Official Guide to the MCAT Exam

QUESTION 3: Does the release of Ach in skeletal muscle cells, cause depolarization or hyperpolarization? The addition of acetylcholine to the medium most likely induced: a. depolarization of the cell membrane that resulted in contraction. b. repolarization of the cell membrane that resulted in relaxation. c. hyperpolarization of the cell membrane that resulted in contraction. d. depolarization of the cell membrane that resulted in relaxation.

A. because we know ach causes contractions also according to the passage it states that ach caused a cell culture to retain contractile activity for longer than 30 mins. Acetylcholine is released at the neuromuscular junction where it binds to receptors on the muscle cells and, depending on the type of muscle cell, causes depolarization or hyperpolarization of the cell membrane. In skeletal muscles, acetylcholine binds to its receptors, which leads to depolarization of the muscle cell membrane and muscle contraction.

QUESTION 30 A researcher measures the initial rate (V0 = Δ[P]/Δt) of an enzymatically catalyzed reaction at a variety of substrate concentrations [S]0. Which graph best represents the observed relationship between [S]0 versus V0? (GRAPHS ON BACK)

A. got correct For enzymatically catalyzed processes, the reaction rate will level off with increasing concentration of substrate as the enzyme becomes the bottleneck for the reaction. This is called saturation kinetics. b. Unlike first-order processes, increasing the concentration of substrate will not linearly increase the rate. c. Unlike second- or third-order processes, where increasing the substrate concentration can cause a squaring or tripling of the initial rate, enzymatically catalyzed reactions will not show such increases. d. In general, increasing the concentration of a reactant will increase the rate of its reaction.

QUESTION 27 The pressure and volume changes that occur during a cycle of breathing are illustrated graphically in the figure shown. (on back) What does the area within the curve represent? a. Work done b. Oxygen removed c. Lung volume change d. Air pressure change

A. got correct This question requires you to interpret graphically a thermodynamic process and the area it encloses when represented in pressure-volume coordinates. The area under a curve that represents graphically the relationship of two physical variables (one independent and the other dependent) has the physical dimension of the product of the measurement units of the variables. In this case, a thermodynamic process is shown in PV coordinates, hence the area under the curve has the dimensions of [N/m2] · [m3] = [N·m] = [J]. The unit of joule (J) is used for energy and work. b. The quantity of oxygen removed is not measured in units of work or energy. c. Lung volume change is shown on the vertical axis of coordinates. d. Air pressure change is shown on the horizontal axis.

QUESTION 22 At the time of the car accidents, which component of the nervous system of both Person A and Person B was NOT likely to be activated? a. sympathetic nervous system. b. parasympathetic nervous system. c. peripheral nervous system. d. central nervous system.

B. got correct B is correct. The parasympathetic nervous system is an energy conserving (rest-and-digest) system and is not likely to be activated at the time of a stressful event. a. This is incorrect because the sympathetic system activation is involved in the stress response and is likely to be activated at the time of a stressful event. c. This is incorrect because the sympathetic nervous system is a part of the peripheral nervous system, and therefore, the peripheral nervous system will be activated at the time of a stressful event. d. This is incorrect because the reticular activating system (part of the central nervous system) will be activated at the time of a stressful event.

QUESTION 25: Enzymes catalyze chemical reactions by stabilizing: a. the substrate. b. the product. c. the transition state. d. the equilibrium.

C. got it correct Enzymes work by stabilizing the transition state of a chemical reaction, which lowers the activation energy. d. Enzymes do not affect the equilibrium of a reaction.

How to assign priority for absolute configuration

1. Compare the atomic numbers of all atoms directly attached to the stereocenter (The higher atomic number has higher priority) 2. If there is a tie, compare all atoms bound to each and assign priority. Continue until the first difference. 3. For isotopes higher atomic mass is higher priority and for double bonds, count the bound atom twice

QUESTION 4: The terminal electron acceptor in lactic acid fermentation is: a. pyruvate. b. oxygen. c. NAD+. d. water.

A. I chose C but thats wrong bc NADH reduces pyruvate to produce lactate and regenerate NAD+ so glycolysis can continue. You have to know the key difference between fermentation and aerobic respiration for this question. In aerobic respiration, oxygen is an electron acceptor while in fermentation, pyruvate is an electron acceptor to regenerate NAD+, so glycolysis can continue. In this process, NADH reduces pyruvate to produce lactate. Therefore, pyruvate serves as the electron acceptor in production of lactate. Remember, 2 ATP produced in fermentation process per mol of glucose (which occurs when no O2 present in eukaryotes)! In glycolysis, however, 32 ATP is produced per mol of glucose. This is a vast difference.

QUESTION 15 What type of learning is taking place in Study 1? a. Operant conditioning b. Classical conditioning c. Social learning d. Observational learning

A. got correct A is correct. In Study 1, the frequency of pressing the lever increases because it results in the delivery of heroin, which is an example of operant conditioning through positive reinforcement. Operant conditioning is associated with BF. Skinner. Reduce/Increase response based on stimuli. b. This is incorrect because classical conditioning does not involve a change in behavior due to the behavior's outcome. c. This is incorrect because social learning refers to learning through observing a model. d. This is incorrect because observational learning, like social learning, refers to learning through a model.

QUESTION 15 The scientists who developed the experimental protocol described in the passage chose TNBS over many potential candidates to label PE molecules. What characteristics about the rate of reaction between TNBS and outer envelope PE molecules allowed the experiment to provide useful data? The rate of TNBS reaction with outer envelope PE molecules is: a. faster than the rate of exchange between inner and outer envelope PE molecules. b. slower than the rate of phosphate transport across the membrane. c. facilitated by the additional phosphate present in solution. d. easily measured by the method of initial rates.

A. got correct but forgot why Phosphatidylethanolamines are a class of phospholipids found in biological membranes. This might seem self explanatory, but for me it took a google search to understand that PE was the lipids in the membrane. Also for this passage, it's important to remember that it is possible for phospholipids to move between both leaflets of the bilayer in transverse movement, in a "flip-flop" manner. Q15 is an explanation question (i.e., you have to answer "why"). As a first step, we can eliminate D quickly because it's really out of scope -- we have no reason to think the researchers dealt with this at all. Now we have to think more about what the question is asking for. There are two ways to approach explaining this question: the "right" way (i.e., if you really try to understand what they're getting at) and the "good enough" way, which uses shortcuts in situations where you might not completely understand the passage or the question. For the "good enough way", note that the question specifically asks about a characteristic relating to the rate of reaction between outer envelope PE molecules. A is the only answer choice that says something specific about outer envelope PE molecules, so that alone makes it likely to be a better explanation of what the question is asking about than answer choices that just say something super general. (We can definitely eliminate C for this reason - it doesn't mention the membrane at all!). In terms of the "right" way, the idea here is that there is a constant "churn" of PE molecules across the lipid membrane (this is generally the case for lipids in the membrane). TNBS allows us to take a "snapshot" of the conditions at the membrane in a given moment, and to do so, its reaction must take place really fast -- that is, before the "churn" of the membrane components could muddy the picture. Think about taking a picture with a short vs. a long exposure -- if you have a long exposure, you'll get a blurry picture because the position of your subjects has been changing.

QUESTION 1 What stereochemical designation can be assigned to naturally occurring aspartic acid? a. S b. Z c. D d. E

A. got correct but guessed a lil bit Glycine - no chirality, Cysteine - R, rest are S. All naturally occurring amino acids are L configuration. (all sugars are D) in eukaryotes AAMC: The correct stereochemical designation can be made by using either the Fischer projection of Compound 8 (with R = CH2CO2H) or the perspective drawing of Compound 1. For the Fischer projection, the priorities of the remaining three groups are NH2 > CO2H > R. This occurs in a clockwise fashion. Since the H is pointing towards the viewer in this drawing, however, the priorities would reverse to counterclockwise, or S when viewed with H (the lowest priority group) in the back. b. Z - For same side cis double bonds. Not relevant here. Z is used when the largest groups are on the same side of the double bond but are not necessarily the same c. All amino acids are in L configuration, not D d. E - for opposite side large groups on double bonds (trans). Not relevant here. Difference between E/Trans is that E is used when the largest groups are on opposite sides of the double bond and aren't necessarily the same.

QUESTION 10 Which independent variable is most relevant for a study that investigates the possible impact of primary groups on the outcome measure discussed in the passage? a. Family structure b. Religious affiliation c. Occupational status d. Population density

A. got it correct Primary groups include the family. Thus, a variable measuring family structure would be most relevant to assessing the impact of primary groups. b. This is incorrect because religious affiliation can encompass both primary groups and secondary groups. c. This is incorrect because occupational status does not clearly address the distinction between primary and secondary groups. Instead, occupational status is more relevant for social status or social roles. d. This is incorrect because the group distinctions, such as the difference between primary and secondary groups, are conceptually distinct from demographic concepts like population density.

QUESTION 30 Which aspect of equality is considered a requirement in a meritocracy? a. Equality of opportunity b. Equality of talent c. Equality of skill d. Equality of outcome

A. got wrong, chose B did not know definition of meritocracy A meritocracy is when societal rewards, status, and positions are awarded to individuals based on their own ability and work (that is, merit). In order for a meritocracy to operate, everyone within the society would need the same opportunity to succeed, so that rewards are actually based (primarily) on merit. b&C&D. It is not necessary for everyone to have the same talent or skill level or outcome. It just means everyone has the same opportunity to achieve. It means achievement is not prescribed at birth (like in a caste system). It means there is a high degree of mobility.

