Missed MCAT Questions

The transcription factor AP-1 is a heterodimer consisting of c-jun and c-fos. C-jun and c-fos are soluble proteins that can be localized to either the cytosol or nucleus of a cell. C-jun and c-fos dimerize through a leucine zipper motif. In a leucine zipper motif, every 7 amino acid residues, or 2 full turns of an alpha helix, are leucine resides. Leucine and other amino acids on one face of the helix come together to form an opposite alpha helix that has a similar arrangement of leucine and other amino acids. Which solvent would be LEAST favorable for c-fos/c-jun dimerization? A. Hexane B. Ethanol C. Water D. Phosphate-buffered saline

A is correct. For long questions like this one, begin by summarizing exactly what the question is asking. In short, leucine residues on different parts of a molecule are coming together to form a dimer. Leucine is hydrophobic, since its side chain contains only carbon and hydrogen. If the solvent were also hydrophobic, the face of a leucine zipper could interact just as favorably with the solvent as with the opposite alpha helix. Some leucine residues would likely interact only with the solvent, preventing formation of the dimer entirely. Hexane, with its nonpolar hydrocarbon structure (shown below), is the least polar solvent listed. B, C, D: All of these solvents are more polar than hexane. They would not interact well with the leucine side chain, leaving it free to form the proper dimer. (Note that we can infer that phosphate-buffered saline must be polar because phosphate is highly negatively charged.) *I didn't read the question thoroughly enough and again jumped to a conclusion*

Given information provided in the passage, which of the following is the most likely standard voltage change for the ½ O2/H2O redox pair? A. +0.82 V B. +0.14 V C. -0.18 V D. -0.45 V

A is correct. In the electron transport chain, electrons are passed from species with less positive reduction potential to those with more positive reduction potential. O2 serves as the final electron acceptor of the electron transport chain and must possess a standard reduction potential that is more positive than any other acceptor in the chain. Of the standard reduction potentials mentioned in the passage, the greatest is that of Fe3+/Fe2+ in cytochrome c, for which E° = +0.22 V. Only choice A exceeds this value. B, C, D: These values are all less than +0.22 V. *Did not understand how to use the passage to address the question*

Boiling chips and vacuum distillation, respectively, are used in distillations to: A. provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; lower the boiling points of the substances to be distilled. B. lower the boiling points of the substances to be distilled; work synergistically with the vacuum system to further lower the boiling points. C. lower the boiling points of the substances to be distilled; provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating. D. provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating; speed up the distillation process by vacuuming the first distillate out of the apparatus.

A is correct. Let's begin with the first part of this question, the function of boiling chips. When transitioning from liquid to gas during boiling, the liquid needs nucleation sites, or places to start forming bubbles. This is typically achieved either by scratching the inside of the flask or by introducing boiling chips. This eliminates all options except for A and D. Next, remember that boiling occurs when the Pvap of the substance in question equals the Patm. Typically, we boil substances by increasing the temperature, thereby increasing Pvap. Alternatively, however, we can lower boiling point by reducing Patm, which can be accomplished through the introduction of a vacuum. Vacuum distillation is often used when components have very high boiling points and would otherwise be difficult to distill. B: The boiling chip itself does not alter the boiling point of the liquid. C: This has the functions reversed. D: The vacuum apparatus removes the atmospheric pressure, not the distillate itself. The distillate simply boils more rapidly as a result of the reduced pressure. *I did not know this*

Which of the following correctly describes the orbital hybridization of XeF4 and NH3, respectively? A. sp3d2, sp3 B. sp3, sp3 C. sp3, sp2 D. sp3d2, sp2

A is correct. One quick way to determine the orbital hybridization around the central atom is to simply count up the number of bonds and lone pairs. For example, ammonia has three bonds and one lone pair around its central nitrogen atom, for a total of four regions of electron density. This orbital hybrid therefore needs four orbitals to hybridize: s, p, p, and p. Thus, ammonia is an sp3 hybrid. We can narrow it down to choices A and B. Next, XeF4 has two lone pairs and four bonds around the central xenon atom. We know this because the central Xe atom has eight valence electrons. It gets four of these eight electrons from the two lone pairs and four from the bonds — one electron from each bond. Alternatively, we could try drawing the Lewis structure of XeF4, knowing that 8 electrons must come from the Xe atom and 7 from each of the F atoms, for a total of 8 + 7(4) = 36 electrons. Drawing XeF4 with Xe as the central atom and single bonds between the Xe atom and each F atom produces a structure with only 32 electrons, so we must add two lone pairs to the central Xe atom. Two lone pairs and four bonds gives us six total regions of electron density. So we need six hybrid orbitals to hold those electrons: s, p, p, p, d, and d. That's an sp3d2 hybrid. B: We can eliminate this option right away if we recognize that XeF4 and NH3 (two very different molecules) do not display the same orbital hybridization. C: XeF4 does not have an orbital hybridization of sp3. Additionally, NH3 does not have a hybridization of sp2; sp2 hybridization would better describe a molecule with three bonded regions and no lone pairs on the central atom, such as acetone. D: Again, NH3 does not have an orbital hybridization of sp2. *I rushed and jumped to a conclusion rather than taking the time to work out the problem to verify, i.e. stupid mistake*

Several families in areas 4 and 5 who read the results of the study believe that their children have no increased risk of developing thyroid cancer. Is this conclusion accurate? A. No, the mutations caused by I-131 exposure may take more than three years to manifest as cancer. B. No, I-131 has a half-life of only 8 days. C. Yes, Table 1 shows that there was no increase in cancer in areas 4 and 5 in years 2013 and 2014. D. Yes, the radiation given off by I-131 is not mutagenic.

A is correct. This question requires passage information as well as basic knowledge about cancer. Cancer is the failure of mutated cells to regulate cell division and proliferation in a normal manner. Since regulatory genes and processes are complex, mutations caused by I-131 exposure may not immediately cause detectable cancer, as the mutated DNA will disrupt the cell cycle over time. Therefore, it is possible that children in areas 4 and 5 were exposed to enough I-131 to cause mutations in the DNA of thyroid cells, but the resulting cancer will take more than 3 years after the accident to become detectable. B: The half-life of I-131 is short, but the radiation is still mutagenic. An 8-day half-life is more than sufficient to be absorbed by the body and possibly damage thyroid DNA. C: Though this represents a plausible statement about Table 1, it is not entirely accurate, as region 5 does show an increase of cancer in 2013 compared to 2012. In addition, I-131-induced cancer may develop in areas 4 and 5 after the conclusion of the study. D: The third paragraph mentions β-decay as well as gamma radiation. Gamma rays are ionizing and potentially mutagenic. In addition, β-particles are able to penetrate living matter and can strike and change the structure of molecules, including DNA. *Ignored aspect of the passage in order to support the answer I wanted*

What is the lift force for the vesicle reported in Table 1 that would be the last to detach from the vascular wall? A. 0.2 pN B. 153.6 pN C. 68.7 Pa/m D. 121.9 Pa/m

B is correct. Do not jump right into calculations simply because the answers are numbers! Forces must be expressed in Newtons (kg•m/s2) or their equivalent. Choices C and D as units of pressure (Pascals, N/m2) divided by meters. This will not result in units of force so we can eliminate both choices immediately. According to paragraph 3, the vesicle that would be the last to detach from the wall will have the largest minimum shear rate value (gc). The second-to-last column in the table indicates that the largest gc value is 2.20 s-1 for vesicle N° = 33, which has a lift force (P = Fl) of 153.6 pN. A: This is the lift for N° = 1, which has a critical wall shear rate of 0.45 s-1. C: This is the Drg (Pa/m) for N° = 1 and is not a lift force. D: This is Drg (Pa/m) for N° = 33; again, it is not a lift force. Force is typically measured in newtons (or micronewtons, piconewtons, etc.), which makes choices C and D less tempting than A and B. *Did not have time to read the passage to utilize its information*

A researcher seeks to monitor the conversion of retinal to retinol using infrared spectroscopy. Which of the following will indicate the reaction is complete? A. The disappearance of peaks in the 3200-3500 cm-1 region B. The disappearance of a peak in the 1700-1750 cm-1 region C. The disappearance of a peak in the 1580-1640 cm-1 region D. The appearance of a peak in the 1700-1750 cm-1 region

B is correct. Retinol differs from retinal in that it contains -OH groups, but does not contain a carbonyl group (C=O). The carbonyl stretching frequency falls in the range of 1700-1750 cm-1, while the O-H stretching frequency is expected to fall in the range of 3200-3500 cm-1. The reaction is thus complete when the signal in the 1700-1750 cm-1 range has completely disappeared. A: This would indicate a lack of -OH groups, which is a characteristic of retinal, not retinol. C: This peak is indicative of C=C groups, which both molecules have and cannot be used to determine when retinal has been converted. D: This would indicate the presence of a carbonyl functionality, which is a characteristic of retinal, not retinol. *I did not know the stretching frequencies associated with each functional group*

According to passage information, is the energy released by the transport of an electron pair delivered by NADH through the electron transport chain sufficient to produce three ATP molecules from three ADP and three inorganic phosphate molecules if the efficiency of the conversion of the energy released via the transport of an electron delivered by NADH into useful work in the body is found to be approximately 50%? A. Yes, with the additional calories of energy released by the electron transfer and not used in the phosphorylation employed to drive the removal of excess hydrogens from the matrix. B. Yes, with the majority of calories of energy released by the electron transfer and not used in the phosphorylation lost mainly as heat. C. No, the energy released in the process is sufficient to drive the formation of only two ATP from two ADP and two inorganic phosphate molecules because Complex I is bypassed. D. No, the enthalpy change of the reaction is negative and the formation of ATP from ADP and inorganic phosphate requires the input of outside heat energy.

B is correct. This is a long question, but don't get intimidated! To obtain the answer, we only need to find two quantities: the amount of energy required to produce three molecules of ATP and the amount of energy released by the transport of one electron pair by NADH (given the efficiency value shown). In fact, we can make this problem easier by considering moles rather than molecules, since one mole of any substance must always be the same number of molecules. According to the passage, ΔG° for the transfer of two electrons from NADH to oxygen is -52.5 kcal/mol, and ΔG° for the phosphorylation of ADP to ATP is +7.3 kcal/mol. First, let's account for the 50% efficiency, so we don't forget to do that later. Of the 52.5 kcal/mol released, only approximately 26 kcal/mol of useful energy will be available to perform work. The amount of energy required to phosphorylate 3 moles of ADP to ATP is (3 moles)(7.3 kcal/mol), or approximately 22 kcal/mol. Thus, sufficient free energy is made available by transport of one mole of electron pairs to drive the phosphorylation of three moles of ATP from ADP. One electron pair, then, would provide sufficient energy to phosphorylate three ADP molecules into ATP. Most of the free energy available to do free work (~26 kcal) was consumed by the phosphorylation (~22 kcal), with only a small amount (~4 kcal) available to do additional, biologically useful work. The remaining energy (~26 kcal) which was not involved in useful work was likely dissipated as heat energy. A: We can eliminate this option immediately because the "removal of excess hydrogens from the matrix" constitutes useful work, as it would help establish the proton gradient required for oxidative phosphorylation. If the excess energy were useful, we would not call the conversion 50% efficient, since all energy would be going toward productive cellular processes. C, D: These choices incorrectly state that the energy mentioned in the question stem is insufficient to produce three ATP molecules. *Was unable to comprehend what the answer choice was actually trying to say*

According to the results presented by the experiment, the relationship between the lift force and the vesicle radius would best be described as: A. linear. B. inverse. C. exponential. D. sigmoidal.

