Next Step FL #2

If the strong base solution used in the titration curve shown in Figure 2 was 0.10 M sodium hydroxide and the volume of the glycine solution titrated was 20.0 mL, what was the molarity of the glycine solution?

0.075 M From Figure 2, the sharp increase in pH that occurs at 15 mL of added NaOH solution represents the equivalence point, at which the carboxylic acid group is fully neutralized. 15 mL NaOH x [0.10 mole/L] x [1 glycine/1 NaOH] x [1/20 mL] This simplifies to: [15/20] x 0.10 = (3/4) x 0.10 = 0.075 moles/L We can calculate our unknown concentration or volume using the formula NaVa = NbVb, where N and V are the normality (mol/L) and volume of the acidic and basic solutions, respectively. It is important to convert from molarity (M) to normality (N) for polyprotic acids and polyvalent bases The flat regions of titration curves represent buffering solutions (a roughly equal mix of an acid/base and its conjugate), while the steep, near-vertical sections of the curve contain equivalence point(s), which indicate that enough of the titrant has been added to completely remove one equivalent (acid or base group) from each of the original molecules in the unknown solution.

When the substrate level is equal to Km, one can infer that the rate of the reaction in Figure 1 will be:

0.43 M/s The passage states that Km represents the substrate concentration required for the reaction rate to reach half of its maximum, or Vmax. (Even if this definition had not been given, Km and Vmax are concepts that you must understand for the MCAT.) Figure 1 depicts Vmax as 0.85 M/s. Half of this value is about 0.43 M/s.

According to the data in Figure 1, what is the probability that a male Robertsonian translocation carrier who mates with a normal female will produce a viable offspring?

1/2 According to Figure 1, there are 6 possible outcomes for the gamete production in a 14/21 translocation carrier. Going from left to right, we have a normal gamete, a balanced translocation (all genetic info is present; this gamete would give rise to another ROB carrier), Trisomy 21, Monosomy 21, Monosomy 14, and Trisomy 14. There are no viable autosomal monosomies, and the only viable autosomal trisomies you should know are Trisomy 21, 18, and 13 (though Trisomy 8, 9, and 22 can also survive to term). Therefore, of the 6 gametes produced by the man, 3 of them contain genetic information that would produce a viable offspring (two normal, one with Down Syndrome). 3/6 = 1/2

According to the passage, which of the following relationships must hold? (Note: 1 m3 = 1000 L.)

100 kPa is equivalent to 100 J/L This is a unit conversion problem: 100 kPa = 100,000 Pa = 100,000 N/m2 = 105 N/m2 100 J/L x (1000 L/m3) = 105 J/m3 = 105 Nm/m3 = 105 N/m2

According to the data in shown in Figure 1, the Km for the demethylation of the histone by KDM4C is most nearly:

120 μM For an enzyme-catalyzed reaction, the Michaelis constant (Km) is the substrate concentration required to reach one-half of the maximal velocity, or Vmax. The question mentions KDM4C, so we are concerned with the graph on the right. The Vmax looks to be just over 1, maybe about 1.1-1.2 μM/min (the test makers will not expect pinpoint accuracy), so half of that value gives us 0.5-0.6 μM/min. Examining the graph, we can see that this velocity corresponds to a point somewhat greater than 100 μM but significantly less than 200 μM. Choice C is the only answer within this range.

Pentane is a straight-chain hydrocarbon with the molecular formula C5H12. How many additional structural isomers ca

2 *Background* If all of the chiral centers have different configurations, the isomers are non-superimposable mirror images (similar to your hands), known as enantiomers. Enantiomers have identical chemical and physical properties, but they differ in their rotation of plane-polarized light (opposite directions) If the isomers have multiple chiral centers but differ only at some, they are known as diastereomers

How many chromosomes are found in a liver cell of a Robertsonian translocation carrier?

45 As stated by the passage, in ROB, two acrocentric chromosomes have broken at the beginning of the short arm near the point where it meets the long arm. The long arms then fuse together. The resulting chromosome consists of two long arms but no short arms. The short arms are lost, but as all the genes on a short arm are available on the short arms of other acrocentric chromosomes, a Robertsonian translocation carrier will have no health problems due to his or her chromosome rearrangement. However, while other people usually have 46 chromosomes, Robertsonian translocation carriers have 45. We can also see that in Figure 1, in order to create ROB two chromosomes are combined and create two more, one of which is lost. Thus we have a net loss of 1 chromosome. The normal human cell has 46 chromosomes, so 46 - 1 = 45.

What is the difference between the maximum and minimum volume of air in the lungs of an 80-kg man?

5.2 L From Figure 1, we see the maximum volume held in the lungs is 80 ml/kg, while the minimum is 15 ml/kg. This is a difference of 65 ml/kg, which, for an 80-kg man, amounts to (65 ml/kg)(80 kg) = 5200 ml, or 5.2 L.

Assuming a 95% yield for each coupling step, what would be the final yield for synthesizing a 10 amino-acid length peptide?

60% Each time we add an amino acid to the chain, we get a 95% pure yield for that step. Here, imagine that each coupling step has a 95% yield and that we are running the cycle 9 times (since no coupling step is needed for the first of the 10 amino acids), with each cycle being independent from the preceding cycle. Thus, a 10-amino acid peptide would be synthesized in a (0.95)9 = 0.63 ≈ 60% final yield.