QUESTION 28: An epitope is a region on the surface of an antigen molecule to which a specific antibody binds. The table shows the physical and biological characteristics of several different molecules. According to the information, which characteristics are most likely to be associated with a molecule's potential to elicit a strong immune response? a. High molecular weight and increased number of epitopes b. High molecular weight and reduced number of epitopes c. Low molecular weight and increased number of epitopes d. Low molecular weight and reduced number of epitopes

A. got it correct but just looked at the table and saw the correlation An epitope binds one specific antibody. Therefore, a molecule with several epitopes will bind several distinct antibody molecules. The presence of several antibodies on the surface of an antigen is expected to elicit a stronger immune response than if fewer antibodies were present. The table shows that molecules with higher molecular weights are associated with higher numbers of epitopes, which will bind a greater number of antibodies. These molecules are therefore expected to elicit a more robust immune response. b. This is incorrect. Molecules with a reduced number of epitopes will bind fewer antibodies, therefore generating less potential for a robust immune response. c. This is incorrect. The table shows that molecules with a low molecular weight do not have an increased number of epitopes. d. This is incorrect. Although from the table a low molecular weight is correlated with a reduced number of epitopes, fewer antibody recognition sites will not generate a robust immune response.

QUESTION 12: The information in the passage supports the prediction that P. falciparum creates unique protein trafficking structures outside the parasite itself for the trafficking of which parasite protein? A. PfEMP1 B. PfSET10 C. Histone H3 D. Hemoglobin

A. got it correct but was debating bw A and B Paragraph 1 states PfEMP is a parasite protein that is present on the surface (plasma membrane) of the RBC that the parasite inhabits. This means that there must be a mechanism for transporting pfEMP1 from the parasite to the RBC plasma membrane. b. pfSET10 is located in the nucleus of the parasite bc passage states that it's a histone lysine methyltransferase c. Histone H3 is located in the nucleus of the parasite d. Incorrect. The parasite does digest the host RBC hemoglobin, but the question specifically asks for a specific parasite protein.

QUESTION 2 How could the researchers use the foot-in-the-door technique to increase the participants' likelihood of adopting a diet diary? a. Encourage the participants to sign a petition in support of diet diaries. b. Have the participants personally interact with the health buddy who adopted the diet diary. c. Tell the participants that the health buddy who adopts the diet diary is a trustworthy health expert. d. Tell the participants that by agreeing to be in the study, they have agreed to cooperate with the researchers.

A. got it wrong chose B bc didn't rmr foot in the door technique properly The foot-in-the-door technique refers to convincing individuals to make a small commitment toward a cause, because this small commitment increases the likelihood of a larger commitment toward the same cause in the future. Option A is an example of this. If the participants make a small commitment toward diet diaries (signing a petition), according to the foot-in-the-door technique, they will be more likely to adopt a diet diary in the future. b. This is incorrect. It describes a situation that can plausibly increase the likelihood of adopting a diet diary but is not an example for the foot-in-the-door technique. c. This is incorrect. It gives an example of how the peripheral route to persuasion can be used to increase the participants' likelihood of adopting a diet diary. d. This is incorrect. It suggests that compliance can be used to increase the likelihood of adopting a diet diary.

QUESTION 9 A researcher wants to determine whether the findings from the first study are also influenced by psychological responses to stress. To test this idea, a random sample of mothers from the first study is later given a stress assessment. What is the flaw in this research design? a. The dependent variable is temporally prior to measurement of the independent variable. b. The independent variable is temporally prior to measurement of the dependent variable. c. The updated sample contains too little variation to draw reliable conclusions. d. The updated sample is not representative of the population of mothers.

A. got it wrong, chose D Hypothesized factors must be temporally prior to their assumed effects. Option A is correct because the hypothesized factor (mediating factor of psychological response to stress) was assessed after the outcome of interest (birth weight). b. This is incorrect because it identifies the correct time order of variables, so would not present a flaw. c. This is incorrect because the sample was randomly constructed so is not likely to present a flaw. In addition, the implied references to variability and reliability in the option are used imprecisely. d. This is incorrect because, as with option C, the sample is not the primary flaw in the design. Instead, the use of a random sample is likely to help ensure the representativeness of the sample.

QUESTION 22: Of the five candidate genes, which produces a factor that most markedly increases the efficiency with which fibroblasts commit to a neuronal lineage in vitro? a. Ascl1 B. Brn2 c. Zic1 d. Olig2

A. got it wrong, chose D but because the graph says "omission of genes" Dont fall for it, the graph says omission of the given genes

QUESTION 5: What control experiment was necessary to ensure that the apparent subcellular locations of the cat6xbs and lacY6xbs transcripts were NOT skewed by the location preference of the bound MS2-GFP? a. Determination of expression of MS2-GFP in cells that lacked the 6xbs insertion upstream of the cat and lacY genes b. Use of E. coli cells that expressed only MS2 instead of the MS2-GFP fusion protein c. Insertion of the 6xbs region upstream of both the cat and lacY genes in the same cells d. Determination of expression of both MS2 and GFP as separate proteins rather than as a fusion protein

A. got this correct but because i guessed. I did not understand the terminology but rationalizing it out, if you are trying to test that the location of MS2 did not affects the locations of cat and lac then you must take out cat and lac and see where MS2 is and then add cat and lac back in and see where it is.

QUESTION 16 According to the passage, one of the reasons Black men have medical mistrust is because seeking help violates their: a. gender schema. b. gender script. c. gender conditioning. d. gender adaptation.

A. got wrong, chose B Gender Schema: What is associated with each identity/what constitutes an identity. Male identity schema includes not seeking social services/help hence they don't need healthcare professionals b. Gender Script: organized information regarding the order of actions that are approximate to a familiar situation. In this situation, they are not following a gender script. or "how to act" c&d. not an actual concept

QUESTION 10 What factor can account for the relative rate of Ca2+ transport across the membrane as a function of pH? a. Deprotonation of the X groups b. Deprotonation of the Y groups c. Protonation of the central O atoms d. Change in ring size of the macrocyle

A. got wrong, chose B, because i didnt understand which groups would be unreactive the key is to understand that talking about changes in pH is equivalent to talking about changes in terms of which functional groups are protonated or deprotonated. This is a key concept for the MCAT that is not really discussed clearly in many chemistry courses, but it shows up again and again, especially with amino acids. The idea is that functional groups that are weak acids or bases are more likely to be protonated at a low pH, and less likely to be protonated at a high pH. This can affect charge -- for instance, a COOH group is neutral, but its deprotonated form, COO-, is negatively charged. Charge shapes all sorts of interactions between biomolecules, so changing pH can change functionality. With this in mind, we need to look for a structure in the crown ether ring (b/c the passage tells us that the crown ether ring controls cation transport) that can meaningfully be protonated or deprotonated. Answer choice D is out b/c we know that we need to focus on protonation/deprotonation in a Q about pH. C is out because ether oxygens are super unreactive and don't engage in acid-base chemistry. This leaves the X and Y groups, which are defined in the legend of Figure 1. Y is some super-large chain with lots of hydrocarbons, an amide group, a highly substituted amine...all very unreactive in terms of acid-base chemistry. So B can be eliminated. Then let's consider A. A is a carboxylic acid group (-COOH), which is a prototypical example of a weak acid that shows pH sensitivity in terms of shifting between its protonated and deprotonated states, so that's exactly what the question is looking for.

QUESTION 11 What are the configurations (R or S) of the chiral centers bonded to substituents X and Y, respectively, in Compound 1? a. R, R b. R, S c. S, R d. S, S

A. got wrong, chose B, didn't realize O has higher priority than C For the carbon atoms bonded to the Y groups, the lowest priority group is already in the back and so the ranking of the remaining groups, which occurs in a clockwise manner, gives the R-configuration. For the carbon atoms bonded to X, the X group is in the back, and the relative rank of the remaining groups occurs in a counter-clockwise manner. When H is placed in the back, however, this would also be clockwise, or R.

QUESTION 6 In helping to explain the results of the study, which other concept would be most similar to a homophilous social network? a. Reference group b. Secondary group c. Out-group d. Social group

A. got wrong, chose D bc did not know definitions of the terms in answer choices A is correct. A reference group is defined as "any group that individuals use as a standard for evaluating themselves and their own behavior," and is similar to the mechanism behind the effect of the "homophilous" group in the study. b. This is incorrect because secondary group refers to a formal, impersonal group. c. This is incorrect because an out-group is defined as a group that people do not feel connected to. d. This is incorrect because a social group, which is a general term that refers to a collection of people with common identity and regular interaction, is not as specific as a reference group.

QUESTION 21 After taking the experimental drug, Person A showed an improvement in: a. anterograde memory. b. retrograde memory. c. semantic memory. d. short-term memory.

B. got correct B is correct. Retrograde memory refers to the ability to remember the information before brain injury. Figure 1 shows that Person A showed a considerable increase in memory for events right before brain injury during the post-test. a. This is incorrect because anterograde memory refers to the ability to form long-term memories after brain injury. c&D: not tested in passage

QUESTION 5 Which biological molecule can react with Compound 11 so that pyridoxal phosphate (Compound 5) is regenerated? a. ATP b. Oxaloacetate c. NADH d. FAD+

B. got correct The last sentence in the passage states that the reaction in figure 1 is reversible. Before going further, notice the difference between compounds 11 and 5, which is the conversion of an amine -> carbonyl. Now refer back to the product side of figure 1 and notice that oxaloacetic acid can be used to accomplish this conversion a. ATP would transfer a phosphate group. Nothing in the passage would suggest this c. NADH/FADH2 and their oxidated forms are high energy electron carriers than play a role in REDOX reactions in cellular respiration and metabolism. This is a transamination reaction d. See rationale c

QUESTION 6 Which wavelength of laser light can be used with the photodiode detector in the atomic force microscope? a. 226 nm b. 633 nm c. 1.26 μm d. 3.17 μm

B. got correct The passage states that visible light laser is used. Find the answer that is within visible light. Visible light is between: 400 - 750 nm. Red light is highest wavelength, blue light is lowest. (ROYGBIV)The only answer within this range is B.