C is correct. Examining the second and third columns in Table 1, we see that as the radius increases, so does the lift force, eliminating choice B. Choosing the first two vesicles, we can estimate the slope, or "rise over run," to be (4.7 - 0.2) / (20.5 - 8.7) ~ 4.5/12 ~ 0.4. If we instead use the last two vesicles, we obtain a value of (153.6 - 87.1) / (67 - 50.9) ~ 66.5/16 ~ 4. Therefore, the slope is increasing at an ever-higher rate, which can be confirmed by inspecting other combinations of data for the vesicles. This suggests that the relationship is exponential. A: If the relationship were linear, the slope would be uniform (as in a straight line), indicating that as one variable changed, the other changed at a constant rate. This is not the case for the data in Table 1. B: An inverse relationship between two variables indicates that as one variable increases, the other decreases. This is clearly not happening here. D: A sigmoidal relationship or function indicates an S-shaped plot. There is no data that indicates that the lift force plateaus above a given radius value. *Did not have time to read the passage to utilize its information*

According to the data in Table 1, what mass of captopril must be dissolved in 3 L of plasma at pH 7.4 to inhibit 50% of ACE enzyme activity in vivo? Assume an equal volume of distribution. A. 7.9 pg B. 7.9 ng C. 7.9 µg D. 7.9 g

C is correct. From the answers alone, we can immediately tell that this is a units question, but let's work through it from the beginning. The passage defines the in vivo IC50 value of captopril to be "the minimum plasma concentration needed to inhibit 50% of [ACE] activity in vivo." From Table 1, the mean in vivo IC50 value of captopril in the pH range which includes pH 7.4 is 0.012 µM. Assuming a plasma volume of 3 L, the necessary gram weight of dissolved captopril can be calculated as follows: (0.012 x 10-6 mol captopril/L plasma) x (3 L plasma) x (220 g captopril/mol captopril) = 7.92 x 10-6 g captopril = 7.92 µg captopril Remember, 1 µg = 1 x 10-6 g. A: 7.9 pg is equal to 7.9 x 10-12 g. This value is far too small. B: 7.9 ng is equivalent to 7.9 x 10-9 g. D: This value is far too large to be correct. *Miscalculated and did not carry the 10^-6 through*

Another possible method of separating 2-methylundecanal and 2-methylundecanoic acid could be based on: A. their differences in the rotation of plane-polarized light. B. a mass spectrometry analysis. C. an extraction based on their differing solubilities. D. the very different scent profiles of each molecule.

C is correct. Note that the compounds discussed in this question are the compounds mentioned in paragraph 2, not the enantiomers depicted in Figure 1. (The compounds that are relevant to this question are pictured below.) With that said, this question asks about separating an acidic compound from a fairly neutral one. The carboxylic acid group, if deprotonated, will be much more soluble in water than the aldehyde group. Thus, a careful extraction with a dilute weak base (such as a solution of sodium bicarbonate) would separate these two molecules. Remember, the more polar a compound is, the higher its solubility in aqueous solution! A, B, D: These all represent ways to analyze, or gather information about, a substance. Analytic techniques are distinct from separatory techniques, which aim to isolate substances from each other. *Did not thoroughly read the passage or pay attention to the question and missed that the compounds weren't enantiomers*

If a 65-kg man undergoes a turning acceleration of 5 m/s2 during a running turn, what is the magnitude of force experienced by the foot due to the ground? A. 325 N B. 650 N C. 750 N D. 1075 N

C is correct. To turn while running, the foot must push off the ground, applying a shearing force while simultaneously supporting the weight of the body. When faced with problems like this, always consider the forces involved. Here, we must account for the normal force exerted by the ground on the foot; this is a vertical force which occurs as a result of the runner's weight. We also must consider the acceleration force, which (since the person is turning) is horizontal. These two force vectors are perpendicular and will form a right triangle. We are looking for the overall force experienced, so we must find the hypotenuse. Specifically, we need to find the hypotenuse of a triangle with legs of Fnormal = mg = (65 kg)(10 m/s2) = 650 N and Fturning = (65 kg)(5 m/s2) = 325 N. The combined vector will be bigger than either component alone, so eliminate choices A and B. To solve, let's round 650 N to 700 N and round 325 N to 300 N. With this in mind, this calculation can be approximated as: √(3002 + 7002) = √(90000 + 490000) = √(580000) = √(58 x 104) = (√58) x 102 The square root of 58 falls between 7 and 8, so the overall value of our answer falls between 700 and 800, meaning that choice C must be correct (the actual value is 761). A: This value is just the turning/acceleration force, not the entire magnitude of force experienced by the foot. B: This is just the normal force; it fails to take into account the turning/acceleration of the man. D: This is greater than the sum of the two force components, which means the two force vectors (normal force and turning acceleration) cannot possibly add up to this value. *I did not understand how to solve this, and ignored the centripetal force*

he reaction to produce the "X" form of compounds 1-4 from standard-state elements will be spontaneous under what conditions? A. The reactions will be spontaneous under all conditions. B. The reactions will be spontaneous at high temperatures. C. The reactions will be spontaneous at low temperatures. D. The reactions will not be spontaneous under any conditions.

C is correct. When determining the conditions under which a reaction is spontaneous, always consider the change in Gibbs free energy. If the ΔG for a reaction is positive, it is nonspontaneous, and if the ΔG for a reaction is negative, it is spontaneous. The ΔG for a reaction can be determined from the change in enthalpy and entropy based on the equation ΔG = ΔH - TΔS. Based on Table 1, the ΔH values for all of the formation reactions (Hf) are negative, which favors spontaneity. However, each reaction starts with the elements in their standard states, which include C (s), O2 (g), H2 (g), and F2 (g). The formation of a more organized compound from these reactants will result in a decrease in entropy (negative ΔS), which will favor a positive ΔG and a nonspontaneous reaction. So, if the magnitude of ΔH is greater than TΔS (which occurs at low temperatures), then the reaction is spontaneous. If the magnitude of ΔH is smaller than TΔS (which occurs at high temperatures), then the reaction is nonspontaneous. A: For this to be true, ΔS would need to be positive, which is not the case here. B: This is the exact reverse of the correct answer. D: For this to be true, ΔH would need to be positive, which is not the case here *Did not have time to read the passage to utilize the information*

If the students perform an enzyme inhibition assay using captopril, which of the following changes in the kinetic parameters of ACE should be expected? A. Vmax decreased; Km unchanged B. Vmax decreased; Km increased C. Vmax unchanged; Km decreased D. Vmax unchanged; Km increased

D is correct. According to the passage, captopril is a "competitive inhibitor of ACE." Competitive inhibitors increase the Km of their associated enzymatic reactions without altering the Vmax value, as shown in the Michaelis-Menten graph below. Here, the blue curve represents the uninhibited reaction, while the red curve is associated with the competitively inhibited reaction. A: These changes are characteristic of noncompetitive inhibition. B: These changes are characteristic of certain mixed inhibitors. C: These changes are not characteristic of any form of reversible inhibition. *Stupid mistake and confused Km*

During the experiment, scientists noted that several of the reaction beakers became hot to the touch. All of the following reactions could cause this result EXCEPT: A. Addition of C(s) + 1 H2 + 1/2 O2 B. Addition of 1/2 F2 C. Addition of C(s) + H2 D. Addition of 1/2 N2 + O2

D is correct. In order for the reactions to make the beaker hot to the touch, they must be exothermic. All exothermic reactions have a negative △Hreaction. The △Hreaction can be found using Hess's law and the Hf , where △Hreaction = ∑ Hf products - ∑ Hf reactants. Since this is an EXCEPT question, the correct answer should be endothermic and have a positive value for △Hreaction. The standard enthalpy of formation of any pure element in its standard state (e.g. C (graphite), N2 (g), O2 (g), etc....) is zero. Thus, the only Hf values required are for the larger compounds, all of which can be found in Table 1. This question does not require an exact solution; any reaction with an Hf for the products that is greater than Hf reactants will lead to a positive value for △Hreaction. The Hf for the products in choice D is 10.1 J/mol, while the Hf for the reactants is -18.8 J/mol. 10.1 J/mol (Hf products) > -18.8 J/mol (Hf reactants), so the reaction is endothermic. A: Hf for the products is 124.9 J/mol, while Hf reactants is 169.3 J/mol. Thus, Hf products < Hf reactants and the reaction is exothermic. B: Hf for the products is 128.5 J/mol; Hf reactants is 169.3 J/mol. Again, Hf products < Hf reactants and the reaction is exothermic. C: This reaction is also exothermic, as Hf for the products is -28.2 J/mol and Hf reactants is -18.8 J/mol, so Hf products < Hf reactants. *Did not have time to read the passage to utilize the exact values*

Vinblastine is a microtubule-disrupting drug that inhibits tubulin polymerization. Which of the following processes would be directly inhibited upon vinblastine treatment? I. Phagosome transport to the lysosome II. Mitosis III. Meiosis IV. Electron transport A. II only B. I and IV only C. II and III only D. I, II, and III only

D is correct. Microtubules are used in the transport of vesicles and the positioning of organelles within the cell. As part of this role, they form structures that assist in the transport of phagosomes (vesicles that contain particles that have been engulfed via phagocytosis) to the lysosomes of the cell, to which the phagosomes fuse. As such, RN I is correct. RN II and RN III are also correct, since microtubules form the spindle apparatus that is an essential part of both mitosis and meiosis. The general structure of a microtubule is shown below; note that these structures are composed of dimers of the protein tubulin. IV: Microtubules play no direct role in electron transport. A: RN I and RN III are also correct. B: RN II and RN III are also correct, while RN IV is incorrect. C: RN I is also correct. *Did not know that microtubules are used in the transport of vesicles*

Which of the following biological substances are likely derived from terpenes? I. Aldosterone II. Glucose III. Insulin IV. Estrogen A. I and II only B. I and III only C. II and III only D. I and IV only

