AAMC MCAT test 4r answers

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MCAT Practice Test IV SOLUTIONS IV M CAT MEDICAL COLLEGE ADMISSION TEST AAMC MCAT P RACTICE T EST IV S OLUTIONS Edited, produced, typeset, and illustrated by Steven A Leduc National Director of Medical Research & Development, The Princeton Review Special thanks to: Jennifer Wooddell Judene Wright Copyright © 2001 by Princeton Review Management, L.L.C All rights reserved MCAT is a service mark of the Association of American Medical Colleges (AAMC) TPR is not affiliated with Princeton University Version 1.0 www.PrincetonReview.com MCAT P RACTICE T EST IV S OLUTIONS C ONTENTS : Verbal Reasoning Physical Sciences 19 Biological Sciences 28 010110 VERBAL REASONING Passage I D Item I: Yes The country’s level of development is included in a list of relevant factors given in lines 53-55 Item II Yes See line 53 “Circumstances” is a synonym for “context” Item III Yes The author posits this as the most important consideration (lines 55-57) B A: The passage never indicates who originated the concept of human rights, only that the idea was not forced on other nations by Western cultures B: Yes In the first paragraph, the author argues that the idea of human rights was familiar to most non-Western cultures before it was advocated to them by Western nations (lines 7-13) C: This choice contradicts the main idea of the first paragraph; that the idea of human rights is ancient and pervasive, and was not invented by certain Western cultures and then forced on the rest of the world There is no mention of resistance to human rights specifically from non-Western cultures D: The author states that they were familiar with the idea of freedom “even if there were no explicit covenants to that effect” (lines 10-12) “Traditional societies” here corresponds to the reference to non-Western cultures in line D A: This is the right answer to the wrong question The claim that the idea of freedom was not alien to non-Western cultures comes later in the paragraph The author cites the two documents mentioned in the question to show that the concept of human rights is an ancient one B: Again, this is the right answer to the wrong question It is true, according to the passage, but the author does not cite these two Declarations in order to show that it is true Compare this choice to answer choice D C: Again, right answer, wrong question The second paragraph includes this statement in lines 14-15, but not in reference to the claim that human rights is an ancient idea as shown by the content of these two documents D: Yes This choice accurately describes the author’s purpose in this part of the passage These two documents are cited as direct evidence that the concept of human rights is an ancient one A A: Yes In lines 55-58, the author argues that the most important factor to consider is whether or not there is a trend toward greater human rights The tone of the passage is strongly positive about increased recognition of human rights, and yet the author says that it will not happen all at once (lines 51-52) Thus, the author would call for cautious praise B: While the passage does discuss monitoring in the third paragraph, the author never connects a positive trend towards recognition of human rights (as described in the question) with a need for intense monitoring (see lines 51-57) C: While the author argues that we must take level of development into account (lines 53-55), the passage never indicates that forgiveness of abuses is called for In fact, the author states that there is no possible excuse for certain kinds of violations (lines 58-62) D: The passage states that implementation of human rights protections may take some time; we must consider whether or not there is a move toward human rights in a particular country when evaluating that case (lines 51-57) The scenario presented by the question clearly indicates a move in the right direction; the author would praise, not criticize this nation D A: In the passage as a whole, the author criticizes human rights abuses, and in the final paragraph sets out certain kinds of abuses that can never be tolerated, regardless of the country’s level of development (lines 58-62) However, the author never indicates that state use of private property qualifies as a human rights abuse at any level Be careful not to use outside knowledge or personal opinion to answer questions B: See the explanation for choice A The author does not suggest that placing conditions (which could include age, citizenship, etc.) on the right to vote qualifies as a violation of human rights C: See the explanation for choice A The author does not argue that freedom can never be curtailed, even in emergency situations D: Yes In lines 58-61 the passage lists torture as one of several abuses that can never be tolerated, regardless of level of development C A: The author claims that the United Nations has failed to become “an effective instrument for the promotion of human rights” (lines 32-35) B: Always pay close attention to the word “most” (as in “most benefit”) when it appears in a question While the Organization of American States did pass a human rights declaration (lines 37-39), the passage does not show that the OAS ever takes direct action to rectify specific abuses Be careful not to use outside knowledge; the credited response must be directly supported by the passage C: Yes The author describes how Amnesty International calls public attention to specific abuses, and may “mobilize public support” to bring about action (lines 46-50) D: The author does not suggest that people being abused by their own government would benefit by appealing to the leaders of the abusive state B A: The correct answer will weaken or be inconsistent with a claim made by the author While the passage never specifically calls for civil disobedience, the author does say that certain abuses are never tolerable (lines 58-62) We not know that these “unjust laws” fall into this category, but the answer choice is consistent, not inconsistent with the overall tone of the passage B: Yes In the second paragraph the author asserts that human rights may transcend or supersede the laws of nations, in part through citing Dr Evatt’s claims in lines 23-28 Thus the author argues that outside interference may in fact by called for, in opposition to the statement made in the answer choice C: The passage itself suggests this to be true in its discussion of trends (lines 51-55) D: This choice is entirely consistent with the author’s statement that “the walls of oppression would not crumble at the first clarion call” (lines 51-52) Passage II A A: Yes In paragraph 5, the author claims that “women writers,” by using that term to describe themselves, send the message that women need to segregate themselves only until they “become politically strong a visible, viable social factor” (lines 48-51) B: This choice takes words from the passage out of context The author asserts that women writers claim to recognize humanity-as-a-whole (lines 45-47), not that they are waiting for literature to recognize it In fact, the passage indicates that true literature, by definition, recognizes the universality of humanity (lines 24-30) C: As in choice B, this answer takes words from the passage, but does not form them into an appropriate answer The author states in lines 38-41 that feminists (who, according to the author are not “women writers”) believe that the imagination cannot be liberated, because it is already free Women writers, as described in the passage, are not waiting for the liberation of the imagination, but for political and social power (lines 48-55) D: Again, this choice takes words and ideas from the passage out of the context of the question The author refers to the appearance of a new generation of authors (lines 58-59), but this does not correspond to the time when women writers plan to rejoin the world (lines 48-55) B A: This choice contradicts the passage The author contrasts women writers who segregate themselves, believing that they have an inherent common ground as women (lines 15-21), with feminists who reject gender-based identities and selfsegregation (lines 31-40) Be careful to use the author’s own definition of feminism, as it is described in the passage, to answer the questions B: Yes According to the author, feminism came into being in order to eliminate the “myth-fed condition” of genderbased segregation (lines 32-34), and feminism in the arts arose to eliminate “mythological divisions” (lines 3840) C: This is what women writers (lines 14-23), not feminists (lines 31-41) D: According to the passage, women writers already accept humanity-as-a-whole (lines 45-47) 10 C A: The author asserts that women who consciously write as women are engaged in the politics of sex (lines 1-3), not that all women who write use the language of politics The author uses the label “women writers” to refer to something much more ideologically specific then simply “women who write.” B: According to the passage, the author believes that “the separate male and female states of intellect” not in fact exist (lines 14-17, 24, 31-38) The author uses the term rather to describe the language of women who write as women, with a particular social and political agenda The politics of sex may include a belief in separate intellects, but the author does not use the phrase to refer to that belief C: Yes In lines 8-13, the author describes contexts in which the politics of sex is appropriate, that is, in movements that fight in political or socioeconomic arenas for equality for women The author objects to “women writers” on the basis that their writing assumes a certain agenda or set of premises (the politics of sex) from the beginning, rather than imaginatively seeking out new ideas (lines 14-23) Thus they import the politics of sex into literature, where the author believes it does not belong D: The author does not believe any real separation exists Furthermore, even women writers who engage in the politics of sex not conceive of the separation as a permanent one (lines 55-56) 11 A A: Yes The correct response will be a statement that is inconsistent with the author’s opinions as they are expressed in the passage The author argues that the idea that women have separate life experiences is a myth (lines 31-38); throughout