MCAT-PREP GS-2 (Shortened) - Questions I missed/need to review
CARS Passages - mistakes
#4: (Series question) missed the NOT in the question stem; picked the opposite Roman numerals #15: extrapolation of the wrong idea; did not directly answer the question; another answer choice was better #20: incorrect interpretation of quote, based on outside knowledge/distorting the passage #23: incorrect interpretation of author's tone; thought author switched themes more than once, when it is really only once; did not refer back to passage #26: (possibly incorrect explanation, and my answer choice was actually correct; but if explanation is incorrect,) I picked an answer that was only partially correct; need to confirm all of the answer choice answers the question #29: missed the EXCEPT in the question; approached the question looking for the choice that is least in line with the passage rather than the choice that is most related to the passage #32: overlooked the overall argument and purpose of the passage; undervalued the difference between "same" and "similar, but different in context" #34: incorrect interpretation of main idea/structure of passage; did not refer back to passage #37: Did not pay enough attention to all the answer choices; did not properly identify the location of the quote in question to answer the question #43: Did not reference the most relevant part of the passage to answer the question; should have paid more attention to the context of the statements in relation to where they are mentioned in the passage In general; before choosing an answer, decide if it is the correct amount of specific and general to fit the focus of the passage; if you can extrapolate the idea, it is probably not the right answer.
Which of the following senses is NOT used to send communicative signals to other organisms? (A) Vestibular sense (B) Seismic sense (C) Haptic sense (D) Bioluminescence
(A) A is correct. In most mammals, the vestibular sense is located in the vestibular labyrinth of the inner ear. Via mechanoreceptors in the hair cells, the labyrinth receives and passes on sensory information critical for the organism's sense of balance and gravity, spatial orientation, motor coordination, body position, and gaze stability during head movement. It is composed of five receptor organs: the anterior, the posterior, the lateral semicircular ducts, and the two otolith organs called the utricle and the saccule. Hence, the vestibular system is not used to send signals to other organisms. Seismic sense (vibrations)- produced by creating vibrational waves using a body part and an external substrate, which is then perceived by other animals via mechanoreceptors/subgenual organs Haptic sense (touch)- involves bidirectional exchange of tactile information arising from the physical, proximal, and intimate interaction of the organism with its surroundings and other organisms
Which option best describes the style of communication of a non-Hispanic White family that is described by others as utterly gregarious, loud, and enthusiastic, and as rarely making any long pauses, or going straight to the point of a story when holding family conversations? (A) Low-context culture communication (B) Hierarchical communication (C) High-context culture communication (D) Paralanguage-reliant communication
(A) A is correct. Low-context communicators can typically be described as employing direct patterns of communication, with explicit descriptions and terms, speaking more and frequently raising their voices (animated, dramatic), and often being impatient to get to the point of the discussion. Communicators from high-context cultures generally utilize indirect communication, talk less, rely on nonverbal cues, and are very comfortable with silences. They tend to use more formal language that emphasizes the hierarchical relationships of individuals. This does not correspond to what was described.
Why did the author claim that "twin studies are particularly revealing, principally when they involve the study of monozygotic twins reared apart," in discussing behavioral genetics? (A) They illuminate the relative importance of nature as opposed to nurture in what concerns psychological attributes. (B) They show how adoption is the best solution for the social and psychological development of twins. (C) They prove that genes are more important than child rearing in determining behavior. (D) They allow for a comparison between genetically related and non-genetically related twins.
(A) A is correct. Monozygotic twins have the same genes. When each twin is raised in a different social environment, behavioral genetics compares their phenotypes. Similar phenotypical traits are thought to result from their genetic similarity, whereas different phenotypical traits are thought to result from their different environments. That is, this research field uses data relative to identical twins reared apart to detect which traits are genetic and which traits are not (nature versus nurture issue). When the twins are reared together, it is more difficult to determine whether a particular trait is the result of genetic or environmental factors. WIMI: Was not correctly thinking about nature and nurture; was under the impression that (A) had it backwards when in fact it was correct.
Which one of the options below is NOT a latent function of schooling? (A) Socializing students into commonly shared values that are expressed in curricula and school manifestos (B) Legitimizing existing class structures (C) Providing child care for parents who are at work (D) Serving as a meeting place for romantic relationships by bringing together people of similar background and age
(A) A is correct. Robert Merton's functionalist view divides social institutions such as education into latent and manifest functions. Manifest functions are those that society explicitly designs to happen within the social institutions. Latent functions are those that are not intended to happen but take place anyway. Educational institutions commit to the goal of teaching commonly shared values that vary by culture and setting. Those values could include respecting other students and teachers, or religious and patriotic values. They are manifest because the pursuit of those values is written down in curricula and school manifestos. WIMI: Ruled out (A) thinking it was latent, but it explicitly states that it is manifest function, since it is "expressed in curricula and school manifestos"
How would the Thomas theorem explain the findings from Figure 1 in relation to race? (A) A common stereotype about Black youth is that they are educational underachievers. This perpetuates their and their teachers' expectations, and they underperform when taking tests. (B) White people have fewer stereotypes to face than Black people. Furthermore, they automatically enjoy greater social status and more cultural affirmation of their identities. This affects their educational performance and leads to better educational attainment. (C) White people acquire an accumulated advantage over the course of their educational careers. This advantage leads to higher achievements in relation to degrees. (D) Black people have less access to goods, services, and opportunities during the course of their education. The underlying reason for this lies in the way educational systems, policies, programs, and interactions are planned and conducted.
(A) A is correct. The Thomas theorem states that if people define situations as real, they become real in their consequences. This theorem states that the perception and interpretation of a situation can have more influence on an individual and social level than objective measurements and empirical findings. In accordance with the Thomas theorem, the comparatively low performance of Black men depicted in Figure 1 would be explained by racial stereotypes that perpetuate Black men's interpretation of the situation when they have to perform in educational institutions. Furthermore, the Thomas theorem would explain the strong influence of teachers' expectations on students' educational attainment (i.e., teacher expectancy effect). Thomas theorem - if people define situations as real, they become real in their consequences.
According to the information provided in the passage, which type of memory shows great decline with age? (A) Working memory (B) Long-term memory (C) Semantic memory (D) Episodic memory
(A) A is correct. Working memory is the term employed to describe people's ability to hold a set of items in memory for a short period of time and to manipulate such information. The tests described in the passage involve holding simpler and more complex information in mind, as well as manipulating it. That is, they seek to evaluate people's working memory. Older people's performance is worse for working memory-related tasks, and principally when the information is complex or the task involves information manipulation. This is the only memory deficit associated with age in the passage. WIMI: tried to use outside knowledge; episodic memory is known for declining with age, but this is not declared anywhere in the passage.