QUESTION 22 Soaps are chemically modified natural products that can be derived from all of the following EXCEPT: a. fatty acids. b. cholesterols. c. triacylglycerols. d. phospholipids.

B. got correct While cholesterols are hydrocarbons found in cell membranes, they are not structurally similar to fatty acids. Essentially = "which are not hydrolyzable" = cholesterol a. Fatty acids are RCO2H which can easily be converted to soaps RCO2Na by the addition of NaOH. c. Triacylglycerols contain RCO2- groups that can be released by hydrolysis and precipitated as soap. d. Phospholipids also contain RCO2- groups that can be released by hydrolysis and precipitated as soap.

QUESTION 29 If sounds produced by the human vocal cords are approximated as waves on a string fixed at both ends, and the average length of a vocal cord is 15 mm, what is the fundamental frequency of the sound? (Note: Use 3 m/s for the speed of sound through the vocal cord.) a. 10 Hz b. 100 Hz c. 1000 Hz d. 10,000 Hz

B. got correct but it was a guess Fundamental frequency of a vibrating string is F=V/2L 3/2 (15 *10^-2)= 1/10^-2=100Hz AAMC: This question requires you to apply knowledge of sound production by vibrating cords and strings, and to identify the physical properties of such cords and their relationship with sound characteristics: frequency, propagation speed, and amplitude. In particular, the relationship between the sound speed and frequency for a string fixed at both ends must be used. The fundamental frequency of a vibrating string is given by f = v/(2L) = (3 m/s)/(30 × 10-3 m) = 1/10-2 Hz = 100 Hz. a. Uses wrong units for L c. Uses speed of sound as 30 m/s d. Uses both units incorrectly

QUESTION 25 A team of researchers wanted to test whether the James-Lange theory of emotional arousal could explain subjects' physical and emotional experiences while they viewed clips from a horror film. Which of the following scenarios is most consistent with the James-Lange theory? a. The participants felt general excitement and simultaneously experienced physical symptoms of autonomic arousal, such as a racing heart. b. The participants experienced physical symptoms of autonomic arousal, such as a racing heart, and then they reported that they felt afraid. c. The participants felt fear, and then began to experience physical symptoms of autonomic arousal, such as a racing heart. d. The participants showed physical symptoms of autonomic arousal, such as a racing heart, and then they reported that they felt general excitement.

B. got correct but need to review theories of emotion B is correct. According to the James-Lange theory, physiological arousal precedes the identification of emotion. An individual first experiences the physiological symptoms of a given emotion and then labels this emotion. a. This is incorrect because the James-Lange theory posits that physiological symptoms precede emotional experience. A is more compatible with the Cannon-Bard theory of emotion. c. This is incorrect because it suggests that the emotional labeling precedes physiological symptoms. d. This is incorrect because the James-Lange theory of emotion suggests that physiological symptoms are recognized as a specific emotion, not as generalized excitement.

QUESTION 19 A scientist proposed that the 32P label was entering PE molecules by direct exchange (swapping phosphate groups with those found in solution) and NOT through synthesis of new PE by bacterial cells. What experimental modification can show this is NOT the case? a. Introduce TNBS prior to pulsing with 32PO43-. b. Measure the rate of incorporation of 32PO43- into acellular PE. c. Use mouse cell cultures instead of bacterial cells. d. Decrease the concentration of 32PO43- and observe the effect on incorporation rate.

B. got correct but recognize that whenever they ask Q's abt proving something, they will have an answer choice that brings up specifically the topic of interest, if not, its probs not the answer. Q19 is similar to Q15 in that the way you want to think about it may vary depending on how clearly you get what they're trying to do. The basic issue that the Q stem introduces is that there may be more than one mechanism through which radiolabeled P shows up on the PE groups -- the logic of the experiment assumes that P is incorporated through biosynthesis, but the question is asking, what if the P just is swapped out in solution through a non-biosynthetic process? The Q is then asking you to figure out a control experiment that would distinguish between those mechanisms. C and D can be eliminated because they're not mechanism-specific. A might be tempting, but hopefully we can realize that this would just wind up measuring nothing -- it'd be like trying to take a picture of the sunrise before the sun actually rises. B involves saying "hey, let's look at what happen if no cells are involved, and that will give us a measure of whether these P groups just get swapped out with those in solution through an equilibrium process." That's the kind of control they're looking for.

QUESTION 8 What is the mechanical power exerted on the protein when the retraction speed is 1000 nm/s? a. 1.5 × 10-18 W b. 7.5 × 10-17 W c. 3.5 × 10-6 W d. 5.5 × 106 W

B. got correct, did math out but did not know that was the power equation The equations for Power: Work/Time, Energy/Time, Force x Velocity. Work and energy can be interchangeable because of the work-energy theorem. The unit for power is a watt (J/S) Power = W/t or Fv. Therefore, from figure 3, at 1000 nms the answer is P = 75pN * 1000 nm/s =75*10^-12 N * 1000 *10^-9 m/s = 75000 * 10^-21 W (J/s or N*m/s)= 7.5 * 10^-17 W

QUESTION 11: The data in the passage suggest that the substrate-binding domain in PfSET10 is: a. the SET domain. b. the PHD domain. c. the N-terminal domain. d. the C-terminal domain.

B. got it correct Look at Figure 2, when lacking PHD domain, no histone binding but when PHD is there, histone binds. Hence, the substrate binding domain on pfSET10 is PHD.

QUESTION 30: Scientists have hypothesized that mitochondria evolved from aerobic heterotrophic bacteria that entered and established symbiotic relationships with primitive eukaryotic anaerobes. According to this hypothesis, the bacteria that entered primitive eukaryotic cells were able to carry out which function(s) that the primitive eukaryotic cells could not? a. Glycolysis b. Citric acid cycle and electron transport c. Cell division d. Transcription and translation

B. got it correct According to the provided information, the primitive bacteria were aerobic and heterotrophic, whereas the primitive eukaryotes were anaerobic. If the primitive eukaryotes were anaerobic they could not exist in an oxygen-containing environment nor engage in metabolic processes requiring oxygen. Thus, the bacteria were likely to be able to carry out the oxygen-requiring reactions of the citric acid cycle and the electron transport chain while the primitive eukaryotes were not.

QUESTION 5 If the study were modified to investigate the effect of homophily on the changes in participants' exercise patterns as well as their likelihood of adopting an Internet-based diary, how would this change the design of the study? a. A new independent variable would be added. b. A new dependent variable would be added. c. Levels of an existing independent variable would increase. d. The study would become an experimental study.

B. got it correct B is correct. "Changes in exercise patterns" corresponds to a new dependent variable because the researchers are interested in the effect of homophily (independent variable) on exercise, along with adopting an Internet-based diary. a. This is incorrect because "changes in exercise patterns" is not an example of adding another independent variable because the researchers are not interested in the effect of changes in exercise patterns on another variable. c. This is incorrect because measuring changes in exercise patterns introduces a new variable to the study rather than changing the levels of an existing variable. d. This is incorrect because adding a new variable does not render a study experimental.

QUESTION 11 A hot water tail-flick test measures the time it takes rats to remove their tail when it is dipped in hot water. Rats housed with a running wheel exhibit a delayed response in the test. Based on this response, which type of sensory receptors are most likely negatively regulated by exercise? a. Baroreceptors b. Nociceptors c. Mechanoreceptors d. Chemoreceptors

B. got it correct Exposure to hot water activates pain receptors (nociceptors); a delayed response indicates that nociceptors are negatively regulated. a. no indication of pressure measured c. no indication of touch measured d. no indication of chemical changes measured

QUESTION 29: Increasing the volume of air that reaches the alveoli and takes part in gas exchange will cause blood pH to: a. increase, because the neural mechanisms that remove acid from the blood will be activated. b. increase, because the partial pressure of CO2 in the blood will decrease. c. decrease, because the affinity of hemoglobin for oxygen will be increased. d. decrease, because the work associated with increased ventilation will come more O2.

B. got it correct Increasing the volume of air that reaches the alveoli and takes part in gas exchange will enhance O2 uptake and CO2 removal, thereby increasing blood pH. MCATBROS: CO2 + H2O <--> H2CO3 <---> H+ + HCO3-. More O2 partial pressure, means decreased partial pressure of CO2 because increased O2 partial pressure and more CO2 removal (gas equilibrates at the alveoli). This will hence increase pH (decrease H+) , shift to the left!! a. This is incorrect. Neural mechanisms control the rate of breathing.

QUESTION 13: The information in the passage suggests that PfSET10 has which function in var gene localization or expression? PfSET10: A. allows active and silent var genes to colocalize in the nucleus. B. marks the chromatin of the active var promoter for reexpression after mitosis. C. marks the chromatin of a silent var promoter to be expressed after mitosis. D. marks the chromatin of multiple var promoters for simultaneous expression.