Given the data discussed in the passage, if a hospital requires at least 250 g of 145Nd to complete a standard cardiac image, how long will it be before it must replace a 2000 g sample?

75 minutes The decay of a substance can be calculated by knowing its half-life, the time it takes for half of the original amount to decay. The final paragraph states that about 93% of the decay occurs in the first 100 minutes. This leaves about 7% of the sample left, which would indicate that close to 4 half-lives (0.54 = 0.0625 = 6.25% remaining) have passed at the 100-minute mark. Thus, 1 half-life = 100/4 = 25 minutes. The hospital sample is 2000 g and must be replaced once it reaches 250/2000, or 1/8 of its original radioactivity. Using the shortcut that the amount remaining = (1/2)n, where n represents the number of half-lives that have passed, we can calculate 1/8 = (1/2)3. Therefore, 3 half-lives will pass before the sample drops below 250 g. At 25 minutes apiece, 25 min (3) = 75 minutes. If we know the half-life of a material, then we can determine how much of a sample is lost (1- ½n) or remains (½n) at any given time, as expressed in the number of half-lives that have passed (n).

Which of the following most closely approximates the pKa of phenolphthalein?

9.3 . Indicators function in acid-base titrations to identify, via color change or a similar mechanism, that an expected pH, and thus the titration endpoint, has been reached. In order to function in this way, an indicator must undergo a color change near the desired pH. This typically occurs because of a reversible change in the protonation state of the indicator. It is desirable then that the pKa of a chosen indicator be within ±1 unit of the target pH. For the titrations performed in the study of acetic acid, a weak acid, and sodium hydroxide, a strong base, the endpoint of the titration will occur at a pH greater than 7.

Which of the following was NOT a finding by Harry Harlow in his experiments with rhesus monkeys and their pairing with a simulated mother made from wire (Wire Mother) or one made from soft cloth (Cloth Mother)?

After early neglectful conditions, monkeys' abnormal behavior could be corrected by pairing them with the appropriate simulated mother. In Harlow's experiment, the infant monkeys preferred spending their time clinging to the cloth mother. Even when only the wire mother could provide food, the monkeys visited her just to eat. Harlow concluded that there was much more to the mother/infant relationship than milk and that this "contact comfort" was crucial to the psychological development and health of infants. After monkeys were paired with a Wire Mother, they showed abnormal behavior, which could not be corrected later in life by pairing them with a Cloth Mother. Go over Harlow's experimeent*

While the composition of oxygen and nitrogen in air does not change with altitude, the decreasing temperature at high altitude does change the percent of air that is composed of H2O. Assuming constant relative humidity, which of the following can be asserted about the total grams of H2O in a given volume of air at 3000 m above sea level versus at sea level?

Air has significantly less mass of H2O per unit volume at 3000 m above sea level. Decreasing temp --> decreases moles of H2O colder hair can hold less H2O so the same relative humidity would result in less total water in air

Which of the following molecules is/are most likely to have selective proteins in the BBB to facilitate its passage into the brain

Amino acids The correct answer will be a molecule or substance that is essential to brain function. Amino acids are necessary for the production of proteins, which are essential for the function of any cell.

Which of the following is an example of how altruistic behavior can improve inclusive fitness?

An animal making noise to alert its brood that there is a predator Inclusive fitness involves an animal behaving in ways that ensures the propagation of its genes. An animal alerting its brood that there is a predator puts that animal at risk, but ensures that its genes may survive via its offspring

Based on the information presented in the passage, which of the following is most likely true about infections of the CNS?

Bacterial infections of the brain are more serious because antibiotics or other treatments have a hard time passing the blood-brain barrier.

If trifluoroacetic acid is the reagent used in SP synthesis, which of the following would be the most effective for creating an effective support system?

Benzene The list of characteristics in the passages states that an ideal support "...must be inert to all reagents and solvents used during SP synthesis." The question tells you that we are using a weak acid in the synthesis, so we want a molecule that will be inert to the actions of an acid. Benzene, the aromatic hydrocarbon shown below, is very stable (inert) in the presence of ac

The findings of the experiment support which of the following conclusions?

Both analogs act as ADAMTS inhibitors

In which of the following molecules does the carboxylic acid functional group have the highest Ka?

CH3CF2COOH A higher Ka is associated with stronger acidity. Adding electron-withdrawing functional groups (like fluorine atoms) provides inductive stabilization of the conjugate base by pulling electron density away from the negatively-charged position (shown below). This stabilization increases the acidity of the original compound. Inductive effects increase if the electron-withdrawing groups are closer to the acid and if more of them are present.

Which of the following molecules will have the highest Rf value when studied with thin-layer chromatography using a silica plate?

CH3CH2CH2CH2CH3 High Rf= non polar Silica is a highly polar molecule; thus, when chromatography is done on a silica plate, a polar substance will move slower on the plate due to polar-polar interactions between the substance and the plate. This means that the Rf value of a polar substance will be smaller than that of a nonpolar substance since the substance will move less on the plate compared to the solvent front than a nonpolar substance would.

Arachidonic acid, released during AEA hydrolysis, is NOT a precursor for the synthesis of what class of molecules?

