoidally at an antinode. A typical laser cavity may contain millions of cavity nodes. A number used to describe standing waves is the mode number, m, which is equal to one less than the number of nodes in the standing-wave pattern. Laser cavities have mode numbers that are related to the allowed cavity wavelength, λm, through the equation mλm = 2L, where L is the length of the laser cavity. For a gas laser, the atomic properties of the lasing medium may limit the number of possible frequencies of oscillation to two or three. These allowed frequencies, fm, are determined by the equation fm = c/λm, where c = 3 × 108 m/s, the speed of light.

67. What is the spacing between adjacent nodes in a standing-wave pattern? A) 2λ B) 3λ 2 C) λ D) λ 2

68. For a given laser-cavity mode, the standing-wave pattern within a laser cavity can be viewed as a superposition of two traveling waves. Their amplitudes and directions are described by which of the following? A) Equal amplitudes; opposite directions B) Equal amplitudes; same direction C) Different amplitudes; same direction D) Different amplitudes; opposite directions 69. A certain laser has only one mode of oscillation. Which of the following are properties of the light it emits? I. II. III.

It is monochromatic. It is coherent. It is diffuse.

A) I only B) I and II only C) I and III only D) II and III only 70. A gas laser has a cavity length of ⅓ m and a single oscillation frequency of 9.0 x 1014 Hz. What is the cavity mode number? A) 1.5 x 106 B) 2.0 x 106 C) 3.0 x 106 D) 6.0 x 106 71. A gas laser can oscillate simultaneously in two adjacent cavity modes. This oscillation produces beats; the beat frequency is ƒb = (fm+1 – fm) where ƒm+1 and ƒm are the frequencies of the two cavity modes. Which of the following is an expression for the beat wavelength? A)

(fm+1 – fm) c B) c(fm+1 – fm) C) 1 c(fm+1 – fm) D) c (fm+1 – fm)

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These questions are not based on a descriptive passage and are independent of each other.

72. An object that is totally immersed in benzene (specific gravity = 0.7) is subject to a buoyancy force of 5 N. When the same object is totally immersed in an unknown liquid, the buoyancy force is 12 N. What is the approximate specific gravity of the unknown liquid? A) 0.3 B) 0.9 C) 1.7 D) 2.3 73. A 1.0-kg object slides along a frictionless surface at 8.0 m/s until it strikes a stationary 3.0-kg block. If the blocks stick together, what is their speed immediately after the collision?

76. The principal quantum number is a measure of which of the following? A) Approximate radial size of an electron cloud B) Approximate shape of an electron cloud C) Number of valence electrons that orbit a nucleus D) Number of protons and neutrons found in the nucleus of an atom 77. An unknown solid weighs 31.6 N. When submerged in water, its apparent weight is 19.8 N. What is the specific gravity of the unknown sample? A) 2.96 B) 2.68 C) 2.02 D) 1.68

A) 1.0 m/s B) 2.0 m/s C) 4.0 m/s D) 8.0 m/s 74. Which of the following will occur if the acidity of a saturated solution of Ca(OH)2 is increased? A) The Ksp will decrease and additional Ca(OH)2 will dissolve. B) The Ksp will be unchanged and additional Ca(OH)2 will dissolve. C) The Ksp will decrease and additional Ca(OH)2 will precipitate. D) The Ksp will be unchanged and additional Ca(OH)2 will precipitate. 75. In a nearsighted individual, the image of a distant object is focused: A) in front of the retina, requiring divergent lens correction. B) in front of the retina, requiring convergent lens correction. C) behind the retina, requiring divergent lens correction. D) behind the retina, requiring convergent lens correction. Sharing or reproducing this material in any form is a violation of the AAMC copyright.

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Verbal Reasoning Time: 85 minutes Questions: 78-137 There are nine passages in the complete Verbal Reasoning test. Each passage is followed by several questions. After reading a passage, select the one best answer to each question. 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.

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).

Passage I As the national government has reordered its economic priorities, state and local governments have become more innovative and active vis-à-vis their economies. The characteristic that distinguishes state and local economic development activity is competitiveness. Nonnational governments are awash in competition for economic development, primarily for a structural reason: A fragmented federal system fosters interjurisdictional competition. More that 82 percent of influential local officials in Southeastern cities termed the economic development environment “very competitive” in a survey conducted in l986. State and local governments have reacted to this situation by taking actions intended to make themselves more attractive to new and relocating enterprises. If a business firm is unhappy with conditions in a community, it may seek a new location, and it is likely to find other communities waiting with open arms. When the Mack Truck Company announced its intention to relocate its manufacturing facility from Allentown, Pennsylvania, it had an array of communities from which to choose. To make themselves more enticing, the beckoning jurisdictions (and their state governments) offered a panoply of incentives, including property tax abatements, belowcost land, infrastructure, and training programs for potential employees. Mack Truck decided to relocate to South Carolina. Economic competition is most apparent when the stakes are high—that is, when the location decision will mean a substantial number of jobs, as in the case of General Motors’ Saturn plant. State after state lined up to offer General Motors generous packages of financial incentives, promising an assortment of tax breaks, access roads, water and sewer systems, and employee training. The eventual winner was Tennessee. There is a great deal of debate about the effect of interjurisdictional competition. As we noted earlier, incentives and concessions amount to a giveaway to business. Critics claim that competition for economic development is nothing more than the relocation of a given amount of economic activity from one community to another, with no overall increase in national productivity. The solution, they argue, is increased cooperation. However, this is elusive. For

example, governors of the Great Lakes states have been unsuccessful in establishing a “no pirating” pact within the region. Counties have found cooperation challenging, too. A National Association of Counties study of urban counties reported that only 5 percent frequently coordinated their economic development activities with other counties. Only slightly more (19 percent) indicated frequent coordination with cities located within their boundaries. Economic development has tended to be a singular proposition, with each jurisdiction pursuing its own destiny. This can be destructive to the jurisdictions involved. For example, the State Development Board in South Carolina, an agency devoted to promoting the state as a place for investment, has encouraged rural counties to band together and pursue a united economic development effort. But the board’s encouragement does not square with political realities. Lingering rivalries between adjacent counties effectively blunt efforts at cooperation. Further, while the board advocates intrastate cooperation, it explicitly engages in interstate competition: The reason that South Carolina counties should work together, it argues, is to become stronger competitors against North Carolina counties. Competition continues, but in a different arena. Economic conditions may ultimately serve as the catalyst for greater cooperation among jurisdictions. This is exactly what has occurred in the Monongahela River Valley area. This 7,400-square-mile section of southwestern Pennsylvania, northern West Virginia, and western Maryland has found that the markets for its products and traditional sources of investment are drying up. Individual jurisdictions have realized that the economic problems are too big for them to solve alone; the troubled economies of the cities and counties are symptoms of a region-wide malaise. After a series of false starts, local leaders have journeyed across county and state boundaries to develop a coordinated agenda for economic revival. Material used in this test passage has been adapted from the following source: A. O'M. Bowman & R.C. Kearney, State & Local Government. ©1990 by Houghton Mifflin.

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78. The passage suggests that economic competition between subnational units of government provides: A) the same positive benefits as does competition between private firms. B) an increase in efficiency for the competing governments. C) incentives for national economic development policy. D) fewer benefits over all than would cooperation between jurisdictions. 79. According to the passage, to whom might one look to foster cooperation rather than competition between jurisdictions? A) National officials B) Local leaders C) Academic researchers D) Media representatives

81. Suppose that a study found that in 47 randomly chosen counties, economic conditions had improved over a five-year period and that after that time, those counties coordinated their economic development activities with other counties. Which of the following statements is an assumption of the author about local jurisdictions that would be called into question? A) They never cooperate on economic development. B) They cooperate only if state law requires it. C) They cooperate most often under conditions of economic stress. D) They cooperate only with other jurisdictions within the same state. 82. According to the passage, competitive behavior with respect to economic development is characteristic of: I. II. III.

national government. state government. local government

80. Suppose that the Monongahela River Valley area prospered during the next ten years, even during times of general economic downturn. The lesson of this experience for local jurisdictions, in general, would be:

A) I only B) II only C) I and II only D) II and III only

A) to compete more intensely than previously. B) to keep their level of competition much the same as it had always been. C) to cooperate more than they had a decade previously. D) to attempt to get additional federal grants for local government.