B. got it correct but might've been a really good guess Looking at the information right above the graph, pfSET10 is a methyl-transferase, which can be involved in reactivation of genes after mitosis. Reactivation must occur because genes/chromosomes are tightly packed during mitosis. AAMC explanation: According to the passage, P. falciparum cells contain the most PfSET10 when the intraerythrocyte parasites are in an actively dividing life cycle phase. To maintain cellular identity, there has to be a mechanism for marking genes that were transcriptionally active before mitosis for reactivation after mitosis. Because PfSET10 colocalizes with the active vargene, it is reasonable to hypothesize that PfSET10 methlytransferase activity is involved in this bookmarking. a. Why is this wrong? Where are active and silent var genes located? Heterochromatin - INACTIVE - in the center where its TIGHTLY bound to HISTONES. Eurochromatin - ACTIVE - outskirts of town where its available to be transcribed. The passage even says "The expressed var gene is located in a different place in the periphery of the nucleus than are silent var genes." c. So PfSET10 is a histone lysine methyltransferase, hence it will make an inactive gene active. This is why it is present near active var genes, not silent ones - you wouldn't want to start making active non silent var. This can also be seen in the graph to the left, where PSET10 is closer in distance for the "on" var gene" and farther for the off var gene. d. pfSET10 is involved in only var gene expression as discussed in the passage (end of paragraph 1). "Only one var gene is transcribed at a time over multiple mitotic generations"

QUESTION 24: As one step in the estimation of the efficiency of neuronal induction, scientists calculated the average number of induced cells present in 30 randomly selected 20× visual fields. Which change to this particular aspect of the experimental protocol would increase the accuracy of the estimates of efficiency? a. Increase the magnification of the oculars used to define the field of view. b. Increase the number of visual fields counted per petri dish. c. Select visual fields from the central portion of the petri dish where cell density is highest. d. Use the presence of green fluorescence to identify cells appropriate for quantification.

B. got it wrong, chose D Increasing the number of visual fields counted would increase the sample of cells observed from the total "population," and result in results that better approximate the true values. a. This is incorrect. Oculars of higher magnification would focus on a smaller area. Thus, the total area of the petri dish evaluated with high magnification oculars would be smaller than the total area evaluated with 20× oculars. c. This is incorrect. This change would bias the scientists' sample of the population. d. This is incorrect. This change would bias the scientists' sample of the population.

QUESTION 4 What thermodynamic and chemical changes (if any) occur during aspartate transamination (Figure 1)? a. Since ΔG < 0, ATP is produced. b. Since ΔG = 0, no ATP is required or produced. c. Since ΔG > 0, ATP is required. d. Since ΔG > 0, ATP is produced.

B. got wrong, chose A but was debating bw A and B bc of Keq = 1 The free energy of the reaction as written in either direction is the same since Keq = 1, and ΔG = -RTln(Keq) and therefore ΔG = 0. When a reaction is thermoneutral ATP is neither produced nor required for the reaction to proceed. a. Since Keq = 1, ΔG = 0 and no ATP is required or produced. c. Since Keq = 1, ΔG = 0 and no ATP is required or produced. d. Since Keq = 1, ΔG = 0 and no ATP is required or produced.

QUESTION 18 The tendency of doctors to use a physician-centered communication style more often with Black patients is an example of: a. prejudice. b. stereotyping. c. discrimination. d. ethnocentrism.

C. got correct The communication style assumed by the doctors is an example of discrimination because it suggests that the doctors are behaving differently based on the patients' racial background. a. Prejudice is just an attitude, no action/behavioral component. Prejudice as an emotional component. b. Stereotyping refer to cognitions regarding social groups, not behaviors toward social groups. Leads to prejudice d. Ethnocentrism refers to the assumption that one's own culture is superior to other cultures. Not the case here.

QUESTION 28 A researcher interested in memory of novel words shows participants unrelated words printed on a card, one after the other. Participants see 20 words in total, wait for 2 minutes, and then are asked to write down all of the words they can remember. The researcher finds that 95% of the subjects remember the first three words. This finding is an example of: a. the recency effect. b. proactive interference. c. the primacy effect. d. retroactive interference.

C. got correct Primary effect: improved memory of the early information. Shown in this, because 95% of the subjects remembered the first three words a. recency effect would mean that the participants were good at remembering the last words. In this example, they remember the recent words b. Proactive interference - earlier information interferes with later information. proactive (effects later) d. Retroactive interference - current information interferes with older information.

QUESTION 28 Human speech is generated in the vocal cords as the lungs push air past them. What property of the vocal cords is changed so that the frequency of sound can be altered? a. Volume b. Density c. Tension d. Number

C. got correct The frequency of the sound produced in vibrating cords and strings (such as vocal cords) of fixed length is proportional to the propagation speed of the sound through the cord. In turn, the propagation speed of a transverse wave (such as the sound wave in the vocal cords) is directly proportional to the tension applied along the cord. a. Speed and frequency of sound is independent of volume b. The frequency of sound does not change when it is in different mediums d. The number of vocal cords used in generating the speech is constant.

QUESTION 18: Which finding, when combined with the data in the passage, is most likely to lead researchers to conclude that the 5-HT2A and 5-HT2B receptor subtypes mediate serotonin-dependent liver regeneration? a. Administration of 5-HT2A receptor agonist resulted in reduced Ki67 staining. b. RNA for seven different receptor subtypes was detectible in naïve liver tissue. c. Up-regulation of 5-HT2A and 5-HT2B was observed during periods of peak hepatocyte proliferation. d. Administration of 5-HT2C and 5-HT3 receptor antagonists reduced the number of Ki67-positive cells.

C. I got it wrong, chose A, didn't read the answer choice said "agonist" if it said "antagonist" it would've been correct An observed up-regulation of 5-HT2A and 5-HT2B during periods of peak hepatocyte proliferation corroborates the data presented in the passage (that administration of antagonists of 5-HT2A and 5-HT2B lead to decreased hepatocyte proliferation) and, of the options presented, is most likely to lead researchers to conclude that the 5-HT2A and 5-HT2B receptor subtypes mediate serotonin-dependent liver regeneration. a. This is incorrect. A reduction in Ki67 staining after administration of a 5-HT2A agonist is not consistent with the data presented in the passage. b. This is incorrect. The presence of RNA encoding all the receptor types in the liver tissues would not lead researchers to conclude that the 5-HT2A and 5-HT2B receptor subtypes directly mediate serotonin-dependent liver regeneration. d. Notice how it says 5-HT2C and 5-HT3!! These two receptors are NOT what the question stem is asking about, they want 5-HT2A and 5-HT2B

QUESTION 23 While Person A was in a coma, researchers considered stimulating her brain to bring her out of the comatose state. The researchers would most likely have stimulated the: a. Wernicke's area. b. parietal lobes. c. reticular activating system. d. somatosensory cortex.

C. got correct The reticular activating system is involved in controlling alertness and is most likely to be stimulated to bring someone out of a coma. a. Wernickle's area is involved in speech processing (temporal lobe) b. Parietal lobe contains the somatosensory cortex (touch/pressure/pain) and is involved in spatial manipulation (orient in 3D). d. Somatosensory cortex - Involved in receiving sensory signals from the skin

QUESTION 29 Researchers conducted an experiment to study Weber's Law. Going from 10- to 12-pound weights created the just noticeable difference for one participant. For this participant, how many pounds need to be added to a 20-pound weight to create the just noticeable difference? a. 1 pound b. 2 pounds c. 4 pounds d. 8 pounds

C. got correct but need to know how to do math correctly Simple math/ratio. 2/10 = x/20 X = (2/10)*20 = 4

QUESTION 26 Anxious about a nagging illness, a patient feels ignored by a doctor who is struggling to catch up with patient examinations on a very busy day. The doctor misinterprets the discomfort and agitation of the patient as hostility. Which sociological paradigm can best explain this scenario? a. Functionalism b. Conflict Theory c. Symbolic Interactionism d. Social Constructionism

C. got correct but need to know terms Symbolic interactionism: Places emphasis on social interactions, symbols, and meanings. a. Functionalism: macro-level theory that understands social phenomena in terms of their functions for society. b. Conflict theory: focuses on the differnece in material resources between groups. A macro perspective d. Some might consider this the correct answer, but it is not because social constructionism is more concerned with concepts instead of micro-level interactions such as one between a patient and doctor. Social Constructionism: The emergence of social-constructs/concepts. Bridges micro and macro levels but places more emphasis on concepts as opposed to social interactions

QUESTION 7: Using knowledge of Michaelis-Menten kinetics, what effect would the addition of chloramphenicol have on the kinetics of its target enzyme? a. Vmax decreases, and KM increases. b. Vmax decreases, and KM remains unchanged. c. Vmax remains unchanged, and KM increases. d. Vmax remains unchanged, and KM decreases.

C. got it correct a. This would be one scenario for Mixed Inhibitor competition. This would occur when binding to the enzyme complex is stronger than enzyme-substrate complex b. This would be the case for Non-competitive inhibition. c. The final paragraph states that chloramphenicol is a competitive inhibitor. Competitive inhibitors bind at the active site of the enzyme and hence Vmax is not effected (the competitive inhibitor can be overcome with additional substrate, but Km is affected (lower affinity, so higher Km) because it takes more substrate to get to 1/2 Vmax of enzyme. d. This would not be the case for any competition type.

QUESTION 20: Which type of enzyme catalyzes the conversion of glutamate to GABA? a. Kinase b. Transferase c. Decarboxylase d. Dehydrogenase

C. got it correct Comparison of the chemical formulas provided in the passage show that the conversion of glutamate to GABA involves the removal of a carbon from the carbon chain. These reactions are often catalyzed by decarboxylases. a. Kinases are enzymes that modify protein targets by the transfer of phosphate groups. b. Transferases are enzymes that catalyze the transfer of functional groups between molecules. d. Dehydrogenases are enzymes that catalyze oxidation reactions.