Catecholamines in the first paragraph of the passage, it's written that AEA is degraded to ethanolamine and arachidonic acid. Ethanolamine is included as a polar head group in the phospholipid phosphatidylethanolamine, while arachidonic acid is important as a precursor for the biosynthesis of the eicosanoid signaling molecules: prostaglandins, thromboxanes, and leukotrienes. Neither molecule contributes to the synthesis of catecholamines, which are a class of molecules derived from tyrosine. Eicosanoids are a large family of lipids derived from arachidonic acid, a 20-carbon omega-6 polyunsaturated fatty acid with four cis double bonds. Like their parent compound arachidonic acid, eicosanoids have 20 carbons, and they have the additional characteristic feature of a five-carbon ring. The most important eicosanoids are a large family of signaling molecules known as prostaglandins, which have a diverse range of effects, including the modulation of inflammation. Additionally, thromboxanes are involved in the clotting cascade. The enzymes cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) are involved in early steps of this pathway, and are targeted therapeutically by non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin.

Which of the following best explains why chemical synapses are slower than electrical synapses?

Chemical synapses require the movement of agents through intercellular space This answer relates to the differences between these modes of transfer between cells. At gap junctions, the cells approach within about 2-4 nm of each other, a much shorter distance than the 20-to-40-nm intracellular space that separates cells at a chemical synapse. In chemical synapses, the chemicals must diffuse over these larger distances, which takes more time. A chemical synapse is shown below; note that it is what we typically think of when we think of a synapse. Indeed, chemical synapses are more common than electrical synapses.

Based upon the researchers' analysis of the extraction equilibria, the organic phase extractant forms what complex or complexes in low-polarity organic solvents and high-polarity organic solvents, respectively?

Complex A; complex B The two chemical equations shown in the passage indicate the structure of the organic phase extractant complex formed in both low-polarity and high-polarity organic solvents. In low-polarity organic solvents, copper (II) is coordinated with the organic phase extractant as part of a complex consisting of two dimers. Both dimers contain one molecule of lauric acid (HL) and another of its conjugate base, laurate (L). This is consistent with the structure of complex A shown in Figure 1. In high-polarity organic solvents, copper (II) is coordinated with the organic phase extractant as part of a complex consisting of two monomers of laurate. This is consistent with the structure of complex B shown in Figure 1.

Which of the following gives the correct formula for cupric laurate?

Cu(C12H23O2)2

*DIDNT GET WRONG BUT WANTED TO REVIEW*

Cultural Norms: Norms are enforced by sanctions, which are punishments for deviations from the norm or rewards for acting in accordance with it. Some norms are formal, meaning that they are written, explicit, and generally enforced with penalties; laws are classic examples of formal norms. In contrast, informal norms are generally understood but implicit, unwritten, and not associated with criminal or legal penalties for their violation Informal norms can be divide into Mores and Folkways - Mores are norms that are deemed highly necessary to the welfare of a society and have consequences if violated. - Folkways are norms that govern everyday behavior (like holding a door open) Breaking a folkway or any other social norm is termed deviance. Deviance can include behavior generally perceived as "bad" or morally wrong, such as stealing. To discourage deviance, societies use many forms of social control, or formal and informal methods of encouraging adherence to norms. One example is stigma, or the extreme disapproval and rejection targeted toward those thought to have broken important norms, such as those who commit incest. Social pressure can backfire, as in the case of strain theory, which is the idea that when social pressure is placed on those who do not have the means to follow it and succeed, they may turn to crime and other deviant behavior. - Taboos are considered unacceptable by almost every culture (like cannibalism or incest). - Laws are established standards of behavior that are written down and have clear consequences

If the DNA of a representative species from each of the major kingdoms was examined, the sequences coding for which of following would be expected to be most similar?

DNA synthesis DNA sequences that are common among different species, phyla, or even kingdoms are called conserved sequences. Conserved sequences tend to remain that way due to the fact that they code for a vital function that is common among disparate species

Which of the following steps could an organization take to make itself into a more ideal bureaucracy?

Evaluating how decisions impact stock price to promote value for stockholders in accordance with the company's mission An ideal bureaucracy will make decisions in accordance with its mission—in this case, to create value for shareholders. Background* The term bureaucracy refers to a rational system of administration, control, and discipline that is characteristic of large organizations. A typical (or ideal) bureaucracy has the following defining characteristics, which were first noted by the German sociologist and political economist Max Weber: it has a formal hierarchical structure; it is managed via a set of defined, specific rules and regulations; it is organized by functional specialty, with different workers performing different, specialized tasks; it has a unified mission that is either "up-focused," that is, to serve shareholders, a board, or some other entity that empowers it, or "in-focused", that is, to serve itself through maximizing profit or maximizing market share; it is purposefully impersonal; and employment is based on technical qualifications, either advanced degrees or training. These characteristics mean that bureaucracies are not very adaptable and that they can be quite inefficient. The British naval historian C. Northcote Parkinson added a seventh characteristic to Weber's six, demonstrating that the management and professional staff of bureaucracies tend to grow at a steady, predictable rate, regardless of what the organization is actually doing. This is known as Parkinson's law.

Extraction Background *

Extractions are a technique used to separate two or more compounds in solution by manipulating their solubility properties using acid-base chemistry. Typically, an extraction setup will have a layer of a less-dense organic (i.e. nonpolar) solvent on top of a layer of water, which is a highly polar compound. Nonpolar compounds in solution will move to the organic layer, while polar (or charged) compounds will be in the aqueous layer.

Which of the following best explains why a Robertsonian carrier may have no health problems due to his or her chromosome rearrangement?