D is correct. Paragraph 1 states that terpenes are precursors to sterols. Terpenes, including those shown in Figure 1, are structurally similar to the fused 4-ring system in steroids and are the metabolic precursor to this important class of biomolecules. Two of the choices (aldosterone and estrogen) are steroid signaling molecules, and two are not. Note that the majority of steroid hormones have names that end in "-one," "-en," or "-ol." The structures of aldosterone and estrogen (specifically, estradiol, which is one form of estrogen) are shown below. Note the similarities in structure, especially the four fused rings. II, III: Glucose is a sugar ring, while insulin is a peptide hormone; neither is a steroid signaling molecule. A: RN II is incorrect, while RN IV is correct. B: RN III is incorrect, while RN IV is correct. C: This option includes only the choices that are not derived from terpenes. This is not a "NOT" question! *Ignored an aspect of the passage in order to justify my assumption*

A child is sliding a toy block (with mass = m) down a ramp. The coefficient of static friction between the block and the ramp is 0.25. When the block is halfway down the ramp, the child pushes down on the block perpendicular to the plane, halting it. What is the minimum force the child must apply to keep the block from starting to slide down the ramp? A. mg sin θ B. 0.25 mg cos θ + mg sin θ C. mg sin θ - 0.25 mg cos θ D. [(mg sin θ) / 0.25] - mg cos θ

D is correct. The gravitational force pulling the block down the ramp is mg sin θ. (This is the typical value for the gravitational force that acts on an object to drag it down an incline.) To stop the block from sliding down the ramp, we must have an equal and opposite frictional force. Since these forces are equal and opposite, we can set them equal to each other as follows: Ff = mg sin θ Now, remember that frictional force is equal to the product of the appropriate coefficient of friction and the normal force: Ff = μFN Ff = 0.25 x FN = mg cos θ The block itself has a mass m and thus generates a normal force of FN = mg cos θ. Again, this is the standard value for the normal force on an object positioned on an inclined plane. From this information alone, we may be tempted to pick C, which is the difference between the gravitational force and the frictional force. If the child were pushing the block upwards along the plane in a parallel fashion, this choice would be correct. However, the child is actually pushing down on the car, perpendicular to the plane. Thus, the force exerted by the child (Fa) will add to the force created by the mass of the car itself and alter the value for the normal force. Our total FN = mg cos θ + Fa. Substituting, we get: Ff = 0.25 x (mg cos θ + Fa) = mg sin θ mg cos θ + Fa = (mg sin θ) / 0.25 Thus, the force with which the child must push down on the car is Fa = [(mg sin θ) / 0.25] - mg cos θ. Graphically, we can set this up by first visualizing the problem: The next step is to set up the forces more precisely. Setting Ff = mg sin θ, we can then solve the problem as follows: A: This fails to account for friction in any way. Since the passage explicitly says that the coefficient of friction is 0.25, and the toy is experiencing friction with the ramp, we're going to need that 0.25 somewhere in our answer. B: This choice adds together the force of gravity (which pulls the toy down the ramp) and the force of friction (which pushes back up the ramp). Since these forces point in opposite directions, they shouldn't be added together. C: Again, this is the force the child would have to apply if he were pushing parallel to the ramp, directly up the ramp to oppose gravity. Always read the question carefully before beginning a problem, especially a calculation-based physics question. *Rushed to answer this question due to lack of time*

A circuit is constructed with a 12-V battery and four identical resistors, each with a resistance of 16 Ω, hooked up in parallel. What is the total power dissipated by the circuit? A. 4 W B. 4 J C. 18 J D. 36 W

D is correct. The question asks us to solve for power, which is measured in watts; choices B and C use the wrong units and can be immediately eliminated. To choose between the remaining answers, we must use one of the three simple power equations: P = IV, P = I2R, or P = V2/R. (These equations are all derived from Ohm's law, so you can use whichever one is most convenient for the situation at hand.) We already have voltage, and we can solve for resistance: 1/Rtot = 1/R1 + 1/R2 + 1/R3 + 1/R4 1/Rtot = 1/16 + 1/16 + 1/16 + 1/16 1/Rtot = 4/16 = 1/4 Rtot = 4 Ω Next, we must solve for power: P = V2/R = (12)2/4 = 144/4 = 36 W A: This option represents the magnitude of the resistance (4 Ω), not the power. B, C: Power does not have units of joules (J). Joules are units for energy. *I did not know the equation for electrical power*

According to the experimental procedure, which of the following describes the physical properties of indium tin oxide? I. Opaque II. Electrically conducting III. Solid at standard temperature A. II only B. III only C. I and III only D. II and III only

D is correct. The second paragraph of the passage states, "The solution was then spread on the conductive faces of two transparent glass plates coated with indium tin oxide (ITO)." The word "conductive" refers to electrical conductivity, and since the device is hooked up to a current generator, RN II is correct (eliminate B and C). Additionally, the plates are described as solid objects. Furthermore, both indium and tin are metals, and the vast majority of metal oxides are solids at standard temperature. Unless told otherwise by the MCAT, we can assume that experiments take place at or near standard conditions, making RN III correct (eliminate A). I: Opaque means NOT transparent. This is in contrast to what paragraph 2 tells us about the ITO-coated plates (they are described as transparent). This makes RN I false. A: RN III is also correct. B: RN II is also correct. C: RN I is incorrect, while RN II is correct. *Did not have time to read the passage to utilize its information*

If a leak develops in the vacuum distillation apparatus, the boiling points of the two components of caraway seed oil will: A.both increase. B.both decrease. C.both remain the same. D.become more similar.

The correct answer is A. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the surface pressure. The normal boiling point is measured at 1 atm pressure. The vapor pressure of a liquid increases with increasing temperature. Hence, the boiling point of a liquid decreases as the pressure on the surface of the liquid is decreased. If a leak develops in the apparatus, the surface pressure will increase, as will the boiling points of both liquids. Thus, answer choice A is the best answer. *I made a stupid mistake and didn't realize that a leak within a vacuum system correlates to less air being sucked out and therefore a pressure increase within the system*

Protein secondary structure is characterized by the pattern of hydrogen bonds between: A.backbone amide protons and carbonyl oxygens. B.backbone amide protons and side chain carbonyl oxygens. C.side chain hydroxyl groups and backbone carbonyl oxygens. D.side chain amide protons and backbone carbonyl oxygens.

The correct answer is A. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is A because secondary structure is represented by repeated patterns of hydrogen bonds between the backbone amide protons and carbonyl oxygen atoms. It is a Knowledge of Scientific Concepts and Principles question because you must work with the scientific theory of secondary structure to determine which components of a protein are indicative of that structure. *Had to guess due to lack of time*

Based on the data presented in figures 2 and 3, what is the most likely role of Y229 in protein stability and cAMP activation? A.Y229 is important for protein stability but not critical for cAMP activation. B.Y229 is important for cAMP activation but not critical for protein stability. C.Y229 is important for protein stability and critical for cAMP activation. D.Y229 is not important for protein stability and not critical for cAMP activation.

The correct answer is A. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is A because the thermal melt shows that removal of Y229 decreases stability, therefore Y229 is important for stability. Removal of Y229 has little effect on protein activation, as the activation curve is similar to WT activation. It is a Data-based and Statistical Reasoning question because you must reason with the melt curve data and the activation data to determine the role of a specific amino acid in the protein. *I misunderstood the graph, and did not see that I was observing the effect of a mutation on Y229, and assumed I was observing Y229's effect*

Which structure represents a component of the HRP cofactor? A. B. C. D.

The correct answer is A. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is A, because the cofactor is heme, which is a porphyrin. The basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom. It is a Knowledge of Scientific Concepts and Principles question because recalling that heme is a porphyrin and remembering the structure of the ring components of a porphyrin are essential for answering this question. *I got this right, but this was entirely a lucky guess

Melanosomes most likely move along microtubules that originate in and radiate from the: A.centrosome. B.kinetochores. C.Golgi apparatus. D.microfilaments under the plasma membrane.

The correct answer is A. This is a Biology question that falls under the content category "Assemblies of molecules, cells, and groups of cells within single cellular and multicellular organisms." The answer to this question is A because microtubules are cellular structures that originate from centrosomes. It is a Knowledge of Scientific Concepts and Principles question because you must recall the organization of microtubules and their role in cellular transport. *I did not know this about microtubules*

In humans, the characteristic tissue of which of the following organs is NOT derived from mesoderm? A.Brain B.Heart C.Kidney D.Skeletal muscle

The correct answer is A. This is a Biology question that falls under the content category "Processes of cell division, differentiation, and specialization." The answer to this question is A because the brain is part of the central nervous system, which is derived from ectoderm. Heart, kidney, and skeletal muscle are derived from mesoderm. It is a Knowledge of Scientific Concepts and Principles question because it involves major structures that arise from primary germ layers. *Despite getting this right, I was unsure of the correct answer choice*

Within the intestines, unabsorbed fats are broken down into fatty acids by intestinal bacteria. Given this, excess unabsorbed fats most likely have which of the following effects within the intestines?o A.They increase the osmotic pressure within the intestines, leading to diarrhea. B.They decrease the osmotic pressure within the intestines, leading to diarrhea. C.They increase the osmotic pressure within the intestines, leading to constipation. D.They decrease the osmotic pressure within the intestines, leading to constipation.

The correct answer is A. This is a Biology question that falls under the content category "Structure and integrative functions of the main organ systems." The answer to this question is A because an excess of unabsorbed fats in the intestines inhibits normal water and electrolyte absorption, resulting in increased osmotic pressure and diarrhea. It is a Reasoning about the Design and Execution of Research question because it requires establishing causal relationships between variables. *This question also tripped me up because I was confused about osmotic pressure, but it shouldn't have*

In the absence of Frizzled activation, β-catenin is covalently modified and: A.bound by a proteasome to initiate degradation into short peptides. B.translocated into the Golgi body for secretion through exocytosis. C.engulfed by a lysosome where it is hydrolyzed by proteases. D.stored in vesicles until the signaling pathway is activated.

The correct answer is A. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is A because according to the passage and Figure 1, in the absence of Frizzled activation, β-catenin is phosphorylated and ubiquitinated. Ubiquitination targets a protein for degradation by a proteasome. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of a posttranslational process. *I did not know what ubiqutinization was*

Which statement best accounts for the hereditary transmission of SDH-linked paraganglioma in a parent specific manner? SDH is: A.an imprinted gene. B.a Y-linked gene. C.an X-linked gene. D.a tumor suppressor gene.