the passage the author asserts a commonality, not a distinction between men and women B: Notice that this choice does not specify that these views would be expressed through literature The author argues that literature [fiction and poetry (line 42)] should not be written in the language of politics (lines 12-14), but never indicates that female authors should not make their views known in other ways C: This is a direct paraphrase of the passage (lines 24-26) The author would most likely agree, not disagree with his or her own words D: The author mentions the struggle for equal employment as an appropriate arena for the politics of sex The passage does not indicate that the author would oppose greater wage equality in any way; what the author criticizes is the incorporation of politics or politicized self-images into literature 12 D A: The passage portrays the beliefs of women writers and feminists as mutually exclusive (lines 14-23, 31-40), and gives no hint that women writers are evolving into feminists B: According to the author, the minute a person calls herself a woman writer, she becomes political (lines 1-7, 14-23) Thus, those who are called women writers not eventually become political, but are already politicized C: This choice is too extreme While the author claims that the human component of literature is denied by women writers (lines 24-30), the passage does not suggest that that component will be eradicated from all literature if the label “women writer” is used D: Yes The author argues that the supposedly temporary strategy of segregation will turn into a permanent reality in 4-5 years, and authors will find themselves divided into two categories: “women writers” and (male) “writers” (lines 58-64) 13 D A: The correct answer will be a statement from the passage that is inconsistent with the scenario presented in the question If the author did in fact admire the fiction or poetry of a woman writer, it would have no bearing on the passage’s discussion of the origins of classical feminism (lines 31-34) B: The author’s admiration for a woman writer’s work would not be inconsistent with the author’s depiction of the beliefs of women writers (lines 19-23) C: The scenario in the question is discrepant with the author’s disapproval of the work of women writers and concern over the potential impact of their use of the term “woman writer.” However, it is not specifically inconsistent with the author’s description of that impact [an uninspiring world in which all the “writers” are men (lines 60-66)] Compare this choice with answer choice D D: Yes According to the author, women writers, by labeling themselves as such, inappropriately incorporate the language of politics into the world of literature (lines 12-14) Literature should be driven by the imagination and should build connections between the sexes This it cannot do, according to the passage, if it is politicized (lines 24-30) Thus, if the author admired the work of a woman writer, it would be discrepant or inconsistent with the author’s assertion that the language of politics should not be used in literature 14 A A: Yes According to the passage, literature “engenders sympathies from sex to sex, from condition to condition ” (lines 24-28) B: The passage defines literature as fiction or poetry when the author defines a “writer” as a “fiction writer or a poet” in line 42 (see also lines 12-13, 24-30) This answer choice describes a nonfiction essay C: While a novel is fiction, true literature according to the author foments sympathy, not antagonism between the sexes (lines 24-26) D: Such a tract would be non-fiction, and written in the language of politics Both of these characteristics would disqualify it as literature in the eyes of the author (lines 12-13, 42) Passage III 15 C A: The passage does not ever raise the issue of prisoners’ beliefs regarding their right to privacy There is no direct evidence in the passage to support this choice B: Prisoners’ concern or lack of concern for their own health is not an issue in the passage C: Yes The author argues that physician–patient confidentiality in prison is especially important, as patient distrust could cause prisoners to fail to disclose important health-related information (lines 13-15, 20-23) Thus it would be reasonable to conclude based on the passage that the inmates refused a diagnostic procedure because of this distrust D: As in choices A and B, this choice requires too much speculation While the author does raise the issue of detection of weapons (lines 38-43, 62-67), the passage does not suggest that prisoners refuse procedures out of fear that a weapon will be detected Furthermore, the author does not indicate whether prisoners carry weapons for self-protection or for other, more aggressive reasons Compare this choice to choice C—the passage directly addresses the possibility that patients may refuse to cooperate fully in their own diagnosis and treatment due to distrust of prison physicians 16 D A, B, and C: All three of these choices are wrong for the same reason: they are not strong enough The author places no conditions on or exceptions to the “duty to warn” held by a physician when a weapon is detected (lines 38-46) Later in the passage, the author does state that a patient should be given the opportunity to surrender the weapon voluntarily, but prison authorities are still involved (lines 62-67) D: Yes In lines 38-46, the author asserts that the imminent threat posed by a weapon overrides the patient’s right to privacy, and the physician has a “duty to warn” the prison authorities 17 D A: The passage indicates that a certain level of confidentiality and physician autonomy is necessary for good medical care (lines 9-15, 24-25) However, the author does not suggest that the absence of these qualities is the only possible cause of a decline in the quality of medicine Therefore, if the quality declines, it is not necessarily because of a lack of confidentiality B: The passage suggests that the ability to keep certain kinds of information from prison authorities is one factor in physician autonomy (lines 24-32) However, we don’t know from the passage that it is the only factor Thus a physician could refuse to reveal information, and still lack autonomy C: This choice is wrong for the same reasons as choice A Respect for confidentiality is one necessary condition for good medical care (lines 9-15), but the passage does not claim that it is the only necessary condition Therefore, confidentiality could be respected while the quality of care is poor for other reasons D: Yes The author claims that confidentiality and physician autonomy are necessary conditions for good medical care (lines 9-15, 24-25) Thus, if a physician was forced to break confidentiality, the quality of care would suffer 18 B A: The author refers to “necessary information” in the context of explaining that without confidentiality, prisoners may fail to reveal information important for their own health care The passage gives no indication that past criminal activities would likely be related to an inmate’s health B: Yes The author introduces the passage through the example of prisoner A, found by a physician to have drugs and paraphernalia on or in his person The author then goes on to argue that information regarding drug use could be crucial to a patient’s treatment, so physicians should not be required to reveal this “necessary information” to the authorities (lines 13-23, 33-36, 67-70) C: The author uses the term “necessary information” to indicate information necessary to the patient’s medical treatment Be careful not to take the words out of the context of the passage D: Pay close attention to the words “most specifically” in the question While one could imagine a patient’s psychiatric history being an important factor in their current medical treatment, psychiatric history is never specifically mentioned in the passage However, the author explicitly and repeatedly argues that doctors must know of a patient’s drug use in order to effectively treat him or her (lines 1-7, 33-36, 67-70) 19 A A: Yes By claiming that “respect for patient confidentiality is particularly important in a prison hospital setting” because patients might distrust prison doctors (lines 20-23), the author indicates that inmates are less likely to expect confidentiality than are non-incarcerated patients of private doctors B: This choice takes words out of context of the passage The author mentions incompetence as an exception to the requirement that informed consent be provided by patients (lines 56-59), not as a reason why confidentiality would be especially important C: The question is not asking when an inmate’s ability to keep secrets is threatened Confidentiality may not apply to cases where diagnostic tools reveal the presence of weapons, but physician confidentiality is not itself threatened by the use of these tools Finally, the use of X rays is not depicted as “invasive” by the author D: The author states just the opposite While inmates not have “full Constitutional rights to privacy,” physician confidentiality is one of those rights which they have in most circumstances (lines 16-19) 20 B A: The correct response will be inconsistent with the author’s claim that physician confidentiality is especially important in prisons because inmates distrust doctors who are hired by the prison (lines 19-23) First of all, the author argues that confidentiality should not be respected when weapons are detected (lines 38-46) Secondly, prisoners’ awareness that X rays will detect weapons would not affect the author’s argument about the need for patients to be able to trust their doctors and the unlikelihood that inmates will so B: Yes The author argues that inmate patients distrust prison hospitals because the doctors may be employees of the prison This is the basis of the author’s assertion of the special need to respect physician confidentiality in prison settings If inmates not believe that prison doctors are controlled by the institution, then prison hospitals not present a unique situation Therefore, while the physician–patient covenant would still be important, it would have no special importance in a prison setting C: This choice would strengthen, not weaken the author’s argument If prison officials often question physicians about