QUESTION 19: The amino acid precursor of serotonin is best described as having which type of R group? a. Nonpolar, aliphatic b. Polar, uncharged c. Aromatic d. Negatively charged

C. got it correct Passage states that serotonin is synthesized from tryptophan and tryptophan contains an aromatic R group (it is one of three non-polar aromatic compounds)

QUESTION 10: Of the three general cell types or cell-derived structures described in the passage as binding P. falciparum-infected RBCs, at least two of the three have which characteristic? a. They have nuclei. b. They are cell fragments. c. They are bone marrow-derived. d. They are connected by tight junctions.

C. got it correct a. Only endothelial cells have nuclei, platelets and mature RBCs do not. RBCs and platelets lack most membrane bound organelles. it is important to know RBCs lack mitocondria and these other membrane bound organelles to maximize oxygen transport. b. Only platelets are cell-fragments. Hence this is wrong. c. The passage states that "infected RBCs adhere to platelets, endothelial cells, and other mature RBCs" These are all derived from bone-marrow. d. Endothelial cells are connected by tight junctions, but RBCs and platelets are not. Remember: tight junction is one of three kinds of cell-cell junction - the others are gap junctions (communicating junctions) and desmosomes (anchoring junctions). Tight junctions are present in the bladder, intestine, kidney (to prevent water), desmosomes are present in skin/intestine (let water through), and gap junctions are present in cardiac muscle and neurons.

QUESTION 13 Based on the passage, ABA-induced rats are most likely to demonstrate: a. increased sensitivity to the effects after running in their wheels. b. increased sensitivity to pain over time. c. withdrawal symptoms if they are prevented from running in their wheels. d. withdrawal symptoms if they are injected with opiates.

C. got it correct C is correct. Rats that have developed exercise addiction should experience withdrawal symptoms if they are hindered from running in their wheels. The running behavior leads to an increase in endorphins which, according to the passage, leads to exercise addiction. Preventing the running behavior is likely to lead to withdrawal, as it would interfere with the increase in endorphins that the ABA-induced rats are addicted to. a. Rats release endorphins after exercise. High endorphins = less pain perception (same stimuli = less response), not More response. b. Sensitivity is INCREASE response to same level of stimulation. It is the opposite of habituation. This is not occurring here. Endorphins are painkillers hence they reduce the sensitivity to pain. d. This is incorrect because opiates are endorphin agonists and will not lead to withdrawal symptoms for the ABA-induced rats.

QUESTION 25 The overall reaction for glycolysis: Glucose + 2NAD+ + 2ADP + 2Pi → 2Pyruvate + 2NADH+ 2H+ + 2ATP + 2H2O can be broken down into two separate processes (reactions 1 and 2). Glucose + 2NAD+ → 2Pyruvate + 2NADH + 2H+ Reaction 1: ΔG° = -146 kJ/mol ADP + Pi → ATP + H2O Reaction 2: ΔG° = +30.5 kJ/mol What is ΔG° for glycolysis? a. -207.0 kJ/mol b. -176.5 kJ/mol c. -85.0 kJ/mol d. -54.5 kJ/mol

C. got it correct Glycolysis is the net sum of Reaction 1 and two rounds of Reaction 2. The overall free energy change can therefore be calculated as (-146 kJ/mol) + 2(30.5 kJ/mol) = -85 kJ/mol.

QUESTION 4 All the participants in the study are given information regarding the benefits of a healthy diet. According to the cognitive dissonance theory, which hypothetical finding is most likely? a. Obese participants will change their unhealthy eating behaviors. b. Non-obese participants will change their unhealthy eating behaviors. c. Obese participants will question the validity of the information provided. d. Non-obese participants will overemphasize the importance of the information provided.

C. got it correct It says on the AAMC explanation that in cognitive dissonance theory, people are more likely to adjust their attitudes to align with behavior instead of the other way around. Why is that?^^this is what research done on the subject has found; when people experience cognitive dissonance, you'd think that they would change their behavior to match their attitude, but instead they change their attitudes to match their behavior. If you think about it, it's true; if you're eating fast food and someone tells you that it's bad for your health, you're more likely to say "screw health" or "it's not that bad" than to stop eating fast food

QUESTION 15: The liver synthesizes factors that act cooperatively with platelets to facilitate which physiological process? a. Cholesterol synthesis b. Glucose metabolism c. Blood clotting d. Fat digestion

C. got it correct Platelets are involved to form a plug at the site of blood vessel damage. Blood clotting factors that are synthesized in the liver in an inactive form (fibrinogen) which floats around in the blood. When this fibrinogen interacts with tissue factors during damage, it initiates a cascade which leads to prothrombin being activated to thrombin, the molecule in charge of converting fibrinogen to fibrin (which forms the clot). The extrinsic cascade is out of scope for the MCAT, but this is how it proceeds: III (TF) --> VIII --> X --> II (thrombin), which activates V, VIII, XI, XIII (intrinsic pathway). which all then amplify II (thrombin). Now there is so much thrombin. a. This is incorrect. Synthesis of cholesterol is an important function of the liver. Platelets may also synthesize cholesterol, but the liver and platelets are not acting together in this process. b. This is incorrect. The liver plays an important role in energy homeostasis by storing glucose in the form of glycogen under conditions of glucose excess and by breaking down glycogen and releasing glucose into the bloodstream under conditions of glucose limitation. The liver also synthesizes glucose from non-carbohydrate molecules. Glucose and insulin imbalances can affect the activation of platelets during coagulation, but the liver and platelets are not acting together in energy homeostasis. d. This is incorrect. The liver synthesizes bile that emulsifies fat and facilitates its digestion in the small intestine. Platelets do not have an obvious role in this process.

QUESTION 17 Which operationalization is most appropriate for the independent variable of the proposed follow-up experiment? a. Level of mistrust, established by an inventory that measures participants' medical mistrust b. Level of mistrust, established by independent judges who rate participants' medical mistrust c. Type of communication, established by training a doctor who is also a confederate to use patient-centered communication or a communication style that is not patient-centered d. Type of communication, established by giving doctors in the study an inventory that assesses whether their communication style is patient-centered or not

C. got it correct but was debating bw C and D This is the correct answer because to operationalize something, you make a variable study-able by figuring out a way to test the communication style. This can bed one by adding a confederate doctor which controls for the type of communication. The dependent variable effect can then be established. a&b. The question asks for independent variable operationalization, in the follow up study , level of mistrust is the dependent variable d. This is close to the right answer but the independent variable must be manipulated to show causality - which this does not. This answer choice simply just establishes if the communication style is patient centered or not based on a survey.

QUESTION 8: The bglF transcript is known to have a short half-life within the cytosol. What mechanism is most likely responsible for transport of this transcript to the cytoplasmic membrane once it is synthesized? a. Diffusion across the cytoplasm b. Transport via attachment to the mitotic spindle c. Active transport along cytoskeletal filaments d. Transport from the endoplasmic reticulum in vesicles

C. got it wrong chose D, but we are talking about E. coli (a prokaryote) does not have any membrane bound organelles. Remember that: prokaryotes have no nuclear membrane, no nucleolus, no golgi apparatus, no ER, and are incapable of phagoctyosis/pinocytosis/ exocytosis (no vesicles), lack sterol in their membrane. They also have different ribosome subunits (smaller, 30+50 = 70S while eukaryotes have 40+60 = 80S). Because they lack Endoplasmic reticulum and vesicles, this is not a possibility as it would be for eukaryotic cells. a. This would be wrong because this would take a long time to occur and hence the protein would degrade in the cytoplasm before reaching the intended target. b. Prokaryotes do not have a mitotic spindle because they do not undergo mitosis. Instead they divide by binary fission c. is correct because it allows for more rapid transport than diffusion. bglF is a protein that is coded for by the bgl gene. For a protein to be made, the following process must occur: Transcription from DNA (to mRNA) then translation (to a protein). In prokayrotes, this process occurs simultaneously as there is no compartmentalization (nuclear membrane). In eukaryotes, once the mRNA transcript is synthesized from the DNA in the nuclear region, it leaves the nuclear region it is readily exposed to cytoplasm. Both eukaryotic and prokaryotic cells have post-transcriptional modifications to mRNA. The post-transcriptional modification that allows the mRNA strand of both eu/prokaryotes to survive in the cytoplasm is a 3' polyA tail addition (repeating Adenosine nucleotide repeats). Prokaryotes (such as E.coli as discussed in the passage) typically have a shorter polyA tail, hence the transcript of prokaryotes is considered less stable/degrades quicker (few minutes). To prevent degradation and to get the protein to the appropriate location (at the cell membrane), the best way would be to involve active transport along cytoskeleton filaments straight to the cytoplasmic membrane once the transcript is synthesized. Also, remember that cytoskeleton lies right under the plasma membrane.

QUESTION 2: Which steps involved in the contraction of a skeletal muscle require binding and/or hydrolysis of ATP? I. Dissociation of myosin head from actin filament II. Attachment of myosin head to actin filament III. Conformational change that moves actin and myosin filaments relative to one another IV. Binding of troponin to actin filament V. Release of calcium from the sarcoplasmic reticulum VI. Reuptake of calcium into the sarcoplasm A. I, II, and III only B. II, III, and IV only C. I, III, and VI only D. III, IV, and VI only

C. got it wrong, chose A, bc did not know that ca reuptake required ATP Also known as "cross bridge dissociation". This occurs after the power stroke to put the myosin head into a low energy position II. Calcium is required to expose the myosin binding sites through the conformational change in tropomyosin III. The conformational change among actin and myosin requires the hydrolysis of ATP which is what allows the power stroke a.k.a. the muscle contraction caused when myosin pulls actin towards the middle of the sarcomere VI. Reuptake of calcium requires ATP because the ions are moving against their concentration gradient into the SR

QUESTION 21: What is the most likely reason why Tuj1 was used to assess the phenotype of cells that have incorporated the five candidate genes? a. Tuj1 induces expression of the TauEGFP protein. b. Tuj1 is expressed in fibroblasts and neurons. c. Tuj1 is an early marker of neural differentiation. d. Tuj1 is present in embryonic and adult cells in culture.