83. Which of the following conclusions can justifiably be drawn from the experience of the Great Lakes states mentioned in the passage? A) State governments have little success in controlling economic competition among local governments. B) State governments usually restrict economic competition among local governments. C) Local governments are more successful than are state governments in controlling their economic competition. D) Only the national government has the power to regulate economic competition among local governments.

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Passage II Knowledge structures called memory schemas have become very important in theories of human learning and thinking. Schemas are organized knowledge structures in memory that can be thought of as generic concepts representing objects, persons, situations, events, sequences of events, actions, or sequences of actions. A memory schema is activated when information similar to its content is processed by the cognitive system. Once activated, the schema influences the processing of the new information and provides a mental context for it. If the information is similar enough to the content of the schema, then it is judged an instance of what the schema represents. The schema is thus instantiated by the new information. For example, if a person sees only an eye and a nose in a picture, with other facial features in shadow and not visible, the person may infer on the basis of this partial information that he or she should look for a face. This example assumes, of course, that the eye and nose have the correct orientation and the correct relative position. There is a special type of schema called a script that not only aids in comprehending and remembering information but also helps guide behavior. For example, when a person is eating in a restaurant, the restaurant script activated in memory enables the person not only to expect certain events (such as being shown a table and being approached by a waiter) but also initiates behavior (such as ordering and paying). If a person reading a passage comes upon the sentence “John was hungry, so he entered a restaurant,” the restaurant script is activated in memory. The advantage of having this active script available to the reader is that it provides general information about restaurants. However, specific information about this particular restaurant event must be selected from the passage as an instance of the script. If the next sentence is “John sat down near the door and gave his order to Paul,” then the generic script allows the reader to infer that John sat down at a table in a particular location and gave his order to someone named Paul who was a waiter. This process is called slot filling because information specific to the restaurant event being read is stored in memory as values for the particular actions, roles, and props involved in the restaurant script. The

script is being instantiated. The table involved is one near the restaurant door, and the waiter involved is Paul. Other information not explicitly mentioned in the passage can be inferred on the basis of what is stored in the generic script. For example, the reader may infer that the restaurant gave John a napkin to use and that the color of the napkin was white. If the reader later tries to remember the information read, the restaurant script is again activated and enables the restaurant event described in the passage to be remembered. The slots of the schema contain the information placed there during its most recent activation, although this information is not retained perfectly. Some forgetting may occur. Other types of recall errors can also occur. Because many inferences are made during schema-based comprehension, some information may be recalled that was never presented. These inferences often cannot be discriminated by the learner from the information presented. Material used in this test passage has been adapted from the following source: F.S. Bellezza, Mnemonic devices and memory schemas. ©1987 by Springer-Verlag.

84. The author would argue that schema theory is important to the study of thinking and learning because it: A) provides a basis for determining the memories of an event that are correct or true. B) explains the way previous experiences affect the comprehension of similar events. C) indicates the way important events, actions, or persons could be forgotten. D) illustrates the way memory is activated in totally unfamiliar situations.

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85. The discussion of scripts includes the assumption that:

89. To judge whether instantiation has occurred, a researcher would need to determine:

A) each different encounter with a type of event is a new learning experience. B) remembered information exactly matches the content of the original event. C) once a script is developed, it cannot be used in new instances. D) schemas help people to cope with new instances of a situation.

A) whether new information contains elements of a new schema. B) whether new information alters a schema. C) the amount of information needed to activate a schema. D) whether new information fits a schema.

86. According to information in the passage, slot filling would be likely to occur when a child: I. II. III.

started a second year of school. learned to ride a bicycle. first saw the alphabet.

A) I only B) II only C) I and II only D) I, II, and III 87. If several readers were to recall conflicting details from the same literary work, this situation would best support the assertion that: A) inferences are made independently of schemas. B) scripts cannot be partially activated. C) schemas are instantiated subconsciously. D) recall errors are a normal feature of schema-based comprehension.

90. The passage states that a reader may later recall information that had not actually been presented. According to the author, this effect would probably have resulted from: A) the careful reading of the text. B) incomplete prior knowledge of the topic. C) inferences made by the reader. D) the instantiation of more than one schema. 91. Which of the following approaches to reading instruction would be most likely to be stressed by an elementary-school teacher who had an understanding of schema theory? A) The development of background knowledge B) The improvement of pronunciation skills C) The importance of rote memorization D) The explanation of unfamiliar words

88. Which of the following statements is the most reasonable conclusion that can be drawn from the author’s description of script activation? A) Instantiation occurs deliberately. B) Behavior is guided by prior knowledge. C) Slot filling provides generalized information. D) Inferencing depends on the processing of new information.

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92. In discussing problems with recall after reading, the author refers to inferences made during schema-based comprehension. This process could reasonably be described as: I. II. III.

activating the wrong script. using prior knowledge to “rewrite” the text. skimming to acquire specific facts.

A) I only B) II only C) I and II only D) II and III only 93. The contention that “the schema influences the processing of the new information and provides a mental context for it” can most justifiably be interpreted as support for the idea that: A) understanding requires concentrated study. B) experience supplies a framework for learning. C) meaning can arise only after all the facts are acquired. D) clear thinking requires a conscious exercise of memory.

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Passage III Research traditions and theories can encounter serious cognitive difficulties if they are incompatible with certain broader systems of belief within a given culture. Such incompatibilities constitute conceptual problems that may seriously challenge the acceptability of the theory. But it may equally well happen that a highly successful research tradition will lead to the abandonment of that world view which is incompatible with it and to the elaboration of a new world view compatible with the research tradition. Indeed, it is in precisely this manner that many radically new scientific systems eventually come to be “canonized” as part of our collective “common sense.” In the seventeenth and eighteenth centuries, for instance, the new research traditions of Descartes and Newton went violently counter to many of the most cherished beliefs of the age on such questions as “humanity’s place in Nature,” the history and extent of the cosmos, and more generally, the nature of physical processes. Everyone at the time acknowledged the existence of these conceptual problems. They were eventually resolved, not by modifying the offending research traditions to bring them in line with more traditional world views, but rather by forging a new world view which could be reconciled with the scientific research traditions. A similar process of readjustment occurred in response to the Darwinian and Marxist research traditions in the late nineteenth century; in each case, the core, “nonscientific” beliefs of reflective people were eventually modified to bring them in line with highly successful scientific systems. But it would be a mistake to assume that world views always crumble in the face of new scientific research traditions which challenge them. To the contrary, they often exhibit a remarkable resilience which belies the (positivistic) tendency to dismiss them as mere fluff. The history of science, both recent and distant, is replete with cases in which world views have not evaporated in the face of scientific theories which challenged them. In our own time, for instance, neither quantum mechanics nor behavioristic psychology has shifted most people’s beliefs about the world or themselves. Contrary to quantum mechanics, most people still conceive of the world as being populated by substantial objects, with fixed and precise properties; contrary to behaviorism, most people still

find it helpful to talk about the inner, mental states of themselves and others. Confronted with such examples, one might claim that these research traditions are still new and that older world views predominate only because the newer insights have not yet penetrated the general consciousness. Such a claim may prove to be correct, but before we accept it uncritically, there are certain more striking historical cases that need to be aired. Ever since the seventeenth century, the dominant research traditions within the physical sciences have presupposed that all physical changes are subject to invariable natural laws (either statistical or nonstatistical). Given certain initial conditions, certain consequences would inevitably ensue. Strictly speaking, this claim should be as true of humans and other animals as it is of stars, planets, and molecules. Yet in our own time as much as in the seventeenth century, very few people are prepared to abandon the conviction that human beings (and some of the higher animals) have a degree of indetermination in their actions and their thoughts. Virtually all of our social institutions, most of our social and political theory, and the bulk of our moral philosophy are still based on a world view seemingly incompatible with a law-governed universe. Material used in this test passage has been adapted from the following source: L. Lauden, Progress and Its Problems: Towards a Theory of Scientific Growth. ©1977 by The Regents of the University of California.