inmates, inmates would have reason to fear that information given to a physician about activities such as drug use might be revealed to the authorities D: This choice is too vague to have any impact on the author’s argument It does not specify whether or not prisoners misunderstand their Constitutional rights to privacy Nor does it indicate whether this misunderstanding is of a sort that would decrease the trust they place in their doctors Passage IV 21 D A: This choice is too narrow to be the main idea It is directly stated in lines 8-9, but it is only one small part of the author’s overall argument that altruism may be as “biological” as selfishness B: This choice (directly stated in lines 20-22) ignores the final three paragraphs of the passage The author goes on to argue that natural selection may allow for altruism as well through kin selection C: While this is an important part of the author’s argument about altruism in animals (lines 32-33), the author goes on to claim that human altruism may therefore be just as “animal” or biological as selfishness Thus it is evidence for the main point, not the main point itself D: Yes The author argues that animals act altruistically when those acts benefit kin Therefore, human kindness may not be a “unique overlay,” but instead a characteristic that we share with the animal kingdom 22 A A: Yes In the first paragraph, the author argues that we tend to attribute selfish acts to our animal nature We also tend to believe that we act for the benefit of others only when we can overcome that animal part of ourselves through our uniquely human capacity for reason or rationality (lines 11-14) Thus, according to common belief, altruism is a uniquely human imposition or overlay on our basic animal nature B: This is the opposite of the correct response In the context of the passage, the “unique overlay” is human rationality, which acts against our animalistic tendencies C: As in choice B, this is the opposite of the correct response The passage describes selfishness as an animalistic, not uniquely human behavior (lines 8-11) D: This choice takes the passage’s reference to self-criticism out of context We criticize ourselves for “animalistic” behavior (lines 8-11), but the passage does not claim that the ability to so is uniquely human Be careful not to use common sense or outside knowledge When the passage uses the term “unique overlay,” it is specifically in reference to altruistic behavior that we (falsely) believe to be non-animalistic 23 C A: Altruism and rationality are not compared to each other The passage states that we tend to believe that it is our rationality that allows us to behave altruistically (lines 11-14) B: Both traits are listed as part of our “apish ancestry” (lines 9-11), but selfishness and aggressiveness are not compared to each other C: Yes A major theme of the passage is the comparison between the belief that altruism is unique to humans (lines 8-14) and the author’s belief that animals as well may act altruistically through kin selection (lines 29-34, 53-56) D: Determinism is discussed in lines 44-52, while rationality is mentioned in line 13 in a very different context; the two are never compared to each other 24 C A: The sentence given in the question refers to the belief that specific behavior (hoarding and giving) can be determined by (“attributed to”) genetics This is just the opposite of free will as it is described in the passage (lines 46-50) B: The main point of the fourth paragraph (lines 51-66) is that altruistic behavior may have a biological basis, but is not completely determined by genetics The passage discusses rationality in the first paragraph in a different context, when it describes the view of many that human beings use their unique capacity for reason to override animalistic, selfish impulses (lines 9-14) C: Yes The section of the passage referred to by the question presents the author’s claim that specific behaviors are not completely determined by genetics The statement in the question, that some have attributed both selfish and altruistic behaviors to genetics, could be used to illustrate “deterministic speculation” (lines 44-46) D: The author argues that human nature is not completely determined by genetics (lines 44-50) Thus a statement describing deterministic beliefs would not illuminate or illustrate that claim 25 A A: Yes This assertion is made in lines 46-50, with no reference to authority or example “Free will” is described, but the passage does not provide an example of how free will affects human behavior B: The author refers to Freud as an authority who has made this claim (lines 56-59), and gives Copernicus, Newton, and Freud as examples (lines 59-63) C: The passage cites Hamilton as an authority on this point (lines 26-32) D: The author supports this assertion through reference to Freud (lines 1-6) 26 B A: The author discusses natural selection in the second paragraph in order to introduce the question of how altruism could be biological (lines 19-25) The author does not deal with that question until the subsequent paragraph, through the discussion of kin selection B: Yes The passage discusses kin selection (lines 26-34) in order to resolve the question of how altruism could have a biological basis C: The passage states that civilization requires altruistic behavior and the suppression of selfish and aggressive biological instincts (lines 1-6) That part of the passage does not deal with the paradox raised in the quoted section of how this altruistic behavior could have a biological basis; that resolution does not come until the author’s discussion of kin selection in the third paragraph D: The question asks where the author most directly deals with the question of biologically-based altruism Evolution is related to kin selection by the passage (lines 29-34), but it is in the discussion of kin selection itself that the author most directly deals with the problem Compare this choice to answer choice B 27 D A: The author indicates that while we once believed that we lived at the hub of the universe, we have been forced to accept that that belief is not valid (lines 56-60) B: The passage states that “before Freud, we imagined ourselves as rational creatures” (lines 61-63), suggesting that we no longer, post-Freud, see ourselves as rational C: This choice is inconsistent with the author’s rejection of genetic determinism (lines 44-50) D: Yes According to the passage, we once believed that our capacity for altruism was not based in biology, and so that our ability to be kind distinguished us from non-human animals (lines 11-14) However, once we recognize that altruism, like selfishness, may have a genetic, evolutionary basis, we may see that we have more in common with other animals than we thought (lines 53-56, 63-66) 28 A A: Yes The main idea of the passage is that while we by nature are selfish and aggressive (lines 3-11), we are also by nature kind and altruistic (lines 42-44, 53-56) Thus the author would likely argue that our natural tendency towards conflict may be tempered or counteracted by our coexisting natural tendency towards kindness B: This choice misrepresents the author’s position The author argues that our true biological nature includes both brutality and altruism (lines 37-39, 42-44) C: The author claims that our biological nature includes both brutality and kindness (lines 37-39, 42-44) Furthermore, the passage never raises the issue of spirituality D: The author introduces this view in the first paragraph in order to go on to reject it The passage indicates that altruism is not imposed upon our biological nature by rationality, but may in fact arise from our biological nature (lines 26-42) 29 B A: The author rejects biological determinism (lines 44-50) B: Yes The passage asserts that human social life and the survival of civilization requires reciprocal altruistic behavior; that is, that we all act for the good of others and of the social body (lines 1-6) C: The passage argues just the opposite: that in order to live together and ensure the survival of our civilization, we must temper or reduce our animal aggression through kindness and altruism (lines 1-6) D: The passage never mentions genetic mutation 30 C A: This statement strengthens Freud’s argument by reinforcing his claim that we have a natural tendency toward aggression B: This choice also strengthens Freud’s claim that our biology drives us towards animalistic, selfish behavior C: Yes If lower animals are capable of altruism as well as selfishness, then we may be able to behave altruistically not by suppressing but by embracing our “animalistic, biological instincts.” Thus this statement weakens Freud’s argument D: The agonizing dilemma mentioned in the passage (with reference to Freud) is that we are selfish by nature, and yet civilization requires altruism (lines 1-6) This is not inconsistent with the statement by Freud cited in the question that we must renounce our nature in order to be altruistic Passage V 31 A A: Yes The passage states that once beetles feeding on sap exuded by ovules (ovules play a vital role in reproduction) became a vehicle for pollination, the ovules themselves had to be protected (lines 24-26) B: This choice reverses the relationship between insects and flowers as it is presented in the passage The author mentions a variety of ways in which flowers evolved so as to take better advantage of insects (lines 21-23, 24-28, 42-50, 53-65) The passage never indicates that flowers influenced the evolution of insects C: The passage does discuss the dispersal of pollen to and from seed-bearing plants in the first two paragraphs (although the range of pollen dispersal is not discussed) However, dispersal of the seeds is never mentioned Be careful not to rely on outside knowledge D: The passage indicates just the opposite Restriction, not expansion of the variety of means of fertilization, was the problem to be solved (lines 56-68) The passage does discuss the advantages of insect over wind pollination, but insects represented an alternative, not an additional means for individual plant species (lines 18-23) 32 B A: The passage refers to the structure and behavior of insects living 70-150 million years ago Modern insect species never explicitly come into the picture B: Yes The tone of the passage is clearly speculative