MCAT FL 3
passive immunity
. Passive immunity is the transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another.
differential association theory
According to differential association theory, individuals engage in criminal choices because they are exposed to it, while individuals who don't commit crimes have not been exposed to this type of behavior. Thus, a child going from an area in which he is likely to be exposed to crime to an area where he is not likely to be exposed will reduce the likelihood of this individual committing a crime.
If a modern portable defibrillator uses as 12 V battery and a 20 μF capacitor, what is the total charge stored on the plates of the capacitor? A. 0.24 mC B. 24 mC C. 24 C D. 60 C
If a modern portable defibrillator uses as 12 V battery and a 20 μF capacitor, what is the total charge stored on the plates of the capacitor? A. 0.24 mC B. 24 mC C. 24 C D. 60 C
conditione stimulus and response?
A conditioned stimulus is a neutral stimulus, like the image of a circle, that (after being repeatedly presented prior to the unconditioned stimulus) evokes a behavior similar to the unconditioned response. The conditioned response is the acquired response, in this case fear, to the formerly neutral stimulus (the image of the circle).
Malonyl-CoA is an intermediate in cytosolic fatty acid biosynthesis. Its inhibition of the β-oxidation of long-chain fatty acids: A. prevents the degradation of newly synthesized fatty acids. B. ensures that ample reducing equivalents are available for fatty acid synthetic activity. C. increases the cellular pool of acetyl-CoA available to condense with oxaloacetate. D. is up-regulated in the presence of decreased insulin secretion.
A is correct. Malonyl-CoA, an indicator of ongoing fatty acid synthesis, inhibits β-oxidation by preventing the movement of long-chain acyl groups into the mitochondrial matrix, thereby preventing a futile cycle of fatty acid synthesis followed by immediate β-oxidative catabolism of those newly synthesized fatty acids. B, C: Inhibition of β-oxidation reduces the available pool of reducing equivalents that would otherwise be produced directly from the reactions of β-oxidation, as well as by the oxidation of acetyl-CoA, the production of which slows as fewer fatty acids flow through the cycle. D: The passage provides no direct or indirect evidence to suggest that the allosteric effect of malonyl-CoA is modulated by insulin. Additionally, decreased insulin secretion tends to globally increase the rate of catabolic processes, such as β-oxidation, and decrease the rate of anabolic ones, including fatty acid synthesis.
In Figure 1, Korsakoff's syndrome patients showed a marked increase in: A. confabulation. B. declarative memory. C. procedural memory. D. aggression.
A is correct. One of the symptoms of Korsakoff's syndrome is confabulation - making up memories to fill in gaps and then believing that those memories are true. When asked to recognize sentences, Korsakoff's patients (at a rate vastly higher than normal) picked incorrect sentences, suggesting they were confabulating the memory of having heard those sentences. B: Declarative (or explicit) memory is the memory of facts and events. The sentence recall/recognition task in Figure 1 is a test of declarative memory. Korsakoff's patients perform much worse on this test than do normal patients, so we would not say that Korsakoff's patients showed an increase in declarative memory. C: Procedural memory relates to the origami task in Figure 2, not Figure 1 (which this question asks about). D: No evidence is given in the passage that the Korsakoff's patients behaved aggressively.
Conn's syndrome, also known as primary hyperaldosteronism, is most likely to cause which symptom? A. High renin concentration B. Low blood potassium C. Low blood sodium D. Hypotension
B is correct. This question is asking you to recall the effects of aldosterone and how it achieves those effects. Aldosterone increases H2O and Na+ reabsorption from the kidney while exchanging K+ ions for Na+ ions. The triggers for and results of aldosterone secretion are shown below. A: Hypersecretion of aldosterone will negatively feed back and inhibit renin production. C: Hypersecretion of aldosterone will result in high blood sodium. D: Hypersecretion of aldosterone will result in high blood pressure.
Which of the following types of electromagnetic radiation would have the shortest wavelength? A. Radiation that ejects an electron from an sp orbital B. Radiation that ejects an electron from an sp2 orbital C. Radiation that ejects an electron from an sp3 orbital D. Radiation that excites but does not eject an electron from an sp3 orbital
A is correct. This question asks us about the wavelength of EMR that ejects an electron from an atom. Shorter-wavelength EMR (such as γ rays) carries much more energy than longer-wavelength EMR (such as radio waves). Therefore, we must look for the answer choice that involves the highest-energy EMR. The closer an electron is to the nucleus, the harder it is to eject. Because sp-hybridized orbitals have the most s character of all of the answer choices, they contain the electrons that are hardest to eject. B: sp2-hyrbridized orbitals have 33% s character, while sp-hybridized orbitals have 50% s character. C: sp3-hyrbridized orbitals have 25% s character, while sp-hybridized orbitals have 50% s character. D: Radiation that excites an electron but does not eject it is of lower energy than radiation that is able to eject an electron.
Which of the following is least likely to be observed in a patient experiencing hyperventilation? A. Hypoxia B. Net exhalation of CO2 C. Increased blood pH D. Increased hemoglobin O2 affinity
A is correct. This question asks us to determine the effects of hyperventilation. During hyperventilation, there is a loss of CO2 and an increase in O2 in the blood. Hypoxia is another term for oxygen deprivation. B: During hyperventilation, CO2 is lost due to excess exhalation. C: Loss of CO2 corresponds with increased blood pH. D: Loss of CO2 corresponds with increased hemoglobin affinity for O2.