Genes on the lost p arms can be found elsewhere in the genome In the figures, we can see that the short chromosomal arms are lost. However, if all of the genes on a short arm are available on the short arms of other acrocentric chromosomes, a Robertsonian translocation carrier will have no health problems due to his or her chromosome rearrangement.

The disruption of which membrane component is most likely to result in cellular traffic complications similar to those seen in gap junction disorders?

Glycoproteins The cell membrane is composed of several different components, each responsible for different functions. Membrane transport is most likely to be affected if the disruption occurs in components that span the entire membrane. Transmembrane proteins (many of which are glycoproteins) are the only component listed that pass all the way through the cell membrane and facilitate membrane transport. Cholesterol does not facilitate membrane traffic, nor does it extend across the entire membrane. Phospholipids and glycolipids are located on the surface of cell membranes and typically do not extend though the entire bilayer. Glycolipids act to provide energy and also serve as markers for cellular recognition. Phospholipids are a structural component of the membrane and are not involved in traffic/transport.

In a follow-up experiment, two identical gurneys are placed side-by-side on a ramp with their wheels locked to eliminate spinning. Gurney 1 has a dummy placed on it to give it a total mass of 200 kg, while Gurney 2 is loaded with a dummy that makes it only 50 kg overall. If the ramp has a coefficient of friction of μs, which gurney is more likely to slide down the ramp?

Gurney 1 and Gurney 2 are equally likely to slide In order for the gurney to slide down the ramp, the force pulling it downward (mgsinƟ) must be greater than the static frictional force (μsFN = μsmgcosƟ). The net force on each gurney is thus Fnet = (mgsinƟ) - (μsmgcosƟ). Since net force is equal to the product of mass and acceleration, we can rewrite this equation as ma = (mgsinƟ) - (μsmgcosƟ), where an acceleration greater than 0 means the gurney will slide down the ramp. The mass of the gurney is present in all terms and can be canceled, meaning that it is not a factor in whether the gurney slides. Thus, both gurneys have an equal likelihood of slipping down the ramp, regardless of the fact that they have different total masses.

Key Psychologist and Experiments:

Hans Eysenck studied personality with a strong focus on the biological perspective, which considers personality differences to be the result of biological factors. Harry Harlow examined parent/child attachment, social isolation, and dependency in rhesus monkeys. Finally, Muzafer Sharif's Robber's Cave experiment examined the intergroup conflicts that arise in response to competition over limited resources.

Researchers noted that when a lysine residue on a histone is acetylated, its side chain becomes neutral in charge. Combined with the information in the passage, which of the following conclusions will the researchers most likely reach?

Histone deacetylation generally decreases gene expression Lysine is a basic amino acid and typically has a positively-charged side chain at physiological pH. When lysine is acetylated, this charge becomes neutral, as shown in the figure below. Since DNA is negatively charged due to its phosphate backbone, the charge on lysine allows for tight histone-DNA interactions thanks to electrostatic attraction between the charged atoms on each molecule. Acetylation of lysine makes the residue neutral, lessening these interactions and promoting a looser structure. Loose chromatin structure is typically associated with euchromatin, the less dense, transcriptionally active chromatin structure that appears light under a microscope. In contrast, histone deacetylation will restore the positive charge to the residue, allowing the electrostatic attractions to return. Therefore, deacetylation of lysine residues on histones should lead to a denser chromatin structure and lowered transcription/gene expression (choice A) Histones are proteins that act as spools for DNA to wind around. Two distinct forms of chromatin exist: euchromatin and heterochromatin. Euchromatin is a loose configuration that is difficult to see under light microscopy and allows DNA to be readily transcribed. Throughout interphase (i.e., most of the cell cycle), DNA generally exists as euchromatin. Heterochromatin is the tightly coiled, dense form of chromatin that is visible during cell division and is present to a lesser extent even during interphase.

The hemoglobin (Hb) dissociation curve at high altitude has a distinct shape from that at atmospheric pressure. Which of the following best explains this shape?

Homotropic regulation by oxygen occurs. The sigmoidal shape of the curve implies that as each oxygen molecule binds to Hb, the affinity of Hb for oxygen goes up. Homotropic regulation is when a molecule serves as a substrate for its target enzyme, as well as a regulatory molecule of the enzyme's activity. O2 is a homotropic allosteric modulator of hemoglobin. The four subunits of hemoglobin actually bind to oxygen cooperatively, meaning the binding of oxygen to one of the four subunits will increase the likelihood that the remaining sites will bind with oxygen as well. This is the cause of the sigmoidal curve shown in the figure.

The table below gives pKa data for selected amino acids. Which of the amino acids listed will exist predominantly as a molecule with both positive and negative charges at pH of 8.0? I. Arginine II. Tyrosine III. Glutamic acid IV. Glycine

I, II, III, and IV At a pH of 8, all of the molecules as free amino acids will have at least one positive and one negative charge, as the carboxylic terminus will have a -1 charge and the amino terminus will have a +1 charge. According to the given table, arginine and glutamic acid will also have charged side chains. Free amino acids contain a minimum of two groups that can become charged. The first is the carboxylic acid terminal, which exists as neutral -COOH when protonated and negatively-charged -COO− when deprotonated. The second is the amino terminal, which becomes the positively-charged -NH3+ when protonated and the neutral -NH2 when deprotonated. Note that "protonated" is not always synonymous with "positive." A protonated position can be either positive or neutral, depending on the group in question. Similarly, a deprotonated position can be either negative or neutral. Low pH --> Protonation (COOH) High pH --> deprotonation (COO-)