The correct answer is A. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is A because imprinted genes are expressed in a parent-specific manner. B is incorrect because based on the passage both sexes may carry the mutated allele. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of regulation of gene expression. *I didn't read the passage carefully enough to see that the allele has an estimated frequency of approximately 10% in the human population*

What is the best experimental method to analyze the effect of tdh2 gene deletion on the rate of histone acetylation? Comparing histone acetylation in wild-type and Δtdh2 cells by: A.Western blot B.Southern blot C.Northern blot D.RT-PCR

The correct answer is A. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is A because posttranslational modification of proteins such as histone acetylation is analyzed by Western blotting. It is a Reasoning about the Design and Execution of Research question because you must reason about the appropriateness of tools that are used to assess posttranslational modification of proteins. *I forgot what each blotting technique was used for*

G542X is another CFTR allele. If a female heterozygous for G542X bears a child fathered by a male heterozygous for the ΔF508 allele, what is the probability that the child would be homozygous for the G542X allele, given that neither parent has CF? A.0.00 B.0.25 C.0.75 D.1.00

The correct answer is A. This is a Biology question that falls under the content category "Transmission of heritable information from generation to generation and the processes that increase genetic diversity." The answer to this question is A because both parents would need to carry the G542X allele in order for a child to be homozygous for the G542X allele. Because only the mother carries the G542X allele, the probability that the child will be homozygous for the G542X allele is 0. It is a Scientific Reasoning and Problem Solving question because it requires you to understand homozygous and heterozygous alleles and calculate genetic patterns of inheritance. *I was unsure of how to manage the mutated alleles*

Which of the following animal pairs best illustrates the outcome of convergent evolution? A.The dolphin and the shark B.The domestic sheep and the mountain goat C.The polar bear and the panda bear D.The light-colored and the dark-colored forms of the peppered moth

The correct answer is A. This is a Biology question that falls under the content category "Transmission of heritable information from generation to generation and the processes that increase genetic diversity." The answer to this question is A because convergent evolution is defined as a process whereby distantly related organisms independently evolve similar traits to adapt to similar needs. It is a Scientific Reasoning and Problem Solving question because it requires scientific evaluation of various animal traits in relation to convergent evolution. *I did not know what convergent evolution was*

Which of the following molecules has an octahedral geometry? A.SF6 B.CBr4 C.XeF4 D.BrF3

The correct answer is A. This is a General Chemistry question that falls under the content category "Nature of molecules and intermolecular interactions." The answer to this question is A because SF6 is an AX6 system with no lone pairs As a result, SF6 will adopt an octahedral bonding arrangement to minimize the repulsive interactions of the bonding domain electrons. It is a Knowledge of Scientific Concepts and Principles question because you must recognize a correct scientific principle. *I made a stupid mistake and confused octahedral geometry with having 6 hybrid orbitals*

Which of the following properties of a 2.3 MHz ultrasound wave remains unchanged as it passes into human tissues? A.Frequency B.Wave speed C.Amplitude D.Wavelength

The correct answer is A. This is a Physics question that falls under the content category "How light and sound interact with matter." The answer to this question is A because the frequency of a wave is not affected by the medium through which it propagates. It is a Knowledge of Scientific Concepts and Principles question because it asks you to use data to recognize correct scientific principles. *Although I got this right, it was primarily due to the fact that the passage provided the answer in an obscure way*

How much work did an 83-year-old female do while stretching the rubber band to the limit of her strength? A.4 J B.5 J C.6 J D.7 J

The correct answer is A. This is a Physics question that falls under the content category "Translational motion, forces, work, energy, and equilibrium in living systems." The answer to this question is A because the work done is W = 0.5 × kx2 where x = 0.20 m. So W = 0.5 × 200 (N/m) × (0.2 m)2 = 4.0 J. It is a Scientific Reasoning and Problem Solving question because the question requires determining and using scientific formulas to solve problems. *I forgot that the formula for the work done by an elastic force is equal to elastic potential energy, and I was running low on time*

The finding from Study 3 regarding the differential effect of emotional arousal on memory for central and peripheral details is best explained by which mechanism? Increasing emotional arousal: A.causes a restriction of the focus of attention. B.improves memory, but only up to an optimal level of arousal. C.impairs the encoding of peripheral details. D.enhances the retrieval of encoded central details.

The correct answer is A. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is A because emotional arousal seems to focus a person's attention on the central features of an event. The hypothesis (Easterbrook, 1959) that a person will notice information that elicits arousal, but fail to process other information, has been supported by studies in which memory for an (emotional) event's "central" aspects (directly tied to the emotion elicitor) is compared to memory for "peripheral" aspects (removed from the source of the emotional arousal). Thus, memory for the fundamental gist of the emotional event is retained, whereas memory for details (if they are encoded at all) either fades or undergoes changes. It is a Scientific Reasoning and Problem Solving question because the question involves the evaluation of different arguments regarding cause and effect. *I ignored the fact that peripheral details were being neglected and only focused on the fact that more central aspects were remembered*

Based on Figure 1, the best conclusion is that: A.all therapies are equally effective 6 months after treatment. B.CT has the most promising immediate effects. C.both BT and CT are as effective individually as CBT. D.CT is effective only at the 6-month follow-up.

The correct answer is A. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is A because it states the overall conclusion of the study. The figure indicates that at the 6-month follow-up, no statistically significant difference was found among the three therapies, which all resulted in group means of self-reported insomnia severity below the threshold for an insomnia diagnosis. It is a Data-based and Statistical Reasoning question because the question involves interpreting empirical results from a study. *I failed to account for the lack of statistical significance in the differences between the therapies*

A study presents participants with fictitious names. The next day, participants are given a list of celebrity names, the old fictitious names from the previous day, and new fictitious names. They are asked to identify the famous names on the list. The most common errors the participants make are source monitoring errors. Which graph demonstrates the most likely outcome?

The correct answer is A. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is A, because the participants made source monitoring errors, such that they were likely to think of the old made-up names as famous names. It is a Data-Based and Statistical Reasoning question because it requires identifying which graph displays the data pattern reported in the question. *Despite getting this right, it was based on a lucky guess*

Based on the information presented in the passage, which correlation coefficient provides the best estimate of the association between SES and level of exposure to stress? A.-0.20 B.-0.05 C.+0.15 D.+0.50

The correct answer is A. This is a Psychology question that falls under the content category "Responding to the world." The answer to this question is A because the passage (last paragraph) implies a negative correlation between socioeconomic position and exposure to stress. The other negative correlation (B) can be ruled out, because it is very weak (and thus not likely to have the kind of disproportionate effect that is discussed in the passage). It is a Data-based and Statistical Reasoning question because the question involves understanding the relationship between the data described in the passage and the way those data may be described using a correlation coefficient. *I knew the answer had to be negative, I just didn't fully understand correlation coefficients, or how large the numbers had to be to indicate a strong correlation, also idk why I didn't think to pick the stronger inverse correlation*

The research design used in the study employed all of the following techniques EXCEPT: A.observational. B.correlational. C.experimental. D.longitudinal.

The correct answer is A. This is a Psychology question that falls under the content category "Social interactions." The answer to this question is A. The study's design established an experimental (yoga) group and control group. The study involved correlational analysis of the data. Follow-up assessments at 3 and 6 month intervals, using the same cohorts, established a longitudinal element. The only method not specifically employed was observational analysis. It is a Reasoning about the Design and Execution of Research question because it requires you to demonstrate your knowledge of different methodological approaches. *I did not know what a longitudinal technique was*

The aging of the U.S. population is most likely to increase: A.the dependency ratio. B.the social gradient in health. C.the life course perspective. D.the intersectionality of medicine.

The correct answer is A. This is a Sociology question that falls under the content category "Demographic characteristics and processes." The answer to this question is A. The dependency ratio is a ratio of the number of economically dependent members of the population to the number of economically productive members. The economically dependent are those considered too young or too old to work, whereas the economically productive are the working-age population (approximately between the ages of 18 and 65). It is a Knowledge of Scientific Concepts and Principles question because it requires identifying the concept that is most relevant to demographic trends. *Despite getting this correct, I only was able to get the right answer through POE and did not know what the dependency ratio was*

Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a mixture, are separated by column chromatography using silica gel with benzene as the eluent. What is the expected order of elution of these four organic compounds from first to last? A.n-Pentane → 2-butanone → n-butanol → propanoic acid B.n-Pentane → n-butanol → 2-butanone → propanoic acid C.Propanoic acid → n-butanol → 2-butanone → n-pentane D.Propanoic acid → 2-butanone → n-butanol → n-pentane

The correct answer is A. This is an Organic Chemistry question that falls under the content category "Separation and purification methods." The answer to this question is A. The four compounds have comparable molecular weights, so the order of elution will depend on the polarity of the molecule. Since silica gel serves as the stationary phase for the experiment, increasing the polarity of the eluting molecule will increase its affinity for the stationary phase and increase the elution time (decreased Rf). It is a Reasoning about the Design and Execution of Research question because you must reason about the features of a research design to identify a causal relationship. *I confused the eluent with the stationary phase*

Radioactive tritium (3H) labeled guanine has been used to measure the rate of biochemical processes that involve its binding or incorporation. Given that water is the solvent for this type of experiment, what is the best site for tritium labeling? A.I B.II C.III D.IV

The correct answer is A. This is an Organic Chemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is A, because the best site for tritium labeling would not exchange the tritium ions for protons in water. All of the N−H sites (II−IV) would readily exchange tritium protons due to their lone pair-facilitating protonation and subsequent tritium exchange with water, but the C−H site (I), lacking a lone pair, would retain its tritium label. It is a Reasoning about the Design and Execution of Research question because the selection of the tritium-labeling site under aqueous conditions is essential to the experimental design. *Despite getting this right, my basis for a correct answer was based primarily on a guess*

Suppose that the ruins of a sixteenth-century monastery are discovered on a remote island off the Swedish coast. Why, according to passage information, is this discovery surprising? A.Few European pilgrims would have been able to reach the site. B.An eremitical motive would have been unlikely at that period. C.The influence of Olav Trygvasson did not spread to Sweden. D.Monks would have been unlikely to learn of such an island.