If sodium sulfate was added to the mixture containing silver ions and the yellow precipitate, what might be observed after a significant amount of time elapsed? A. Little to no silver sulfate formation, because the Ksp of silver sulfate is very large compared to the Ksp of the yellow precipitate. B. Little to no silver sulfate formation, because sodium sulfate cannot be dissolved at all in water. C. Significant silver sulfate formation, because the solubility of sodium sulfate releases sodium ions which catalyze the necessary reactions. D. Significant silver sulfate formation, because the solubility of sodium sulfate releases sulfate ions which catalyze the necessary reactions.
A is correct. This question is asking us to find a possible outcome and explanation for the outcome when adding sodium sulfate to the silver/yellow precipitate mix. This means we need to choose the answer that has a valid outcome and a proper explanation for that outcome. The Ksp, or solubility product, of a substance is defined as the product of each of the substance's dissolved ion concentration raised to the power of its stoichiometric coefficient. For silver sulfate, the dissolution reaction is: Ag2SO4 (s) → 2 Ag+ (aq) + SO42- (aq) which means that the Ksp equation is: Ksp = [Ag+]2[SO42-] A large Ksp suggests that a substance is more soluble than a substance with a lower Ksp. It is not certain, given that the coefficients might be different and might affect the power to which the ion concentrations are raised. However, it provides a better possible explanation than the other answer choice options (and the phrasing of the question prompt, using the words "might explain," notes that there is some uncertainty involved). B: This answer cannot be correct as sodium sulfate will dissolve completely in water; this is actually true of all salts containing sodium. Even if it were a so-called "insoluble" salts, these will typically dissolve to a minute extent. (This is why they will have dissolved ion concentrations which can be multiplied to form a Ksp solubility product.) C: Sodium ions do not catalyze the reaction of silver ions with sulfate ions; they are attracted to each other though electrostatic attraction (positive ions attracting negative ions). D: In the proposed reaction, sulfate ions constitute a reactant, not a catalyst. Remember that the definition of a catalyst is a molecule which speeds up a reaction rate, without itself being used up as the reaction progresses.
A. natural immunity.
A: Natural immunity is immunity that is present in the individual at birth, prior to exposure to a pathogen or antigen, and that includes intact skin, salivary enzymes, neutrophils, natural killer cells, and complement.
Which of the following would likely decrease an individual's self-efficacy in regard to a particular task? A. Seeing a task performed successfully B. Feeling that past failures were due to other individuals C. Being offered positive encouragement by others D. Learning stress-reduction techniques in regard to the task
B is correct. This is an example of an external locus of control, which might increase an individual's self-esteem, but would be expected to have a negative effect on self-efficacy. A, C, D: Ways to increase self-efficacy include social modeling, social persuasion, and modifying psychological responses, as well as mastery of tasks. These choices are all examples of one of these methods.
At very low CTP concentrations, kinetic data fitted to the Michaelis-Menten equation predicts that the initial rate of the CCT-catalyzed reaction is most nearly what order with respect to CTP? A. Zero order B. First order C. Second order D. Third order
B is correct. For an enzyme-catalyzed reaction with a very low initial substrate concentration, and where Km >> [S], the Michaelis-Menten equation may be approximated as V = Vmax [S] / Km, where Vmax / Km is a constant of the reaction. Under these conditions, the reaction is approximately first order with respect to S. This can be seen graphically in Figure 1, where at low initial CTP concentrations, the enzyme activity (and the reaction velocity to which it is proportional) increases in a roughly linear fashion with CTP concentration. A generic Michaelis-Menten curve is shown below. Note that at low substrate concentrations, the reaction approximates first-order kinetics, as described above. In contrast, at very high substrate concentrations (where the enzyme is nearly or entirely saturated), the reaction approximates zero-order kinetics, since reaction rate ceases to depend on substrate concentration. A: The reaction would display zero-order kinetics only if increasing CTP concentrations did not lead to an increase in the reaction velocity. As mentioned above, this is generally true under saturating conditions, when substrate concentration is high relative to Km and when V = Vmax. C, D: A second- or third-order relationship at low substrate concentration would show a primarily non-linear relationship between CTP concentration and reaction velocity.
A follow-up study finds that first-generation immigrants between the ages of 25 and 34 are more likely than the participants in this study to experience poverty. However, second-generation immigrants 25-34 experience poverty at the same rate as the study participants. This finding would serve as societal evidence of: A. intragenerational mobility. B. intergenerational mobility C. social reproduction. D. meritocracy.