The author constantly uses words and phrases like “probably” (lines 3, 6) and “must have,” “would have,” “may have,” or “could be” (lines 13, 17, 19, 29, 32, 48, 51) As for the theoretical basis of the passage, the author does not argue for or defend natural selection as an appropriate theoretical model, but simply assumes that the reader will accept it as valid C: The only reference to modern times is a brief mention of modern survivors of ancient plants (lines 8-10) The passage is not framed in terms of (nor does it even discuss) ongoing evolutionary trends, however D: Only once does the passage specifically mention the fossil record (lines 1-3) While the author may well be drawing on fossil evidence for his or her conclusions, the passage is primarily characterized by the author’s educated guesses about the likely course of flower evolution (see the explanation for choice B) 10 93 A Since the metal is at its exact melting point, it is ready to undergo a phase transition from solid to liquid Since the temperature of a compound remains constant during a phase change, choices C and D are eliminated A small amount of additional heat energy absorbed by the sample will thus melt some of it, but the temperature will not change It is safe to assume that if the 0.1 kg sample of metal is held over the flame for only a “fraction of a second,” there won’t be enough heat energy to melt all of it, so A is a better response than B Passage V 94 C The passage gives the molar mass of KHP as M = 204.2 g/mol, and Table shows that Student A had 0.55 g of KHP Therefore, the number of moles of KHP present in the sample of KHP used by Student A is n= m 0.55 g 0.5 g 1 = ≈ = g mol = × g mol = 0.25 × 10 −2 g mol = 2.5 × 10 −3 g mol M 204.2 g mol 200 g mol 400 100 95 C Since the temperature rose during the mixing process, ∆H must be negative for Equation 1, so Item I is true This eliminates choices B and D Since an aqueous solution of a dissolved solute has greater disorder than the separate pure solid NaOH(s) and pure liquid H2O(l), the entropy increased during the mixing process, so Item III is also true Therefore, the answer must be C [Since the solid NaOH dissolved spontaneously in solution, the value of ∆G must be negative for this reaction, which is why Item II is false.] 96 A The passage states that the instructor “prepared a solution of NaOH(aq) by dissolving g of NaOH(s) (MM = 40.00) in L of H2O.” Eight grams of NaOH(s) thus represents 8/40 = 1/5 = 0.2 mol; dividing this by L, we find that [NaOH] = (0.2 mol)/(2 L) = 0.1 mol/L = 0.1 M 97 D At the equivalence point of the titration of a weak acid by a strong base, the solution is basic (that is, pH > 7) 98 D To find the conjugate base of chlorobenzoic acid, HC7H4ClO2, simply remove an H+; the result is C7H4ClO2– 99 B First, eliminate choices C and D: According to the formula given in Table 1, succinic acid is diprotic, not triprotic And, since the acid is diprotic, more base will be required to neutralize this acid than if the acid were only monoprotic, so the answer must be B, not A 100 A If the KHP sample contains water, then the mass of the sample will be greater than the mass of the KHP alone As a result, when the student uses this to calculate the number of moles of KHP in the sample, the student will derive a value that’s greater than the true value Using Equation 2, the student would then conclude that more NaOH is needed to reach the equivalence point (since the student derived a greater-than-actual value for the number of moles of KHP) Therefore, the molarity determined for the NaOH(aq) solution would be too high, because the number of moles of KHP used in the calculation is greater than the actual number of moles of KHP titrated This statement is equivalent to choice A Passage VI 101 C Nothing in the passage supports choice A or B Choice D must be eliminated, since momentum is conserved in the collision and, in addition, momentum is not converted to energy Choice C says it best: The kinetic energy of the gas from the ordinary companion star that collides completely inelastically with the surface of the white dwarf becomes heat energy 102 A By equating mg with GMm/r2, we see that the gravitational field strength, g, at the surface of a star is given by the formula g = GM/r2, where M is the mass of the star and r is its radius The passage states that a white dwarf has the same mass, M, as the Sun, but a much smaller radius, r Since M is the same but r is much smaller for a white dwarf, the value of g = GM/r2 is much greater at the surface of a white dwarf than at the surface of the Sun Thus, choice A is the answer Choice B is false, since all three hypotheses include the fact that the white dwarf does experience nuclear fusion, and nothing in the passage supports choice C or D 22 103 B First, eliminate choices A and C: Fusion of bare nuclei is not the same as bonding of atoms containing electrons And choice D is false, since hydrogen nuclei (which are simply protons) are much lighter than carbon nuclei, and therefore should move much faster, on average, than carbon nuclei at the same temperature The answer must be B: It is easier to fuse two hydrogen nuclei (two protons) than two carbon nuclei, because each hydrogen nucleus is only a single proton, while each carbon nucleus contains six protons The electrical repulsion is much lower between a pair of single protons than between a pair of 6-proton nuclei 104 D The following balanced nuclear reactions show that decay of either 56Ni or 56Co is accompanied by the emission of 56 + 56 + (that is, both 56Ni and 56Co undergo β+ decay) a positron, e+: 56 and 56 28 Ni → 27 Co + +1 e 27 Co → 26 Fe + +1 e 105 D While choices B and C are both true, they don’t answer the question As for choice A, the second sentence in the paragraph describing Hypothesis III would, if anything, cast doubt on this statement The best response is D: The “runaway” (that is, very rapid) nature of the fusion reaction would be manifested by a sudden, large increase in brightness Passage VII 106 B The oxidation of Zn(s) has a potential of +0.76 V (reverse the reaction given in Table 2) Combining this with the reduction of Cu2+ (E° = +0.34 V) gives a cell voltage of +1.10 V, which is the measurement made by Student 3: oxidation: reduction: Zn(s) → Zn2+(aq) + 2e– 2+ – Cu (aq) + 2e → Cu(s) E° = +0.76 V E° = +0.34 V Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq) E° = +1.10 V 107 D Since the molar mass of the white solid used by Student is 58.5 g/mol, a mass of 29.25 g represents 0.5 mol of the solid If this is present in an aqueous solution of volume 250 mL = 0.25 L, then the concentration is (0.5 mol)/(0.25 L) = M 108 C Consider each molecule of Fe2(SO4)3 as composed of Fe3+ cations and SO42– anions Thus, iron is in a +3 oxidation state—that is, iron(III)—eliminating choices A and B Since SO42– is sulfate (SO32– is sulfite), the compound is iron(III) sulfate 109 B Since the reaction is spontaneous, the cell voltage must be positive (Ecell > ⇒ ∆G < ⇒ spontaneous) Therefore, the half-reactions must be reduction: oxidation: Ag+(aq) + e– → Ag(s) Al(s) → Al3+(aq) + 3e– E° = +0.80 V E° = +1.66 V Balancing the electrons in these reactions, we multiply the reduction half-reaction by (but not its potential!): reduction: oxidation: Ag+(aq) + 3e– → Ag(s) Al(s) → Al3+(aq) + 3e– E° = +0.80 V E° = +1.66 V Giving the overall reaction, Ag+(aq) + Al(s) → Ag(s) + Al3+(aq) E° = +2.46 V Since pure solids are omitted from the equilibrium and reaction-quotient expressions, we have Q= [Al 3+ ] [Ag + ]3 23 Passage VIII 110 B The molar mass of KNO3 is 101.g/mol and that of H2O is 18 g/mol Therefore, in a L solution whose KNO3 concentration is 226.5 g/L and whose H2O concentration is 906.1 g/L (see Table 1), the mole fraction of KNO3 in the solution is XKNO = nKNO nKNO + nH O = ( ( )(1 L) )(1 L) )(1 L) + ( 226.5 g L 101.1 g mol 226.5 g L 101.1 g mol 906.1 g L 18 g mol 111 C Each of the compounds in choices A, B, and D contains a common ion with KNO3—that is, either K+ or NO3– By the common-ion effect, any of these added to a saturated solution of KNO3 would cause precipitation of crystals However, Choice C, NH4Cl, has no common ion with KNO3 and would not cause precipitation 112 D The passage states that the condosity of a solution is the molar concentration of sodium chloride that has the same conductance as the solution According to the data in Table 1, the student’s KNO3(aq) 2.241 M solution has a condosity of 2.49 M So, if we plot conductance vs molarity, the fact that the student’s solution and the 2.49 M NaCl(aq) solution have the same conductance means that they’d lie on the same horizontal line in the plot, eliminating Points A and C And since the molarity of the student’s solution is less than that of the NaCl(aq) solution, the KNO3(aq) point should be to the left of the NaCl(aq) point in the plot Thus, the answer must be Point D 113 C According to Table 1, the solute concentration of the KNO3(aq) solution is 226.5 g/L, which is equivalent to 22.65 g in 0.1 L (= 100 mL) 114 D Since the concentration of the KNO3(aq) solution is 2.241 M, the student’s 1-liter solution contains 2.241 moles of KNO3 Since each mole of KNO3 contains 6.02 × 1023 K+ ions, 2.241 moles of KNO3 contain (2.241) × (6.02 × 1023) ≈ 1.3 × 1024 K+ ions Independent Questions 115 C The balanced reaction is CH4(g) + O2(g) → CO2(g) + H2O(g) Therefore, the mole fraction of H2O(g) in the product mixture is nH O 2 XH O = = = nCO + nH O + Applying Dalton’s law, we find that the partial pressure of H2O(g) in the product mixture is pH O = XH O ⋅ ptotal = 23 ⋅ (1.2 torr) = 0.8 torr 116 A Since carbon, hydrogen, and oxygen have molar masses of 12 g, g, and 16 g, respectively, the sample described in the question contains mole of C atoms, moles of H atoms, and mole of O atoms Therefore, the formula for this compound must be CH2O (Note that choices C and D can be eliminated immediately since they’re not empirical formulas An empirical formula contains the smallest whole number subscripts that have the same ratio as the subscripts on the atoms in the compound’s actual molecular formula.) 