The correct answer is B. A.Remote, inaccessible locations are described throughout the passage as attractive to religious pilgrims. These communities, by definition, were not meant to be hospitable to large numbers of pilgrims. B.This is a Social Science passage that falls within the content category "History." This is a Reasoning Beyond the Text question, as it describes a scenario not discussed in the passage and asks you to apply passage information to that scenario. The answer is B because the passage says that the eremitical movement flourished "until the fourteenth century." After that, "all across Europe, the . . . oratories of hermits were superseded by . . . urban cathedrals" (final paragraph). So the scenario described in the question would be surprising because it would be anachronistic. C.The passage does not suggest that Trygvasson's influence was necessary to establish a monastery or the impulse towards a remote religious settlement. The passage simply says that his conversion ended the attacks on Skellig Michael by Vikings. D.Again, the passage describes remote locations as deeply attractive to monks, mentioning the "many monastic communities on the wilder coasts of Europe" (paragraph 3). *I completely missed the aspect of the passage that would have answered this question*

A visitor to Skellig Michael who kissed its stone cross probably did so for which of the following reasons? A.To fulfill a qualification for sainthood B.To atone for wrongs committed C.To be spared by Viking marauders D.To be accepted into the monastery

The correct answer is B. A.This is not supported by the passage. B.This is a Foundations of Comprehension question because it asks you to understand the implied meaning in a passage claim. B is the answer because the passage describes "penitents . . . [who] made the grueling . . . climb to the Needle's Eye" (final paragraph), a climb which culminated in kissing the stone cross. Because the passage refers to "penitents," it is most likely that these people sought to kiss the cross in an act of atonement. C.The Viking marauders were described as active in the eighth and ninth centuries, while the pilgrims who kissed the stone cross are described as traveling to Skellig Michael in the eighteenth century. D.The monastery was no longer active in the eighteenth century; the first paragraph says that the cliff was inhabited into medieval times. *I overlooked a minute detail in the passage, and I didn't know what penitent meant*

Overexpression of which enzyme is likely to result in increased levels of HIF? A.Succinyl decarboxylase B.Succinyl-CoA synthetase C.Succinate dehydrogenase D.Succinate carboxylase

The correct answer is B. This is a Biochemistry question that falls under the content category "Principles of bioenergetics and fuel molecule metabolism." The answer to this question is B because the passage states that succinate modulates the level of HIF by inhibiting HIF hydroxylase, an enzyme that induces HIF degradation. Thus, overexpression of succinyl-CoA synthetase, which results in the increased production of succinate, will enhance HIF levels. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of enzymes and their products in metabolic pathways. *I did not know which enzyme in the Krebs cycle was responsible for producing succinate*

Which component of the electron transport chain is defective in cells from an SDH-linked paraganglioma tumor? A.Complex I B.Complex II C.Complex III D.Complex IV

The correct answer is B. This is a Biochemistry question that falls under the content category "Principles of bioenergetics and fuel molecule metabolism." The answer to this question is B because the passage states that the paraganglioma tumor is associated with loss of function of succinate dehydrogenase, which is also known as Complex II, in the electron transport chain. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of enzymes involved in metabolic pathways. *Despite getting this right, I did not know that Complex II was also known as succinate dehydrogenase*

Which statement about the unfolding cooperativity and pK of the oligonucleotides is consistent with the data in Figure 1? A.The oligonucleotide with the highest pK displays the highest unfolding cooperativity. B.The oligonucleotide with the lowest pK displays the highest unfolding cooperativity. C.The oligonucleotide with the second highest pK displays the highest unfolding cooperativity. D.The oligonucleotide with the second highest pK displays the lowest unfolding cooperativity.

The correct answer is B. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is B because the pK is the pH at which the fraction of folded DNA is 0.5. This occurs at the lowest value in 5hmC-WT. Cooperativity is measured as the slope of the unfolding transition. This is also highest in 5hmC-WT. It is a Data-based and Statistical Reasoning question because it requires interpreting graphical data in order to draw scientific conclusions. *I looked at the wrong portion of the graph to determine my answer*

A transient shortage of oxygen (global ischemia) releases excess glutamate into the extracellular fluid of the brain. This causes neuronal death by hyperexcitation to a greater extent in the hippocampus than in the cortex. Which reason best explains why the hippocampus is selectively vulnerable during global ischemia? A.The magnitude of action potentials is greater in hippocampal than cortical neurons. B.The expression of NMDA receptors is more abundant in hippocampal than cortical neurons. C.Hippocampal neurons generate a more negative postsynaptic potential than cortical neurons. D.Hippocampal synapses have faster neurotransmitter diffusion rates compared to cortical synapses.

The correct answer is B. This is a Biology question that falls under the content category "Individual influences on behavior." The answer to this question is B because NMDA receptors are a subtype of glutamate receptor. Higher expression of NDMA receptors in the hippocampus than the cortex would render the hippocampus more vulnerable to the excess release of extracellular glutamate. It is a Scientific Reasoning and Problem Solving question because it requires evaluation of the scientific processes that result in a particular outcome. *I did not know that NMDA receptors were a sub type of glutamate receptors*

NPY amplified pituitary responses to GnRH by: A.27%. B.48%. C.67%. D.83%.

The correct answer is B. This is a Biology question that falls under the content category "Structure and functions of the nervous and endocrine systems and ways in which these systems coordinate the organ systems." The answer to this question is B. From Table 1, GnRH + NPY = 7.03 and GnRH alone = 4.74. 7.03 / 4.74 = 1.48, so NPY amplified pituitary responses to GnRH by 48%. This is a Data-based and Statistical Reasoning question because you must determine the percentage increase in LH levels from the data presented in Table 1. *I performed a miscalculation*

The Cgr1 and Cgr2 proteins are produced from: A.separate mRNAs transcribed from different promoter sequences upstream of each gene. B.a single mRNA transcribed from a single promoter sequence upstream of the operon. C.a single RNA transcribed from a single promoter sequence and alternately spliced to produce separate mRNAs. D.separate mRNAs translated from a single promoter upstream of the operon.

The correct answer is B. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is B because an operon containing two genes in prokaryotic cells is transcribed from a single promoter upstream of the first gene in the operon. It is a Scientific Reasoning and Problem Solving question because it requires scientific evaluation of the process that produces the Cgr1 and Cgr2 proteins. *I did not know that operons containing two genes transcribes the genes on a single mRNA molecule*

HDACs change chromatin by: A.decreasing its coiling and promoting DNA replication. B.increasing its condensation and inhibiting transcription. C.decreasing charge repulsion between acetyl groups, which increases transcription. D.loosening the attachment of DNA to nucleosome core particles.

The correct answer is B. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is B because the passage states that HDACs counter the effects of histone acetyltransferases (HATs). As histone acetylation typically promotes transcription by modifying chromatin structure, HDACs would inhibit transcription by condensing chromatin structure. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of how transcription can be altered by histone and chromatin modification. *I did not know what histone acetylation did to chromatin structure in order to make an inference*

Consider the reaction shown in Equation 1 at equilibrium. Would the concentration of [Cu(NH3)4]2+ increase if the equilibrium were disturbed by adding hydrochloric acid? A.Yes, because the equilibrium in Equation 1 would shift to the left B.No, because the equilibrium in Equation 1 would shift to the left C.Yes, because the equilibrium in Equation 1 would shift to the right D.No, because the equilibrium in Equation 1 would shift to the right

The correct answer is B. This is a General Chemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is B. Hydrochloric acid will protonate ammonia in a Brönsted acid-base reaction and reduce the amount of ammonia present. The disturbed equilibrium responds in a way to restore ammonia, but this causes the amount of [Cu(H2O)2(NH3)2]2+ to decrease. This means that the equilibrium shifts to the left. It is a Scientific Reasoning and Problem Solving question because you must use Le Châtelier's principle as well as the behavior of acids and bases to draw a conclusion about the effect of adding hydrochloric acid to a reaction. *I neglected the fact that ammonia is a stronger base than water*

A patient puts on a mask with lateral openings and inhales oxygen from a tank as shown. What phenomenon causes static air to be drawn into the mask when oxygen flows? A.Doppler effect B.Venturi effect C.Diffusion D.Dispersion

The correct answer is B. This is a Physics question that falls under the content category "Importance of fluids for the circulation of blood, gas movement, and gas exchange." The answer to this question is B because oxygen pressure is the sum of the oxygen static pressure P and the oxygen flow pressure ρv2/2. In the area of the mask openings, Pair = P + ρv2/2, thus Pair > P. Air enters the mask because the static pressure of the air is larger than the static pressure of the oxygen in flow. This is the Venturi effect, and the mask is called the Venturi mask. It is a Knowledge of Scientific Concepts and Principles question because the question requires recognizing correct scientific principles. *I did not know what the Venturi effect was*

Every time a volunteer in a sleep study begins to exhibit rapid eye movements (REM), the experimenter wakes the person up. On the following night, when his or her sleep is uninterrupted, the person will most likely: A.have difficulty falling asleep. B.have more REM sleep than usual. C.have less REM sleep than usual. D.have the same sleep pattern as before the study.

The correct answer is B. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is B because after being REM-deprived the night before, the volunteer is going to exhibit "REM rebound." It is a Scientific Reasoning and Problem Solving question because the question involves making a prediction based on your understanding of phenomena related to sleep and the information provided in the question. *Despite getting this correct, it was based primarily on an inference as I was unfamiliar with the concept of REM rebound prior*

Which type of psychoactive drug has the lowest risk of dependence? A.Stimulants B.Hallucinogens C.Alcohol D.Sedatives

The correct answer is B. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is B. Hallucinogens have low risk of dependence, whereas the other substances listed as possible answers carry a moderate to high risk of physical or psychological dependence (the question does not require making a distinction between either). It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of the relative risks of various substances for of physical or psychological dependence. *I straight up did not know this lol*

In order to balance on one foot, many people need to have their eyes open. This is an example of: A.motion parallax. B.sensory interaction. C.vestibular sense. D.perceptual maladaptation.

The correct answer is B. This is a Psychology question that falls under the content category "Sensing the environment." The answer to this question is B because sensory interaction is the idea that one sensory modality (e.g., vision) may influence another (e.g., balance). It is a Knowledge of Scientific Concepts and Principles question because the question involves understanding of a basic concept from behavioral science. *I had no idea what any of these were*

Which set of images would be LEAST likely preferred by 6- to 7-month-old infants in Study 2? A. X O ________________________ X O | X O | X O | B. XXXXXXXXXX ________________________ OOOOOOOO ________________________ C. XXXXXXXXXX | | OOOOOOOO | | | | | | D. X O \ \ X O \ \ X O \ \ X O \ \

The correct answer is B. This is a Psychology question that falls under the content category "Sensing the environment." The answer to this question is B. Six- to seven-month-old infants had a preference for novel perceptual stimuli, and the display in B shows rows or bars in the test phase that are similar to the rows of Xs and Os in the familiarity phase of Study 1. It is a Scientific Reasoning and Problem Solving question because it requires you to apply previous research findings to predict the outcome of a specific situation. *I made a stupid mistake and ignored the LEAST*

The predictive models described in the final paragraph of the passage are most likely based on which assumption? A.Some psychosocial stressors will be perceived as out-group socialization. B.Exposure to some psychosocial stressors will be attributed to social identity. C.The health consequences of some behaviors will affect identity formation. D.The socioeconomic gradient in health will affect some minority groups.