B is correct. Intergenerational mobility describes upward or downward movement in social class between two or more generations. In this example, the first-generation immigrants tended to be in a lower socioeconomic class than the study sample, whereas second-generation immigrants had achieved parity with the study sample, which would qualify as upward mobility. A: Intragenerational mobility describes changes in social class that occur within one lifetime. Since the change in social class occurred across generations, this is not an example of intragenerational mobility. C: Social reproduction describes a phenomenon in which poverty tends to beget poverty, and wealth tends to beget wealth across generations. This is not an example of social reproduction because the second generation of immigrants experiences less poverty than the first generation. D: A meritocracy describes a society in which individuals' mobility is determined by their achieved status, talent, and work. In a meritocracy, every individual will have equal opportunity to succeed. In this case, first-generation immigrants likely did not have equal opportunity compared to the average American, which would have resulted in the first-generation immigrants experiencing greater rates of poverty.
In a third test, patients are given sentences that contain content that relate to their lives (such information having been gained through prior interviews with family members). Moreover, these sentences state facts that are either wrong (e.g. "Your niece is named Juliana" when in fact her name is "Julia") or distorted somehow. Using such sentences would likely show: A. increased recall but significantly lower recognition. B. proactive interference in the normal patients but not in the Korsakoff's patients. C. proactive interference in the Korsakoff's patients but not in the normal patients. D. proactive interference in both groups in the experiment.
B is correct. Proactive interference refers to the fact that currently existing long-term memories can interfere with the process of forming new long-term memories. This is unlikely to affect patients with Korsakoff's syndrome, as they are already unable to form new long-term memories. A: The facts in these sentences are not correct, so using them does not exemplify increased recall (retrieval of information from memory without recognition cues). C: This choice may be tempting, since we might expect the Korsakoff's patients to be more likely to display a memory problem (here, proactive interference) than the normal patients. However, normal individuals are absolutely subject to proactive interference. In contrast, Korsakoff's patients already have such impaired memory formation (as evidenced by the results in Figure 1) that they are unlikely to display additional impairment as a result of previously formed memories. After all, if memory formation is already so impaired that it is nonexistent or almost nonexistent, there is little room for more impairment due to proactive interference. D: This choice is incorrect for the reasons detailed above.
Assuming that oligomycin has a high affinity for ATP synthase, which of the following is the best explanation for the findings presented in Table 1 regarding the amount of ATP produced with oligomycin pre-treatment? A. Oligomycin binds directly to acetyl-CoA roughly 33% of the time. B. An insufficient concentration of oligomycin was used. C. Despite the inhibition of oxidative phosphorylation, glycolysis can still produce a smaller baseline amount of ATP. D. Substrate-level phosphorylation, instead of oxidative phosphorylation, accounts for roughly 33% of the ATP produced through the electron transport chain.
B is correct. Table 1 shows that oligomycin pre-treatment reduced the ATP production from fatty acids by about 67%. The acetyl-CoA generated from fatty acids is passed through the citric acid cycle, culminating in oxidative phosphorylation. Oxidative phosphorylation, which is powered by the electron transport chain, produces ATP by using ATP synthase. Thus, the information in the passage and question stem indicating that oligomycin effectively blocks ATP synthase would lead us to expect that ATP production from fatty acids would completely, or almost completely, cease in response to oligomycin pre-treatment. However, we don't see anything close to a complete reduction. Keeping in mind that for oligomycin to completely block ATP synthase, there must be enough oligomycin molecules in a location where they can physically interact with ATP synthase molecules, the simplest explanation for this finding is that the oligomycin concentration might not be high enough for complete effectiveness. A: There is no information given in the passage to support this proposal. Moreover, even if true, it would not be a strong explanation for the findings, since a sufficient quantity of oligomycin would render this possibility irrelevant. C: Baseline ATP production through glycolysis would be a plausible explanation on the level of the cell, but the table provides the amount of ATP produced in the mitochondria by fatty acid metabolism, which generates acetyl-CoA, which cannot enter glycolysis. D: Substrate-level phosphorylation occurs in glycolysis and in the citric acid cycle (to produce 1 equivalent of GTP per turn of the cycle), but not as part of the electron transport chain.
Based on passage information, which of the following post-transcriptional modifications are likely involved in the IAV life cycle? I. Splicing II. Polyadenylation III. Glycosylation A. I only B. I and II only C. I and III only D. I, II, and III
B is correct. The passage states that splicing (RN I) is part of the IAV life cycle, and also states that IAV uses host machinery for other post-transcriptional modifications. Since IAV genomic material is synthesized in the nucleus, this most likely includes polyadenylation, which is needed to export mRNA from the nucleus to the cytoplasm (RN II). Glycosylation is described in the passage, but it is a post-translational modification (RN III). A: RN II is also correct. C, D: Only RNs I and II are correct.