94. The author of the passage characterizes the theory of quantum mechanics as one that: A) most people accept even though it seems to conflict with common sense. B) challenges the view most people have about the world in which they live. C) is incompatible with the idea that we live in a universe governed by natural laws. D) has led most people to change their world views.

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95. According to the author, our social, political, and moral beliefs: A) are rooted in the idea that the same set of laws should apply to everyone. B) often coexist with a broader system of cultural attitudes with which they are inconsistent. C) conflict with scientific research traditions that have been accepted since the seventeenth century. D) grew out of the acceptance of Darwinism and Marxism among educated people in the late nineteenth century. 96. If the public reception of Einstein’s theory of relativity repeated the reception that the author claims was given to Newton’s ideas, most people would: A) accept the theory readily and quickly revise their ideas about natural laws. B) resist the theory initially but gradually modify their view of the universe. C) claim to believe the theory but ignore its profound implications. D) reject its version of reality as contrary to common sense. 97. The claim that natural laws should be as true of humans as of stars, planets, and molecules is most in accord with the view that: A) some scientific laws take a long time to become widely accepted. B) some physical changes can be explained by statistical laws only. C) in the seventeenth century, physical theories were thought to apply to all physical objects. D) all physical changes are completely determined by natural laws.

98. Assume that strong evidence from research in genetics has led many thoughtful people to change their ideas about what it means to be human. Which of the following claims would be strengthened? I.

II.

III.

“A highly successful research tradition will lead to the abandonment of that world view which is incompatible with it and to the elaboration of a new world view.” “It would be a mistake to assume that world views always crumble in the face of new scientific research traditions which challenge them.” “Very few people are prepared to abandon the conviction that human beings . . . have a degree of indetermination in their actions.”

A) I only B) III only C) I and II only D) I and III only 99. The author probably mentions that most people talk as if inner mental states existed in order: A) to demonstrate the weakness of some scientific theories. B) to provide an example of the application of natural law to human behavior. C) to illustrate the persistence of beliefs that conflict with scientific theories. D) to support the claim that behaviorism is a very new research tradition.

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Passage IV Approximately 65 million years ago, at the boundary between the Cretaceous and Tertiary geological periods (the K-T boundary), there was a large-scale and rapid extinction of plants and animals, including the dinosaurs. The discovery of high levels of the element iridium in rocks laid down at this time led to the proposal that an asteroid or a comet struck Earth, leading to the extinctions. This scenario proposes that the impact of the interplanetary object filled Earth’s atmosphere with dust and smoke, blocking out sunlight and lowering temperatures. The resulting “winter” would have had dire ecological consequences, including slowing plant growth. However, in the case of the K-T boundary, some scientists have expressed doubt that the dust could have made Earth cold enough for a long enough period to cause the massive extinctions observed. These doubts have led to a search for other possibly disastrous atmospheric effects of a collision between a celestial object and Earth. One might involve sedimentary rocks rich in carbonates, which are found in shallow ocean beds or on dry land that was once under the ocean. If an asteroid with a radius of 50 km struck a 4-km thick carbonate layer, there would be a significant release of carbon dioxide (CO2) into the atmosphere, enough to raise the atmospheric concentration of CO2 about a hundredfold. When sunlight hits Earth, a significant portion of its heat is radiated out into the atmosphere. Atmospheric CO2 absorbs the heat that is radiated from Earth and radiates it back to Earth. This warming is called the greenhouse effect. Over the past century, atmospheric CO2 has increased, primarily due to the burning of fossil fuels such as coal and oil. Projections of future fuel usage have prompted many experts to be concerned about further increases in atmospheric CO2 because these increases could lead to global warming and significant climatic changes. The temperature increases projected by some for the next century are on the order of 2°C to 4°C. Atmospheric modeling indicates that such increases could lead to, among other effects, a partial melting of the polar ice caps, causing flooding of low-lying coastal areas.

at the K-T boundary. A hundredfold increase in CO2 would lead to an increase of 20°C in global temperature within ten days. A smaller impact, such as an asteroid with a radius of 10 km hitting 2-km thick layer of carbonate rock, would lead to a warming of 5°C in the same period of time. Because of the slow mixing of atmospheric CO2, these increases in CO2 would persist for 10,000 years. The ecological effects of such rapid, significant, and persistent global warming would have been profound. For example, CO2 is less soluble in water as the temperature rises. Therefore, as the temperature of the upper ocean rose, its dissolved CO2 concentration would have decreased, and this decrease would have inhibited the growth of marine algae. Because these tiny plants are at the base of the oceanic food chain, many marine species would have become extinct. On land, the elevated temperatures would have disrupted weather patterns and thus the growth of land plants which form the basis of terrestrial food chains. Thus, global warming could have led to the extinction of the dinosaurs.

100. Evidence shows that at the K-T boundary, many species of fish became extinct within a short time. This fact tends to support the hypothesis concerning increased CO2 because: A) dissolved CO2 is poisonous to fish. B) fish would die because of the increased dust in the water. C) fish eat algae, which would flourish as atmospheric CO2 increased. D) warmer water holds less CO2.

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101. It is possible to measure the amount of dissolved CO2 that was present at the K-T boundary by examining cores of ice deep in the polar ice sheets. Such information would be relevant to the CO2 theory presented in the passage because it would: A) indicate whether CO2 levels had changed significantly. B) show that oceanic CO2 levels rose at the K-T boundary. C) prove that an asteroid had struck Earth. D) prove that dust did not cause climatic change at the time. 102. According to passage information, what would happen if an asteroid 10 km in diameter hit Earth in the deepest part of the ocean? A) Global temperatures would rise by 5°C. B) Large-scale extinctions of species would occur. C) Only aquatic species would become extinct. D) The passage does not address this possibility. 103. Which of the following scientific advances would most seriously challenge the hypothesis involving increased levels of CO2?

105. Which of the following assertions is most clearly a thesis presented by the author? A) No species can survive in high levels of CO2. B) Rapid temperature increases can occur if there is dust in the air. C) Marine species are less sensitive to CO2 concentrations than are terrestrial species. D) Extinctions at the K-T boundary may have occurred in part because a large celestial object hit Earth. 106. If the hypothesis of the passage is correct, one should find that at the K-T boundary: A) sea levels rose. B) excess iridium was not present. C) no large-scale extinctions occurred. D) the atmosphere was of constant composition. 107. Which of the following suppositions is most clearly believed by the author? A) Dinosaurs lived near the site of an asteroid impact. B) Many species died of starvation at the K-T boundary. C) Dust did not fill the air after an asteroid impact. D) Marine food chains are not dependent on CO2.

A) The dating of a major asteroid impact on carbonate rock not followed by a climatic change B) Proof of high iridium levels at the K-T boundary C) Further correlation of increased CO2 with global warming D) Confirmation of increases in global CO2 without an asteroid impact 104. In the late nineteenth century a volcano erupted, spewing massive amounts of ash into the air. According to the passage, this event could have led to: A) decreases in carbonate rocks. B) excess sunlight reaching Earth. C) temporary global cooling. D) increases in atmospheric CO2.