C. got it wrong, chose B but i was debating between these two Goal is fibroblasts -> neurons. A marker for neural development is what we want a. The EGFP gene is in mice engineered to express a green fluorescent protein in their neuronal tissues only b. The goal of the experiment is to turn fibroblasts into neurons. If the Tuj1 protein is in both cell types then you can't assess a difference d. Tuj1 is used to select for cells that have differentiated into neurons. Since fibroblasts were isolated from postnatal mice, no embryonic cells were used in the experiment, which involves the conversion of one adult cell type into another adult cell type.

QUESTION 14 Which statement provides the most likely explanation for the results in Figure 1? a. ABA-induced rats show a decrease in withdrawal symptoms because an opioid agonist mimicked the effects of wheel-running. b. Rats with 24-hour access to food show a decrease in withdrawal symptoms because an opioid agonist increased the reinforcement value of food. c. ABA-induced rats show an increase in withdrawal symptoms because an opioid antagonist interfered with the effects of wheel-running. d. Non-ABA-induced rats show an increase in withdrawal symptoms because an opioid antagonist enhanced the effects of wheel-running.

C. got it wrong, chose D did not understand that naloxene was an opioid antagonist but bc it blocks endorphin release, it is C is correct. ABA-induced rats (the rats with restricted access to food and access to a running wheel) show increased withdrawal symptoms because naloxone, an opioid antagonist, likely interferes with the physiological effects of wheel-running. MCATBROS: Reinforcement = Increase behavior. Positive = adding something to increase behavior. This is Positive reinforcement (adding nalaxone increases endorphine seeking activities). a. A is incorrect. ABA-induced rats (the rats with restricted access to food and access to a running wheel) do not show a decrease in withdrawal symptoms. b. B is incorrect. The drug used in the study, naloxone, is an opioid antagonist. d. D is incorrect. Non-ABA-induced rats do not show an increase in withdrawal symptoms.

QUESTION 8 Which concept is most relevant for explaining the relationship between social resources and birth-weight outcomes that was found in the first study in the passage? a. Poverty b. Heredity c. Social networks d. Socialization

C. got wrong, chose A Option C is correct because reciprocal exchange, as it is described as a social resource with the first study in the passage, is best identified as a social network process. a. No passage information to support this answer choice. Passage only mentions lack of social resources--not financial. It is possible that poverty is a contributing factor, but it was not specifically identified in the passage. b. not mentioned in passage d. This is incorrect because socialization refers to the lifelong process by which norms and values are learned, and thus does not specifically address a social resource (such as reciprocal exchange).

QUESTION 17 In Reaction 1, what is a possible structure for either R1 or R2 of the reactant? a. CH3 b. NH2 c. (CH2)15CH3 d. (CH2O)10CH3

C. got wrong, chose A bc i did not know phosphatadylethanolamine (PE) are the lipids in the membrane. Because PE is a lipid, the R groups must represent the acyl chains.

QUESTION 19 Based on the passage, unpleasant healthcare experiences act as: a. positive reinforcement. b. negative reinforcement. c. positive punishment. d. negative punishment.

C. got wrong, chose A, didn't rmr diff between reinforcement and punishment a. Positive reinforcement: adding something (a pleasant healthcare experience) to increase the effect (of seeking healthcare). Does not occur here, because behavior is being REDUCED (which means punishment). Not a reinforcer - so cross out choices A and B. b. Negative reinforcement: removing something (a unpleasant healthcare experience) to increase the effect (of seeking healthcare). Does not occur here, because behavior is being REDUCED (which means punishment). Not a reinforcer - so cross out choices A and B. d. This would mean that a pleasant stimulus is removed to reduce behavior (of seeking healthcare). Does not occur here - something is not being taken away (negative) to reduce behavior, rather a positive stimuli is being added).

QUESTION 27 A teacher rewards his students by distributing plastic chips. Students receive a chip for each instance of desirable behavior. At the end of each month, they can exchange their chips for prizes. The teacher sees major decreases in undesirable behaviors as a result of this system, which is known as: a. aversive conditioning. b. operant extinction. c. a token economy. d. an unconditioned stimulus.

C. got wrong, chose B bc did not know what token economy was Token economy is a type of secondary reinforcement in which something of meaningless value is paired indirectly to other reinforcers (such as a prize). In this economy, a token is given and it can be exchanged for a prize (also a secondary reinforcer) a. Wrong, this is type of conditioning where a undesirable action (US) is paired with a undesirable response in order to reduce behavior. The undesirable action becomes the CS and is paired with an undesirable response (CS). This leads to a decrease in the action. This is an example of positive punishment - something is added (undesirable CR) to reduce behavior (reduce behavior= punishment). In this example, children are being rewarded to increase behavior (positive reinforcement) b. Operant extinction only occurs when the behavior does not occur anymore (it becomes extinct). This is not occurring in this example because desirable behaviors are being acquired (and not going extinct) d. Eliminate right away, Unconditioned stimuli are involved in classical conditioning. this experiment is speaking about operant conditioning

QUESTION 7 What is the mechanical work done by the cantilever when the extension increases from 10 nm to 15 nm? a. 2.00 × 10-22 J b. 4.70 × 10-20 J c. 2.50 × 10-19 J d. 5.00 × 10-18 J

C. got wrong, chose D bc did not know how to calculate but kinda was on the same page but must've done the math incorrectly Triangle Area = ½ × base × height Look at figure 2. Extension from 10-15, means the area under that triangle since W = Fd. Therefore, the answer is 0.5*100pN * 5nm = 0.5*100*10^-12 N * 5 *10^-9 m = 250 *10^-21 = 2.5*10^-19 J

QUESTION 21 What happens to the pH of a soapy solution as a result of the introduction of hardness ions? a. The pH increases as [H+] increases. b. The pH is not changed since no acid-base reaction occurs. c. The pH decreases as [OH - ] decreases. d. The effect on pH depends on the identity M2+.

C. got wrong, chose D did not recognize how to solve problem Removal of weak bases such as RCO2- results in a decline in pH and a decrease in OH-. Remember that RCO2- is a WEAK base, and the conjugate of this creates a strong acid. a. This can be eliminated, pH decreases as H+ increases b. An acid-base reaction does occur. Moreover, this reaction will affect the pH of the solution since weak bases are eliminated from solution. d. The effect on pH is always the same for the three cations listed.

QUESTION 17: The structure of serotonin is shown. Where are the serotonin receptors 5-HT2A and 5-HT2B most likely to be located in hepatocytes? a. In the nucleus b. In the cytosol c. Embedded in the mitochondrial membrane d. Embedded in the cell membrane

D. Got it correct but not sure if my reasoning was correct Bc PM has hydrophilic heads gfacing out that means nonpolar molecules can pass through easily and not polar. The hydroxyl group and amine group of serotonin makes the molecule polar and thus, it does not readily cross the phospholipid bilayer that is the cell membrane. It is most likely that the serotonin receptors on hepatocytes are embedded within the cell membrane to facilitate serotonin transport. a,b,c. This is incorrect. The hydroxyl group and amine group of serotonin makes the molecule polar and thus, it does not readily cross the phospholipid bilayer of the cell membrane. Therefore, it is not likely to be located in the nucleus, cytosol, or mitochondrial membrane

QUESTION 20 The hardness ions described in the passage (Mg2+, Fe2+, Ca2+) are: a. alkaline earth metals. b. strongly acidic cations. c. formed in nature by reduction of other cations. d. derived from atoms upon loss of two electrons.

D. got correct All the ions described in the passage have a +2 charge, meaning they lost two electrons.

QUESTION 26 Positron Emission Spectroscopy (PET) imaging involves injecting a patient with a positron (anti-electron) emitting isotope. The emission of positrons occurs during: a. alpha decay. b. alpha absorption. c. gamma absorption. d. beta decay.

D. got correct Beta decay is the decay in which a beta particle (electron or positron) is emitted from a heavy-atom nucleus. a. During alpha decay, alpha particles (He nuclei) are emitted by the heavy-atom nuclei. b. During alpha absorption, alpha particles (He nuclei) are absorbed by the target atoms. c. Absorption of gamma rays consists of the process in which high energy photons (also called gamma ray photons) are absorbed by target atoms.

QUESTION 12 Compound 1 remains mainly confined to the central phase during the experiments because it is: a. hydrophilic with only polar groups. b. hydrophilic with both polar and nonpolar groups. c. lipophilic with only nonpolar groups. d. lipophilic with both polar and nonpolar groups.

D. got correct Compound 1 mimics a membrane symport. Thus, it is lipophilic. The structure has both polar (X: carboxyl group) and nonpolar (18-crown-6 itself and Y: amide and ether) groups.

QUESTION 24 Which conclusion is supported by Figure 1? a. Person A showed improvement in both types of memory at post-test. b. Person B showed improvement in memory for childhood events at post-test. c. Both Person A and Person B showed improvement in both types of memory at post-test. d. Person A showed improvement in memory for events right before the brain injury at post-test.

D. got correct D is correct. Figure 1 shows that Person A showed an improvement in memory for events right before the injury at post-test.

QUESTION 20 Another researcher reviews the study described in the passage and suggests that the medical mistrust experienced by Black men can be explained, in part, by the concept of institutional discrimination. Which statement best describes that concept? a. Discrimination is not systematic, except when observed within institutions. b. If they have a history of unfair treatment, institutions are labeled as discriminatory. c. When several individuals exhibit prejudiced attitudes within an institution, then that institution will also be discriminatory. d. As opposed to discriminatory acts committed by individuals, there are institutional policies that disadvantage certain groups and favor others.