What is the maximum deceleration felt by the driver (using the points (70 ms, 30 kph) and (90 ms, 0 kph), as the maximum |slope| occurs at t = 80 ms)? (A) 0.5 km/s^2 (B) 1.5 km/s^2 (C) 10 km/s^2 (D) 1500 km/s^2
(A) Acceleration is the rate of change in velocity, a=v/t. From Figure 1, the acceleration is given by the slope m. The maximum slope m occurs at t = 80 ms. Taking the two points (70 ms, 30 kph) and (90 ms, 0 kph) the slope at 80 ms can be calculated as: m = [(30 kph) - (0 kph)]/(70 ms - 90 ms) = (30 kph)/(-20 ms) = (0.008 kps)/(-20*10-3 s) ~ -0.4 km/s2. This is a deceleration of 0.4 km/s2. Step-by-step Dimensional Analysis and Calculation: The actual conversion is: 30 km / hour x 1 hour / 60 min x 1 min/ 60 sec = 30 km / 3600 sec = 1/12 x 10^-1 = 0.08 x 10^-1 = 0.008 kps. Now we wish to divide by -20 ms (milliseconds) which is -20 x 10^-3 s.Acceleration = v/t = -(0.008/0.2) = 0.4 km/s2.
All of the following explain the ionic concentrations in Table 1 EXCEPT: (A) Na+ and Cl- ions passively diffuse more quickly into the extracellular fluid than K+ ions. (B) Na+ ions are actively pumped out of the intracellular fluid. (C) the negative charge of the cell contents repels Cl- ions from the cell. (D) the cell membrane is more freely permeable to K+ ions than to Na+ and Cl- ions.
(A) Answer choice (A) is a false statement making it the correct answer! Table 1 shows us that the inside of the membrane is negatively charged (Vm = -70 mV), yet there are 10 times the number of sodium cations outside the membrane as compared to inside. The passage suggests that there should be a strong gradient for positively charged sodium to diffuse into the intracellular fluid (P2, S2-3; opposite charges attract). Also, since Table 1 shows that the ionic concentration of sodium outside the cell is so much greater than inside, then this would be another reason that sodium should diffuse into the cell. Thus the only way for sodium to be driven against its charge and concentration (= electrochemical) gradient is by active transport not diffusion (P2). WIMI: Did not carefully review the answer choices; thought that (A) said intracellular, not extracellular
All of the following are true about a blood pressure of 150/60 EXCEPT: (A) the value normally indicates the venous pressure in the arm. (B) 150 indicates the pressure as a consequence of ventricular contraction. (C) the pulse pressure is 90. (D) 60 indicates the diastolic pressure.
(A) Blood pressure is not measured in the veins, it is routinely measured in the brachial artery (in the arm). Note that 150 mmHg indicates the systolic blood pressure when the ventricle contracts, 60 mmHg is the diastolic blood pressure during ventricular relaxation, and the pulse pressure is simply systolic minus diastolic (you will see this come up again in the AAMC's practice materials), thus 150 - 60 = 90.
In the body tissues, cortisol is converted to cortisone by which of the following enzymes? (A) 11-Hydroxysteroid dehydrogenase (B) 11-Oxysteroid isomerase (C) Steroid ligase (D) Transferases
(A) Cortisol has a hydroxyl at the 11' carbon and cortisone has a carbonyl at the 11' carbon, thus 2 H's were removed requiring a dehydrogenase that acted at the 11th carbon (11-Hydroxysteroid dehydrogenase). It cannot be an isomerase because the 2 molecules differ by 2 hydrogens, meaning they must have different molecular formulae (thus they are not isomers). A ligase joins 2 molecules which is clearly not the case. And lastly, a transferase transfers a group of atoms but the reaction described is simply the removal of 2 hydrogens (= dehydrogenase; note that enzymes are often named as per their action).
Which of the following best states the relationship between methylene chloride (density ~ 1.33 g/mL) and the aqueous extract? (A) Methylene chloride will make up the bottom layer of liquid and aqueous extract the top layer in the separatory funnel. (B) The aqueous extract will make up the bottom layer and methylene chloride the top layer in the separatory funnel. (C) The aqueous extract is soluble in the methylene chloride. (D) Impurities in the mixture are extracted from the methylene chloride to the aqueous extract.
(A) On the Surface: the density of water is 1 g/ml (you are expected to know the density of water; also, water = aqueous) and the density of methylene chloride is given in the passage as 1.33 g/ml. Clearly, the more dense layer would be found at the bottom (answer choice A).
Which of the following would explain the non-separation of cortisol from cortisone by the method of gas-liquid chromatography (GLC)? (A) The solid material in the column of the GLC, through which substances pass in their mobile phase, absorbs cortisol and cortisone equally well. (B) Cortisol and cortisone have relatively high boiling points. (C) Cortisol and cortisone have very similar boiling points. (D) Cortisol moves through the column of the GLC, through which substances pass in their mobile phase, at a much quicker rate than cortisone.
(A) The correct answer is A. GLC separate compounds by molecular weight and polarity. If the solid material in the column absorbs both cortisol and cortisone equally well, then they cannot be separated by this method. Answer choices B and C allude to the distillation method, in which compounds are separated by their boiling points. Therefore, these two choices are incorrect. Answer choice D is also incorrect because it suggests that Cortisol can be separated out through GLC from cortisone, which is the opposite of what the question is asking. WIMI: Thought gas chromatography did not involve a mobile phase/column, and just separated compounds by boiling point. In actuality, it does have mobile phase and a column containing solid material through which substances pass and get absorbed.
Researchers repeated the experiment with new mice, this time using a 30-hour schedule, with 15 hours each of period light and dark. They found that: (A) the wild type mouse adopted the 30 hour schedule, while the Per1m/mPer2m/m mouse continued to be arrhythmic. (B) both the wild type and Per1m/mPer2m/m mouse adopted the 30 hour schedule. (C) the wild type mouse remained on a 24 hour schedule, while the Per1m/mPer2m/m mouse continued to be arrhythmic. (D) both the wild type and Per1m/mPer2m/m mouse displayed arrhythmic behavior.
(A) The passage mentions that circadian oscillations are entrainable, which means that the patterns match that of patterned environmental stimuli. Thus, although circadian rhythms are endogenous, and occur even when isolated from environmental cues, they will adapt to external cues, such as a prolonged light-dark cycle. The extended light-dark cycle will not affect the double-mutant mouse, which will continue to display erratic activity. WIMI: Thought that circadian rhythms are always 24 hours (C), but they in fact can be changed.
Which of the following does NOT follow the normal anatomical sequence? I. gametogenesis → seminal vesicles → seminiferous tubules II. seminiferous tubules → epididymis → vas deferens III. vas deferens → ejaculatory duct → urethra (A) I only (B) II only (C) I and II only (D) II and III only
(A) The structures and processes of the male reproductive system should be understood from the biology review.