Which of the following contradicts Weber's law? A. A weightlifter who doesn't notice a 5-pound difference in weight added in 1 pound increments, but who notices the difference in weight added in one 5-pound increment B. A non-linear relationship between the intensity of a stimulus and an individual's ability to detect it C. The existence of a threshold, above which stimuli are detectable and below which stimuli are not detectable D. Hearing a whisper in a quiet room but not hearing a shout in a noisy room
B is correct. Weber's law postulates that there is a linear relationship, not a non-linear relationship, between the intensity of a stimulus and its detection. A: This is an example of Weber's law because the change in weight at 1-pound increments may not be large enough to be noticeable. C: This is the idea postulated by Weber's law. D: Stimulus detection is relevant to background stimulus.
beta oxidaiton
Beta-oxidation is a process in which fatty acids are broken down into acetyl-CoA, which can be fed into the citric acid cycle (similarly to the effects of glycolysis and the pyruvate dehydrogenation complex). Beta-oxidation also generates the electron carriers NADH and FADH2, which produce energy in the electron transport chain. This process is known as beta-oxidation because the beta carbon of each fatty acid is oxidized to a carbonyl group (C=O). It occurs in the mitochondria in eukaryotic cells. The basic logic of beta-oxidation is to chop up extended fatty acid chains into two-carbon units of acetyl-CoA. Step 1 of beta-oxidation involves forming a C=C double bond between the alpha and beta carbons of the carbonyl group at the head of the acyl-CoA molecule. This is coupled to the formation of FADH2. Then, in step 2, an -OH group is added to the beta carbon. The C-OH bond on the beta carbon is oxidized to C=O in step 3, and NADH is formed. Then, in step 4, the molecule is broken up, yielding an acetyl-CoA group and a shorter acyl-CoA group. This process is easiest to visualize with a saturated fatty acid with an even number of carbons, but special enzymes exist to handle unsaturated fatty acid and odd numbers of carbons. Beta-oxidation can produce very large amounts of ATP, which is connected to the fact that fats are a form of long-term energy storage in the body. For instance, the beta-oxidation of palmitic acid (a saturated fatty acid with 16 carbons) yields approximately 106 ATP.
A person experiences a prolonged deficiency of thiamine and as a result may develop which of the following neurological disorders? A. Down syndrome B. Alzheimer's disease C. Korsakoff's syndrome D. Schizophrenia
C is correct. Korsakoff's syndrome is a neurological disorder that is most often seen in people who have severe prolonged alcoholism, as a result of which they experience severe thiamine deficiency. A: Down syndrome is trisomy 21, in which the individual's cells have three copies of chromosome 21 instead of two. Down syndrome does not result from thiamine deficiency. B: Alzheimer's disease has no known relationship with thiamine deficiency. D: Schizophrenia is not known to develop due to thiamine deficiency, or nutritional imbalances in general.
Which regions of Figure 1 are most likely to be explained by the movement of sodium ions into a cardiac neuron? I. P II. Q III. R IV. T A. I only B. II and III only C. I, II, and III only D. I, II, III, and IV
C is correct. Let's begin with RN I. As stated in the passage, the P wave is associated with the depolarization and contraction of the atria. A rest potential is created when sodium ions are pumped to the outside surface of the membrane of a cell. When ion channels open, the sodium ions spontaneously flow back into the cell, resulting in depolarization and an action potential. Roman numeral (RN) I is thus correct. Regarding RNs II and III, the passage states that the Q and R waves are associated with the contraction of the ventricles. Like atrial contraction, ventricular contractions result from depolarization, which would involve the inward movement of cations like sodium ions. Thus, RN II and III are accurate as well. IV: The passage states that the T and U waves occur due to repolarization, which takes place when positive ions are pumped back out of the cell to return to rest potential prior to the next heartbeat. This is the opposite of what the question asks for. A: RN II and RN III are also correct. B: RN I is also correct. D: RN IV is incorrect.
What is the absolute configuration of the alpha carbon in selenocysteine? A. D B. L C. R D. S
C is correct. When assigning absolute configuration, imagine the molecule so that the lowest-priority group is facing away. In this case, it is the implicit hydrogen, which by the tetrahedral geomtry of the alpha carbon already happens to be facing away. Then, assign priority based on molecular weight of the attached atoms. Nitrogen > C-Se > C-O > H. Follow those atoms in a clockwise circle to assign the R configuration, as shown below. A, B, D: D and L are relative configurations, not absolute configurations. S is the opposite of the correct configuration. Content Foundations: Chirality Chirality, or chemical "handedness," occurs when an atom is connected to four unique groups. Such molecules are not superimposable upon their own mirror images. Atoms within a molecule that connect to four unique groups are known as chiral centers, and a molecule with n chiral centers will have 2n stereoisomers (excluding meso compounds, which are molecules with multiple stereocenters that have an internal plane of symmetry that allows their mirror images to be superimposable). The MCAT often asks questions about the number of chiral centers in a molecule, and care must be taken when answering such questions to account for implicit bonds to hydrogen that might not be shown in bond-line notation. An interesting manifestation of chirality is that solutions of chiral compounds rotate planes of polarized light at angles unique to each compound. This is defined as the specific rotation [α] of the molecule. Compounds that produce clockwise (+) rotation of plane-polarized light are dextrorotatory (d), and compounds that produce counterclockwise (−) rotation are levorotatory (l). The specific rotation of a chiral compound in solution can be calculated according to the equation [α] =α/cl, where α is the observed rotation, c is the concentration in g/mL, and l is the length of the polarimeter tube in decimeters (dm). Chirality is emphasized on the MCAT because it is biologically relevant. Amino acids are chiral, and the L-stereoisomers comprise the overwhelming majority of amino acids that occur in nature. Correspondingly, D-isomers of carbohydrates occur in nature. Many enzymes are stereospecific, meaning that they only function for specific stereoisomers, and the biological functionality of compounds can vary depending on their chirality. Therefore, much attention in chemistry has been devoted to developing stereospecific reaction and purification procedures, many of which involve chiral catalysts or intermediaries. Adapted from Next Step Chemistry and Organic Chemistry Ch. 9, where more information on this topic can be found.
spring equations?