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Passage V From 1890, when he was nine, Picasso’s family saved virtually every scrap of paper on which he drew. Harbingers of Picasso’s later genius appear in fragmented and distorted aspects of form and scale, depictions garlanded by numerical and alphabetical symbols, a proliferation of trompe l’oeil, visual puns, outrageous caricatures, incongruous juxtapositions, and the like. We do not know whether Picasso consciously thought back to these graphic experiments when, two decades later, he and Georges Braque were inventing cubism, but at least at an unconscious level, Picasso could tap this reservoir of youthful experimentation. The standard story told of Picasso is that his precocious talent enabled him to surpass, without effort, all other artists in his milieu. It is worth considering Picasso’s own opinion that what is often considered early genius is actually the naïveté of childhood. “It disappears at a certain age without leaving traces.” It is possible that a young child who shows unusual flair will one day become an artist, but he or she “will have to begin again from the beginning. I did not have this genius. For example, my first drawings could not have been hung in a display of children’s work. These pictures lacked childlikeness. . . . At a youthful age I painted in a quite academic way, so literal and precise that I am shocked today.” At an exhibition of children’s art, Picasso once quipped, “When I was their age, I could draw like Raphael, but it has taken me a whole lifetime to learn to draw like them.” In such remarks, Picasso exalted children’s productions but also distanced his youthful self from the romantic view of artistic talent. It is true that the works preserved by Picasso’s family support the notion of Picasso as an aspiring academic painter (as his father was) and not as a charming naïf. However, we lack drawings by Picasso from his first eight years and so cannot determine the resemblance of his earliest efforts to those of other children. Moreover, his youthful caprices and marginalia may have been as crucial in his artistic development as his formally conceived early paintings. My own conclusion is that Picasso’s output during the first decade of his life was unusually skilled rather than frankly precocious but

that no word short of prodigy can describe him in his spectacular progress over the next several years. Apollinaire asserted that there were two kinds of artists: the unreflective virtuoso, who relies on nature, and the cerebral structurer, who relies on understanding. Mozart could serve as prototype for the first, Beethoven for the second. As a prodigy, Picasso epitomized the second type, but, said Apollinaire, he was able to convert himself into the first. “Never has there been so fantastic a spectacle as the metamorphosis he underwent in becoming an artist of the first type.” Picasso himself sensed the paradox of this transformation when he complained to Gertrude Stein, “If I can draw as well as Raphael, I have at least the right to choose my way, and they should recognize that right, but no, they say no.” The Portrait of Gertrude Stein (1906) stands out as an indicator of this transformation: Picasso asked his subject to remain for over eighty sittings. Then he went away for the summer, annihilated the recognizable facial features, and finished the portrait away from Stein, substituting masklike features for realistic ones. (Chastised because the portrait did not look like Stein, Picasso reportedly responded with one of the notable artistic one-liners of the century: “Don’t worry, it will.”) Material used in this test passage has been adapted from the following source: H. Gardner, Creating Minds. ©1993 by H. Gardner.

108. According to the author, Picasso’s artistic achievements were in large part the result of his: A) retention of the effortless genius of childhood. B) rejection of the art movements of his time. C) practice of making multiple revisions and amendments. D) learning to work with apparent spontaneity. 109. The word nature is used in the sense of: A) objects and scenes of the natural world. B) elementary aesthetic principles. C) intuitive artistic mastery. D) uncontrolled creative impulses.

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110. What is the author’s response to the standard story about the origin of Picasso’s genius? A) Acceptance: Picasso’s early drawings are described as unusually skilled and his progress as spectacular. B) Neutral: It is mentioned only to introduce the discussion of Picasso’s eventual virtuosity. C) Revisionist: It is presented as applicable only to Picasso’s earliest efforts. D) Skepticism: Picasso’s earliest drawings are presumed to be not especially precocious. 111. The assertion that Picasso’s early productions contain harbingers of his later art is NOT clearly consistent with the information about: A) the way Picasso described his first drawings. B) the distortions of form and scale in these works. C) the lack of drawings from his first eight years. D) the playfulness of his graphic experimentation.

114. The author’s characterization of Picasso’s artistic aims suggests that the retort, “Don’t worry, it will” meant that the painting: A) was intended to portray Stein as she would probably look in old age. B) would become a more accurate portrait as Picasso continued to work on it. C) was concerned with pictorial qualities other than a literally accurate likeness. D) was an attempt to teach viewers to look at portraits in a more analytic way. 115. A novel that would best represent the literary style of a reflective “cerebral structurer” would probably have: A) many layers of meaning. B) great emotional power. C) terse, realistic dialogue. D) universally symbolic images.

112. Which of the following innovative forms of art that are identified with Picasso most clearly exemplifies his own implied goals? A) Sculptures constructed of various surprising “found objects” B) “Blue period” paintings with muted colors and elongated figures C) Plates decorated with boldly colored, simply indicated faces D) Single-tone paintings with “hard-edged” multifaceted perspectives 113. Which passage information provides the strongest reason to suppose that Picasso had always been an artist of Apollinaire’s first type? A) Picasso quipped that as a child he could draw as well as Raphael. B) Picasso’s early drawings indicate exuberant experimentation. C) Picasso wrote that in his youth he painted “in a quite academic way.” D) Picasso revised his portrait of Gertrude Stein from memory.

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116. Assume that an art historian discovers scores of drawings done by Picasso between the ages of four and eight and that they resemble those of many children of artists. What is the relevance of this discovery to the author’s views about Picasso’s development? A) It strengthens them by demonstrating that Picasso’s mature work reverted to the level of his first drawings. B) It is consistent with them because the author suggests that Picasso became a prodigy only after age nine. C) It weakens them by showing that the transition to a cerebral structurer took place sooner than the author assumes. D) It weakens them by supporting Picasso’s own assessment of his first drawings. 117. Which of the following assertions is the most effective argument against Picasso’s statement that to become an artist, one “will have to begin again from the beginning”? A) The supposed genius of children’s art is really an appealing naïveté. B) The productions of childhood have left unconscious traces on which an artist can build. C) Some untrained artists produce only paintings with a childlike quality. D) Some widely admired painters produce work that is quite academic and unimaginative.

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Passage VI One of the hottest topics in anthropology today centers around the place of the mysterious Neandertals on the human family tree. These people lived at the juncture between the demise of Homo erectus and the advent of Homo sapiens sapiens, our own species. What role the Neandertals played in this transition has been the subject of long and contentious debate among anthropologists. Call them Homo sapiens neanderthalensis and acknowledge them as direct ancestors of modern humans? Or type them as Homo neanderthalensis and more distant relatives, members of a separate species outside our direct ancestry? If someone were to meet a Neandertal on the New York subway, he or she would be struck by the size and protrusion of the nose, the prominent ridges above the eyes, and the distinct absence of a chin. In addition, the forehead was much flatter and the skull longer, and although not readily apparent to fellow passengers, the bones of the skull would be much thicker than those in modern humans. What was inside that long, low cranium is the key to what it was to be a Neandertal. If quantity was the only measure, then the Neandertal’s apparent mental powers were impressive, because the average brain size was larger than a modern human’s—about 1,400 cc as compared with 1,360 cc. Some clues to their potential “humanness” do exist. For the first time in history, the Neandertal people performed ritual burials—a uniquely human activity. At the site of Le Moustier in France, the body of a Neandertal teenager was apparently lowered into a pit, where he was placed on his right side, his head resting on his forearm, as if asleep. Around the body were scattered the bones of a wild cow. Some prehistorians speculate that these bones were covered with meat at the time of the boy’s burial and were included as sustenance for his journey to the next world. The evolution of the Neandertals was a gradual affair, with roots going back at least 200,000 and maybe even 300,000 years. By 130,000 years ago, they were well established. And by the end of that interglacial respite, which ended 70,000 years ago, the exaggerated features of the classic Neandertals were well set. For the next 35,000 years or so—until they finally disappeared—Neandertals were truly people of the Ice

Age, and in many ways their anatomy reflects adaptations to cold climes. Subsistence for these people must have been demanding, particularly for those on the tundra of icebound Eurasia. Reindeer, wooly rhinos, and mammoth provided not only meat but also hide for clothing and bone for building shelters, as wood and other plant resources were scarce or absent. The resourceful Neandertals also manufactured a wide range of artifacts with which to tackle their daily chores. Stone tools clearly signal the pace of change in human prehistory. For the million years after the appearance of tools in the record, they remained crude in structure and limited in variety: choppers, scrapers, and flakes. Only about 200,000 years ago did the pace begin to change. The Levallois technique was developed, enabling toolmakers to produce several large flakes from a single lump of rock. When the Neandertals came onto the scene, they further refined this technique. Nevertheless, no further innovations were introduced for more than 50,000 years, when the modern human era began. Material used in this test passage has been adapted from the following source: R. Lewin, In the Age of Mankind. ©1988 by The Smithsonian Institution.