What characteristics of society are associated with high levels of anomie? I. Rapid changes in society II. Low levels of income III. High heterogeneity

I, II, and III Anomie refers to society feeling fragmented and lacking cohesiveness. All of the characteristics listed are associated with anomie. Background* Within sociology, several models have been developed to describe social dysfunction. Anomie refers to the breakdown of social bonds, such as social norms, between individuals and communities. Sociologists use strain theory to study how the social breakdown characteristic of anomie can lead to social deviance and crime, which can in turn reinforce social stratification and dysfunction. Social dysfunction may also involve poverty, which refers to the state of having low socioeconomic status and few resources, financial or otherwise.

If a psychologist were to claim that the ideomotor effect is unconscious, Freudian psychologists could argue this effect resides in which components of the psychic apparatus? I. The id II. The ego III. The superego

I, II, and III All work subconsciously

Which of the following phase changes are exothermic processes? I. Liquid to gas II. Liquid to solid III. Gas to solid

II and III only This question tests your understanding of reaction enthalpies. Reactions that proceed from solid to liquid to gas are endothermic reactions, since gases have more heat energy than liquids and liquids have more heat energy than solids. On the other hand, reactions that proceed from gas to liquid to solid release heat, making them exothermic reactions. Thus, II and III are both exothermic reactions, while I is an endothermic reaction Endothermic process: melting, evaporation and sublimation (require heat | bond breaking) Exothermic process: freezing, condensation and deposition (release heat | bond forming)

Based on information in the passage, what type of inhibition best describes the action of NADPH on G6PD? I. Competitive II. Allosteric III. Irreversible

II only The passages states that high levels of NADPH inhibit G6PD, and Equation 1 shows that the substrate of G6PD is G6P. Because the structures of G6P and NADPH are very different, it is unlikely that that NADPH competes with G6P at the active site; thus, this is not competitive inhibition. The passage also never suggests that the inhibition of G6PD is irreversible; rather, it is likely to be dynamic based on the amount of NADPH available. Therefore, NADPH most probably binds to a site that is not the active site, which is characteristic of allosteric inhibition. A generic model of allosteric inhibition is included below.

Which of the following statements accurately describes a major assumption of the functionalist theory of social stratification? I. Social stratification affects what people believe about themselves and others and influences their daily life, lifestyle choices, and interactions with others. II. Social stratification is unnecessary and results from both lack of opportunity and discrimination against the poor and people of color. III. Social stratification is necessary and results from the need for those with special intelligence, knowledge, and skills to be a part of the most important professions and occupations.

III only Functionalist theories assert that aspects of culture are necessary and need-based. Background* The three main high-level sociological theories for the MCAT are symbolic interactionism, conflict theory, and functionalism. Symbolic interactionism focuses on the symbolic meaning that people develop and rely upon in the process of social interactions. Conflict theory instead emphasizes the role of coercion and power in producing social order. It sees society as fragmented into groups that compete for social and economic resources. Social order is maintained by those with the most power, usually those with the greatest political, economic, and social capital. Finally, functionalism views society as a system of interconnected parts that carry out a specific role that enables them to cooperate to maintain social equilibrium for society as a whole. An important point is that these perspectives do not contradict each other Turning to how individuals make choices, rational choice theory posits that people make individualistic, rational, and calculated decisions about all things in their lives. Since money is of primary importance to most people, individuals are often motivated by money and will calculate the costs and benefits of any action before deciding what to do. Game theory views social interaction as a game in which there will be winners, losers, and proper ways to "play" in order to achieve "victory." Finally, social exchange theory views society as a series of interactions that are based on estimates of rewards and punishments.

Which of the following changes occur immediately following the consumption of a carbohydrate-rich meal?

Insulin secretion increases; G6PD activity increases. From outside knowledge, we know that insulin secretion increases after a meal to help the cells take up glucose from the bloodstream. The passage states that the PPP is a parallel (alternative) path to glycolysis, so it makes sense that it would also be activated when blood sugar levels rise after a meal. Background* The two main hormones associated with glucose regulation are insulin and glucagon. Insulin is a peptide hormone released by the beta cells of the pancreas in response to high blood glucose levels. Its basic function is to reduce blood glucose levels by promoting the transport of glucose into cells via insulin receptors, which activate membrane-bound glucose transporters. The glucose transported into the cell can be used immediately through glycolysis; alternatively, muscle and liver cells can store the glucose as glycogen, and adipocytes (fat cells) can mobilize fatty acids to store downstream byproducts of glucose metabolism in the form of triglycerides. Insulin upregulates all those processes, as well as protein synthesis. Glucagon is a peptide hormone released by the alpha cells of the pancreas, and its mechanism and function are essentially the opposite of insulin. Glucagon is released in response to low glucose levels and has the effect of increasing blood glucose levels by promoting glycogenolysis and gluconeogenesis in liver cells.

Of what significance to the experimental goals is the finding that AAEL004181 has no introns?

It suggests that AAEL004181 originated from bacteria. For the most part, bacteria lack introns, whereas large eukaryotic genes usually contain several introns. A large, eukaryotic gene without introns suggests a bacterial origin. The researchers found that not only does the mRNA lack introns (expected for a eukaryote), but the gene itself lacks introns.