117 D If the pipe is open at both ends, then both ends are displacement antinodes (A) The simplest standing wave—the fundamental standing wave—must therefore have a node (N) in the center of the pipe: A N A The distance from one antinode to the adjacent antinode on a standing wave is always equal to one-half the wavelength So, if the length of the pipe is m, the distance from one antinode to the other antinode on the fundamental standing wave is m Since this must be equal to λ/2, we find that λ = m 24 118 A When the voltage is turned on, charge begins to build up on the capacitor plates The rate at which the charge builds is not steady, but gradually decreases, since it’s more difficult to place additional charge on a capacitor that already has some charge, because we’re “fighting against” the electric field in the capacitor created by the charge that’s already there Then, once the voltage is turned off, the charge gradually leaks off, quickly at first and then more slowly near the end Since the voltage between the capacitor plates is proportional to the charge (Q = CV), the voltage between Points A and B will exhibit the same behavior as the charge on the capacitor Thus, the voltage rises, at a rate that decreases with time, then the voltage drops, also with a rate that decreases with time This is shown in graph A 119 B Mechanical waves transport momentum and energy from one point to another, but they not cause particles of the medium to travel great distances For example, the wave in a rope does not transfer rope particles from one end of the rope to the other, and water waves created thousands of miles offshore not transport water that distance Passage IX 120 A The total momentum of the colliding objects is conserved in a collision It makes no sense to say that impulse (choice D) was conserved, since impulse is force multiplied by time; there was no contact force between the continents before their collision, so there was no impulse before the collision Also, we know that energy was not conserved; only in elastic collisions, where the objects simply bounce of each other, is kinetic energy conserved But these continents did not cleanly bounce of each other: The formation of the mountain ranges in North America and Africa tells us that As for potential energy (gravitational, supposedly), there is no reason to believe (or evidence to support) the extraordinary contention that the total potential energy of the continents before the collision was equal to their total potential energy afterwards Collisions conserve the momentum of the system; energy (in either form) is not necessarily conserved 121 C First, we can eliminate choice A The second paragraph of the passage tells us that 40K is radioactive, so no organic material need be present to use this type of radioactive dating procedure to ascertain the age of the rock [Radiocarbon (carbon-14) dating, on the other hand, does require the presence of organic material However, the half-life of carbon-14 is only about 5700 years, so radiocarbon dating is not a reliable method for determining the age of specimens (such as rocks) that are hundreds of millions of years old Radiocarbon dating is used only for artifacts that are at most tens of thousands of years old.] The second paragraph contains the clue to answering this question We’re told that “the age of the rock can be determined by measuring the amount of radioactive potassium in the rock and the amount of its decay product, argon gas in the sample.” Clearly then, it is measuring the relative amount of parent and daughter nuclei that is critical So, to obtain an accurate dating, researchers would want the decay product to be trapped in the rock since its formation, so all of it can be measured to determine how much decay has occurred Choice B is eliminated because it says “any gases” (only the relative amounts of potassium and argon gas are necessary for this procedure), and nothing in the passage supports choice D 122 A If the continents stick together after the collision, then by Conservation of Momentum, we have m1v1 + m2v2 = (m1 + m2)v′, so v′ = (m1v1 + m2v2)/(m1 + m2) 123 D The passage states that the daughter nucleus of the decay of 40K is 40Ar The following balanced nuclear reaction 40 + shows that the decay of 40K is accompanied by the emission of a positron, e+: 40 19 K → 18 Ar + +1 e 124 B By Newton’s Third law, the force that the first continent exerts on the second continent is equal in magnitude to the force that the second continent exerts on the first (The masses of the continents are relevant to their resulting accelerations, but not to the magnitude of the force the continents exert on each other Newton’s Third law says nothing about mass.) 25 Passage X 125 A First, eliminate choices C and D Changing R will not affect the voltage between the electrodes As the passage states, “the potential difference between the cathode and anode is approximately equal to the battery voltage, V = 50 V.” However, the electric field between the electrodes does depend on L, the distance between the plates; in fact, we’re told that E = V/L So, to decrease E, we should increase L 126 B Since the electron is ejected by a photon whose energy is only slightly greater than the work function of the metal, there is very little energy left over as kinetic energy of the electron So, all of the photoelectron’s energy after its release from the cathode is its electrical potential energy This energy is then converted to kinetic energy as the electron accelerates across the gap to the anode 127 A Each photon with energy above the metal’s work function that is absorbed by the metal surface will eject an electron So, if more such photons strike the cathode, more electrons will be ejected 128 C Since the cathode is negatively charged and the anode is positively charged, the electric field between the plates points to the left in Figure The force on the electron is FE = qE = eE, directed to the right Because the electron feels a force to the right, it will accelerate to the right, moving across the gap toward the anode 129 B The power dissipated by a resistor, R, that carries a current I is given by the equation P = I2R Since R = 100 Ω, the power dissipated when I = 10–3 A is P = (10–3 A)2(100 Ω) = (10–6 × 102) W = 10–4 W 130 C The net movement of charge through an element in a circuit—which occurs here when an electron moves from the cathode to the anode—is the definition of current 131 D Increasing the frequency of each incident photon increases the energy of each incident photon However, each absorbed photon can cause the ejection of only a single electron, so increasing the energy of each photon will not change the number of electrons ejected (only changing the number of incident photons would that) This eliminates choices A and B If φ denotes the cathode metal’s work function (which is a constant for each metal), then the maximum kinetic energy of each ejected electron is equal to Ephoton – φ So, if Ephoton is increased, then so will KEmax for the ejected electrons If the ejected electrons have more kinetic energy, they’ll have a greater speed Passage XI 132 B According to the data in Table 1, the element X has a melting point of 839°C and a boiling point of 1484°C Therefore, at the intermediate temperature of 1200°C, X must be melted and thus a liquid 133 A Molarity is equal to moles of solute divided by liters of solution If we know the density of the saturated solution in, say, grams per liter of solution, then if we divide this by the known molar mass of the solute (in grams per mole of solute), we’ll get: (grams/L) ÷ (grams/mol solute) = mol solute/L, which is the molarity 134 B It is reasonable to conclude that the oxide of X under study is a neutral molecule, so choices A and D may be eliminated Since oxygen has a much greater electronegativity than X (according to Table 2), oxygen should have a much greater electron density than X in the oxide molecule This is also consistent with the statement in the passage that the oxide is an ionic compound Therefore, we expect X to have a positive charge, and oxygen a negative charge in the oxide 135 C The passage states that the evolved gas is flammable, so the answer must be C (hydrogen gas) [Note: Oxygen is not flammable since it does not reaction with oxygen to produce heat.] 136 B Since the difference between the second ionization energy and the third is so large, it’s reasonable to conclude that element X has two valence electrons The third ionization energy is so high because an electron is being removed from a +2 cation with a noble-gas configuration Therefore, X is a Group element; that is, it is an alkaline earth metal 26 Independent Questions 137 C Choice A is eliminated since it’s too general: An electron may change its orbit by moving into a higher-energy orbit, but this process would correspond to an absorption, not radiation of energy Choice B is also eliminated: An object (such as an electron) in a circular orbit is always undergoing acceleration, but in the Bohr model, this type of charge acceleration does not cause energy to be radiated And choice D is wrong, since to move to an orbit of larger radius, an electron must absorb energy The answer is C 138 A “Fusion” means melting, and the heat of fusion is the amount of heat absorbed when a substance is transformed from the solid to the liquid phase 139 B If the current through the Ω resistor is A, then the voltage drop across this Ω resistor is V = IR = (2 A) × (2 Ω) = V Since the Ω resistor is in parallel with the Ω resistor, the voltage drop across the Ω resistor must also be V Therefore, the current through the Ω resistor is I = V/R = (4 V)/(4 Ω) = A This means that the total amount of current in the parallel combination is A + A = A, so this must have been the current in the Ω resistor 140 B According to Bernoulli’s Equation, fluid pressure in a horizontal pipe is highest where the flow speed, v, is lowest To find the point of minimum flow speed, we use the Continuity Equation, which says that Av is constant, where A is the cross-sectional area of the pipe The speed v is lowest at the point where the cross-sectional area is greatest, and this would occur at the point where the pipe diameter is greatest 141 B For a plane mirror, the image distance behind the mirror, i, is equal to the object distance in front of the mirror, o (disregarding the sign convention that merely tells us that the image formed by a plane mirror is behind the mirror and is virtual) Therefore, the total distance from the person to his or her