The correct answer is B. This is a Sociology question that falls under the content category "Self-identity." The answer to this question is B because the passage describes the predictions of minority stress theoretical models, which suggest that the stressors of prejudice and discrimination will contribute to elevated levels of alcohol consumption among racial/ethnic minority group members. The question asks for an assumption that underlies this prediction. The link between prejudice, discrimination, and health rests, at least partly, on the assumption that individuals will attribute stressful experiences to their status as members of a racial/ethnic group (in other words, stressors will be linked to their social identity). It is a Scientific Reasoning and Problem Solving question because the question involves determining an assumption that underlies a prediction. *This question was just tough, but I somehow got it right. I think it must include the elements of prejudice and discrimination in order to link the correct order of determination, but I honestly am not 100% sure*

In response to the findings of this study, a religious leader sets up a website to attract young people to his or her congregation. Which sociological application of the findings best describes the leader's response? A.By creating a webpage for the congregation, the religious leader has demonstrated the increased secularization of religion. B.There are cohort differences that impact individual behavior, and by responding to those differences, the religious leader may be able to attract young people. C.The religious leader has identified the importance of period effects, such as the use of technology, in everyday life. D.Technology and religious institutions are both important to the functioning of society, and the religious leader is reinforcing this idea.

The correct answer is B. This is a Sociology question that falls under the content category "Social interactions." The answer to this question is B because different generational cohorts will have distinct life experiences based on their place in history. One example of a generational difference is patterns of internet usage. If the religious leader is trying to attract young people to the congregation, he or she would want to be aware of generational differences, and use them to craft messages (with a website, for example). It is a Scientific Reasoning and Problem Solving question because the question involves applying a solution in response to a research finding. *My answer was incorrect because it is a little off topic and doesn't completely answer the question. B is a better answer because it is more directly associated with the cause for the religious leader's actions*

A researcher conducts observational research on the study habits of college students. When students are aware of the researcher's presence, they are more attentive, focused, and structured. When students are not aware of the researcher's presence, they are inattentive, unfocused, and distracted. Which concept best describes this phenomenon? A.Impression management B.The Hawthorne effect C.Self-fulfilling prophecy D.The Thomas theorem

The correct answer is B. This is a Sociology question that falls under the content category "Social interactions." The answer to this question is B. The Hawthorne effect describes changes in research participants as a result of their awareness that they are being observed. The changes to the students' study habits are best explained by the Hawthorne effect, which was first observed among workers. The incorrect options refer to related but distinct concepts. A self-fulfilling prophecy is an individual's internalization of a label that leads to a fulfillment of that label. Impression management refers to individuals actively managing how they are perceived by others. The Thomas theorem states that if an individual believes something to be real, then it is real in its consequences. This question involves Scientific Reasoning and Problem Solving because it requires selecting the concept that best explains the research scenario in the question. *I did not know what the Hawthorne effect was*

Absorption of ultraviolet light by organic molecules always results in what process? A.Bond breaking B.Excitation of bound electrons C.Vibration of atoms in polar bonds D.Ejection of bound electrons

The correct answer is B. This is an Organic Chemistry question that falls under the content category "How light and sound interact with matter." The answer to this question is B. The absorption of ultraviolet light by organic molecules always results in electronic excitation. Bond breaking can subsequently result, as can ionization or bond vibration, but none of these processes are guaranteed to result from the absorption of ultraviolet light. It is a Knowledge of Scientific Concepts and Principles question because you must recognize a correct scientific principle. *I actually got this correct, but this was due to luck as I did not know this*

Why does the author most likely mention Norway? A.To provide an exemplar of clinical practice B.To provide an exemplar of evidence-based medicine C.To provide an example of accounting for economics D.To provide an example of one drug being less effective than it seems

The correct answer is C. A.The Norwegian example does not mention clinical practice. B.The author invokes the example of Norway as an example of an aspect of patient care that evidence-based medicine "does not account for," not as an instance of evidence-based medicine. C.This is a Reasoning Within the Text question because it asks you to understand how the author uses a particular piece of evidence—to identify the argumentative point that the evidence serves. The answer to this question is C because after discussing the advantages of evidence-based medicine, the author writes of evidence based medicine: "This approach does not, however, account for other aspects of patient care, such as patient preferences, economics, and ethical issues. Norway, for instance, is discouraging the use of the osteoporotic agent alendronate; although the drug decreases hip fractures, ninety high-risk women would have to be treated with the drug for three years to prevent one hip fracture at a cost that could bankrupt the country's medical plan" (final paragraph). The emphasis on the cost of a particular treatment is, of course, a reference to economic factors in health-care decision-making. D.The Norwegian example does not involve a comparison of two different drugs. It only discusses one drug—and it is not the effectiveness of this drug that is at issue but its cost. *I ignored the portion of the passage that this sentence was supporting and isolated it*

The number of monks who resided on Skellig Michael was probably due to: A.insufficient food and water in the monastery. B.extreme difficulty in reaching the monastery. C.limited available living space on the site. D.buildings that were precariously situated.

The correct answer is C. A.There is nothing in the passage that indicates this. B.Although the monastery is difficult to access, this would not necessarily limit the number of people who were able to reach it. C.This is a Foundations of Comprehension question because it tests your understanding of basic elements of the passage. C is the answer because the passage makes clear that the monastery had little available living space. After describing the elevated "monastic enclosure," the author writes: "Most of the rock is too steep for human habitation. At no time could the little cluster of cells have sheltered more than a dozen monks" (paragraph 3). D.It is specifically the climb to the Needle's Eye that is described as precarious. The buildings are described as built on a narrow shelf of sandstone, but it is not the way the buildings are situated that itself limits the number of inhabitants; it is the available amount of living space. *I made a personal assumption rather than utilizing the passage's explicit statements*

The most likely function of the ebulliator is to: A.keep the condensed vapors cool in the receiving flask. B.promote the establishment of a high vacuum in the system. C.prevent superheating of the liquid to be distilled. D.provide an outlet when the pressure inside the system becomes too high.

The correct answer is C. The passage mentions that the ebulliator was added to introduce small air bubbles into the system. This is the same function provided by a boiling chip at atmospheric pressure. The air bubbles break the surface tension of the liquid being heated and prevent superheating and bumping. Thus, answer choice C is the best answer. *I still failed to identify the function of both ebulliators and boiling chips*

The ion responsible for the color of the solutions is: A.sulfate, because sulfur has s and p orbitals. B.nickel(II), because it has a charge of +2. C.nickel(II), because it has unfilled d orbitals. D.sulfate, because it is a resonance-stabilized anion.

The correct answer is C. The solution containing nickel(II) ions is green-colored. The color arises because nickel(II) ion has partially filled d orbitals and the electrons in the lower energy d orbitals absorb visible light to move to the higher energy d orbitals. Thus, C is the best answer. *I assumed that s electrons would move to the lower energy d orbitals, but I forgot that this movement of electrons leads to either emission or absorption of visible light*

What event will most likely occur if Protein X is inserted into the inner membrane of mitochondria? A.The citric acid cycle will cease to function. B.The electron transport chain will cease to function. C.The proton gradient across the inner membrane will dissipate. D.The pH of the intermembrane space will decrease.

The correct answer is C. This is a Biochemistry question that falls under the content category "Principles of bioenergetics and fuel molecule metabolism." The answer to this question is C because based on information from the passage, Protein X forms membrane-spanning channels that alter the permeability of the inner membrane, thereby dissipating the proton gradient across the inner membrane. It is a Knowledge of Scientific Concepts and Principles question because it requires the knowledge of proton motive force across the inner mitochondrial membrane. *I was thinking too general, and failed to identify the direct effect of what the question was asking*

In designing the experiment, the researchers used which type of 32P labeled ATP? A.α32P-ATP B.β32P-ATP C.γ32P-ATP D.δ32P-ATP

The correct answer is C. This is a Biochemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is C because the phosphoryl transfer from kinases comes from the γ-phosphate of ATP. Therefore, the experiment should require γ32P-ATP. It is a Reasoning about the Design and Execution of Research question because you must determine the correct way of conducting an experiment to test the desired hypothesis. *I did not know this information about kinases*

What causes duplex DNA with a certain (A + T):(G + C) ratio to melt at a higher temperature than comparable length duplex DNA with a greater (A + T):(G + C) ratio? A.Stronger van der Waals forces of pyrimidines B.Stronger van der Waals forces of purines C.Increased π- stacking strength D.Reduced electrostatic repulsion of phosphates

The correct answer is C. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is C. G-C base pairs form stronger π-stacking interactions than A-T base pairs, thereby creating the most thermal stability. This disparity has often been used to explain the increased melting temperature of DNA rich in GC content. It is a Knowledge of Scientific Concepts and Principles question because you must identify the relationship between DNA melting temperature and the number of hydrogen bonds. *This was the answer I picked at first, but shyed away from for no sound reason*

One consequence of advanced malnutrition is reduced amounts of plasma proteins in the blood. This condition would most likely cause the osmotic pressure of the blood to: A.decrease, resulting in a decrease of fluid in the body tissues. B.increase, resulting in a decrease of fluid in the body tissues. C.decrease, resulting in an increase of fluid in the body tissues. D.increase, resulting in an increase of fluid in the body tissues.

The correct answer is C. This is a Biology question that falls under the content category "Assemblies of molecules, cells, and groups of cells within single cellular and multicellular organisms." The answer to this question is C because large plasma proteins, such as albumin, in the blood increase the osmotic pressure of the blood, which in turn, increases the return of fluid to the circulatory system from the body tissues. Therefore, with malnutrition, the osmotic pressure of the blood would decrease resulting in an increase of fluid in the body tissues. It is a Scientific Reasoning and Problem Solving question because it involves prediction of the outcome of a scientific scenario. *I dont know why but these questions tripped me up big time, but now I know*

Individual M has longer limbs and muscles than Individual N. Both individuals lift the same amount of weight from the ground to their shoulders an equal number of times. If all repetitions were completed in synchrony, which statement about the amount of work completed by the individuals is true? At the end of the workout: A.both individuals will have done the same amount of work because the force was applied for the same duration of time. B.Individual M will have done less work because the object was moved a greater distance. C.Individual N will have done less work because the object was moved a shorter distance. D.Individual M will have done more work because the muscle contracted faster to achieve synchrony with Individual N.

The correct answer is C. This is a Biology question that falls under the content category "Structure and integrative functions of the main organ systems." The answer to this question is C because work is equal to the product of the force applied to an object and the distance over which the distance is moved. Individual N has shorter limbs (and likely a shorter ground to shoulder distance), thus this individual will perform less work because the muscles contracted a shorter distance, and the object was moved a shorter distance. A is incorrect because the stem indicates that Individual M has longer limbs than does Individual N. Given this, Individual M will have done more work than Individual N because the distance the muscles contracted when moving the load from ground to shoulder (also a greater distance for Individual M) is greater. B is incorrect because work is equal to the product of the force applied to an object and the distance over which the distance is moved. Thus, moving an object a longer distance would result in more, not less, work being done. D is incorrect because while it is true that Individual M did more work, work is not dependent on speed, and thus, the rate of muscle contraction is not relevant to the amount of work done by the individuals. It is a Scientific Reasoning and Problem Solving question because it requires comparing the physiological form and function of two individuals. *This was just a stupid mistake because I knew that the individual with longer muscles did more work*

Based on the passage, β-catenin most likely has: A.multiple subunits. B.very few disulfide bonds. C.a nuclear localization sequence. D.a high proportion of surface-exposed nonpolar residues.