Key Psychologist and Experiments:

John B. Watson's Little Albert experiment involved the use of classical conditioning and stimulus generalization to cause a healthy young boy to fear furry animals and objects. Solomon Asch's conformity experiment demonstrated that individuals often conform to a group view, even when the group view differs from a clearly correct answer. Asch used a task in which a participant, along with several of Asch's confederates, were told to judge the relative lengths of drawn lines. The confederates would give a clearly-incorrect opinion regarding which line was shorter or longer, causing the participant (who did not know that the others in the room were "in on it") to conform to this incorrect view in some cases. Albert Bandura, a social cognitive psychologist, famously conducted his "Bobo doll" experiments, which showed that children can display observational learning for aggressive behavior when they watch adults exhibit such behavior.

What is the approximate partial pressure of oxygen at 1500 m? *DIDN'T GET WRONG BUT WANTED TO REVIEW*

Math: 642 mmHg *21 O2/100 = 132 torr =132 torr = x atm | 780 torr = 1 atm (so cross multiple) = 0.178 ~ 0.18

A climber using bottled oxygen accidentally drops the oxygen bottle from an altitude of 4500 m. If the bottle fell straight down this entire distance, what is the velocity of the 3-kg bottle just prior to impact at sea level? (Note: ignore air resistance) *DIDN'T GET WRONG BUT WANTED TO REVIEW*

Math: KE=PE 1/2mvˆ2 = mgh = 1/2(3kg)(vˆ2)=(3)(10)(4500) = vˆ2= 90,000 v= squareroot(90,000) = 300 m/s

What measure of central tendency most accurately captures the average wealth of most Americans, and why?

Median American wealth, because the median is less sensitive to outliers Median wealth is not influenced by those at the upper range of wealth, who disproportionally increase the mean wealth value.

Which phase of mitosis is likely to be first interrupted if a cell has no microtubules?

Metaphase This question requires us to remember the workings of mitosis. In mitosis, the spindle fibers that move chromosomes are made up of microtubules. They are attached to chromosomes in metaphase and pull them apart in anaphase. Therefore, the first phase to be affected by lack of microtubules will be metaphase

If it was found that individuals in the first study who took Truvada but had a high level of perceived stigma relating to Truvada use were more likely to use condoms than those who took Truvada but had a low level of perceived stigma relating to Truvada use, then which of the following terms would best describe the role of perceived stigma on the relationship between taking Truvada and using condoms?

Moderating variable A moderating variable is one that either decreases or increases the strength of an association. In this case, perceived stigma moderates the relationship between taking Truvada and using condoms.

Which of the following is NOT a correct description of a cognitive bias that adolescents may experience when making health-related decisions?

Negativity bias; only focusing on the good aspects of alcohol use and ignoring the bad This is an incorrect pairing of bias and description. Negativity bias is when the negative aspects of a situation are focused upon, not the good aspects Background* Cognitive biases are ways in which our perceptions and judgments systematically differ from reality. - The representativeness heuristic is the tendency to make decisions about actions or events based upon our standard representations of those events. - The closely related availability heuristic is the tendency to make decisions about how likely an action or event is based upon how readily available similar information is in our memories. - Belief bias is the tendency that people have to judge things based not upon sound logic, but upon already held beliefs. - Confirmation bias is a tendency that people have to focus on information that is in agreement with the beliefs they already have, rather than the information that is contrary to those beliefs. Another set of biases relate to how we interpret our and others' behavior.The fundamental attribution error refers to the tendency to place less importance on the import of a situation or context on behavior, and instead place undue emphasis on dispositional or internal qualities in order to explain behavior. Moreover, we often blame our own actions on external situations but the actions of others on personality. This is called the actor-observer bias. Similarly, self-serving bias is the tendency people have to credit their successes to themselves and their failures either to the actions of others or to situations. Biases can also relate to perceptions of group belonging, as in the in-group bias where people are biased towards those viewed as being part of their in-group. Biases can also play a role in responses to questionnaires; for instance, social desirability bias refers to the tendency that people have to give socially approved responses to questions in the context of research.

Which of the following charged particles will be attracted to the particle emitted during the decay of 145Nd?

Paragraph 2 tells us that the particle emitted during this decay is a β- particle, which is the name given to the electron emitted during nuclear decay. Coulomb's law states that the force between two charged particles is attractive when the charges are opposite and repulsive when the charges are the same. Thus, if the emitted particle is negatively charged, then the particle attracted to it must be positive, like a positron. A positron is the same size and charge as an electron, but has a positive charge. Note that the process taking place here is β- decay, which is depicted below. We can think of this process in two ways: either simply as the emission of an electron, or as the conversion of a neutron into a proton, an electron, and a neutrino

oxidative phosphorylation

Part of the electron transport chain. A process occurring in the mitochondria that results in the formation of ATP from the flow of electrons across the inner membrane to bind with oxygen. Note: - oxygen is always reduced (to H20) but never oxidized - Ubiquinone accepts electrons, then passes them off. Therefore, it is both reduced and oxidized - Nicotinamide adeninedinucleotide refers to NAD+/NADH. This compound is reduced to form NADH by upstream metabolic processes and oxidized back to NAD+ after transferring an electron to Complex I of the electron transport chain -ADP is oxidized to ATP This process begins by passing electrons through a series of chemical reactions, known as the electron transport chain (ETC), to a final electron acceptor, oxygen ---> produce 30-36 ATP and uses NADH and FADH2 from glycolysis and Krebs Cycle Composed of four complexes: I is known as NADH dehydrogenase II is known as succinate dehydrogenase III is known as cytochrome bc or c IV is known as cytochrome c oxidase Electrons are released from NADH and FADH2 through a series of reactions.