118. The author implies that the primary significance of Neandertals is their: A) uncertain classification. B) position as premodern humans. C) use of stone tools. D) burial of the dead. 119. The statement that stone tools “signal the pace of change in human prehistory” means that: A) stone tools indicate the need for a more advanced technology. B) innovations are normally followed by a slowing of the rate of technological change. C) radiocarbon dating reveals the chronology of technological change. D) changes in tools indicate changes in the toolmaker.

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120. A form of Homo erectus with apelike features and standing three feet tall lived in Ethiopia 700,000 years before Neandertals appeared. This information increases the likelihood of which of the following answers to the author’s question about the place of Neandertals on the “human family tree”? A) Homo sapiens sapiens and Neandertals have a common ancestor. B) Neandertals are the “missing link” between apes and humans. C) Multiple human family trees exist. D) Neandertals are the direct ancestors of humans. 121. The author claims that the Neandertals were resourceful in manufacturing artifacts. The support offered for this conclusion is: A) weak; their tools remained few and crude. B) weak; no examples of their tools are given. C) strong; their impressive intelligence implies resourcefulness. D) strong; they invented the Levallois technique of toolmaking. 122. If the author’s primary criterion for judging the “humanness” of Neandertals were applied to computers, which of the following systems would be most human? A) A mainline computer with a very large capacity B) An assembly-line robot that uses tools to make tools C) A weapons system that locates and destroys specified targets D) A child’s toy that is programmed to recite religious verses

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Passage VII Rita Dove’s Pulitzer-Prize-winning volume of poems, Thomas and Beulah, is divided into two almost equal parts called “Mandolin” and “Canary in Bloom.” The collection presents not only the single most important events and the resultant mind-sets in the separate lives of Thomas and Beulah but also the significant events of their shared lives from their different perspectives. “The Event” (from “Mandolin”) presents the night when Thomas and his friend Lem, both drunk, leaned on the rail of a river boat. Thomas challenged Lem to swim to an island, resulting in Lem’s death. “Taking in Wash” (from “Canary in Bloom”) presents Beulah’s memory of the tension between her mother and father. The shaping events of Thomas’s and Beulah’s lives create or contribute to psychological mind-sets represented, on the one hand, by a mandolin, ships, and water, and on the other, by a silk handkerchief, the Eiffel Tower, an unusual flower, and a ballerina music box. The mandolin represents both Thomas’s carefree days with Lem and the guilt suffered because of his death. In “Variation on Pain,” the “one pierced cry” of the strings of the mandolin are identified both with music and guilt (“Sound quivered like a rope stretched clear to land, tensed and brimming, a man gurgling air”) and with the strings Thomas used after piercing his ears, which in turn were also connected with his guilt (“Since what he’d been through, he was always jiving, gold hoop from the right ear jiggling and a glass stud, bright blue, in his left”). The references to ships and water are linked not only to Thomas’s guilt but also to his sense of a lack of freedom even on happy occasions, his disappointments, and ultimately, the escape from ordinary life that he has always desired—but not in the form he has wanted. After Lem’s death, Thomas eventually lands “on the dingy beach of a man-made lake.” When Thomas and Beulah marry, the parlor is “festooned like a ship”; later, he has “raised a mast and tied himself to it.” Still later, he is drowning in his disappointment in being “too frail for combat.” His fatal heart attack is “the river he had to swim”; he has the sensation that “his chest was filling with water,” and he becomes “a pod set to sea.”

In the “Canary in Bloom” section, the beautiful objects represent the juxtaposition of Beulah’s desire for a sensuous, beautiful life in faraway places and the realities of her life. In “Taking in Wash,” Beulah watches her parents quarrel. When she finds a picture of the Eiffel Tower in the newspaper, she takes it as a sign that “she would make it to Paris one day.” Sweeping the floor after Thomas tracked in sand, she recalls “a flower—very straight, with a spiked collar . . . she had gathered . . . in Tennessee.” Even as she dies, looking at the ballerina music box, she thinks, “In China, they do everything upside down.” Other poems in Thomas and Beulah present two perspectives on the same event. “Courtship,” “Courtship, Diligence,” and “Promises” set forth Thomas’s and Beulah’s attitudes toward their courtship and wedding. “Courtship” (in “Mandolin”) reveals Thomas’s longing as “his wrist flicks for the pleats all in a row” and he wraps “the yellow silk . . . around her shoulders.” Later, at his wedding, he wonders, “how did I get here?” In “Courtship, Diligence,” Beulah would “much prefer a pianola and scent in a skycolored flask, not that scarf, bright as butter.” In “Promises,” Beulah reluctantly turns her back on her father at her wedding, plunging “through sunbeams and kisses” to begin her life with Thomas.

123. The main idea of the passage is that Thomas and Beulah: A) won the Pulitzer Prize for its author, Rita Dove. B) is divided into two almost equal parts. C) reveals different perspectives on the same events. D) delineates the psychological and emotional lives of two individuals.

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124. On the basis of the passage, it is reasonable to conclude that: A) events linked to beautiful objects are associated with pain and guilt. B) events linked to ships and water can be associated with a desire for a sensuous life. C) some events, whether ordinary or extraordinary, have a profound impact on individual lives. D) events linked to ships and water are always associated with the gap between desire and fulfillment. 125. The similarity in Thomas’s and Beulah’s mixed feelings about their marriage is reflected in: A) Thomas’s “one pierced cry” and Beulah’s preferring “a pianola . . . not that scarf, bright as butter.” B) Thomas’s “always jiving” and Beulah’s desire “to hear wine pouring.” C) Thomas’s landing “on the dingy beach of a manmade lake” and Beulah’s recalling “a flower—very straight, with a spiked collar.” D) Thomas’s wondering “how did I get here” and Beulah’s reluctantly turning her back on her father. 126. If Rita Dove’s psychological insights are accurate, then: A) some married couples’ individual and shared lives are characterized by ambivalence and ambiguity. B) humans are rarely happy. C) couples are always mismatched with regard to their emotional lives. D) married men always long for freedom. 127. The lines “Perfect bystander, high and dry with a scream caught in his throat” and “On the other side of the world they are shedding robes sprigged with roses” can be connected, respectively, to: A) Thomas and Beulah. B) Beulah and Thomas. C) “Canary in Bloom” and “Mandolin.” D) Lem and Thomas.

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Passage VIII The biosphere, all organisms combined, makes up only about one part in ten billion of Earth’s mass. Yet life has divided into millions of species, each playing a unique role in relation to the whole. The hallmark of life is this: a struggle among an immense variety of organisms weighing next to nothing for a vanishingly small amount of energy. Life operates on only ten percent of the sun’s energy reaching Earth’s surface, that portion fixed by the photosynthesis of green plants. The free energy is then sharply discounted as it passes through the food webs from one organism to the next; very roughly ten percent passes to the caterpillars and other herbivores that eat the plants and bacteria, ten percent of that (or one percent of the original) to the spiders and other low-level carnivores that eat the herbivores, ten percent of the residue to the warblers and other middlelevel carnivores that eat the low-level carnivores, and so on upward to the top carnivores, which are consumed by no one except parasites and scavengers. Top carnivores, including eagles, tigers, and great white sharks, live on such a small portion of life’s available energy as always to skirt the edge of extinction. A great deal can be learned quickly about biological diversity by noticing that species in the food web are arranged into two hierarchies. The first is the energy pyramid, a straightforward consequence of the law of diminishing energy flow. The second pyramid is composed of biomass, the weight of organisms. By far the largest part of the physical bulk of the living world is contained in plants. The second largest amount belongs to the scavengers and other decomposers, from bacteria to fungi and termites, which together extract the last bit of fixed energy from dead tissue and waste at every level in the food web. Each level above the plants diminishes thereafter in biomass until you come to the top carnivores, which are so scarce that the very sight of one in the wild is memorable. No one looks twice at a sparrow or squirrel, but a peregrine falcon or mountain lion is a lifetime experience.