D. got correct D is correct. Medical mistrust could be considered part of a general mistrust in institutions (for example, medicine, government, economy) that some social groups experience. Of the options, D is the best description of institutional discrimination, since it identifies the contrast with individual discrimination. a. This is incorrect because discrimination is not considered random, and so the contrast is not accurate. b. This is incorrect because a history of unfair treatment is imprecise as a description of institutional discrimination. The option does not address the distinction with individual discrimination. c. This is incorrect because institutional discrimination is not an additive process. This option also misses the distinction between prejudice (attitude) and discrimination (behavior).

QUESTION 7 A study finds that low birth weight is associated with delayed cognitive development in childhood. Based on this result and the studies in the passage, children born to women living in which neighborhoods are likely to be at greater risk of falling behind in elementary school? a. Asian American enclaves b. Neighborhoods next to Asian American enclaves c. Neighborhoods with extensive reciprocal exchange d. Neighborhoods with high rates of violent crime

D. got correct The independent variable is the low birth weight and the dependent variable is the psychological response to stressors before the birth. If you measure the psychological response after the birth has already occurred, the response you are measuring could be totally different from the response you would have got before the birth. In general, the independent variable must be before the dependent variable because the independent variable is manipulated to see the effects on the dependent variable. AAMC: In this question, information from both studies in the passage is used to set up a scenario involving an additional psychological factor. Identifying the correct answer relies on knowledge that scholastic achievement can be affected by cognitive development. D is correct because environmental stressors (such as high violent crime rates) are associated with an increased risk of low-weight births. a. This is incorrect because the second study in the passage suggests that low birth weight is less frequent in metropolitan areas with clusters of Asian American enclaves. b. This is incorrect because proximity to an Asian American enclave, although seemingly related to the second study in the passage, is not a factor that is specifically identified in the study. c. This is incorrect because limited reciprocal exchange is identified as a factor associated with low birth weight. Extensive reciprocal exchange, on the other hand, is more likely to be a protective factor.

QUESTION 2 The side chain of which amino acid is used by transaminases to bind to pyridoxal phosphate in the enzyme's resting state? a. Val b. Asp c. Phe d. Lys

D. got correct The side chain depicted in Figure 2, is -(CH2)4NH2 which corresponds to lysine, or Lys. The resting state is shown as Compound 7 in Figure 2. a. This is valine whose side chain is -CH(CH3)2. b. This is aspartic acid whose structure is shown in Figure 1. c. This is phenylalanine whose side chain is -C6H5.

QUESTION 16 Which statement correctly describes both PO43- and TNBS? a. Both TNBS and PO43- are hydrophobic. b. TNBS is hydrophobic and PO43- is hydrophilic. c. PO43- is hydrophobic and TNBS is hydrophilic. d. Both TNBS and PO43- are hydrophilic.

D. got correct The structure of TNBS shows that it contains three polar substituents on a benzene ring and it says in passage and it also says "membrane-impermeable reagent", which makes the molecule hydrophilic. Also, it does not cross the hydrophobic membrane. Phosphate is a negatively charged hydrophilic ion. Phosphate is a charged species and TNBS is also hydrophilic because it does not cross the lipid membrane and it also has polar substituents such as the nitrate groups.

QUESTION 23 A pump is used to force an aqueous solution through a pipe at high temperature according to Poiseuille's Law: where ΔP is the pressure difference applied by the pump, r is the radius of the pipe, L is the length of the pipe, and η is the viscosity of the solution. Which graph depicts the rate of energy consumed over time in order to maintain constant flow through a pipe subject to boiler scale? graphs on other side

D. got correct You're basically looking for a graph that will give you a positive, nonlinear relationship based on the form of Poiseuille's law they show you -- i.e., you'll need more energy to push through a constricted pipe, and the radius term is to the fourth power.

QUESTION 13 What modification of Compound 1 will favor transport of Na+ relative to K+? a. Replace X with CH3. b. Replace Y with CH3. c. Increase the ring size by adding one -CH2CH2O-. d. Decrease the ring size by removing one -CH2CH2O-.

D. got correct, but don't know why Reducing the ring size could favor one molecule transported over another that are chemically similar. Looking at the periodic table, Na+ is smaller than K+ (K+ is below Na+ on the periodic table). Reducing the ring size would favor this. a&b. The X and Y group would not favor one molecule over another because the "CENTRAL portion of the molecule is what selectively binds to cations based on their ionic radius" as discussed in the passage. c. Increasing the ring size would favor larger cations, not smaller ones

QUESTION 3 Which change to an equilibrium mixture of compounds 1-4 will increase the ratio of Compound 4 to Compound 1? a. Adding Compound 3 b. Increasing the temperature c. Adding more catalyst and pyridoxal phosphate d. Adding Compound 2

D. got correct, recognized that it was asking about Le Chatelier's Principle Application of Le Châtelier's principle can be used to arrive at the key. The ratio of Compound 4 to Compound 1 can be increased by removing some Compound 3 or adding Compound 2. a. Removing, not adding, Compound 3 will increase the ratio of Compound 4 to Compound 1. b. For this reaction, since Keq = 1.0 and the similarity of the products and reactants it can be assumed that the reaction is nearly thermoneutral. Changing the temperature will not change the position of equilibrium. Even if the equilibrium is disturbed by temperature changes, it is not possible from information supplied in the passage to assess in which direction the equilibrium will be shifted. c. Adding catalyst or cofactor will only speed the rate at which equilibrium is attained, but will not affect the equilibrium concentrations of the reagents.

QUESTION 14: Lysine and amino acids with similar chemical characteristics in histones most likely promote the interaction of histones with which DNA components? a. Purines b. Pyrimidines c. Deoxyribose d. Phosphate groups

D. got it correct Lysine is a basic, positively-charged amino acid that interacts with negatively-charged phosphate groups on DNA.

QUESTION 3 Which statement is NOT compatible with the hypothesis that the self-serving bias can account for participants' explanations of their body weights? a. Obese participants view their unhealthy weight as a result of having too many fast-food restaurants near home. b. Non-obese participants view their healthy weight as a result of having strong willpower. c. Obese participants view their unhealthy weight as a result of not having time to exercise regularly. d. Non-obese participants view their healthy weight as a result of not having any fast food restaurants near their home.

D. got it correct Self-serving bias suggests that when explaining their own behavior, individuals attribute positive behaviors to internal, stable sources, but attribute negative behaviors to external sources. A non-obese individual would attribute his or her healthy weight to an internal, stable source, such as strong willpower. However, a non-obese individual would not attribute his or her healthy weight to an external source, such as not having any fast food restaurants near home. Therefore, D is incompatible with the self-serving bias. NOT taking credit for a positive outcome a. Obese person blaming their fatness due to an external factor (i.e. fast food chains) b. Skinny person claiming their fitness to an internal factor c. Fat person blaming external factors (i.e. lack of time) for their laziness

QUESTION 26: The Gibbs free energy equation can be used to predict whether a reaction will proceed spontaneously. For which relative values of ΔH and ΔS will a spontaneous reaction always occur? a. A positive ΔH and a negative ΔS b. A positive ΔH and a positive ΔS c. A negative ΔH and a negative ΔS d. negative ΔH and a positive ΔS

D. got it correct The Gibbs free energy equation is ΔG=ΔH-TΔS. In order for a reaction to occur spontaneously, the final value for ΔG must be negative. The only combination of ΔHand ΔS that will always result in a negative ΔG is a negative ΔH and a positive ΔS because of the presence of the -T term.

QUESTION 27: Which type of molecule is LEAST likely to be found in a eukaryotic cell membrane? a. Phospholipid b. Cholesterol c. Glycoprotein d. Peptidoglycan

D. got it correct Peptidoglycan is found in the cell walls of some bacteria, but not in the cell membranes of eukaryotes. refer to Q6 for what prokaryotes and eukaryotes contain in PM

QUESTION 16: According to the passage, platelets are LEAST likely to contain: a. transmembrane serotonin transporters. b. ribosomes. c. serotonin. d. Ki67.

D. got it correct Remember that platelets are cell fragments without nuclei, therefore they would not be expected to have a protein like Ki67 which is "detected exclusively in the nuclei of proliferating cells" (paragraph 2) as mentioned in the passage. a. This is incorrect. The passage states that platelets are carrying serotonin that has been synthesized outside the platelets; therefore, there must be a mechanism for transporting serotonin into platelets. Serotonin would be transported into platelets by transmembrane transporters. This option is very likely to be true; therefore, it is not the correct answer. b. This is incorrect. Platelets are formed from large cells called megakaryocytes. Platelets consist of plasma membrane-encased megakaryocyte cytoplasm, which contains ribosomes. This option is very likely to be true; therefore, it is not the correct answer. c. This is incorrect. A major point of the passage is that platelets carry serotonin. This option is very likely to be true; therefore, it is not the correct answer.

QUESTION 1 Which conclusion is best supported by the findings in Figure 1? a. Non-obese participants experience more cognitive dissonance than obese participants. b. Participants experience more cognitive dissonance in homophilous groups. c. Non-obese participants conform more than obese participants. d. Participants conform more in homophilous groups.

D. got it correct The question requires identifying the concept that is assessed in the study as conformity and combining this information with the numeric information in Figure 1. The "Fraction of diary adopters" refers to the fraction of participants who adopted a diary after they were told that their buddy had started using one, which is an example of conformity. The figure shows that all participants conform more in homophilous groups (indicated by the gray bars). A&B. Misidentifies the concept that is being assessed as cognitive dissonance. C. Suggests that non-obese participants conform more than obese participants, but this is not correct across all conditions. Figure 1 shows that in the homophilous condition, obese participants conform more than non-obese participants.