F=-kx is used for Force, usually the question will give a spring constant and a distance and ask the spring force or something. U= 1/2kx2 is used for energy, equating maybe the kinetic energy of a box on a spring to the potential energy of the spring and asking you to find either the spring constant or the distance compressed. Think of the difference like the difference between F=ma and K=1/2*mv2
A student determined that her yield of aspirin was 3.9 g. What was her percent yield? A. 45% B. 60% C. 78% D. 92%
FIND which one is limiting first! ten work from there, all the information is given in the steps!!1
A hospital purchases brand-new GKS-Co and GKS-X machines. Five years after installation, what is the expected ratio of the total atomic mass of material in the Co machine to that in the X machine, assuming both machines start with the same mass of radioactive material? A. 1:16 B. 1:5 C. 1:1 D. 5:1
C is correct. When reading questions, be careful not to read too quickly. In this case, fast but inefficient reading will lead us to assume that it is asking about the percentage of a certain isotope that is left after radioactive decay. However, the question is asking about atomic mass. While β-decay does cause a nuclear transmutation of protons to neutrons (β-plus) or neutrons to protons (β-minus), the atomic mass lost in these processes is negligible. This means that whether after one (Co) or five (X) half-lives, the atomic mass will be the same in both samples. A: This is the ratio of undecayed nuclei between the two samples. The GKS-Co machine has 1/2 of its nuclei undecayed and the GKS-X machine has 1/32 of its nuclei undecayed. The question, however, asks about all of the nuclei, both decayed and undecayed. B, D: These choices both involve the differences in half-live between 60Co (5 years) and X (1 year). However, since the question is asking about undecayed and decayed material, this distinction does not matter.
cell mediated immunity
Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
Which of the following represents a limitation to the design of this study? A. The age of the participants B. Lack of knowledge about OCD C. Ethical implications of delivering shocks to participants D. Using a non-clinical patient sample
D is correct. Any findings during this study would be more valid if the researchers could have gathered patients who had been diagnosed with OCD, instead of having participants that simply had obsessive-compulsive traits. An important note here is that this limitation specifically pertains to the goal of the study, which was conducted to investigate overgeneralization. In turn, paragraph 1 tells us that overgeneralization is linked to OCD. Therefore, conducting a study among participants with OCD, perhaps in addition to those with only obsessive-compulsive traits, would have strengthened the findings of the study. A, B: When answering questions that ask for limitations, it is important to be careful of answers that reflect a knee-jerk impulse to say that the researchers should have gathered more data or that a subject is insufficiently understood. While this may be the case, to some extent, from a practical standpoint all studies have constraints in terms of sample size, and if a topic was perfectly understood, there would be no need to study it further. The passage gives us no reason to think that age is a specific limitation, since none of the issues being investigated are strictly age-dependent (choice A). Additionally, it is safe to conclude that OCD has been widely studied in order to be recognized as a disorder, and in any case, gaps in the understanding of OCD would motivate further research. C: Conducting research ethically does not necessarily mean avoiding all techniques that might be uncomfortable for participants. In particular, delivering shocks to participants is a fairly common research method. Ethical considerations apply to the need to obtain informed consent and to conduct the procedure in the least harmful possible way that is consistent with the research goals (a concern that would be evaluated as part of IRB approval). However, using shocks is not inherently unethical.
Which of the following is NOT a strategy to induce compliance in a target group, as described in the passage? A. A dress code at an organization B. Referring to military recruits by their military number C. Hazing rituals in a club involving humiliation D. Pointing out differences between one group of students' performance and another group's performance
D is correct. Compliance is induced in groups that view themselves as similar. The other strategies were specified in the passage as ways to induce compliance. A, B, C: Since all of these groups view themselves as similar, these choices serve as good examples for inducing compliance.
What is the approximate size of the IgG protein? A. 30 kDa B. 50 kDa C. 100 kDa D. 150 kDa Mixture A contained 1.5 M of the isolated immunoglobulin. In mixture B, the unknown molecule was incubated with an endopeptidase, an enzyme that cleaves a single peptide bond on the immunoglobulin, separating the chains. Gel electrophoresis was performed on both samples and the results were compared to known immunoglobulins.
D is correct. Figure 1 shows the results of gel electrophoresis, which separates molecules based on size. The molecule migrates through the gel, and smaller molecules can migrate further down the gel. Lane A shows the larger-sized sample and, thus, is the intact immunoglobulin. The MW reference lane allows us to estimate the size of IgG at somewhere between 109 and 205 kDa. A, B, C: All of these values are less than the IgG band identified in lane A. 50 and 30 kDa are the approximate sizes of the IgG fragments left after endopeptidase digestion.