How is this inversion possible? The answer is that the photosynthetic organisms are not plants in the traditional landbound sense. They are phytoplankton, microscopic single-celled algae carried passively by water currents. Cell for cell, planktonic algae fix more solar energy and manufacture more protoplasm than plants on the land, and they grow, divide, and die at an immensely faster pace. Small animals, particularly copepods and other small crustaceans carried in the sea currents, hence called zooplankton, consume the algae. They harvest huge quantities without exhausting the standing photosynthetic crop in the water. Zooplankton in turn are eaten by larger invertebrate animals and fish, which are then eaten by still larger fish and marine mammals such as seals and porpoises, which are hunted by killer whales and great white sharks, the top carnivores. The inversion of the biomass pyramid is why the waters of the open ocean are so clear, why you can look into them and spot an occasional fish but not the green plants—algae—on which all the animals ultimately depend. Material used in this test passage has been adapted from the following source: E.O. Wilson, The Diversity of Life. ©1992 by E.O. Wilson.

128. Information in the passage suggests that biologists might speak of “the ten percent rule” to refer to which of the following quantities? I. II. III.

The proportion of available energy retained by a life form from photosynthesis or feeding The proportion of the total biomass at each level of the food hierarchy The relative number of species at each level of the food hierarchy

A) I only B) III only C) I and II only D) II and III only

The biomass pyramid of the sea is at first glance puzzling: It is turned upside down. The photosynthetic organisms still capture almost all the energy, but they have less total bulk than the animals that eat them. Sharing or reproducing this material in any form is a violation of the AAMC copyright.

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129. Which of the following phenomena violates the hierarchical organization of the food web described in the passage? I. Copepods feeding on algae II. Killer whales feeding on seals III. Ticks feeding on jackals A) II only B) III only C) I and II only D) I and III only 130. Assume that the following statements are true. Which one is inconsistent with the assertion that the biomass pyramid of the sea is inverted? A) The algae capture almost all the available energy. B) Whales are on the brink of extinction. C) The total bulk of zooplankton is greater than that of phytoplankton. D) The total bulk of invertebrate fish is greater than that of marine mammals. 131. If certain top carnivores evolved the ability to utilize the sun’s energy directly instead of through the consumption of plant-eating animals, how would the energy pyramid of their ecosystem be affected? A) It would be inverted. B) It would retain its structure. C) It would broaden at the top. D) It would be flattened. 132. The claim that photosynthesis absorbs only ten percent of the energy reaching Earth necessitates which of the following conclusions? A) The percentage of the sun’s energy that serves life on Earth directly is greater than the percentage converted to food energy. B) Green plants process energy from the sun more efficiently than do other life forms. C) Only a small percentage of the energy used by plants is provided directly by the sun. D) Only a small percentage of the energy used by top carnivores is provided directly by the sun.

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Passage IX Some people may have no friendships of a high level of moral excellence. And, as Aristotle recognized, some people may actually be incapable of such friendships. A truly selfish person could not have friends in the fullest sense. If someone were genuinely able to care for another person for the other’s own sake, if someone were able to give much of him- or herself to the other freely and for the other’s own sake, then he or she would not be selfish. It is true that selfish people can be very attached to one or another person—e.g., a spouse or friend. But it seems that such a friendship could not be a friendship of the most morally excellent kind. The attachment or friendship would be too grounded in self-centered considerations. Thus, a selfish man could be very attached to his wife, dote on her, and in some ways do a lot for her. But this would not mean that he really cared for her for her own sake. His behavior would be compatible with his caring for her, so to speak, for her willingness to serve him, to be at his command, to flatter his ego. His giving could be a minor concession for her serving him or even a further expression or assertion of his power over her and of her dependence on him. If he were truly selfish, then something like this would be the most likely explanation of his “beneficent” behavior. Nevertheless, it would be wrong to say that selfish people cannot really have friends at all, in any sense of the term. For first of all, there are important aspects of friendship besides caring for the other—i.e., enjoying being with the other person, or sharing certain kinds of activities, or liking the other person. So selfish people can have friends, in that there are others whom they like and enjoy sharing certain kinds of activities with. Second, even selfish people can wish others well, be well disposed toward others.

someone whom I like, whom I know likes me, who cares about my weal and woe, whom I trust, who is personally important to me, who cares about our friendship, etc. In acting from friendship toward Dave, I express my acknowledgment of a relationship which includes all these feelings and attitudes. This is why the caring and the acts of beneficence are not separate from my own interests, from what is personally a good to me. In fact, friendship is a context in which the division between self-interest and other-interest is often not applicable. Material used in this test passage has been adapted from the following source: L.A. Blum, Friendship, Altruism and Morality. ©1980 by Routledge & Kegan Paul.

133. Which of the following actions is an example of what the author probably means in implying that giving can be an assertion of power? A) A judge gives lighter sentences to criminals if they address the judge respectfully. B) Office workers give money to the boss’s favorite charity because the boss asks them to do so. C) A citizen distributes food to the homeless so that no one will go hungry. D) A husband suggests that he and his wife treat themselves to a vacation. 134. For which of the following of the author’s assertions is NO support provided in the passage? A) A truly selfish person cannot have friends in the truest sense. B) There is more to friendship than caring for another. C) There are plausible explanations for seemingly “beneficent” behaviors of selfish people. D) Even a selfish person can wish another well.

Thus, there are very different levels of friendship, levels which are understood in moral terms, in terms of how fully one cares for the other. Friendship always involves a giving of self to the other and a valuing of the other for his or her own sake. Friendship is an expression of moral activity on our part. In caring about the weal and woe of my friend Dave, it is integral to the nature of this caring that it be for Sharing or reproducing this material in any form is a violation of the AAMC copyright.

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135. Assume that the author’s friend Dave was interviewed. If Dave remarked that he and the author often argue about the way they will spend their time together, this remark would weaken the passage assertion that: A) friendship is an expression of moral activity. B) among friends, the line between self-interest and other-interest is often not applicable. C) some people may not be capable of friendships in the fullest sense. D) the author’s friendship with Dave helps to define what is important to the author. 136. If the author of the passage is right that friendship blurs the distinction between one’s own interests and the interests of one’s friends, then it follows that: A) by their very nature, friendships foster cooperation and reduce antagonism. B) selfishness must still find expression, but only in relationships with those who are not one’s friends. C) friendship can really begin only between people who know each other very well. D) friends become more and more alike the longer they are together. 137. Regarding the reciprocity and transitivity of friendship, the passage strongly implies that: A) if Mary is a friend to Bill, and Bill is a friend to Tom, then Mary is a friend to Tom. B) if Mary and Bill are friends, they satisfy the same needs in one another. C) Mary and Bill could have a true friendship in which Bill does most of the giving and Mary does most of the receiving. D) Mary cannot be a friend to Bill if Bill is not a friend to Mary, and vice-versa.

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Writing Sample Time: 60 minutes 2 Prompts, separately timed: 30 minutes each This is a test of your writing skills. The test consists of two parts. You will have 30 minutes to complete each part. Use your time efficiently. Before you begin writing each of your responses, read the assignment carefully to understand exactly what you are being asked to do. Because this is a test of your writing skills, your response to each part should be an essay of complete sentences and paragraphs, as well organized and clearly written as you can make it in the time allotted.

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138. Consider this statement: Education comes not from books but from practical experience. Write a unified essay in which you perform the following tasks. Explain what you think the above statements means. Describe a specific situation in which books might educate students better than practical experience. Discuss what you think determines when practical experience provides a better education than books do.

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139. Consider this statement: Scientific inquiry is rooted in the desire to discover, but there is no discovery so important that in its pursuit a threat to human life can be tolerated. Write a unified essay in which you perform the following tasks. Explain what you think the above statements means. Describe a specific situation in which a threat to human life might be tolerated in the pursuit of scientific discovery. Discuss what you think determines when the pursuit of scientific discovery is more important than the protection of human life.

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Biological Sciences Time: 100 minutes Questions: 140 - 216 Most questions in the Biological 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.