Which of the following is the strongest reducing agent? Electrochemical reaction = E° value (V) MnO2 + 4H+ + 2e- <--> Mn^2+ + 2H2O = +1.23 Fe^3+ + e- <--> Fe^2+ = +0.771 N2 + 5H+ + 4e- <--> N2H5+ = -0.230 Cr^3+ + e- <--> Cr^2+ = -0.410 (A) Cr^3+ (B) Cr^2+ (C) Mn^2+ (D) MnO2
(B) The reduced species of the electrochemical equilibrium with the most negative E° value is the strongest reducing agent (CHM 10.1). Memory aside (!), it is of value to note that a reducing agent reduces the other substance, thus a reducing agent is oxidized. Note that only answer choices (B) and (C) are oxidized (= lose electrons). When you write the two relevant equations as oxidations, instead of reductions like the table provided, you will note that only answer choice B. has a positive E° value indicating the spontaneous nature of the reaction. The table provided demonstrates half-reactions written as reduction potentials. In order to write the oxidation, simply reverse the reaction and change the sign of E°: Oxidation: Cr2+ ↔ Cr3+ + e- E° = 0.410
75 grams of glucose (C6H12O6) and 75 grams of sucrose (C12H22O11) were each added to beakers of water (beaker 1 and beaker 2, respectively). Which of the following would be true? (A) Boiling point elevation for beaker 1 would be greater than the boiling point elevation for beaker 2. (B) Boiling point elevation for beaker 1 would be less than the boiling point elevation for beaker 2. (C) The same degree of boiling point elevation will occur in both beakers. (D) No boiling point elevation would be observed in either of the beakers.
(A) This question tests your understanding of colligative properties. From the equation Tb = Kbm, where Kb is constant, or the molality is the factor to be considered. Recall that m = (Number of moles solute)/(1000 g solvent) and number of moles = (Mass of substance present)/(Relative molecular mass). Since glucose has a smaller relative molecular mass than sucrose, there will be a greater number of moles of glucose present when equal masses of the two substances are used. Therefore, the molality of glucose is greater and hence the boiling point elevation is greater.
A patient is being treated for deep vein thrombosis using warfarin, but needs to undergo an imaging scan using a radiopharmaceutical tracer. Based on the data presented, which is likely to be the best tracer to use? (A) Cu-ETS (B) Cu-PTSM (C) Cu-ATSM (D) Either Cu-PTSM or Cu-ATSM
(A) Warfarin is a 'blood thinner' (= anticoagulant) used in the treatment of disorders that require the dissolution of a blood clot or for the prevention of clotting as suggested by the passage. A patient with deep vein thrombosis will be receiving warfarin to function as a blood thinner. The data presented in Tables 1 and 2 reveal that Cu-PTSM and Cu-ATSM are both readily displaced from HSA by warfarin, as indicated by increasing amounts of free Cu-PTSM or Cu-ATSM in the presence of increasing molar ratios of warfarin to HSA. Conversely, Table 2 shows that increasing molar ratios of warfarin to HSA did not displace Cu-ETS significantly; therefore, Cu-ETS would be the optimal choice in these patients. WIMI: The more that is displaced (the higher the concentration displaced), the more effective warfarin is in displacing it. I was thinking the opposite (chose D).
In the reoxidation of QH2 by the enzyme Complex III ubiquinone-cytochrome c reductase, the stoichiometry of the reaction requires 2 moles of cytochrome c per mole of QH2 for which of the following reasons? (A) Cytochrome c is present in Complex III as 2 separate molecules. (B) Cytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor. (C) Cytochrome c is a two-electron acceptor, whereas QH2 is a one-electron donor. (D) As a result of the entropic penalty, twice as much cytochrome c as compared to QH2 is required.
(B) As long as you recognize coenzyme Q from QH2, the difference of course being the loss of the 2 hydrogens WITH their electrons making QH2 a 2-electron donor (reminder: a covalent bond is composed of 2 electrons), and that you recall the relationship between coenzymes and metal ions (most often iron, and especially for cytochrome c), then you also recognize that cyt c is a one-electron acceptor in the reaction shown: QH2 + 2 ferricytochrome c (Fe3+) --> Q + 2 ferrocytochrome c (Fe2+) + 2 H+ In summary, for many cytochromes, the metal ion present is iron, which interconverts between Fe2+ (reduced) and Fe3+ (oxidized) states (electron-transfer processes) or between Fe2+ (reduced) and Fe3+ (oxidized) states (oxidative processes), the difference between reactant and product in each case is one electron.
Given what is known about narcissistic personality disorder, what hypothesis might researchers, interested in the relationship between low vs. high narcissistic personality survey scores and patterns of financial investments, formulate? (A) Subjects who score low on narcissism are more likely to feel they belong to the group of high-powered and successful investors than those who score high on narcissism. (B) Subjects who score high on narcissism are more likely to invest in stocks that exhibit high volatility (i.e., large price fluctuations) than those who score low on narcissism. (C) Subjects who score low on narcissism are more likely to multiply their investments without great evidence of viability than those who score high on narcissism. (D) Subjects who score high on narcissism are more likely to seek conservative investments with a stable rate of return than those who score low on narcissism.
(B) B is correct. Individuals diagnosed with narcissistic personality disorders display patterns of arrogance, a lack of empathy, a focus on self, and a belief they are unique. Although they appear to be very self-confident and self-assured, when their self-esteem is threatened they become defensive. They also exhibit impulsiveness and tend to seek risks so as to show the world they are invincible and better than everyone. For this reason, high volatility investments would most likely appeal to them. A. and C. These are incorrect. These hypotheses do not reflect characteristics of a "low" narcissistic personality survey scores. They rather point to the presence of narcisistic traits. D. This is incorrect. This hypothesis does not reflect characteristics of narcissistic personality disorder, or high narcissistic personality survey scores.
The passage described a set of strategies that can be used to facilitate memorization and recall. These include conceptualization, prior knowledge activation, and semantic associations. These types of cognitive processes are examples of: (A) maintenance rehearsal. (B) elaborative rehearsal. (C) shallow processing. (D) priming.
(B) B is correct. Instead of defining structures or memory components, Fergus Craik and colleagues argued that differences in recall were associated with different levels of information processing. They proposed that there were two main levels: narrow and deep. Narrow processing involves the repetition or rehearsal of superficial aspects of the material, such as the font type, and simple repetition of the material to be remembered (maintenance rehearsal). One example would be repeating a phone number out loud until one writes it down. Deep processing involves establishing semantic associations with the material to be remembered (elaborative rehearsal), for example, considering the meaning of the material and associating images with each item. The strategies mentioned all involve deep processing. Deeply rehearsed material is found to be more easily memorized and retrieved. Maintenance rehearsal - narrow processing (rote memorization). Elaborative rehearsal - deep processing (semantic associations).