An individual with Wernicke's aphasia would likely have difficulty with what part of communication? A. Producing sound B. Constructing words C. Forming sentences D. Expressing meaning
D is correct. People with Wernicke's aphasia have difficulty connecting meaning to language. The diagram below depicts Wernicke's area (located in the temporal lobe) as well as Broca's area (located in the frontal lobe). A, B, C: These are all parts of communication related to the physical production of speech. As such, an individual with Broca's aphasia might have trouble accomplishing them, but an individual with Wernicke's aphasia would not. (For choice C, note that it says "Forming sentences," not "Forming meaningful sentences." As such, it refers to the physical production of sentences and is not the answer here.) Content Foundations: Speech Production and Comprehension In humans, language production and comprehension are largely controlled by two brain areas: Broca's area and Wernicke's area. Broca's area, located in the left hemisphere of the frontal lobe, controls the physical production of speech. Damage to Broca's area, termed Broca's aphasia, weakens the ability to speak. Individuals with Broca's aphasia typically have significant trouble producing words, although their comprehension (or understanding) is relatively undamaged, and they may be able to read or listen to others speak fairly normally. In contrast, Wernicke's area is located in the back of the temporal lobe, just posterior to the Sylvian fissure (the part of the brain where the temporal and parietal lobes meet). This brain area controls the comprehension of speech and written language. When Wernicke's area is damaged, the resulting condition - termed Wernicke's aphasia - causes the loss of speech comprehension. Patients with this disease can still speak and often do so at great length, but their words are nonsensical. In other words, their problems are with creating meaningful, intelligible speech, not with producing the sounds that make up words. Both Broca's and Wernicke's aphasia can result from brain injury, such as stroke. On the MCAT, questions about these brain areas most often includes both of them as answer choices, so be certain to understand the differences between Broca's and Wernicke's area - including their roles, locations, and the effects of damage to them - by Test Day. Adapted from Next Step MCAT Psychology and Sociology Ch. 4, where more information on this topic can be found. Give feedback on this question
Examining the results in Figure 2, the common ion effect accounts for: I. the increased yellow precipitate observed in Figure 2 when AgNO3 is added. II. the increased yellow precipitate observed in Figure 2 when K3PO4 is added. III. the decreased yellow precipitate observed in Figure 2 when Ba(OH)2 is added. A. I only B. II only C. III only D. I and II only Attempts to replicate this were conducted at a macroscopic scale, and mass spectrometry showed the yellow precipitate to contain two absorption peaks, correlating to both a phosphate group and a silver component.
D is correct. The common ion effect occurs when a solution contains a salt that partially dissolves into ions, and an extra quantity of one of these ions is added. This results in the combination of this ion with existing dissolved ions, causing an additional quantity of the salt to precipitate out of solution. In this case, the partially-dissolved salt is Ag3PO4. Adding AgNO3 causes dissolution of extra Ag+ions, which then combine with already-present PO43- ions and precipitate out of solution into the yellow Ag3PO4 precipitate (identified with the mass spectrometer used in Figure 1). Similarly, adding K3PO4 results in dissolution of extra PO43- ions, which then combine with already-present Ag+ ions and precipitate into yellow Ag3PO4. I and II are therefore both correct. III: This is not accurate because Ba2+, after dissolving from Ba(OH)2, combines with dissolved PO43- to create Ba3(PO4)2 (the white precipitate referenced in Figure 2). Taking PO43- ions out of solution in this way causes more Ag3PO4 to dissolve, hence the observed decrease in yellow precipitate. A: RN II is also correct. B: RN I is also correct. C: RN I and RN II are correct, while RN III is incorrect.
The true weight of the p53 protein, as calculated by summing the weight of the amino acids encoded by its gene, is 43.7 kDa. Which of the following possible mechanisms would best explain this discrepancy from its estimated weight, as mentioned in the passage? A. The protein migrated a greater distance because it contains many positively charged residues. B. The protein migrated a smaller distance because it contains many negatively charged residues. C. The protein migrated a greater distance because it contains many negatively charged residues. D. The protein migrated a smaller distance because it contains many positively charged residues.
D is correct. The final paragraph of the passage mentions that p53 is so named for its estimated molecular weight using SDS-PAGE. This question is asking us to determine a plausible reason for the 9.3-kDa discrepancy. SDS-PAGE is used to grant a uniform negative charge to all proteins in an assay. However, if the protein has enough charged residues on its own, it causes the measurements to be less accurate. If there are enough positive charges, the negative charge of the protein will not be as great as anticipated and the molecule will travel a smaller distance, which, to the individual running the assay, usually means the mass of the protein is greater and would lead to the discrepancy described. A, C: The SDS-PAGE measurement is artificially large (53 kDa rather than the actual weight of 43.7 kDa). This means that the p53 protein migrated a smaller distance, not a greater distance. (Remember, the smaller the distance traveled in SDS-PAGE, the larger we would expect the protein to be.) B: In SDS-PAGE, proteins migrate toward a positively-charged pole. As such, containing many negatively-charged residues would make a protein migrate a larger distance, not a smaller one.
explicit and implcit attitudes?
Explicit attitudes are conscious attitudes. Student E was aware of his attitudes towards study pills and how they changed over time. He once viewed study pills as a negative habit; now he sees them as a means to an end. A: Implicit attitudes towards study pills are unconscious attitudes.