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Periodic Table of the Elements

1

H

2

He 4.0 10

1.0 3

4

Li

Be

B

C

N

O

F

Ne

6.9

9.0

10.8

12.0

14.0

16.0

19.0

20.2

5

6

7

8

9

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 Autoimmune diseases result when lymphocytes from the immune system attack the body’s own tissues. This is normally prevented by the body’s ability of selftolerance; that is, the immune system “recognizes” the body’s own tissues and forms very few lymphocytes that act against them. Autoimmune diseases may affect any type of body tissue. Two hypotheses have been advanced to explain how autoimmunity develops. Hypothesis 1 Most of the body’s self-tolerance is generated within a few months of birth, when the body is processing T and Blymphocytes. Identical groups (clones) of circulating lymphocytes remain inactive until they encounter their specific antigens, after which they proliferate. During this time, the process of clonal deletion destroys any newly formed groups of lymphocytes that might attack the body’s own tissues. If clonal deletion of such lymphocytes does not occur or is hindered, these lymphocytes will incorrectly recognize a specific body tissue as foreign or non-self, and begin to destroy it. Hypothesis 2 In addition to effector lymphocytes (such as helper T cells and cytotoxic T cells) that selectively attack and destroy antigens, the body contains other lymphocytes (suppressor T cells) that prevent this destruction by selectively limiting the action of the effector cells. Normally, a regulatory balance is maintained between effector and suppressor T cells. However, when this balance is disturbed (for example, by loss or inactivation of suppressor-cell clones), an autoimmune disease may result.

140. Certain individuals with autoimmune thyroid disease have an increased susceptibility to autoimmune liver disease. According to Hypothesis 2, which of the following groups of effector or suppressor cells have most likely been lost or inactivated in these individuals? A) Suppressor cells that respond to thyroid cells but not those that respond to liver cells B) Suppressor cells that respond to both thyroid cells and liver cells C) Effector cells that respond to thyroid cells but not those that respond to liver cells D) Effector cells that respond to both thyroid cells and liver cells 141. The human body never develops self-tolerance to the proteins of the cornea. According to Hypothesis 1, one reason for this might be that the corneal proteins: A) never circulate in the body fluids; therefore, they are never exposed to lymphocytes. B) are not part of a living tissue; therefore, development of self-tolerance is unnecessary. C) are adequately protected by tears and other external barriers to antigens. D) are protected by suppressor T cells rather than by clonal deletion. 142. According to the normal mechanism of selftolerance described in the passage, the body will respond to each antigen it encounters by activating: A) either B or T lymphocytes, but not both. B) lymphocytes against the antigen, if the antigen is from the body’s own tissues. C) all clones of lymphocytes that have not been destroyed by clonal deletion. D) a clone of lymphocytes specific for that antigen.

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143. According to Hypothesis 2, the normal balance between effector cells and suppressor cells specific for a certain tissue will most likely be disturbed if the tissue is injected with: A) cells for that tissue obtained from an identical twin. B) cells from another tissue to which the tissue has already been exposed. C) a foreign substance that cross-reacts with cells of that tissue. D) a foreign substance that does not cross-react with cells of that tissue. 144. Does acceptance of the mechanism of selftolerance described in Hypothesis 1 rule out acceptance of the mechanism described in Hypothesis 2? A) Yes; if clonal deletion occurs, no self-reactive lymphocytes will be left for suppressor T cells to act upon. B) Yes; Hypothesis 1 deals with the formation of selftolerance and Hypothesis 2 deals with its maintenance. C) No; suppressor T cell formation can only occur after clonal deletion has occurred. D) No; clones of self-reactive lymphocytes not destroyed by clonal deletion may be controlled by suppressor T cells. 145. The mechanism of self-tolerance described in Hypothesis 1 is generated in which of the following regions of the body? A) Bone marrow and thymus gland B) Bloodstream and lymph nodes C) Thyroid gland and adrenal gland D) Brain and spinal cord

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Passage II The defensive secretions of some termites contain biologically active alcohols. Chemists have attempted to synthesize and characterize these alcohols, and two partial syntheses are shown in Scheme A.

In Step 1, the C8 carbonyl group on Compound I is converted to a acetal, resulting in the formation of Compound II, which can be subjected to either of two synthetic pathways. In one pathway, when Compound II is treated with CH3MgBr, the methyl group adds to the remaining C1 carbonyl group, and the corresponding alcohol is formed (Compound III). It has been proposed that the methyl group adds to only one side of the molecule because of the steric hindrance by the C11 methyl group. Alternatively, Compound II can be converted to Compound V via an olefination reaction. When Compound VI is treated with LiAlH4, the hydride (H–) attacks an epoxide carbon, the ring opens, and the resulting oxygen anion is subsequently protonated with water to form Compound VII.

146. Compound Y is shown below.

Based on Scheme A, Compound Y can most likely be synthesized by substituting: A) an ethyl group for the methyl group on C11. B) a methyl group for the C1 carbonyl group. C) (CH3CH2O)3CH for (CH3O)3CH in Step 1. D) CH3CH2MgBr for CH3MgBr in Step 2. 147. Why did the chemist convert the C8 carbonyl group in Compound I to a acetal group in Step 1? A) Acetal groups are inert to all reaction conditions. B) Acetal groups are more reactive than carbonyl groups; therefore, the subsequent reactions require milder conditions. C) The C8 carbonyl group must be protected to prevent it from reacting in steps 2 and 4. D) The C8 carbonyl group must be protected to prevent it from reacting in steps 3 and 7.

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148. In the infrared spectrum of Compound IV, the stretches at 3,300 cm–1 (broad) and 1,700 cm–1 (sharp) correspond to which of the following bonds, respectively? A) C=O and O_H B) O_H and C=O C) C_O and C_H D) C=O and C_O 149. In Step 6 of Scheme A, if H2O is replaced with D2O, what will be the structure of the product? A)

B)

C)

D)

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Passage III When the neurotransmitter acetylcholine (ACh) is released from vesicles in the presynaptic terminals of neurons, it diffuses across synapses and stimulates specific postsynaptic receptors of adjacent neurons. Normally, most of the ACh is degraded in the synapses by the enzyme acetylcholinesterase, which is synthesized by the same neurons that produce ACh. ACh is abundant in brain regions that mediate learning and memory, and, when present at relatively high levels, is also involved in pain relief. A researcher used two drugs to study the role of ACh in the learning and memory processes of rats. Drug X is an acetylcholinesterase inhibitor, and Drug Y is a noncompetitive blocker of postsynaptic ACh receptors. Groups of rats were maintained on different treatment regimens, consisting of either a placebo (an inert substance) or a specific concentration of either Drug X or Drug Y. Using mild foot shocks as a deterrent, the researcher trained rats to avoid the darker compartment of a two-chamber training box. At the beginning of each learning session, rats were placed in the dark chamber and given 60 seconds before mild foot shocks were initiated. Additional shocks were administered every 60 seconds while any rats remained in the dark chamber. Learning was scored by the number of trials required before rats learned to avoid shock 100% of the time, and memory was scored by the number of incorrect reentries into the dark chamber (errors). Some results are shown in figures 1 and 2.

Figure 2 Effect of Drug Y on shock avoidance

150. ACh is the transmitter in the striated (voluntary) muscular system. What effect would Drug Y have on the functioning of this system? A) It would increase the synthesis of acetylcholinesterase. B) It would increase Ca2+ influx into the T tubules. C) It would block muscular contraction. D) It would stimulate muscular contraction. 151. An underlying assumption of the researcher regarding the actions of Drug X was that it: A) increased the amount of ACh in the synapse. B) affected learning by stimulating the autonomic nervous system. C) acted on the postsynaptic receptors. D) was synthesized in the same neurons as ACh was. 152. If Drug X and Drug Y are given together, will the rate of learning most likely increase or decrease? A) Increase, because the increased production of ACh caused by Drug X will overcome the blocking effect of Drug Y B) Increase, because, in general, both Drug X and Drug Y act to increase ACh production C) Decrease, because the excess ACh produced by Drug X will be degraded by Drug Y before it can affect learning D) Decrease, because although Drug X will increase ACh production, Drug Y will prevent it from being taken up by postsynaptic receptors