A fish tank distributes food from two stations at an equal rate. After some time, one tank doubles the amount of distributed food. The ideal free distribution theory predicts that the six fish living in the tank will: (A) consume resources in proportion to the available resources. Hence a change in rate will provoke a change in the amount consumed. (B) Distribute themselves per food station in proportion to the available resources. Hence a change in rate will provoke a change in the fishes' distribution. (C) consume resources in proportion to the existing food needs. Hence a change in rate will not provoke a change in the amount consumed. (D) distribute themselves per food station in proportion to the existing population. Hence a change in rate will not provoke a change in the amount consumed.
(B) B is correct. The ideal free distribution theory is a model originally developed by Fretwell and Lucas (1969) to explain foraging behavior in animals. Given that the quality of available food (e.g., amount and accessibility of resources) varies by location, it could be thought that all animals would compete over the best spots. However, according to the ideal free distribution theory, animals that are free to sample the environment will distribute themselves as a function of the feeding areas' quality. After a period of sampling, the animals begin to settle into spots as a function of the payoff received from that spot. Given that a higher number of predators and competitors will reduce the payoffs of the best spots, lower-quality spots will start being populated. In the simple example given, the fish were equally distributed along equally good stations. An increase in food distribution rate at one of the stations makes it twice as good as the other. Hence a redistribution of the fish would be expected in densities proportional to the ability of the station to support the fish. Instead of groups of three, a group of four and a group of two should result from the rate increase.
Researchers conducted a study that compared 50 smokers with brain damage to the insula and 50 smokers who did not have any brain damage to find out how brain damage to the insula affected smoking cessation. What would the data most likely indicate? (A) Smokers without brain damage to the insula were more likely to have more intense sleep cycles, and therefore they were able to "sleep off" the withdrawal effects of smoking. (B) Smokers with brain damage involving the insula were more likely to quit smoking more easily and immediately without persistence of the urge to smoke than smokers without any brain damage. (C) Smokers with brain damage in the insula region were more likely to have more intense sleep cycles, and therefore they were able to "sleep off" the withdrawal effects of smoking. (D) Smokers without any brain damage to the insula were more likely to quit smoking more easily and more quickly without persistence of the urge to smoke than smokers with brain damage to the insula.
(B) B is correct. The insula of the brain is implicated in conscious urges and emotions. Therefore smokers with brain damage involving the insula would be more likely to quit smoking more easily without relapse than smokers without brain damage to the insula. A. and C. These are incorrect. The insula of the brain is implicated in conscious urges and emotions. It is not related to sleeping. D. This is incorrect. Since the insula of the brain is implicated in conscious urges and emotions, smokers who do not have damage to the insula do not have any disruption to emotions (e.g., feelings of frustration) or conscious urges to smoke. Insula - conscious urges and emotions
Which of the following best explains why the protocol requires the student to add the tea leaves to 80 °C H2O in Step 1? (A) H2O at 80 °C to dampen the dry tea leaves. (B) Caffeine is relatively soluble in H2O at 80 °C. (C) H2O at 80 °C serves as a solvent for the reaction of calcium carbonate and caffeine. (D) H2O at 80 °C is below the boiling point.
(B) Consider the various answer choices. Answer choice A does not make sense since liquid water is sufficient to dampen the leaves, hot water (80 °C) is more likely to solubilize something (answer choice B). Answer choice C is not consistent with the objective of the experiment: to extract caffeine NOT to react caffeine with another chemical. Answer choice D is a true statement which is essentially unrelated to the question. WIMI: Looked to far into the procedure; no reaction between calcium carbonate and caffeine is implied in the passage, so (C) goes too far. (B) is a better choice since it states that caffeine is soluble in water at 80 °C, but does not go any further than what was mentioned in the passage.
Certain drugs are able to induce Per1 and Per2 gene expression, offering possible treatment options for those with circadian rhythm disorders. One would expect that periodic dosage of these drugs would: (A) restore regularly oscillating activity patterns to Per1m/mPer2m/m mice. (B) have minimal effect on Per1m/mPer2m/m mice. (C) restore the function of Per1 and Per2. (D) shorten the time of light-dark adaptation in Per1m/mPer2m/m mice.
(B) It's likely that drugs that specifically induce Per1 and Per2 gene expression would have minimal effect on Per1m/mPer2m/m mice, as the genes themselves are mutated. Dosage of the drug would merely induce the expression of mutated Per1 and Per2 genes. WIMI: "unregulated broken gene is still a broken gene"; inducing expression of Per1 and Per2 genes in mutated mice would only exacerbate the irregular pattern, not make it better
20 mL of 0.05 M Mg2+ in solution is desired. It is attempted to achieve this by adding 5 mL of 0.005 M MgCl2 and 15 mL of Mg3(PO4)2. What is the concentration of Mg3(PO4)2? (A) 0.065 M (B) 0.022 M (C) 0.150 M (D) 0.100 M
(B) On the Surface: Don't convert mL to litres because it will cancel out. x = molarity of Mg3(PO4)2 --> Solve for x (.005M Mg2+)(5mL) + (3x)(15mL) = (20mL)(.05M Mg2+) Note the 3 in front of x because there are 3 potential Mg2+ generated from each Mg3(PO4)2 in aqueous solution. .025 + 45x = 1 45x = 0.975 thus x = 0.022
Which of the following tissues most benefits from the shifts in the oxygen-dissociation curves caused by GBP and myoglobin? (A) Cardiac muscle tissue (B) Skeletal muscle tissue (C) Loose connective tissue (D) Intestinal wall tissue
(B) The passage suggests that when exposed to body tissues other than lung, in other words parts of the body with relatively low oxygen concentrations, both myoglobin (P2, S2) and hemoglobin with GBP (P1, S5) begin to release oxygen at a tremendous rate. The question can be translated thus: which of the following tissues can deplete its oxygen reserves quickest and thus would benefit most from a molecule which is used to delivering oxygen to oxygen-starved tissue? Oxygen debt can be most pronounced in skeletal muscle. Voluntary or skeletal muscle can deplete its oxygen stores so quickly that it switches to anaerobic respiration thus incurring an oxygen debt. The oxygen tension (= partial pressure = concentration) in this tissue is extremely low and will therefore benefit most from an influx of oxygen. {Note that myoglobin like myosin implies muscle}
If cyanide was added to nerve cells, what would be expected to happen to the ionic composition of the cells? (A) Na+ ions would be actively pumped into the cell and K+ ions would be pumped out. (B) Intracellular Na+ would increase since the sodium pump would be impaired. (C) The potential of the cell membrane would not be reversed so that Cl- ions would freely enter the cell. (D) The cell membrane would become freely permeable to Na+ and Cl- ions.