If the Gibbs free energy of the liquid-crystalline phase for an aqueous dispersion of DPCC and raffinose is 17.9 kcal/mol, which of the following values is nearest the Gibbs free energy of the associated gel phase? A. 3.5 kcal/mol B. 32.3 kcal/mol C. 566.1 kcal/mol D. 601.9 kcal/mol
MAKE SURE YOUR UNITS LINE UP WITH EACHOTHER........LOOK AT THE ANSWER CHOICES, WANT kcal/mol ......you extrscted the correct equations to use, but forgot to cahnge the entropy to the right thing....MAKE SURE YOU USE THE CORRECT UNITS, READ CAREFULLY
quantum numbers and what they can be and what they indicate??
The first quantum number is the principal quantum number (n). It denotes the energy level of the electron, and can take any integer value (≥1). Higher principal quantum numbers (for example, n = 2 rather than n = 1) have greater energy and are farther from the nucleus. The principal quantum number relates to the row of the periodic table in which the element in question is found. The azimuthal, or angular momentum, quantum number (l) describes the subshell of the principal quantum number in which the electron is found, with values ranging from 0 to n − 1, where l = 0 is the s subshell, l = 1 is the p subshell, l = 2 is the d subshell, and l = 3 is the f subshell. Next, the magnetic quantum number (ml) describes the spatial orientation of the orbital in question within its subshell. Potential values of ml range from −l to +l. Since each orbital can hold a maximum of two electrons, this means that an s subshell can contain up to two electrons, a p subshell can hold up to six electrons, a d subshell can contain up to 10, and an f subshell can hold up to 14. Finally, the spin quantum number (ms) describes the spin orientation of the electron, which relates to its angular momentum. The two possible spin orientations are ms = −1⁄2 and ms = +1⁄2. Two electrons in the same orbital (and thus with the same ml value) are said to be paired and must have opposite spin.
Underproduction of pulmonary surfactant in IRDS leads to decreased compliance of alveolar tissue. Based upon this information, which of the following must be true regarding pulmonary surfactant? A. Its adsorption to the water-alveolar interface increases surface tension, preventing alveolar collapse due to intra-thoracic pressure. B. Its absence decreases the minimum radial size of alveoli able to avoid collapse at a given pressure of inspired air. C. Its adsorption to the water-alveolar interface decreases surface tension, decreasing the pressure difference required to inflate the airway. D. Its presence increases the efficiency of gas exchange across the alveolar membrane by decreasing the surface area of the alveolus at a given pressure of inspired air.
The high surface tension generates pressure and causes the tendency of alveoli to collapse and oppose lung expansion. Surfactant breaks up these strong IMFs between water molecules coating the inner surface of the alveolus (what's creating the high surface tension in the first place) to help with lung expansion. note, we want the surface tension for expiration though...........however the surfractant helps the alveoli from collapsing too much
nonspecific immunity
The innate (non-specific) immune system includes anatomical barriers, secretory molecules, and cellular components. Among the mechanical anatomical barriers are the skin and internal epithelial layers, the movement of the intestines, and the oscillation of bronchopulmonary cilia.
E cell reduction potnetials for galvanic and electrolytic cells?
While galvanic cells have positive Ecell values (indicating spontaneity), electrolytic cells are characterized by negative Ecell values.
The total standard potential generated by a cell, Ecell??
an be calculated from the standard reduction potentials of the half-reactions. The simplest way of defining Ecell is presented below: Ecell = E°cathode − E°anode
looking glass self
an image of yourself based on what you believe others think of you t. The looking-glass self is a social psychological concept stating that a person's self grows out of society's interpersonal interactions and the perceptions of others. The term refers to people shaping their self-concepts based on their understanding of how others perceive them. If the man feels bias from society and/or police (as mentioned in paragraph 1) the looking-glass self theory states that he will internalize the bias/stigmatization directed towards him.
capacitance affected by?:?
area and distance(seperation)
atomic mass and atomic number?
atomic number is numebr of protons atomic mass: protons and neutrons
atomic radii trend
increases down a group, decreases across/to ,the right a period
Which of the following would be LEAST useful in cellular movement? A. Flagella B. Actin polymerization C. Microtubule depolymerization D. Cilia
note: flagella and cillia are formed from microtubules
periodic table periods and groups?
periods: horizontal groups: vertical
The researchers interviewed one of the participants in the study, who, at 50 years of age, recently experienced her first year of poverty. When asked to explain her financial history, she credits her hard work and determination for her success despite being from a low-income neighborhood, and attributes her recent financial struggles to her employer's refusal to give her a raise. Her story is an example of: A. self-serving bias. B. fundamental attribution error. C. prejudice. D. ethnocentrism.
self serving: focus on self fundamental attribution error: focus on other person A is correct. Self-serving bias is the tendency to attribute good outcomes with internal factors (for example, hard work), and ascribe bad outcomes to external factors (boss not giving a raise). B: Fundamental attribution error describes the tendency for individuals to overemphasize internal characteristics, such as personality, in attempting to explain someone's behavior at the expense of situational factors. This is not an example of fundamental attribution error. C: Prejudice describes attitudes towards particular groups that do not have a basis in reality. Without more knowledge of the boss's reasons for not giving her a raise, we cannot ascribe this example to prejudice. D: Ethnocentrism means judging another culture by one's own cultural values. The participant's story does not really hint at any cultural factors, so this is not a likely answer.