When 2 moles of hydrofluoric acid are added to 100 mL of water, the resulting solution has a pH equal to 4. What is the percent dissociation of HF? *DIDN'T GET WRONG BUT WANTED TO REVIEW*

Percent Dissociation: [H+]/[HA] * 100 1. Find [H+] --> pH= -log[H+] = 4= -log[H+] = 10ˆ-4 = [H+] 2. Find Molarity of HF = 2 moles HF *( 1 mol HF/ 0.1 L ) = 20 M HF 3. Put into equation = 10ˆ-4/ 20 M = 5 x10ˆ-6 * 100 = 5x10ˆ-4 = 0.0005%

What type of control does siRNA exert on G6PD expression?

Post-transcriptional control . Due to its structure, siRNA is only able to bind to other RNA strands, not to DNA or protein. Therefore, it must interfere with gene expression after transcription has already occurred, but before translation. Specifically, it prevents the translation of mRNA corresponding to the target protein.

How do the chemical modifications described in the passage differ from eukaryotic post-transcriptional modifications?

Post-transcriptional modifications are carried out entirely within the nucleus The modifications were first mentioned in the first paragraph ("acetylation of lysine residues, methylation of lysine and arginine..."), and then a detailed example was given in the last paragraph. These are all modifications to amino acids and/or proteins. Protein modifications must be post-translational modifications. Such modifications can take place in a variety of locations within the cell, such as the interior of the endoplasmic reticulum or the cytoplasm. In contrast, post-transcriptional modifications (those performed on mRNA) occur in the nucleus; these include the addition of the poly(A) tail, the addition of the 5' cap, and splicing.

Which of the following is NOT a function of the blood-brain barrier?

Protection of the brain from carbon dioxide poisoning The passage states that the blood-brain barrier protects the brain from harmful agents that are large or polar. Carbon dioxide is both small and nonpolar, making it highly lipid-soluble. Thus, it will freely pass through the BBB. Hormones are large and will not be able to enter the brain. This is a protective function of the BBB. Nonetheless, Glucose is virtually the sole fuel for the human brain, except during prolonged starvation. The brain lacks fuel stores and requires a continuous supply of glucose. It consumes about 120 g daily, accounting for some 60% of the utilization of glucose by the whole body in the resting state. The abundance of high-affinity GLUT-1 transporters allows the brain to absorb more glucose than any other tissue.

Which of the following variables are negatively correlated with globalization?

Protectionism Protectionism refers to a country rejecting trade with others and being isolative, which is inversely proportional to globalization Background* Globalization refers to the process by which the exchange of worldviews, products, services, ideas, and other cultural ideas leads to international integration. This lessens geographical constraints on businesses, ideas, and people. One of the benefits of globalization is that in-season produce can be shipped from countries across the world, where produce that is currently out of season in the U.S. is in-season. Globalization also accounts for the spread of major international businesses and increased manufacturing. As such, one of the negative effects of globalization is the pollution that this business growth brings with it. World systems theory has been proposed in the context of globalization as a way of addressing how labor, capital, and expertise are distributed across core countries (such as Australia, nations in Western Europe, and the U.S. and Canada) that specialize in skilled forms of economic production and semi-peripheral and peripheral countries, which specialize in lower-skilled economic production and raw material extraction. Urbanization has occurred simultaneously with globalization. This term refers to the shift of populations from rural to urban areas. One of the drivers of urbanization has been the decline in the worldwide agricultural jobs: simply put, there are more job opportunities in major cities.

If pharmacologists wished to convert morphine into a form available to brain tissue, which of the following changes could be made to its molecular structure to allow for the best chance to use the drug as a direct brain treatment?

Replace the alcoholic protons with acetyl groups This question asks us to consider the structure of morphine given in the passage. What needs to change for morphine to enter the brain while maintaining its function? We are told in the passage that lipid-soluble molecules are able to pass through, while hydrophilic molecules are not. Morphine is hydrophilic in part because of its hydroxyl groups. So, replacing them with acetyl groups would allow the drug to become more lipophilic; although the C=O bond in the acetylated molecule is polar, it cannot undergo hydrogen bonding, so the acetylated structure is effectively much more lipophilic than the original structure with -COOH groups. Interestingly, diacetylated morphine is heroin. The effects and pharmacology of heroin are somewhat distinct from those of morphine, although they belong to the same general class of opiates, and heroin does indeed more readily cross the BBB.

Key Psychologist and Experiments:

Sigmund Freud, the "father of psychoanalysis," developed well-known theories focused on unconscious desires. Freud's work centered around his ideas of the id (one's largely unconscious set of primal urges), superego (one's sense of moral purpose), and ego (the logic-based, more conscious balance between the two). Freud put his theories into practice in psychoanalytic therapy, a process in which a psychologist or other therapist converses with a patient one-on-one to address certain mental or emotional issues. American psychologist B. F. Skinner was an early behaviorist, meaning that he systematically studied behavior in conjunction with other factors (environmental, motivational, etc.). Skinner is best known for his work in operant conditioning, where he used a device called a "Skinner box" to study the effects of rewards and punishments on behavior. Psychologist Gordon Allport is known for his studies of personality, where he outlined a form of trait theory that included three basic types of traits: cardinal traits, central traits, and secondary traits. Cardinal traits are those around which people organize their entire lives. In contrast, central traits are defining characteristics of a person that can be easily inferred from that person's behavior. Finally, secondary traits are those that only occur sometimes, particularly when a person is in a certain social situation.