image is o + i = o + o = 2o The question tells us that this distance, 2o, must be at least 300 cm, so o must be at least 150 cm 142 D The pH of a solution is equal to –log [H3O+] If this is equal to 6, then log[H3O+] = –6, so [H3O+] = 10–6 M 27 BIOLOGICAL SCIENCES Passage I 143 A The question states that morphine increases parasympathetic impulse traffic to the iris, and this, as indicated in the last paragraph of the passage, would cause constriction of the pupil (choices C and D can be eliminated) Furthermore, the passage states that acetylcholine is the neurotransmitter released by the parasympathetic system at the organ level (choice B can be eliminated) 144 A Since atropine is preventing acetylcholine (the normal parasympathetic neurotransmitter) from binding to its receptor, it is blocking the effects of the parasympathetic system, and this is described in the question as a passive mechanism (choices B, C, and D can be eliminated) 145 D Acetylcholine is the parasympathetic neurotransmitter, thus if it is removed from circulation faster than norepinephrine (the sympathetic neurotransmitter), parasympathetic effects must turn off faster than sympathetic effects Choices A, B, and C all describe sympathetic effects; only choice D, stimulation of digestive secretion, is a parasympathetic effect, and would be inactivated the fastest 146 C Any nerve fiber that causes an effect on an organ is a motor fiber; sensory fibers only pick up information from an organ and send it to the brain Thus nerve fibers that cause cardiac slowing must be motor fibers (choices B and D can be eliminated) Specifically, the fibers that reduce the heart rate are parasympathetic fibers (choice A can be eliminated) 147 A The type of neurotransmitter released is irrelevant (choices B and D, while true, not answer the question and can be eliminated) The interconnected ganglia of the sympathetic system allow for rapid systemic response, because if one ganglion gets stimulated, it can rapidly stimulate all ganglia in the system If the ganglia are not interconnected, as in the parasympathetic system, this is not possible (choice D can be eliminated) 148 D Physostigmine in this case is acting as an “inhibitor of an inhibitor.” Acetylcholinesterase breaks down acetylcholine, thus decreasing its levels If physostigmine inhibits acetylcholinesterase, then acetylcholine would not be degraded, and its levels would rise (choices A and C can be eliminated) The passage states that the effect of acetylcholine on the pupil is to cause constriction (choice B can be eliminated) Passage II 149 C First, glucose is never used directly as an energy source; it is oxidized and the energy released is stored in the form of ATP In any case, osmosis is a passive process and does not require an energy source (choice A can be eliminated), nor does water cross the plasma membrane through “ion exchange pumps” (choice B can be eliminated) Choice C is true Additional glucose molecules would raise the osmotic pressure (think “concentration”) of the extracellular space; this in turn would promote the movement of water out of the cell by osmosis (cellular dehydration) Choice D may or may not be true The passage implies that tissue glucose increases, but whether this occurs by exchange with water molecules is not clear This makes C a better choice than D 150 A Hyperglycemia is high extracellular or plasma glucose levels Insulin’s job is to reduce plasma glucose levels, so suppressing insulin secretion could lead to higher plasma glucose, and would support the hypothesis Glucagon has the opposite effect of insulin Its job is to raise plasma glucose; suppression of this hormone could not lead to hyperglycemia (choice B can be eliminated) Glucose released from the liver into the plasma comes from the catabolism (breakdown) of glycogen If this process were slowed, it could not cause hyperglycemia (choice C can be eliminated) Lastly, increased sensitivity of all pancreatic endocrine responses would lead to increased levels of both insulin and glucagon in the blood While excess glucagon could certainly lead to hyperglycemia, excess insulin could not — the hormones have opposite effects (choice D is eliminated) 28 151 A The question specifically asks for the relationship of a beating heart to the cryoprotective role of glucose; since temperature equilibration and a reduction in the rate of ice formation are not glucose-related, choices B and C can be eliminated on the basis of irrelevance Choice D is just false; a beating heart requires a constant supply of ATP, not glucose, as an energy source Choice A is true and has the most relevance with respect to the question being asked 152 D The passage states that only extracellular water freezes Cytoplasm is intracellular fluid, so Item I is false and choice C can be eliminated Blood plasma is extracellular; Item II is true, and choice B can be eliminated Lymph is also extracellular; Item III is true, and choice A can be eliminated 153 D The frog’s tissues would be forced to rely solely on anaerobic respiration once the heart stopped beating and no longer circulated blood and oxygen throughout the body Based on the graph of Heart Rate in Figure 1, this occurs between 12 and 24 hours after the onset of freezing 154 A Figure shows that frogs injected with glucose had a much higher rate of survival than frogs injected with saline, and that the rate of survival increased with increased glucose Thus it is clear that glucose has some cryoprotective role in frogs (choices C and D can be eliminated) 155 B Choices A, B, and D to some extent are true However, the main “theme” of the passage is that wood frogs can survive freezing episodes by increasing their extracellular glucose concentrations, and that the primary mechanism by which this occurs is accelerated glucose release from glycogen stores in the liver Therefore, it seems that the most effective physiological condition for surviving freezing episodes would be to have ample liver glycogen stores (choice D is true, but B is better) Choice A might be tempting, since the role of the excess glucose is to cause cellular dehydration, but simple dehydration in the absence of glucose is not described in the passage as a survival mechanism Choice C is not discussed anywhere in the passage as being a method of surviving freezing Passage III 156 D The passage states that Compound C is soluble in both dilute acid and base These data suggest that Compound C has both a basic and an acidic functional group Of the choices given, only D contains both a basic (amine) and an acidic (carboxylic acid) functional group 157 C Since all four compounds in Table contain a C=O double bond, they will all have a strong, sharp band at 1700 cm–1 in their IR spectra 158 B While pure compounds typically have sharp melting points, impure mixtures tend to melt over a broad temperature range This eliminates choices C and D Choice A can be eliminated since the melting point of a mixture is never higher than that of the components of the mixture 159 C The passage states that Compound B is a water-soluble alcohol It is most likely water soluble due to the hydrogen-bonding ability of its hydroxyl group 160 B The fact that Compound A slowly dissolves in refluxing aqueous NaOH to result in the formation of two new compounds is consistent only with choice B An ester is hydrolyzed under such conditions to form a carboxylate and an alkoxide 161 C Only choice C, 4-aminobenzoic acid, is an amine Hippuric acid and diethylbarbituric acid are amides, not amines 162 D Since three of the four compounds in Table contain carboxylic acids, they cannot be distinguished based on solubilities or reactivities toward alcohols Thus, we can eliminate choices A and B Since all four compounds melt in the range of 183–191°C, they cannot be unambiguously distinguished based on their melting points They can only be distinguished by their molecular weights 29 Passage IV 163 C The passage states that the genes for conjugation are carried on a plasmid (choice A can be eliminated), and that during cell division, plasmids may not be equally distributed among daughter cells It may be that one of the daughter cells failed to receive the plasmid that carried the genes for conjugation The cell membrane has nothing to with moving the replicated chromosomes apart (choice B can be eliminated), and bacteria are prokaryotic and not contain membranebound organelles like lysosomes (choice D can be eliminated) 164 D Antibiotics not lead to mutations in bacteria (choice A can be eliminated), nor can bacteria develop an “immune reaction” to antibiotics An immune system is required for that, which bacteria not have! (Choice B can be eliminated.) There is nothing in the passage to support choice C, so it can be eliminated It is most likely that, due to random mutation, some of the patient’s E coli were resistant before treatment Since they were not killed by the antibiotics, they continued to reproduce 165 A Of the choices given, the best answer is choice A, although this is still a relatively unlikely possibility However, antibiotics not induce mutation (choice B can be eliminated), the rate of reproduction has nothing to with antibiotic sensitivity (choice C can be eliminated), and modification of metabolism would not alter antibiotic sensitivity (choice D can be eliminated) 166 C The appendix is found at the beginning of the colon, so if it were to rupture, the E coli that normally inhabit the colon could enter the abdominal cavity and cause serious problems (choice C is true, and choices B and D are false) M tuberculosis causes tuberculosis, not appendicitis (choice A can be eliminated) 167 A The persistence of an organism in any environment is determined primarily by the number of surviving offspring it can produce (A is true) The ability to produce more vitamins (choice B) or to metabolize glucose faster (choice C) not affect E coli’s ability to reproduce, nor does their lack of pathogenicity (choice D) 168 B No digestive enzymes are produced by the bacteria, and no nutrient absorption occurs in the colon (choices A and D can be eliminated) Choices B and C actually are equally likely to occur; the “jobs” of E coli in the large intestine are to produce vitamins and to reduce the growth of other, pathogenic bacteria However, since the passage specifically mentions vitamin production and does not mention reduced growth of other bacteria, choice B is a better answer than C Independent Questions 169 B Of the choices given, actin will bind only to myosin molecules (Don’t be tempted by choice A; during muscle contraction, ATP binds to myosin, not to actin.) 