alpha particle
theyre the NUCLEI of a helium atom, so have no electrons and will be a +2 charge
The transition from N to O offers an exception to the trend for first ionization energy due to Hund's rules of spin pairing. If this spin pairing was not present, what would be the expected first ionization energy for the p-orbital on an oxygen atom? A. 400 kJ/mol B. 1300 kJ/mol C. 1700 kJ/mol D. 2000 kJ/mol graph on next slide
was a very easy question!!!1 all you had to do was LOOK AT THE GRAPH and EXTRAPOLATE THE INFOO!!!
visible spectrum contains wavelengths ranging from??
wavelengths ranging from 400 nm to 700 nm
A cell's ATP-to-ADP ratio is most nearly equal to the ratio of its fluorescence emission intensities when Y32 is excited at: A. 500 nm versus when it is excited at 420 nm. B. 420 nm versus when it is excited at 500 nm. C. 500 nm versus when it is in its ground state at 500 nm. D. 420 nm versus when it is in its ground state at 420 nm.
you didnt interpret the graph correctly, let it intimidate you. had to use info in the passage to extract the fact the fluorescne get highest at certain wavelgnths, indicating optimal peak absorbance
The results of a separate study of the thermodynamic parameters for the interactions of proteins with cyclohexanol and quartenary ammonium salts indicate that the hydrophobic solute-solute interaction is spontaneous, and that ΔH and ΔG have opposite signs. Which of the following must be true for this interaction when temperature is a positive value? I. ΔH > ΔG II. 0 < ΔS III. ΔH < ΔS A. I only B. I and II only C. II and III only D. I, II, and III
you picked D, III: The quantity TΔS, not ΔS, must be greater than ΔH. For this reason, RN III does not have to be true......could have a really huge temperature, and rxn would be exothermic....READ QUESTIONS CAREFULLY, ASKING WHAT "MUST" BE TRUE
how many rings in purines and pyrimidines?
you should know that adenine and guanine are purines (2-ring stuctures) and that thymine, cytosine, and uracil are pyrimidines (single-ring structures). As such, this is a conversion from a pyrimidine (single-ring structure) to another pyrimidine (single-ring structure).
Which of the following electronic transitions for a hydrogen atom would result in the emission of a photon that would be visible to the human eye? A. n = 1 to n = 3 B. n = 2 to n = 4 C. n = 2 to n = 1 D. n = 4 to n = 2 E n = -RH/n2 (Note: n = principal quantum number; RH = 1.097✕10^7 m-1)
you're transitioning from 2 to 1 and 4 to 2........so to find the change in energy you would do the 1-2 value and 4-2 value.....you got a litle confuused about that...... D is correct. The visible spectrum contains electromagnetic signals with wavelengths ranging from 400 nm to 700 nm. The wavelength of light emitted during a particular electronic transition is determined by the energy difference (ΔE) between the final and initial energy levels. The energy of each level can be determined using Equation 1 and the principal quantum number in question. For light to be emitted at all, an electron must travel from a higher to a lower level, a process that releases energy. This automatically eliminates options A and B; however, we must actually perform calculations to choose between C and D. Begin with choice C, using Equation 1 and approximating the Rydberg constant as 1 ✕ 107 m-1. The energy of the n = 2 level is: E2 = -1 ✕ 107 m-1 / 22 = -0.25 ✕ 107 m-1 Since the energy of the n = 1 level is equivalent to the Rydberg constant, ΔE is: ΔE = E2 - E1 = (-1 ✕ 107 m-1) - (-0.25 ✕ 107 m-1) = -0.75 ✕ 107 m-1 Note that this value is in units of m-1, but due to the passage and the units given in the question stem, we need to convert to nanometers ( 1 nm = 10-9 m). We can ignore the negative sign, since this simply means that energy was released rather than absorbed. 1 / (0.75 ✕ 107 m-1) = 1.33 ✕ 10-7 m = 133 nm This falls in the UV range of the electromagnetic spectrum, below the visible range. This eliminates choice C, and we can choose option D and move on. However, if you would like to confirm using math, calculating the energy of the n = 4 level gives: E4 = -1 x 107 m-1 / 42 = -1/16 x 107 m-1 ΔE = E2 - E4 = (-4/16 ✕ 107 m-1) - (-1/16 ✕ 107 m-1) = -3/16 ✕ 107 m-1 To make the fraction easier to work with, round 3/16 to 3/15, or 1/5. Again, we must convert wavenumbers to nanometers: 1 / (1/5 ✕ 107 m-1) = 5 ✕ 10-7 m (5 ✕ 10-7 m)(1 ✕ 109 nm/m) = 500 nm While this is also an approximation, it falls well within the visible spectrum. The actual color of the n = 4 to n = 2 transition of hydrogen is teal (blue-green), with a wavelength of 486 nm. A, B: Moving from a lower to a higher energy level is associated with absorption of energy, not emission. As such, these choices can be eliminated right away. C: This answer is the result of miscalculation.