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153. The researcher discovered that increasing the concentration of Drug X resulted in greater inhibition of the hydrolysis of ACh by acetylcholinesterase. However, this effect was counteracted by increasing the concentration of ACh. These results indicate that Drug X acts on acetylcholinesterase as: A) an irreversible inhibitor. B) a competitive inhibitor. C) a noncompetitive inhibitor. D) a mixed competitive/noncompetitive inhibitor. 154. Based on the experiment in the passage, the best overall description of the effect of ACh on rat learning and memory is that: A) moderate increases in ACh utilization appear to disrupt memory and learning. B) moderate increases in ACh utilization appear to improve memory and learning. C) blockage of ACh receptors appears to improve memory and learning. D) blockage of ACh receptors appears to improve learning at low doses and disrupt it at high doses. 155. The fastest way to counteract the effects of Drug Y would most likely be to: A) increase its rate of metabolism and elimination from the body. B) administer increasing amounts of Drug X. C) administer a competitive receptor stimulator. D) administer another noncompetitive ACh receptor blocker that acts at the same site as Drug Y. 156. An autosomal recessive, nonlethal mutation (deletion) of the ACh receptor gene occurs in some rats. Which of the following organelles will most likely be abnormal in the rats having this mutation? A) Microtubules B) Ribosomes C) Endoplasmic reticulum D) Plasma membrane

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Passage IV The ciliate protozoan Tetrahymena contains two nuclei: a diploid, germ-line micronucleus and a 45-ploid macronucleus that is the site of gene expression during the vegetative state. Sexual reproduction in Tetrahymena occurs by the process of conjugation (Figure 1, Steps 1–8).

Figure 1 Adapted from Elizabeth H. Blackburn and Kathleen M. Karrer, “Genomic Reorganization in Ciliate Protozoans.” ©1986 by Annual Reviews Inc.

After conjugation, the four sexually produced progeny divide by binary fission. Each daughter cell receives an exact copy of the micronuclear DNA and an uneven (but approximately equal) amount of DNA from the amitotic macronucleus. To minimize fluctuations in DNA content, small macronuclei undergo an additional S phase before division, and large macronuclei eliminate an S phase.

157. Sexual reproduction is advantageous to Tetrahymena primarily because sexual reproduction: A) increases genetic variability in the population. B) produces a new somatic micronucleus in the sexual progeny. C) maintains genetic stability in a changing environment. D) allows a rapid increase in the population size.

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158. In the macronucleus, the genes for rRNA are located extrachromosomally. This suggests that the rRNA genes are: A) nonlinear. B) nonfunctional. C) self-replicating. D) rearranged. 159. An extra S phase occurs during amitotic division in a small macronucleus to minimize fluctuations in DNA content. This is most likely triggered by the presence of:

163. In a mating of two Tetrahymena strains that are homozygous in their macronuclei and heterozygous in their micronuclei for a recessive gene, what percentage of the F1 generation will express the recessive phenotype? A) 0% B) 25% C) 50% D) 100%

A) low concentrations of DNA in the macronucleus. B) centromeres in the macronucleus. C) high concentrations of DNA in the micronucleus. D) mitotic enzymes in the micronucleus. 160. The macronuclei of the asexual progeny in Tetrahymena and the cytoplasm of the ovaproducing cells of female vertebrates share a common feature in that both: A) undergo uneven division. B) contain uneven amounts of nuclear material. C) regulate their contents by adding or skipping an S phase. D) are apportioned at mitosis. 161. When an initially heterozygous macronucleus undergoes repeated binary fission, the result will be: A) the loss of macronuclear chromosomes. B) an increased rate of crossing over in the macronucleus. C) the production of a macronucleus with a genetic origin distinct from the micronucleus. D) a variable allele distribution in the macronucleus. 162. Some of the DNA sequences that are eliminated during macronuclear differentiation (Figure 1, Step 6) may be sequences involved in: A) transcription. B) translation. C) meiosis. D) ribosome production.

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These questions are not based on a descriptive passage and are independent of each other.

164. Which of the following properties is associated with the existence of glycine as a dipolar ion in aqueous solution? A) High dipole moment B) High molecular weight C) Low dielectric constant D) Low solubility in water 165.

β-D-glucuronide The compound shown above is the β-derivative of the D-glucuronic acid. The α-D-glucuronide differs in configuration from the β-derivative at: A) C-1. B) C-2. C) C-3. D) C-4. 166. Suppose that the amino acid sequences of a protein such as cytochrome oxidase are compared for a large number of species. The greatest number of amino acid differences will most likely be found between members of different: A) phyla. B) orders. C) species. D) families. 167. Which of the following recombinant processes depends on the F factor plasmid? A) Transformation B) Transduction C) Conjugation D) Translocation

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Table 1 Selected Amines and pKa Values of Their Conjugate Acids

Passage V The actual yield of an organic reaction in water is often lower than the theoretical yield because of a competing hydrolysis reaction that is pH dependent. Equation 1 shows the reaction of acetic anhydride with an aliphatic amine, and equations 2 and 3 show two possible competing reactions that can occur in water.

Equation 1

Equation 2

168. What is the pHi for allyl bromide if it reacts with N-methylmethanesulfonamide (pKa 11.79) at a maximum pH of 12.2 to give N-allylmethylmethanesulfonamide? A) 6.30 B) 7.00 C) 12.0 D) 12.6

Equation 3 Chemists have shown that the maximum yield for coupling of an electrophile-nucleophile pair such as the reactants in Equation 1 occurs at a maximum pH (pHmax) given by Equation 4, in which Hi is a characteristic of the electrophile and Ka is the acidity constant of the conjugate acid of the nucleophile. pHmax = 1/2(pHi + pKa) Equation 4 Table 1 shows pKa values for the conjugate acids of aniline, benzylamine, valine, and lysine.

169. The compound formed by replacing the oxygen atom between the two carbonyl groups in acetic anhydride with an –NH– group is classified as an: A) amide. B) imide. C) imine. D) eneamine. 170. Equation 3 can be reversed by: A) heating only. B) acidification only. C) heating followed by acidification. D) acidification followed by heating.

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171. The first step in the mechanism of the reaction shown in Equation 1 is the: A) protonation of a carbonyl oxygen atom by a hydrogen atom from the amino group. B) protonation of a carbonyl oxygen atom by a hydrogen atom from water. C) attack at a carbonyl carbon atom by the lone pair of electrons on the nitrogen atom of the amino group. D) attack at a carbonyl oxygen atom by the lone pair of electrons on the nitrogen atom of the amino group. 172. Aniline and benzylamine are both: A) primary amines. B) secondary amines. C) aromatic amines. D) nonaromatic amines.

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Passage VI In the human lung, both alveolar ventilation and pulmonary blood flow are required for the continuous exchange of oxygen and carbon dioxide between alveolar air and alveolar capillary blood. Ventilation of the alveoli (VA) results from alternating contraction and relaxation of thoracic respiratory muscles that cause changes in thoracic and lung volumes, alveolar pressure (PA), and intrapleural pressure (IPP, the pressure of the fluid surrounding each lung). The intrapleural cavities surrounding the two lungs are separate. IPP is negative relative to atmospheric pressure (P, pressure outside the body) because lung elastic recoil tends to reduce lung volume and the thorax tends to expand. The mean pulmonary arterial pressure is only 20 mmHg, compared with a mean aortic pressure of 100 mmHg. The lower pressure pulmonary circulation supplies systemic venous blood to alveolar capillaries (Q, the blood flow rate to the lung). In the upright human lung, gravity causes an uneven distribution of VA and Q (Figure 1) because it has different effects on IPP and on alveolar capillary perfusion pressure. In an upright (seated or standing) human, IPP is more negative at the apex of the lung than at the base.

Figure 1 Alveolar ventilation (VA) and lung blood flow (Q) decrease linearly from the lung base to the apex. The decrease from base to apex is greater for Q than for VA.

173. Pulmonary arterial blood differs from the aortic blood because it has: A) more O2, less CO2, and higher pH. B) more O2, more CO2, and higher pH. C) less O2, more CO2, and lower pH. D) less O2, less CO2, and higher pH. 174. Contraction of the diaphragm results in a: A) more negative IPP and inspiration. B) more negative IPP and expiration. C) more positive IPP and inspiration. D) more positive IPP and expiration. 175. Air flows out of the lungs when: A) PAP. C) IPP