QUESTION 9: Chloramphenicol did NOT inhibit translation in E. coli cells containing the cat6xbs expression plasmid. What experimental parameter could be changed in order to affect translation inhibition? A. Increase the chloramphenicol concentration. B. Increase the chloramphenicol incubation time. C. Alter the incubation temperature by a few degrees. D. Use an alternate antibiotic.

D. got it wrong and chose A chloramphenicol is ineffective -- any type of alteration other than the change of the type of antibiotic will not be effective As stated in the passage, the cat transcript encodes chloramphenicol acetyltransferase. Without even being familiar with this protein, the reader should be able to tell by looking at the name of the protein that it is an enzyme (-ase) that causes chloramphenicol to undergo a chemical change (acetyl transfer). This renders chloramphenicol ineffective and confers antibiotic resistance to the cell regardless of the chloramphenicol concentration or incubation time. A moderate increase in the temperature should increase the translation efficiency. Thus, use of an alternate antibiotic is the only reasonable choice of those presented. Thus, D is the correct response.

QUESTION 14 Suppose that, under the experimental conditions employed, Compound 1 is "saturated" with cations. What graph depicts the expected change in rate of K+ transport from the "IN" to the "OUT" phases at pH 2 (Trial 1 conditions) as a function of increasing K+ ion concentration in the "IN" phase? graph answer choices on other side

D. got wrong, chose C Increasing the amount of substrate at saturation will not change the rate of reaction.

QUESTION 23: Does the experimental approach described in the passage yield cells that could be used in an animal model of Parkinson disease to replace dopamine-deficient neurons in the brain? a. Yes, because the cells obtained have the functional characteristics of nerve cells. b. Yes, because the cells obtained are similar to cells in the central nervous system. c. No, because the cells obtained may contain tumorigenic pluripotent cells. d. No, because the cells obtained lack the correct neurotransmitter phenotype.

D. got it wrong, chose B Although the cells obtained under the experimental conditions are similar to CNS neurons and may therefore be similar to neurons found in the brain, the neurons that are generated produce either glutamate or GABA. Since Parkinsonism is associated with deficiency of dopamine-producing neurons, neither of these 2 types of cells would alleviate the symptoms of this disorder. a. This is incorrect. It is not sufficient that the cells are functional neurons, the cells have to be dopamine-synthesizing neurons. b. This is incorrect. It is not sufficient that the cells are similar to neurons that may be found in the brain, the cells have to be dopamine-synthesizing neurons. c. This is incorrect. The cells obtained are differentiated neuron-like cells that are derived from differentiated fibroblasts; no pluripotent intermediate is involved in the production of the reprogrammed cells.

QUESTION 6: Which other cellular components are likely to be located near the lacY6xbs transcript in the cell membrane? A.Proteins and glycolipids B. Glycolipids and sterols C. Sterols and phospholipids D. Phospholipids and proteins

D. got this correct but because I did was thinking of cell membrane components but needed to recognize that the passage was about E.coli (a prokaryote). The passage states lacY is located near the cell membrane, so the answer will have to be the cell components of an E.coli membrane (a prokaryote). E.coli is a gram negative cell. Gram negative cells have a thin peptidoglycan layer and a outer cell wall (which contains LPS). E.coli membranes, like all cells, have plasma membranes (inner most) and this plasma membrane contains 75% protein, and 25% phospolipids. Typically, these are the major two components of all cell membranes Prokaryotes CM: do not contain sterols, glycolipids or glycoproteins do have phospholipids, proteins, sphinglolipids (see below in extra info) Eukaryotes CM: contain sterols (cholesterol for fluidity), glycolipids and glycoproteins (serve as recognition molecules) Extra Info: Most prokaryotes cell membranes also do contain include spingolipids (which can be a phospolipid when head group contain a phosphates - this is then called a spingomyelin. The other types of spingolipids are eramide (OH head group), or glycolipids (sugar head group) such as cereboside (one sugar), globoside (2+ sugar), and ganglisoide (oligosacharide with NANA/Salic acid)

QUESTION 1: The muscle subtype represented by Culture C is LEAST likely to be characterized by: A. a fast rate of muscle contraction. B. the ability to engage in oxidative and anaerobic respiration. C. the presence of medium-sized motor units. D. low densities of mitochondria and capillaries.

D. got this wrong because i did not understand which culture (A, B or C) related to which muscle type in the table in the passage. Don't be fooled by this answer choice. Even though in the "Activity used for" section it states anaerobic. The type IIA muscle fiber still exhibits "high oxidative capacity" which means it would be able to perform BOTH anaerobic and aerobic processes. Based on the passage, it can be inferred that Culture B is I, Culture A is Type IIx. Further, Culture C is then Type IIa. There are many clues to figure this out. If this is the case, Type IIa will have HIGH density of mitochondria for oxidative phosporylation (which is indicated as being high for IIA). make sure to look at LEAST likely in the passage.

QUESTION 12 According to the hypothesis presented in the passage, which drug is most likely to cause a decline in the wheel-running behavior of ABA-induced rats? a. Alcohol b. Cocaine c. Marijuana d. Morphine

D. got wrong, chose A D is correct. The hypothesis suggests that exercise addiction results from the fact that exercise increases endorphin levels. If this neurotransmitter is stimulated by a drug, then ABA-induced rats would be less likely to run in their wheels (because their endorphin levels would be elevated by an alternative method). The only drug in the list that is an endorphin agonist is D, morphine. a. This is incorrect because alcohol is not directly associated with increases in endorphin levels. b. This is incorrect because cocaine is not directly associated with increases in endorphin levels. c. This is incorrect because marijuana is not directly associated with increases in endorphin levels.

QUESTION 24 Which experimental approach can be used to analyze the metal content of soapy precipitate produced by Reaction 1? Dissolve the solid in a known volume of: a. 0.1 M NaHCO3(aq), then titrate with standardized 0.1 M HCl(aq) using an indicator. b. 0.1 M NaOH(aq), then titrate with standardized 0.1 M HCl(aq) using an indicator. c. 0.1 M NaCl(aq), then titrate with standardized 0.1 M NaOH(aq) using an indicator. d. 0.1 M HCl(aq), then titrate with standardized 0.1 M NaOH(aq) using an indicator.

D. got wrong, chose B bc don't rmr enough abt acids and bases titrations Thanks for the question -- this is definitely one that a lot of students get confused about. In order to understand this, let's work through why D is correct first. I'm going to use "X" to refer to the stearate chain and "XH" to refer to its protonated version, stearic acid, just to avoid typing out C17H32COO.Per reaction 1, the precipitate is MX, and our goal is to dissolve that. Even an "insoluble" compound with a tiny Ksp will have some of its components in solution, so what we want to do is to find something that will react with M2+ or with X- in a way that will "get rid of it" in order to push the dissolution reaction forward through Le Chatelier's principle. HCl will do the trick perfectly by forming XH. This will push the dissolution reaction forward AND give us a nice weak acid to titrate with strong base.Now what about NaOH? Theoretically the OH- could interact with M2+ to form M(OH)2 compounds. The thing is that at least for two of the M2+ ions (Ca2+ and Mg2+), M(OH)2 is soluble, so we'd still just have a few M2+ ions floating around, and it wouldn't really push the dissolution reaction forward. For Fe2+, we would get an insoluble hydroxide, so that could conceivably work, but it's not a general solution for all M2+ ions that the passage discusses.

QUESTION 9 What are the units for the rate constant ku discussed in the passage? a. M-1•s-1 b. M•s c. M•s-1 d. s-1

D. got wrong, chose B did not know how to go about solving This is the unit for a first-order reaction. We know that this is a first-order reaction because the passage states that the unfolding occurs in a unimolecular mechanism Question: How do you know this is a unimolecular mechanism Answer: bc unfolding of protein only depends on the protein itself (not anything else) a. This is the unit for second-order rate constant. Second-order graphs are [A]/t (inverse parabola) or 1/[A] vs time where k = slope (linear positive slope) b. not units for any rate constant, all rate constants are 1/s c. This is order for zeroth-order where graph is depicted as [A] vs time where k = -slope

QUESTION 18 The 32P label was generated from naturally occurring phosphorous by: a. removing a neutron from the nucleus. b. adding a proton to the nucleus. c. adding three electrons to the atom. d. adding a neutron to the nucleus.

D. got wrong, chose C, did not know to use B- decay Check the periodic table; see that P is normally 31. Therefore to get P32, you need to add a neutron AAMC: This question requires you to apply knowledge of the nuclear structure of the naturally occurring 31P nucleus, and of nuclear radioactivity through the process of beta decay. The 32P isotope contains an additional neutron in the nucleus compared to the naturally occurring 31P nucleus, which does not change the identity of the atom. The extra neutron emits a beta particle via beta-minus decay.

What is the difference between Type I and Type II muscle fibers?

Understand the difference between Type I and Type II Muscle fibers. Type I (slow-twitch) - mitochondria rich, slow twitch (slow conduction velocity), slow contraction speed, aerobic, long, low power, long duration, fatigue-free. Type II fibers - two types, Type IIA, and Type IIB. Type IIA are intermediate between I and IIB. Type IIB are white, fast contraction speed, fast-twitch (fast conduction velocity), anaerobic, short, easily fatigue, power, ATP from creatine phosphate.

Types of cell-cell signaling

cell-cell junction - the others are gap junctions (communicating junctions) and desmosomes (anchoring junctions). Tight junctions are present in the bladder, intestine, kidney (to prevent water), desmosomes are present in skin/intestine (let water through), and gap junctions are present in cardiac muscle and neurons.