(B) The sodium-potassium pump uses energy to transport these molecules against their concentration gradients. Cyanide is an inhibitor of an essential enzyme of the electron transport chain, which is a major source of ATP (energy) for the cell. If cyanide is added to the cells, considerably less energy will be produced, and the sodium potassium pump would be impaired, and depending on the concentration of cyanide and energy resources, the pump may be unable to function. WIMI: forgot what cyanide does in cell (disrupts ATP synthase); ATP needed for sodium/potassium pump; without ATP pump is impaired so intracellular Na+ would increase
A biologically active agent, which completely diffuses through capillary beds, is injected into the brachiocephalic vein of the left arm. Which of the following would be most affected by the agent? (A) Heart (B) Lung (C) Left arm (D) Left leg
(B) This question can be translated thus: if something enters a vein in your arm, where is the first capillary bed which will be encountered? The following is simply part of the basic cardiovascular anatomy you need to know: vein in arm (= upper body) --> larger veins --> superior vena cava --> right atrium of the heart --> right ventricle of the heart --> pulmonary artery --> smaller arteries in the lung --> arterioles in the lung --> capillary beds in the lung --> venules in the lung --> veins in the lung --> pulmonary veins --> left atrium of the heart --> left ventricle of the heart --> aorta --> many different arteries --> many different arterioles --> many different capillary beds of the body system including those that supply the heart muscle, the arms, the kidneys, the brain, the liver, etc. --> venules --> veins, and the story repeats itself. WIMI: Agent will reach the capillary beds of lungs before the capillary beds of the heart
Which of the following personality traits shows greater heritability, as based on the results presented in Table 1 and identified below in parentheses? (A) Positive emotionality (r = 0.63) (B) Positive emotionality (r = -0.07) (C) Negative emotionality (r = 0.61) (D) Negative emotionality (r = 0.41)
(C) C is correct. Correlations vary from −1 to 1. The greatest positive correlations translate to stronger associations. The group that better allows for determining a certain trait's heritability or genetic influence is the monozygotic-twins-reared-apart group, because these twins share the same genes, and thus environmental factors that could enhance the twins' similarity are controlled for. Hence, from the listed options and with regard to this group, the higher intraclass correlation refers to the higher-order "negative emotionality" trait. WIMI: was not paying attention to what exactly the correlations were referring to. In order to demonstrate heritability, monozygotic-twins-reared-apart would be more telling (C) than monozygotic twins raised together (A - incorrect).
An adult female survivor of sexual child abuse started therapy. Within a month, she began to unconsciously reenact the dynamics of her abusive relationship with her male therapist, whom felt silenced, as if he had minimal options or solutions for problems. What phenomenon best classifies the therapist's experience? (A) Bystander effect (B) Dissociation (C) Countertransference (D) Transference
(C) C is correct. Countertransference is a clinical phenomenon whereby the therapist or counselor consciously and unconsciously reacts to the client's experience. Sometimes this reaction involves identification with the client's experiences and sometimes identification with the experience of significant others' in the clients' life. Victims of abuse often feel silenced because they do not feel they have any power to change their situation without retaliation from the perpetrator. The therapist feeling silenced can be considered as a countertransferential reaction that involves identification with the client. WIMI: (D) This is incorrect. Transference in therapy refers to the phenomenon in which the client unconsciously transfers or redirects his/her feelings to the therapist or counselor. The question asks about the therapist's experience, not the client's.
At a bus stop, a male confederate placed a bag down. In condition 1, he left immediately. In conditions 2, 3, and 4, he said he would be right back when asking a female subject, vs. a group of subjects, and vs. the subject who was most similar to him in terms of demographics (gender, race, and age), respectively, to watch his bag. The step which followed across conditions was a male confederate picking the bag up, and quickly walking away, while subjects' reactions were registered. Which condition measured for diffusion of responsibility with greater reliability? (A) Condition 1 (B) Condition 2 (C) Condition 3 (D) Condition 4
(C) C is correct. Diffusion of responsibility refers to the social phenomenon in which individuals are less likely to intervene or help in a crisis situation when there are other individuals around who are witnessing the situation. Since every individual assumes that another witness will intervene, everyone keeps delaying their intervention. It has been argued that this happens because as the number of witnesses increases, the lower is each individual's sense of personal responsibility. In the described experiment, there was no way of controlling for the number of bystanders at a bus stop, or whether they would witness the confederate leaving the bag. Thus, the most reliable condition is the third, where a group is explicitly asked to look after the bag. Diffusion of responsibility (similar to bystander effect?) - social phenomenon in which individuals are less likely to intervene or help in a crisis situation when there are other individuals around who are witnessing the situation.
Studies have shown that downward comparison is correlated with affect. How might researchers go about testing this hypothesis? (A) Ask research subjects to select the shortest string and arranging for a confederate to select the longest string. Then administer an instrument to measure personality disorders. (B) Have research subjects read vignettes about someone who recently won a grand prize worth several hundred dollars. Then administer an instrument to measure self-efficacy. (C) Describe, to research subjects who have recently received a diagnosis about their chronic illness, someone worse off than they are. Then administer an instrument to measure for mood. (D) Ask research subjects to rate their willingness to help people in distress, including strangers, friends and family members. Then administer an instrument to measure well-being.
(C) C is correct. Downward comparison refers to the process wherein individuals compare themselves with those who are worse off than themselves. In applying this process to those who have been recently diagnosed with a chronic illness, because they have experienced a loss, they may compare themselves with those who are worse off. Studies have shown that downward comparison reduces negative affect, emotions, or mood. Downward comparison - process wherein individuals compare themselves with those who are worse off than themselves
When teaching a psychology of gender class, the teacher takes on the perspective of essentialism in regard to gender. Consequently, what is the main theme that runs through the class? (A) Gender serves an important purpose so that a variety of social functions can be maintained and reinforced. These social functions include common ideology, purpose of life, and belonging. (B) Gender is an essential, socially constructed concept and has specific meaning for individuals as they live out their gender; the meanings are culturally laden. (C) Gender is an unchangeable characteristic that resides in an individual. All women share the same psychological characteristics, which are different from men's psychology. (D) Cross-cultural research is at the heart of essentialism, as gender and other psychological traits are not universal but culturally specific.
(C) C is correct. In philosophy, essentialism maintains that there is a set of characteristics that can be applied to a specific form or entity (a group of people, animals, objects, etc.). In the case of gender, essentialists argue that psychological dimensions for gender are universal. All women share the same psychological characteristics, and the same holds true for men. In other words, there are no cultural variations, and therefore essentialists do not believe that cross-cultural research is necessary.
To evaluate how Lawrence Kohlberg's first stage of the "conventional morality" level affected the findings of the study about moral versus immoral procurement of money, participants in the immoral condition could be split in half randomly, and one half would be further told that: (A) the person who had dropped the winning lottery ticket was a friend of theirs. The other half would be told that the person who dropped the ticket was a stranger. (B) their actions would be rewarded or punished, in accordance with their ethical rightness. (C) observers would judge whether they were a good or a bad person in the light of their actions. (D) their principles of justice and equality were paramount.