170 C N-1 has two covalent bonds and two lone pairs, so it is similar to a deprotonated amine and has a (–) charge N-7 has four covalent bonds and is thus an ammonium ion and has a (+) charge 171 A Beginning with the neuron that senses the painful stimulus, the neurons, in order, are a sensory neuron, an interneuron, and a motor neuron In order to perceive the pain, the sensory information would have to be relayed to the brain and processed Additional neurons could be placed anywhere around the interneuron (which is found in the central nervous system at the spinal cord level); in other words, at either synapse II or synapse III 172 C First, always remember that the phrase “randomly mating population” is a tip off for using Hardy–Weinberg in some way The question states that 160 members of a 1000-member population exhibit a specific recessive trait A homozygous recessive genotype is required to exhibit a recessive trait, thus 16% of the population is homozygous recessive In the equation for genotype frequency, p2 + 2pq + q2 = 1, the value of q2 is 0.16; thus, q = 0.4 Plugging this value for q into the equation for allele frequency, p + q = 1, we find that p = 0.6 The question asks for the number of individuals in the population that are carriers of this trait Carriers are those individuals heterozygous for the trait; they “carry” the allele, but don’t express it because of their dominant allele In the equation for genotype frequency, these are the “2pq” individuals Plugging in the values we obtained previously, we get 2pq = × 0.6 × 0.4 = 0.48, or 48% of the population is made up of carriers Since 48% of 1000 is 480, the answer is choice C 30 Passage V 173 A Blood cells generally have short life spans; if they were not replaced continuously by stem-cell division and differentiation, we would quickly run out of blood cells, and the number of cells remaining would be incompatible with life Blood cells are stored in the spleen (choice B is false), they not exit the body through the urinary and digestive systems (choice C is false), and they not differentiate into other cell types (choice D is false) 174 A The development of hormone receptors on the cultured stem cells implies that their differentiation will be controlled by the hormones that bind there More rapid division (choice B) does not address the differentiation issue; in other words, the cells are dividing more rapidly, but is their differentiation random or controlled? Random differentiation supports the stochastic view (choice C can be eliminated), and choice D does not seem to support either the deterministic view or the stochastic view 175 B Stem cells that express hormone receptors support the deterministic view, but if the expression of the receptors is random, this also supports the stochastic view If hormone X causes the formation of erythrocytes, this supports only the deterministic view (choice A can be eliminated) If the receptors are being expressed in response to specific signals, this also supports the deterministic view (choice C can be eliminated) Choice D does not seem to support either view 176 D If all blood-cell types need to be replaced, then a totipotent stem cell (one that can differentiate into all cell types) needs to be introduced (choices A and B can be eliminated) Furthermore, the greatest advantage would come from a totipotent stem cell that differentiated deterministically, as this would allow it to produce cell types according to the specific needs of the new host, as directed by the host’s hormones and other external signals (choice C can be eliminated) Passage VI 177 C While hydration and oxymercuration–demercuration make the more-substituted alcohol, hydroboration–oxidation makes the less-substituted alcohol Therefore, choice C is correct 178 A After Step 1, the organomercurial alcohols formed have the –OH and the Hg(OAc) groups trans on the ring This relative stereochemistry is most likely achieved through the intermediate in choice A wherein the 3-membered ring is opened by H2O, as shown below: HgOAc HgOAc H2O HgOAc –H OH2 OH 179 C This reaction sequence places the –OH group on the less-substituted carbon atom of the C=C double bond, and as stated in the passage, does not involve skeletal rearrangements 180 D The O–H stretch of alcohols occurs at 3500 cm–1 in IR spectra 181 A Since Items II and III are two-step synthetic reactions, they are not likely to be reversible Therefore, only choice A can be correct 182 C Since the two isomeric organomercurial alcohols in Equation are non-superimposable mirror images of each other, they are enantiomers 31 Passage VII 183 C The fact that relaxation due to ACh only occurred in the ring with intact endothelium supports the conclusion that intact endothelium is necessary for this process The tension increases in both rings upon addition of NE (intact endothelium and damaged endothelium), so this gives us no information about the role of the endothelium specifically, and in any case NE is not ACh! (Choice A can be eliminated.) Tension decrease in both rings is approximately equal, and if anything, is slower in the ring without endothelium (choice B can be eliminated), and of course tension decreases during washout in the ring without endothelium The NE that caused the increase in tension in the first place is being removed Still, this gives us no information about the role that the endothelium plays in response to ACh (choice D can be eliminated) 184 C Since we have no data on the effects of ACh in the absence of NE, we cannot make any conclusions about NE’s effect on the smooth muscle’s sensitivity to ACh (choices A and B can be eliminated) Clearly ACh, which would cause a reduction in tension, has no effect at 10–8 M, so it is untrue to say that its effect is greatest at this concentration (choice D can be eliminated) Since concentrations of ACh above 10–6 M were not tested, and since the ring with endothelium responded to an ACh concentration of 10–7 M, it is fair to say that the presence of endothelium caused at least a 10-fold increase in sensitivity of the aortic muscle 185 B Muscle tension should decrease in the presence of ACh This only occurred in the ring with endothelium; the ring without endothelium was not sensitive at all to ACh at any concentration tested (choice D can be eliminated) Since muscle relaxation occurred at 10–7 M ACh, choice B is the best response 186 B The two major factors that determine blood pressure are the cardiac output and the peripheral resistance L-NMMA is not a naturally-occurring substance; the passage describes it as one of the enzyme inhibitors that “were developed” (choice A can be eliminated) While blood volume does play a role in blood pressure, not all the L-arginine consumed will be converted to NO, so the amount of L-arginine in the diet cannot tell us anything about the status of the blood pressure (choice C can be eliminated) Choice D is tempting because it mentions the two factors that determine cardiac output (heart rate and stroke volume) and we know that cardiac output is a major determinant of blood pressure However, choice D fails to take into account the other major determinant of blood pressure, the peripheral resistance 187 A The somatic nervous system deals only with the stimulation and contraction of skeletal muscle, not blood vessels (choices C and D can be eliminated) Furthermore, since ACh causes vasodilation (a parasympathetic effect) and NE causes vasoconstriction (a sympathetic effect), choice B can be eliminated 188 D Vasoconstriction would lead to an increase in blood pressure (choice A can be eliminated) and a reduction in blood flow (choices B and C can be eliminated) It would be most helpful in a situation where blood pressure was rapidly dropping and needed to be increased, such as during a hemorrhage Passage VIII 189 A The bond angle in an equilateral triangle is 60° 190 A According to the passage, hydrolysis of an epoxide under acidic conditions results in inversion of stereochemistry This means that a trans diol must result, eliminating choices C and D Choice B can be eliminated because it makes no sense; one cannot have a diol that is both axial and equatorial 191 A Since both carbon atoms of the epoxide are equally substituted, the regiochemistry is dictated by sterics Since R is much larger than R′, attack of Nu: will be primarily at the carbon bearing R′ This eliminates choice C Choice B can be eliminated because the stereochemistry of the left carbon in the product is drawn incorrectly (it is inverted) Choice D can be eliminated because the passage states that the configuration of the carbon that is attacked by the nucleophile undergoes inversion This leaves choice A as the answer 32 192 C A 5-membered ring results from intramolecular hydrogen bonding in a 1,2-diol: H O H O Ph 193 D Since styrene oxide acts as an electrophile in these ring-opening reactions, the greater nucleophilicity of diethylamine over ethanol explains its higher reactivity Independent Questions 194 A CBr4 is the least polar of the bromomethanes because the four C–Br bond dipoles cancel each other out due to the tetrahedral symmetry of the molecule This results in no dipole whatsoever for CBr4 195 C Tautomerism is a structural equilibrium and usually involves movement of a proton, as in this keto–enol equilibrium 196 B Remember the basic themes about fungi: they have a haploid life cycle (choice A can be eliminated), they possess a cell wall (choice D can be eliminated), and they can reproduce asexually by spore formation Spores are, in a sense, like seeds They are surrounded by a tough coat that helps them survive environmental extremes When they have “weathered the tough times” and are again in a favorable environment, they will germinate (choice C can be eliminated) 197 B The heart is derived from mesoderm, and so is the skeletal system The eye and spinal cord are derived from ectoderm (choices A and C can be eliminated), and the liver is derived from endoderm 198 A A man with normal blood clotting has the genotype XY Because women