The correct answer is C. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is C because according to Figure 1, β-catenin activates transcription factors for Wnt target genes. As transcription factors are found in the nucleus, β-catenin must enter the nucleus. Proteins that are translocated into the nucleus usually contain a nuclear localization sequence. It is a Scientific Reasoning and Problem Solving question because it requires you to bring together assumed knowledge and passage-based observations to make a conclusion. *I did not know what a nuclear localization sequence was, and therefore took a guess*

Which single bond present in nitroglycerin is the LEAST polar? A.C-H B.C-O C.C-C D.O-N

The correct answer is C. This is a General Chemistry question that falls under the content category "Nature of molecules and intermolecular interactions." The answer to this question is C because bonds between identical atoms are likely to be the least polar. This is true in this case since each C atom is bonded to one nitro group only. It is a Scientific Reasoning and Problem Solving question because you must use the theories of covalent bonding and electronegativity to predict the relative polarity of bonds within a molecule. *This was just a stupid mistake*

The pH of a 1 L phosphate buffer solution was measured as 7.6, but the experimental procedure calls for a pH 7.2 buffer. Which method will adjust the solution to the proper pH? (Note: The pKa values for phosphoric acid are 2.2, 7.2, and 12.3.) A.Add enough 1 M Na2HPO3 to increase the phosphate anion concentration ten-fold. B.Add 1 M NaOH to neutralize a portion of the hydronium ions found in the solution. C.Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species. D.Add 100 mL distilled, deionized water to dilute the basicity of the buffer.

The correct answer is C. This is a General Chemistry question that falls under the content category "Unique nature of water and its solutions." The answer to this question is C because, in order to lower the pH of a buffer, the proportion of acidic buffer component must be increased. Adding strong base, diluting with water, or adding a different basic salt will not lower the pH. It is a Reasoning about the Design and Execution of Research question because you reason about the appropriateness of a specific experimental change in order to conduct research in the natural sciences. *Despite getting this right, my answer was based primarily on a guess*

What is the approximate percentage of a 10C sample left after the time it took a 75-year-old male to walk one lap around the gym? (Note: The half-life of 10C is 20 seconds.) A.5% B.10% C.25% D.75%

The correct answer is C. This is a Physics question that falls under the content category "Atoms, nuclear decay, electronic structure, and atomic chemical behavior." The answer to this question is C because the 75-year-old person takes 200 s to walk 5 laps, which is on average 40 s per lap. This time represents two half-lives of 10C, so only 1/(22) = 0.25, or 25% of 10C is left. It is a Scientific Reasoning and Problem Solving question because the question requires determining and using scientific formulas to solve problems. *Had to gues due to lack of time*

What is the resistivity of the best-performing PANI described in the passage? A.0.002 Ω•cm B.50 Ω•cm C.200 Ω•cm D.500 Ω•cm

The correct answer is C. This is a Physics question that falls under the content category "Electrochemistry and electrical circuits and their elements." The answer to this question is C because resistivity is the inverse of the conductivity, which is 1/5.0 × 10-3 (Ω∙cm)-1 = 200 Ω∙cm. It is a Scientific Reasoning and Problem Solving question because it asks you to determine and use scientific formulas to solve problems. *I got this right, but this was entirely a lucky guess*

A tall tube is evacuated, and its stopcock closed. The open end of the tube is immersed into a container of water (density 103 kg/m3) that is open to the atmosphere (pressure 105 N/m2). When the stopcock is opened, how far up the tube will the water rise? A.1 m B.5 m C.10 m D.20 m

The correct answer is C. This is a Physics question that falls under the content category "Importance of fluids for the circulation of blood, gas movement, and gas exchange." The answer to this question is C because the water will rise to a height such that the weight (mass multiplied by gravitational acceleration) of the water column equals the atmospheric pressure multiplied by the tube cross-sectional area A. Because mass is density times volume, it follows that 103 kg/m3 × h × A × 10 m/s2 = 105 N/m2 × A, where h is the height sought. Solving for h yields h = 105 N/m2/(104 N/m3) = 10 m. It is a Scientific Reasoning and Problem Solving question because it asks you to determine and use scientific formulas to solve problems. *Despite getting this right, this was primarily an educated guess and I couldn't derive the equation quickly

Which component of attitudes is assessed by the study's online questionnaire? A.Affective B.Behavioral C.Cognitive D.Subconscious

The correct answer is C. This is a Psychology question that falls under the content category "Individual influences on behavior." The answer to this question is C. The questionnaire is described as assessing participants' ideas about how people gain weight, as well as their beliefs about the relative contribution of genetics, personality, and environment in gaining, maintaining, and losing weight. This description identifies beliefs and ideas, which are part of the cognitive component of an attitude. The other possible answers are other components that are not relevant to the description of the questionnaire (which measured explicit attitudes). It is a Knowledge of Scientific Concepts and Principles question because it requires recognition of examples of one component of a person's attitude toward some attitude object. *Despite getting this right, it was primarily based upon an educated guess as I did not know the different components of attitude*

A dopamine agonist is found to have dose-dependent effects. Based on this finding, which correlation is most likely to be supported? A.A positive correlation between the dose of the dopamine agonist and the duration of the visual hallucinations that occur when the dopamine agonist is administered B.A negative correlation between the dose of the dopamine agonist and the duration of the visual hallucinations that occur when the dopamine agonist is administered C.A positive correlation between the dose of the dopamine agonist and the intensity of euphoria experienced when the dopamine agonist is administered D.A negative correlation between the dose of the dopamine agonist and the intensity of euphoria experienced when the dopamine agonist is administered

The correct answer is C. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is C. A dopamine agonist enhances the functioning of dopamine in the nervous system. Because the agonist is said to have dose-dependent effects, a positive correlation between the dose and the intensity of euphoria experienced is most likely. It is a Data-based and Statistical Reasoning question because it requires you to determine the sort of association that exists between these two variables. *Confused the word 'agonist' with 'antagonist'*

A researcher criticizes the methods used in the study, stating that teachers' ratings may not be a valid way of assessing the students' emotional problems. Which hypothetical finding is most likely to reduce this concern? A.A positive correlation between the number of emotional problems observed in students and the number of classmates reading below grade level B.A negative correlation between the number of emotional problems observed in students and the number of disruptions experienced by the teacher per day C.A positive correlation between the teachers' ratings of the number of emotional problems observed in students and the parents' rating of the same variable D.A negative correlation between the teachers' ratings of the number of emotional problems observed in students at two different times

The correct answer is C. This is a Psychology question that falls under the content category "Responding to the world." The answer to this question is C because when two independent measures of the same variable converge, it supports the validity of both measures. It is a Reasoning about the Design and Execution of Research question because the question involves determining how additional information can be used to judge the validity of specific measures of the variables (teachers' ratings of children's behavioral and emotional problems). *I made a stupid mistake and misread the question as determining a finding to reinforce this concern*

Based on the findings in Study 2, which strategy for decision-making groups would be most likely to prevent groupthink? A.Make certain that all decision-making groups are made up of groups of friends. B.Whenever possible, avoid the selection of a group leader through popular vote. C.Encourage a group norm of critical evaluation and dissent in decision-making. D.Require decision-making groups to verify that groupthink did not influence their decision.

The correct answer is C. This is a Psychology question that falls under the content category "Social processes that influence human behavior." The answer to this question is C. Those in the social identity condition exhibited more groupthink symptoms than those in the interpersonal condition. They make more rationalizations, introduce fewer facts, and discuss risks less frequently. Pressures to reach consensus and stifle dissent are key to groupthink, and thus a group norm that encouraged dissent and critical evaluation would address the central problem of groupthink. It is a Scientific Reasoning and Problem Solving question because it requires you to extend basic research findings to infer a potential solution to a novel applied problem. *I went with an extreme and irrational answer despite my reservations*

What is the general structure of a hydroxamic acid? A. B. C. D.

The correct answer is C. This is an Organic Chemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is C because a hydroxamic acid was described in the passage as resulting from the acetylation (attachment of RC=O) of the hydroxylamine nitrogen (NHOH) in Compound 2. Only Response C fits this description. It is a Scientific Reasoning and Problem Solving question because the concepts of acetylation and hydroxylamine structure must be combined to ascertain the correct answer. *Despite getting this right, I was unsure of the answer choice I selected and primarily used reasoning to find the right answer*

What is the net charge of sT-loop at pH 7.2? A.-2 B.-1 C.0 D.+1

The correct answer is C. This is an Organic Chemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is C because at pH 7.2, the N-terminus will be positively charged and the C-terminus will be negatively charged. In addition, the lysine side chain will carry one positive charge and the glutamic acid side chain will carry one negative charge. It is a Scientific Reasoning and Problem Solving question because you must calculate a value based on the scientific principle of amino acid charge to solve the problem. *I made an incorrect assumption about amino acid deprotonation*

The purpose of Experiment 2 was to: A.be certain that the supportive observer was truly supportive. B.isolate the reason for adopting a cautious performance style. C.test the effect of an incentive to improve one's performance. D.determine the relevance of friendship to the audience effect.

The correct answer is D. A.The "true" supportiveness of the observer is never at issue in the experiment; rather, the participants believe that the supportiveness of the observers varies, based on whether or not the observers stand to benefit from the participants' performance. B.There is nothing in the description of Experiment 2 to support this. C.In both conditions, the performer had an incentive to perform well; what differed was whether the participant believed that the observer would benefit from a strong performance. D.This is a Foundations of Comprehension item because it tests your ability to understand the connections between the author's points; the author first describes a problem with Experiment 1 and then a design for Experiment 2 that addresses this problem. The answer to this question is D because in Experiment 1, all of the supportive audience members were friends. The author writes, "the reason for this effect [of the supportive audience] was unclear . . . Friends and strangers differ in many ways" (paragraph 5). In Experiment 2, all of the audience members were strangers, and some of them were in the supportive condition. This experimental design makes it possible to test the effects of a supportive audience, independent of the role of friends. *I overlooked the primary focus of experiment 2 and went too narrow on my assumption*

Which experimental condition is NOT necessary to achieve reliable data for Michaelis-Menten enzyme kinetics? A.Initial velocity is measured under steady state conditions. B.Solution pH remains constant at all substrate concentrations. C.The concentration of enzyme is lower than that of substrate. D.The reaction is allowed to reach equilibrium before measurements are taken.