(C) C is correct. Stage three of the second, "conventional morality" level of Kohlberg's theory of moral development emphasizes social approval. In other words, a person in this stage and level will make moral decisions based on whether they will be evaluated as a good person or a bad person by others. In this new experiment, the immoral condition has two levels: one where subjects are instructed to take "conventional morality" into account; and another where they are not told anything. This allows for the inspection of the effects of conventional morality instructions, in comparison with both the moral condition and the absence of conventional morality instructions in the same immoral condition. WIMI: Kohlberg's stages of moral development - 6 stages but 3 levels; conventional stage is the second level, so first stage of conventional is actually the 3rd stage overall (has to do with social approval).
The high ΔE value measured for biotin complexed with the streptavidin mutant could be explained by: (A) the loss of van der Waals bonds formed between biotin analogs and streptavidin. (B) the introduction of structural strains in the complex. (C) the electrostatic attraction between biotin and the mutant being weak. (D) the electrostatic attraction between biotin and the mutant being strong.
(C) Electrostatic energy is directly related to attraction/repulsion between surfaces. The high values in electrostatic energy means the weak attraction, which is counterintuitive at first glance. Since the charge was altered in the streptavidin mutant, its binding affinity to biotin was reduced as reflected by the reduction in Ka values. Binding affinity depends on the ability of residues to form short-range interactions like salt bridges and hydrogen bonds, which is defined by the electrostatic properties of a binding domain (recall that 'electrostatic' simply refers to the fact that opposite charges attract and like charges repel). The electrostatic properties of a protein domain, in turn depend on the presence of polar and charged amino acid residues. Because of that, we conclude that the electrostatic attraction between the biotin and the streptavidin mutant should be weak. WIMI: Fell for the counterintuitive trap; if the electrostatic energy is higher, than the attraction is weaker (harder for the attractions to occur due to repulsion of opposite charges).
Almost all mammals, and certainly humans, are endotherms ("warm-blooded"). Consider radiant heat passing between an endotherm and its cooler environment. Heat would be expected to be radiated and absorbed in which of the following ways? (A) Only the endotherm radiates heat, which is then absorbed by the environment. (B) Only the environment radiates heat, which is then absorbed by the endotherm. (C) Heat exchange occurs in both directions: the endotherm radiates more and absorbs less heat per unit area than the environment. (D) Heat exchange occurs in both directions: the environment radiates more and absorbs less heat per unit area than the endotherm.
(C) On the Surface: Radiation happens when heat moves as energy waves, infrared waves (electromagnetic), directly from its source to something else. The environment can radiate, for example, from the sun, fire or artificial sources of heat. Blood flows to the skin so the heat can radiate into the environment. A two-way dynamic equilibrium occurs and, because the question stem puts the endotherm in a "cooler environment", overall the endotherm radiates more and absorbs less. If you had some doubts, consider that your body temperature is about 37 Celsius (98.6 Fahrenheit), but how would you feel if the environmental temperature was 30 Celsius (86 Fahrenheit)? Despite being in a cooler environment, you would still feel that the environment is radiating heat to you, even if overall (net) you were losing heat. The preceding is just a simple, tangible example illustrating the nature of the 2-way equilibrium.
The biceps muscle holds the forearm and any load held by the hand, if present. There are forces at the elbow joint where the humerus meets the radius. The human forearm can be considered as a set of levers as illustrated below. Consider that the arm is in rotational and translational equilibrium, as the load held in the hand increases, what would be the expected change in the vertical and horizontal components of the forces at the elbow, respectively? (A) Decreased, increased (B) Increased, does not change (C) Increased, increased (D) Decreased, does not change
(C) On the Surface: The new MCAT requires a basic understanding of torque forces, and more importantly, how the concept can be applied to biological systems. You can see (or imagine from your experience) that as the weight in the hand increases, the biceps must contract more to maintain equilibrium. But you can see from the illustration and the line diagram that the biceps is not connected to the forearm in a perfectly vertical way. There is the angle α which means that to counteract the increasing weight, there will be an increasing cosine(α) component (vertical) and an increasing sine(α) component (horizontal). Just to clarify: The position where the biceps is attached to the forearm clearly does not change and therefore the function of the angle remains unchanged, but the biceps force B is increasing so the vertical and horizontal components of the force, Bcos(α) and Bsin(α), both increase. {Recall: SOH-CAH-TOA: Sine is Opposite over Hypotenuse, Cosine is Adjacent over Hypotenuse, Tangent is Opposite over Adjacent.} WIMI: The bicep is not completely vertical; it has both a vertical and horizontal component that form a 2D vector, which counters the weight of the object held by the forearm. Even though the weight of the object is increased vertically by gravity, the forearm must increase the force of both the horizontal and vertical component to adjust the force of the 2D vector so that it can hold the object in place at a 90 degree angle.
Apo-X is a drug which blocks prophase from occurring. When Apo-X is added to a tissue culture, in which phase of the cell cycle would most cells be arrested? (A) Mitosis (B) G1 (C) G2 (D) Synthesis
(C) The order of events in the cell cycle is: G1, S (synthesis), G2, Prophase, Metaphase, Anaphase, Telophase. If a drug prevents prophase from occurring, most cells will be arrested at the stage immediately prior to prophase, G2.
What effect would injecting lidocaine into an infected site have on the onset time of analgesia? (A) It would decrease it. (B) It would have no effect. (C) It would increase it. (D) It would have a result more like mepivacaine.
(C) The pH of normal body tissue is 7.4. According to the passage, "active infections can increase the acidity of surrounding tissues considerably" (in fact, active infections can reduce tissue pH as low as 5 or 6). As the local anaesthetic becomes more acidic, the concentration of hydrogen ions increases, and these combine with the uncharged anaesthetic. This shifts the equation to the left (see Figure 2), reducing the neutral/unionized (RN) form available to diffuse through the nerve cell membrane. Thus the fraction of the base form is inversely related to how long it takes for them to act (onset time). Therefore, answer choice C is the correct answer. Analgesia - inability to feel pain In active infection sites, there is a higher [H+], which react with the anesthetic to form an ionized anesthetic that is unable to enter the membrane and reduce the pain, making the onset of time before the pain is gone (analgesia) longer.
All of the following contain a phospholipid bilayer except: (A) neurolemma. (B) sarcolemma. (C) basement membrane. (D) cell membrane.
(C) The sarcolemma and the neurolemma are specialized plasma membranes located in muscle cells and neurons, respectively. Recall that the plasma membrane consists of a lipid bilayer, in accordance with the Fluid Mosaic Model. When the plasma membrane surrounds cells, it is called the cell (or cellular) membrane, or cytoplasmic membrane, or plasmalemma. The basement membrane, formed from a homogenous noncellular material lies at the base of the epithelial cells of the body. WIMI: Basement membrane is not made up of phospholipid bilayer
According to the information provided, a conclusion that can be made with certainty is that neither mutant strain P nor Q have the defective enzyme: (A) carbamoyltransferase (B) argininosuccinate synthase (C) argininosuccinase (D) None of the above enzymes are defective in either mutant strain nor P nor Q.