receive an X chromosome from their fathers, a woman with a hemophiliac father must carry at least one X chromosome with the recessive allele for hemophilia on it However, because she displays normal blood clotting, her other X chromosome must be normal; in other words, she is heterozygous and has the genotype XhX Here’s the Punnett square: Xh X X X h X XX Y X h Y XY From the Punnett square we can see that the probability of having a son with hemophilia (genotype XhY) is 1/2 For the probability of all three of their sons having hemophilia, use the Rule of Multiplication: 1/2 × 1/2 × 1/2 = 1/8 33 Passage IX 199 D Since T cells are not discussed in the passage anywhere, and since the antibody binds to a macrophage protein, choices B and C can be eliminated From the diagram, it is clear that the events leading to septic shock involve activation of macrophages If this is to be prevented, macrophage activation must be inhibited (choice A can be eliminated) 200 A Drugs that decrease inflammation would not affect platelet or red blood cell counts (choices B and C can be eliminated) The inflammatory response depicted in the diagram shows hypotension, a decrease in blood pressure, as part of the events leading to shock However, blocking the inflammatory response would not necessarily lead to an increase in blood pressure, it would merely prevent the decrease associated with this cascade of events (choice D can be eliminated) (Note that while choice A is not obviously true based on the passage and requires some outside knowledge to answer, this question should be tackled using process of elimination, as the other three choices are clearly incorrect.) 201 C If the blood is pooling in the venous circulation, then less of it is returning to the heart Decreased venous return leads to decreased stroke volume, which leads to decreased cardiac output, which leads to decreased blood pressure Thus, choice B would occur and can be eliminated Because of the decreased cardiac output (and the venous pooling), less blood is being passed through the pulmonary system, so the blood overall will have a lower oxygen content (choice D is true and eliminated) Lastly, if oxygen content is decreased, cells will rely more heavily on anaerobic respiration, the end-product of which is lactic acid (choice A is true and eliminated) Only choice C would not occur Venous pooling would lead to edema as fluid moved from the veins to the surrounding tissues, and in an attempt to compensate, lymphatic fluid volume, if anything, would increase 202 A Fever (increased body temperature) would lead to dilation of capillaries in the skin in an effort to direct more blood to the surface of the body so as to increase heat loss Increased skeletal muscle activity (i.e., shivering) and decreased respiration rate are compensatory mechanisms for when the body temperature is too low (choices B and C can be eliminated) If anything, fever would result in increased fluid loss in an attempt to cool the body through perspiration (choice D can be eliminated) 203 C Since DNA replication occurs in S phase, a drug that interferes with DNA replication would cause cells to arrest in this phase Passage X 204 B AlCl3 is quite a strong Lewis acid since the aluminum atom has only a sextet of electrons In electrophilic aromatic substitutions, a catalyst such as AlCl3 is usually used 205 D Since a new group is added (alkyl), and an old group is removed (H), this is termed a substitution, not an addition Thus, choices A and B can be eliminated Since the incoming group is an electrophile (n-propyl chloride), this is an electrophilic aromatic substitution 206 D Choices B and C can be eliminated since the molecules contain no stereocenters Choice A can be eliminated since the molecules not differ in σ-bond rotations The molecules are structural (constitutional) isomers because they have different structures 207 C Molecule will elute first since it has the lowest molecular weight, and molecules elute on GC approximately according to increasing boiling point This eliminates choices B and D Since branched isomers boil at lower temperatures than their straight-chain isomers, choice C is a better response than choice A 34 Passage XI 208 B The best evidence that something is required to activate a pathway is to show that the pathway cannot be activated in the absence of that something Therefore, choice B clearly shows that G proteins are required to regulate intracellular signaling Choice A is good evidence, but not as good as choice B Choice C is extremely weak evidence; if the ratios are not even consistent from cell type to cell type, how can it be said that G proteins and adenylate cyclase play any role together in signaling pathways? Lastly, choice D presents evidence for the fact that G proteins may not play a role in intracellular signaling, since the pathway can be activated in their absence 209 D Choices A, B, and C are all described in the second paragraph as being part of the chain of events involved in intracellular signaling Choice D, however, is not mentioned anywhere, and what would we get if GTP were phosphorylated anyway? GQP (guanosine quadrophosphate)? 210 D Binding of an activated G protein to an inactive enzyme is unlikely to change the primary structure (i.e., the amino acid sequence) of either player involved (choices A and B can be eliminated) Furthermore, it can be assumed from the passage that binding of an activated G protein to an inactive enzyme would activate that enzyme Remember that the two most common ways to activate (or for that matter, to deactivate) an enzyme is to (1) phosphorylate it, or (2) change its shape (tertiary structure) Since the enzyme is clearly not being phosphorylated, the best answer here is choice D Note that it is unlikely that binding of the G protein to the inactive enzyme would have any effect on the structure of the G protein itself; the point is to change the enzyme, not the G protein (choice C can be eliminated) 211 A As in Question 208, choice D, if the enzyme can be activated in the absence of a G protein, this would clearly refute the hypothesis that the G protein is required If choice B were true, this would present weak evidence for the necessity of the signaling pathway; and if choice C were true, this would present even better evidence for the role of the G protein in this pathway If the enzyme were always found in the activated state (choice D), this would help refute the hypothesis, but this is not as good as choice A 212 B This is another question that is best tackled by process of elimination The GTP is not bound to the protein until after it binds to the receptor (choice A is false) Hydrolysis of GTP does not occur until the end of the pathway, well after the activation of both the G protein and the membrane-bound enzyme (choices C and D are false) In fact, hydrolysis of GTP serves to inactivate the G protein While choice B is not explicitly stated in the passage, it seems a likely method, and with the other three choices being false, it is the best answer choice 213 C This is specifically stated near the end of the second paragraph (choice C is true and choice A is false) Choice B may be true, but does not deal with the question being asked, which assumes that the G protein has already been activated Lastly, choice D is simply false Binding of the G proteins to the membrane-bound enzyme does not result in hydrolysis of GDP Independent Questions 214 D Diffusion of gases is not rapid enough to inflate the lungs (choice A can be eliminated), and respiratory gases not need to be actively transported, because they are lipid soluble (choice B can be eliminated) The lungs are inflated when the diaphragm contracts, increasing the size of the chest cavity and creating negative pressure; air then rushes in to fill this “vacuum” (choice C can be eliminated) 215 A Bacteria reproduce by fission, but viruses not Bacteria have a rigid cell wall but are not the only organisms that do; plants also have a cell wall, so the presence of this structure would not necessarily classify the organism as a bacterium (choice B can be eliminated) Bacteria not have a nuclear membrane (choice C can be eliminated), and some viruses contain both RNA and protein (enzymes, choice D can be eliminated) 35 216 A The function of aldosterone is to increase Na+ reabsorption by the kidneys (choices B and D can be eliminated), in other words, to increase the amount of Na+ retained by the body (remember that reabsorption means to take something from the urine and return it to the bloodstream) If excessive quantities of NaCl were consumed, there would be no reason to increase reabsorption of Na+; if anything, the level of aldosterone would decrease (choice C can be eliminated) 217 A Only Molecule is not an ether (R–O–R) Molecule is an ester (RO(CO)R) 218 B The thyroid gland and the adrenal glands have no role in the menstrual cycle (choices A, C, and D can be eliminated) The hypothalamus releases GnRH, which stimulates the anterior pituitary to release FSH and LH, which stimulate the ovary to undergo oogenesis and follicle maturation, as well as the secretion of estrogen and progesterone, which regulate the uterus during the menstrual cycle 219 D A cross between homozygous long white plants (LLWW) and homozygous short red plants (llRR) would produce an F1 generation that was heterozygous at both locations (LlWR) These plants would be pink and have long leaves If they were bred randomly, all phenotypes would appear There are two leaf phenotypes (long and short) and three color phenotypes (white, pink, and red), and thus × = total phenotypes: long white, long pink, long red, short white, short pink, and short red 36 ... the author states that both primal spirits (Angra Mainyu and Ahura Mazda) deliberately chose between good and evil, and that all persons are required to make the same choice B: Only Ahura Mazda... steady, but gradually decreases, since it’s more difficult to place additional charge on a capacitor that already has some charge, because we’re “fighting against” the electric field in the capacitor... central thesis of the passage The author uses orangutans as one example in the context of the passage’s overall argument about training and sensitivity B: The author writes that orangutans are

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