The correct answer is D. This is a Biochemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is D because once the reaction reaches equilibrium, measurement of Vo will be impossible and the kinetic data will look the same regardless of substrate concentration. Hence, response D is not necessary (nor desirable) to achieve reliable data for Michaelis−Menten enzyme kinetics. In contrast, Distractors A−C are essential to obtain reliable Vo versus substrate concentration data to calculate KM and Vmax using Michaelis−Menten enzyme kinetics. It is a Reasoning about the Design and Execution of Research question because the question probes the experimental conditions required to obtain reliable data. *I genuinely did not know this and tried my best to take an educated guess*

Based on the data from Table 1, what effects do acid and chloride have on the enzymatic activity of laccases? A.Both acid and chloride decrease the activity. B.Both acid and chloride increase the activity. C.Acid decreases the activity, whereas chloride increases the activity. D.Acid increases the activity, whereas chloride decreases the activity.

The correct answer is D. This is a Biochemistry question that falls under the content category "Principles of chemical thermodynamics and kinetics." The answer to this question is D. Activity increased at lower pH, which corresponds to a higher acidity of the solution, while introduction of chloride lowered activity dramatically. It is a Data-based and Statistical Reasoning question because you must use data to explain the relationship between activity and either acidity or chloride ion concentration. *I did not read the table carefully enough, and made a stupid mistake*

When used in place of spHM, which peptide would be most likely to achieve the same experimental results? A.FLGFAY B.FLGFQY C.FLGFGY D.FLGFEY

The correct answer is D. This is a Biochemistry question that falls under the content category "Structure, function, and reactivity of biologically-relevant molecules." The answer to this question is D because the phosphorylated threonine would most likely be mimicked by glutamic acid in terms of size and charge. It is a Reasoning about the Design and Execution of Research question because you must reason about how a change in the experiment design would affect the outcome of the experiment. *I made an incorrect association about what the question was asking for and I did not think the question through enough*

In the experiment with wild-type rats, each press of the lever delivered 0.1 mL ethanol. Which figure shows the expected effect of R121919 treatment on the number of lever presses of dependent rats versus nondependent rats after vapor exposure ceased?

The correct answer is D. This is a Biology question that falls under the content category "Individual influences on behavior." The answer to this question is D because this graphic shows that the CRF1 antagonist R121919 reduced the number of lever presses in the ethanol dependent rats. Nondependent rats showed an equal number of lever presses in both groups, which is expected because they were also trained to self-administer ethanol, but did not become ethanol dependent. It is a Data-based and Statistical Reasoning question because the question involves interpreting results from data presented in figures. *This was also challenging primarily because I wasn't too clear on the role of R121919 or CRF1, but somehow got the correct answer*

Assume that S. typhi immediately enters the bloodstream from the small intestine. Of the following, which would be the first major organ that bloodborne S. typhi would encounter? A.Stomach B.Pancreas C.Large intestine D.Liver

The correct answer is D. This is a Biology question that falls under the content category "Structure and integrative functions of the main organ system." The answer to this question is D because blood from the small intestine is transported first to the liver, which regulates nutrient distribution and removes toxins from the blood. It is a Knowledge of Scientific Concepts and Principles question because it requires knowledge of how organ systems function in the body and their relationship to one another. *Despite getting this right, I wasn't completely sure, and primarily guessed*

Which type(s) of restriction enzyme(s) can recognize the HIF binding sequence? A restriction enzyme that has: I.a four-base recognition sequence II.a six-base recognition sequence III.an eight-base recognition sequence A.I only B.II only C.III only D.I and II only

The correct answer is D. This is a Biology question that falls under the content category "Transmission of genetic information from the gene to the protein." The answer to this question is D because only the CCCGGG within the HIF binding sequence is palindromic. Therefore, only a restriction enzyme that recognizes a four-base sequence or a six-base sequence can recognize this sequence within the HIF binding sequence. It is a Reasoning about the Design and Execution of Research question because it requires reasoning about use of restriction enzymes in research. *I did not know that restriction enzymes aim to recognize palindromic sequences*

Which of the following best describes the phenotype of an individual who is heterozygous with one ΔF508 and one wild-type CFTR allele? A.More susceptible to typhoid fever than wild-type homozygotes and has CF B.More susceptible to typhoid fever than ΔF508 homozygotes and does not have CF C.More resistant to typhoid fever than ΔF508 homozygotes and has CF D.More resistant to typhoid fever than wild-type homozygotes and does not have CF

The correct answer is D. This is a Biology question that falls under the content category "Transmission of heritable information from generation to generation and the processes that increase genetic diversity." The answer to this question is D because the passage states that individuals homozygous for the ΔF508 allele have CF. Therefore, an individual who is heterozygous for the ΔF508 allele does not have CF. However, this individual is more resistant to typhoid fever because the passage states that human epithelial cells expressing ΔF508 ingest significantly fewer S. typhi than do epithelial cells that express wild-type CFTR. It is a Scientific Reasoning and Problem Solving question because it requires you to predict the effect that a particular genotype would have on disease outcomes. *I don't think I had a complete understanding of the passage because I assumed that the allele wasn't expressed unless homozygous*

The lone pair of electrons in ammonia allows the molecule to: A.assume a planar structure. B.act as an oxidizing agent. C.act as a Lewis acid in water. D.act as a Lewis base in water.

The correct answer is D. This is a General Chemistry question that falls under the content category "Nature of molecules and intermolecular interactions." The answer to this question is D because, by definition, a Lewis base is a substance that donates an electron pair in forming a covalent interaction. It is a Knowledge of Scientific Concepts and Principles question because you must identify the relationship between Lewis basicity and the existence of lone pairs of electrons. *I made an incorrect assumption that caused me to not answer the question I was presented*

What kind of image is formed by the lenses of the glasses worn by a 68-year-old male who sees an object 2 m away? A.Real and enlarged B.Real and reduced C.Virtual and enlarged D.Virtual and reduced

The correct answer is D. This is a Physics question that falls under the content category "How light and sound interact with matter." The answer to this question is D because the lenses have a negative focal length which means they are diverging lenses. Such lenses form virtual and reduced images of objects situated at distances larger than the focal length. It is a Knowledge of Scientific Concepts and Principles question because the question requires identifying the relationships among closely related concepts. *Had to guess due to lack of time*

What is the ratio of the minimum sound intensities heard by a 64-year-old male and a 74-year-old female? A.20 B.40 C.50 D.100

The correct answer is D. This is a Physics question that falls under the content category "How light and sound interact with matter." The answer to this question is D because the relative intensities of the two sound waves are 20 dB and 40 dB, respectively. The difference is 20 dB, meaning that the decimal log of the ratio of their intensities is 2, which means that the ratio of their intensities is 100. It is a Scientific Reasoning and Problem Solving question because the question requires determining and using scientific formulas to solve problems. *Another stupid mistake due to being pressed for time, I looked in the 64 age group rather than 74 for females*

The regulation of which neurotransmitter is implicated in the specific finding reported with Study 1? A.Acetylcholine B.GABA C.Endorphins D.Serotonin

The correct answer is D. This is a Psychology question that falls under the content category "Individual influences on behavior." The answer to this question is D because the specific finding from Study 1 states that aggression and oppositional behaviors had the strongest association with the risk of hunger. Serotonin is involved in the regulation of both mood (specifically, aggression) and appetite (it is also used to regulate intestinal movements). The distractors are other neurotransmitters that are not specifically involved in the hunger drive, mood, or aggressive behavior. It is a Knowledge of Scientific Concepts and Principles question because the question involves understanding how different neurotransmitters are involved in motivation, emotion, behavior, etc. *I did not know what endorphins were, and assumed that they were linked to mood*

A patient who is experiencing severe marital problems reports having no memory of any life events surrounding the marriage and the spouse. The patient's memory for other life events is intact. This patient is most likely to be diagnosed with: A.a conversion disorder. B.schizophrenia. C.retrograde amnesia. D.a dissociative disorder.

The correct answer is D. This is a Psychology question that falls under the content category "Individual influences on behavior." The answer to this question is D. The patient is selectively forgetting distracting elements of his/her life, which indicates a dissociative disorder. It is a Knowledge of Scientific Concepts and Principles question because it requires identifying the relationship between the specified symptom and the type of disorder. *I did not attribute this symptom to a dissociative disorder, and I incorrectly defined retrograde amnesia*

Individuals who have the ability to delay gratification in pursuit of long-term rewards are most likely to be categorized as having which type of intelligence? A.Analytical B.Creative C.Interpersonal D.Emotional

The correct answer is D. This is a Psychology question that falls under the content category "Making sense of the environment." The answer to this question is D. Emotional intelligence refers to the ability to perceive, express, understand, and manage one's emotions. Emotionally intelligent people are self-aware and can delay gratification in pursuit of long-term rewards, rather than being overtaken by immediate impulses. None of the other answer choices is related to delaying gratification. It is a Scientific Reasoning and Problem Solving question because it requires you to determine which type of intelligence is characterized by the abilities described in the question. *I did not know the different forms of intelligence*

Which graph best describes the baboon data for the color-matching test?

The correct answer is D. This is a Psychology question that falls under the content category "Sensing the environment." The answer to this question is D, which is the only graph that shows a continuous response pattern. It is a Scientific Reasoning and Problem Solving question because it requires identifying which graph displays the data pattern reported in the passage. *I didn't understand the information the passage was presenting*

At the end of Study 2, the researchers' recommendation suggests that parents in food-insecure households are subject to which role dynamic? A.Role engulfment B.Role confusion C.Role conflict D.Role strain

The correct answer is D. This is a Sociology question that falls under the content category "Social interactions." The answer to this question is D because the relevant statement in the passage refers to how researchers recommended interventions focusing on parents who experience stress from trying to satisfy both their children's needs and their own needs. By identifying tension stemming from the parental role, the recommendation suggests role strain (which refers to stress from different expectations associated with a single role). For parents with depression, the parental role can cause competing obligations of satisfying their children's needs when they are coping with psychological distress (and thus are unable to meet their own needs). It is a Knowledge of Scientific Concepts and Principles question because the question involves recognizing the concept that best illustrates something that is being portrayed in the passage. *I forgot the difference between role conflict and role strain, and also I incorrectly identified the number of roles associated with the parents*

Which statement is NOT consistent with a conflict theoretical analysis of the findings in the passage? A.Religion is an instrument of social control. B.Religion helps to legitimate inequality in society. C.Religion encourages passive acceptance of material conditions. D.Religion helps to increase social solidarity.Which statement is NOT consistent with a conflict theoretical analysis of the findings in the passage?

The correct answer is D. This is a Sociology question that falls under the content category "Understanding social structure." The answer to this question is D because it represents a functionalist understanding of religion, with the reference to social solidarity. The other options each articulate how a conflict theorist, focused on social control and social inequality, would view the role of religion in society. It is a Scientific Reasoning and Problem Solving question because the question involves understanding how different theoretical perspectives would be applied to research findings. *I misread the question and assumed it was looking for a statement that was consistent with a conflict theoretical analysis*