(C) You should recognize that enzymes typically end with -ase and so you can see that the figure provided indicates the 3 enzymes that are catalysts for the three reactions as shown. Now let's reinterpret the question: if neither P nor Q have a defective enzyme X, then both P and Q must have a functioning enzyme X (the other interpretation is that they have no enzyme but that is not consistent with the data in the table provided). In other words, "Which of the answer choices corresponds to an enzyme that is fully functional in strains P and Q?" The information in the table shows a (+) symbol in the last two columns indicating that both P and Q are able to convert argininosuccinate to arginine (see Table 1). This necessarily means that both P and Q have a functioning enzyme argininosuccinase (see Figure 1). WIMI: Did not pay enough attention to understanding the table, was thinking the opposite in terms of the meaning of the (+) and (-).
Smoking raises the level of a "feel-good" chemical in the body called: (A) melatonin. (B) cortisol. (C) oxytocin. (D) dopamine.
(D) D is correct. Nicotine widens the capillaries and can foster certain emotions like anxiety and pleasure. Dopamine, a "feel-good" neurotransmitter, raises levels of awareness and general pleasure. When nicotine enters the system, dopamine levels increase. WIMI: Mistook oxytocin to be the "feel-good" chemical since it is released during bonding/social activities; however dopamine is the typical "feel-good" chemical.
The "tip of the tongue" phenomenon can be explained by: (A) loss of memory due to temporally graded retrograde amnesia. (B) interruption in the encoding process while the memory is being formed. (C) cue failure that is affecting metacognition processes. (D) failure of the retrieval component of memory.
(D) D is correct. The "tip of the tongue phenomenon" is the inability to recall familiar information fully, while having access to fragments of the information or information that is semantically close to the target. The frequency of this phenomenon seems to increase with age, and has been used to illustrate how retrieval can be flawed independently of the workings of other components of the memory system.
According to the information provided in the passage, a comparison between the patient H.M. and Alzheimer's patients shows that both had/have: (A) anterograde amnesia. (B) retrograde amnesia. (C) episodic memory problems. (D) difficulty accessing newer information.
(D) D is correct. The passage states that: "Alzheimer's patients have temporally graded amnesia, as well as short-term and semantic memory impairment". Temporally graded amnesia consists of having more ease remembering older memories, where the older the memories are, the more easily they are remembered. These are the "newer memories" that Alzheimer patients have difficulties remembering. They even often lack short-term memory, that is, they have difficulties remembering present information. Anterograde amnesia, that of H.M., amounts to having more difficulty remembering events that happened after the onset of the disease; this is why it is stated in the passage that they could not form new memories. Thus, both H.M. and Alzheimer patients experience(d) difficulties with remembering information "newer information"; H.M could not recall events occurred after the trauma, whereas Alzheimer patients have difficulties remembering more recent events. WIMI: (A) A. This is incorrect. H.M. was described as having anterograde amnesia. However, Alzheimer's patients are described as having temporally graded amnesia, which is a particular type of retrograde amnesia. Yet, those with this type of amnesia cannot be said to have anterograde amnesia; there is no known disease onset and the manifestations of each only coincides in that both forget newer information.
What is the difference between monozygotic and dizygotic twins? (A) The zygote undergoes mitosis for monozygotic twins, whereas dizygotic twins do not undergo this process. (B) The zygote undergoes mitosis for dizygotic twins, whereas monozygotic twins result from two zygotes. (C) Monozygotic twins result from two ova, whereas dizygotic twins result from one single ovum. (D) The zygote undergoes a split for monozygotic twins, whereas dizygotic twins result from two ova.
(D) D is correct. Zygotes are fertilized eggs that develop into embryos. Normal prenatal human development of singletons involves successive mitoses of zygotes. Twins' development is similar. However, in the beginning of pregnancy, the zygote sometimes undergoes a split. That is, the zygote separates into two identical embryos, each developing normally through successive mitoses. This results in monozygotic (or identical) twins. Other times, the womb has two different eggs or ova and both are fertilized. Each one of these zygotes grows into a separate embryo, originating dizygotic (or fraternal) twins.
One of the latest adaptations of the Sanger method uses four different colored fluorescent derivatives attached to the four different ddXTP terminators. The most likely main advantage of this new approach is that: (A) electrophoresis treatment to the denatured DNA would no longer be necessary. (B) ddUTP can be used as a chain-terminating dideoxynucleotide triphosphate. (C) the technique would be faster and more economical. (D) all four reactions could be carried out simultaneously prior to electrophoresis and then can run on one gel.
(D) P2 describes how all four reactions are carried out in separate reaction mixtures or containers and Figure 1 shows the four different reactions running in four different gels. In so doing, it is clear which fragment contains A, T, G or C at its labelled end. However, if the dideoxynucleoside triphosphates were color labelled, different reactions could occur simultaneously in the same vessel and detected on one gel using the radiogram and then analysing the color of each band (i.e. all red = ddA, green = ddC, etc.) instead of using four different containers and then checking under each ddX as in Figure 1. WIMI: Answer choice (C) is unlikely since adding a step is unlikely to make the procedure faster, moreover, adding a fluorescent compound to an established procedure will not make it cheaper! Did not carefully review all the answer choices
One of the the possible injuries during a high speed motor vehicle accident includes a traumatic hemothorax in which blood accumulates in the pleural cavity. With regards to a traumatic hemothorax, which of the following would be of greatest concern? (A) High oxygenation due to an elevated diaphragm (B) Low oxygenation due to blood in the main bronchi (C) High oxygenation due to excess blood inside of the alveoli (D) Low oxygenation due to compression of the lung
(D) The lung is covered by a membrane (= the pleura). Lungs reside in the thoracic cage which includes the ribs, sternum and the muscles between the ribs (intercostal muscles). If blood accumulates in the space outside the lungs (the pleural space), since the thoracic cage is firm, the blood will apply pressure on the pliant lung thus reducing the size of the lung (reducing the surface area for the exchange of oxygen and carbon dioxide). Thus blood oxygen levels can become dangerously low. Note that since the blood is in the pleural space, it is not in the bronchi nor in the alveoli since they both reside withint the lung itself. Nonetheless, if blood poured into the alveoli, oxygenation would decrease remarkably since the surface to exchange gas by diffusion has been interrupted. Note that an elevated diaphragm (answer choice A.) compresses the lung and would not cause high oxygenation. Not to mention, blood in the pleural cavity would not likely lead to an elevated diaphragm (if there is a large volume of blood, it could compress the lung and displace the diaphragm downward).
Which phenomenon best explains the findings in Figure 1? (A) Magical law of contagion (B) Implicit memory (C) Anchoring bias (D) Distributive justice
(NOTE: possible mistake in question) (A) A is correct. 'Magical law of contagion' was the explanation offered by the authors of the experiment (Thomas Gilovich, Dale Griffin, and Daniel Kahneman) to explain findings. This law consists of believing that harmful or beneficial properties can be transmitted by objects, including physical or moral properties. To minimize the odds of being contaminated by the so-perceived negative qualities of objects, contact with those objects is minimized. If the object is perceived instead as carrying beneficial proprieties (e.g., good luck charms), contact with those objects is increased. The authors argued that the immoral condition participants were trying to minimize the odds of being contaminated by the 'immoral' money, and as such of becoming immoral themselves. This explanation is hinted upon at the end of the passage, which states that "experimental subjects felt that they had "dirty money" on their hands." WIMI: Did not know what "Magical Law of Contagion" meant Anchoring bias - tendency to value more the first, vs. the following pieces of information when making a decision Distributive justice - organizational psychology term that refers to beliefs about how the amount or value of compensations, usually salary related, is fair.
Components of anesthetics
1) an aromatic group on one side 2) an ester or amide linkage in the middle 3) an amine functional group on the other side
IR Absorption peaks (most important ones to know)
Alcohol (OH, 3200-3650) Carbonyl group (C=O, 1630-1780)
2-iminobiotin shows a drastically lower binding affinity to the natural streptavidin as compared to biotin. Also, the streptavidin mutant has a significantly lower binding affinity to biotin as compared to the 2-iminobiotin, which is reflected by Ka values in the table. The main reason for such difference could be due to which of the following? (A) The protonation change in the 2-iminobiotin affecting the formation of hydrogen bonds. (B) The difference in electrostatic properties as defined by the presence of the guanidine group in 2-iminobiotin and the absence of the ureic group in biotin. (C) The change in thermal energy in 2-iminobiotin as compared to biotin. (D) The structural differences between the biotin and its analogs.
The binding free energy modeling and mutant design was based on a local electrostatic charge distribution between biotin and its two analogs. This information was used to alter the electrostatic properties of streptavidin mutant by introducing a negative charge in the position S27. While other listed suggestions may have indirectly affected the binding affinity between streptavidin and biotin analogs, the main reason for such differences is the change in the ability to form multiple hydrogen bonds - in both cases as a result of altered electrostatic properties.Note that answer choice A is a trap because it indicates that the formation of hydrogen bonds is affected, which is correct. However, the reason for affecting hydrogen bonds suggested is incorrect. WIMI: (A) is incorrect because, while there is a difference between the hydrogen bonds, the difference is not just because of protonation change; the atom is changed from oxygen to nitrogen (no guanidino group to guanidino group). NOTE: (B) may actually be incorrect since "the absence of ureic group in biotin" implies that the ureic group is removed, when in fact it is not.
Which complex in the electron transport chain does NOT contribute to the proton gradient? (A) Complex I (B) Complex II (C) Complex III (D) Complex IV
The electron transport chain occurs on the inner mitochondria membrane, as part of the oxidative phosphorylation. The overall process of the electron transport chain includes the flow of electrons from NADH and FADH2 to O2, coupled with the synthesis of ATP via the proton motive force. This is powered by the proton gradient across the inner mitochondrial membrane, from protons pumped into the intermembrane space. Among the four complexes involved in the electron transport chain, Complex I transports 4 protons, Complex III transports 4 protons, and Complex IV transports 2 protons. Complex II is the only component that does not involve the transport of protons into the intermembrane space. Therefore, answer choice B is the correct answer. Side note: The idea behind this question is commonly tested. Here is an alternate way the question could have been asked: As part of the electron transport chain, protons are pumped out of the mitochondrial matrix at each of the following major sites EXCEPT for: Yes, the answer is still B! Spoiler alert: Knowing that Complex II is succinate dehydrogenase (or succinate-CoQ reductase) is necessary to answer one of the AAMC's MCAT Practice Exam 3 BB questions.
At normal tissue pH of 7.4, which of the anaesthetics in Table 1 would have the highest percentage of diffusible form available to penetrate the cell membrane? (A) Procaine (B) Mepivacaine (C) Bupivacaine (D) Either lidocaine or prilocaine
The pKa (the pH at which 50% of the drug is ionized and 50% is present as base) of the anaesthetic is related to pH and the concentrations of the cationic and base forms by the Henderson-Hasselbalch equation: pH = pKa + log ([base]/ [cation]). When an anaesthetic solution is injected into healthy tissue, it eventually takes on the pH of the surrounding tissue which is 7.4. As pKa approaches pH there is more of the uncharged base form present. WIMI: was trying to overanalyze the structures of the molecules (thought incorrectly that bupivacaine had more C-H bonds and therefore was more nonpolar than mepivacaine so it could pass more easily through the membrane). Actually has to do with the pKas; because mepivacaine has a pKa closest to physiological pH, it is more likely to be neutral than charged, and therefore can diffuse the best through the membrane.
The temporary increase in the sarcolemma's permeability to Na+ and K+ ions that occurs at the motor end plate of a neuromuscular junction is immediately preceded by: (A) The release of acetylcholine from the motor neuron into the synaptic gap. (B) The release of adrenaline from the motor neuron into the synaptic gap. (C) The passage of a nerve impulse along the axon of a motor neuron. (D) The release of noradrenaline from a sensory neuron into the synaptic gap.
To answer this question you must know that acetylcholine is an excitatory neurotransmitter that is important in motor neurons. Acetylcholine must cause an action potential in the following cell to continue the signal to the appropriate muscle. Action potentials start with the membrane becoming temporarily more permeable to sodium ions, causing depolarization of the membrane. Therefore, the post-synaptic membrane (motor end plate; BIO 5.1F) will become more permeable to the positive ions immediately following acetylcholine being released from the pre-synaptic membrane and reaching receptors on the post-synaptic membrane by diffusion. WIMI: Missed the word "preceded" in the question, incorrectly chose (C).
Sherif's Robbers Cave experiment
focused on group membership and conflict and competition over resources. Twenty-two boys were recruited and randomly placed in either the "Eagles" or "Rattlers" groups. Time was given for the boys in both groups to bond with each other by having them do activities, with T-shirts given out with the name of their group. After this initial bonding time, it was announced that there would be a series of competitive games and a prize for the winning group. Each group began to show competitive and aggressive behavior, marking off its territory and flinging taunts at the other. Sherif's findings showed how in- and outgroups can be easily formed whereby those in the ingroup begin acting in a prejudicial manner toward those in the outgroup. While Stanley Milgram's experiment focused more on obedience to authority figures, Sherif's experiment focused more on group membership/conflict over resources.
Urie Bronfenbrenner's ecological system theory
maintains that there are layers of systems in a person's environment that affect human behavior. The mesosystem is one of the five systems and comprises school, peer groups, and neighborhood. This approach discusses spheres of influence in development.