Shopper A, a customer at Store 3, rudely screams at a staff member. He then receives a discount plus a free item from the manager while checking out. Shopper B witnesses the event. When it is her turn to check out, she behaves rudely and screams at the staff member too. Which theory best describes how she learned this behavior?

Social cognitive theory This asserts that people learn by watching others, and if they see someone is rewarded for a behavior, they are more likely to behave that way too.

In order to find the concentration of metal ions needed to determine the distribution coefficient of copper (II), what calculation could the researchers have performed in addition to the procedure described in the passage?

Subtract the concentration of metal ions in the aqueous phase after extraction from the concentration before extraction The passage defines the distribution coefficient as "the ratio between the concentration of metal in organic and aqueous phase following extraction." In order to determine D, the researchers must know the concentrations of metal ions in the organic phase and of the metal ions remaining in the aqueous phase following the extraction. According to the description provided by the passage of the researchers' procedure "after the two phases were separated completely, concentrations of the metal remaining in the aqueous phase were determined spectrophotometrically at 820 nm." This measurement provides the concentration of metal ions remaining in the aqueous phase directly. The concentration of metal in the organic phase after the extraction is not directly known.

Cefixime displays what inhibitive behavior on PBP?

Suicide inhibition According to the passage, cephalosporins bind irreversibly to the active site of PBP. Of the inhibitor types given as answer choices, only a suicide inhibitor acts as an irreversible enzyme inhibitor. Suicide inhibition occurs when an enzyme binds the inhibitor (structurally a substrate analogue) and forms an irreversible complex with it, usually through a covalent bond. This can involve the inhibitor being chemically modified by the enzyme during the normal course of catalysis to produce a reactive group that is specifically responsible for the formation of the irreversible inhibitor-enzyme complex. Competitive: binds to active size and Vmax=0 and Km= increases (Line plot intersects Y-intercept and as line moves closer to the ---> the Km is getting smaller) Noncompetitive: when the inhibitor does not compete with the substrate for the active site, but reduces enzyme activity by binding to another site (the allosteric site) on the enzyme. Vmax= decreases Km= unaffected (Line plot is connected at the X-intercept) Uncompetitive: when the inhibitor binds to only the enzyme-substrate complex, and inactivates it. Vmax= decreases Km=decreases (Line plot is parallel)

If cefixime complexes were shown to interact with AChE by binding its active site, which of the following hypotheses regarding the effect of the complexation of cefixime with copper (II) would be most consistent with findings of the enzyme inhibition study?

The effect of complexing cefixime with copper (II) is less favorable for the binding of PBP than for AChE compared to cefixime alone Figure 3 shows that, relative to the copper (II)-containing complex C2, cefixime displays a greater inhibitory effect against PBP and a smaller inhibitory effect against AChE. This indicates that complexation favors binding AChE and disfavors the binding of PBP.

Oxidative Phosphorylation background*

The end purpose of oxidative phosphorylation is to phosphorylate ADP into ATP. We should know for the MCAT that the very final step is ATP synthase allowing protons to move down the electrochemical gradient while forming ATP

What is the wavelength of the photons emitted by the 145Pm-m? (Note: 1 eV = 1.6 x 10-19 J) *DIDN'T GET WRONG BUT WANTED TO REVIEW*

The energy of the photon is given as 300 keV. This will need to be converted to joules using the equation 1 eV = 1.6 x 10-19 J. The energy of a photon is related to its wavelength via the equation: E = hc/λ, λ = hc/E λ = [(6.62 x 10-34 J*s)(3 x 108 m/s)] / [(300 x 103 eV)(1.6 x 10-19)] λ = 4.1 x 10-12 m

Cognitive Biases to Know

The gambler's fallacy is the mistaken belief that, if something happens more frequently than normal during some period, it will happen less frequently in the future, or vice versa. For example, someone who bets on red on a roulette wheel because the last 5 spins have all landed on black. This does not match with the reasoning discussed in paragraph 3. The prisoner's dilemma is a standard example from psychological game theory that shows why two completely "rational" individuals might not cooperate, even if it appears that it is in their best interests to do so. According to the Cannon-Bard theory of emotion, emotions and bodily changes do not share a cause-and-effect relationship. Rather, they occur simultaneously, following a stimulating event. This is unrelated to the task mentioned in the passage.

Which decision-making phenomenon best explains why researchers told participants that monies held at the end of session one would be used to fund games in session two?

The house money effect Paragraph 3 tells us that the researchers sought to avoid excessive risk-taking in session one, so they told the participants that the money earned in the session was not theirs free and clear, but would serve as the financial basis for their participation in the second session. The researchers most likely did this to avoid the subjects treating the money as if it was not important to their continuation in the study. The researchers needed the subjects to think of this money as their own. Thaler and Johnson have found that individual risk-taking behavior is affected by prior gains and losses. They found that after a prior gain, people become more open to assuming risk since the new money is not treated as one's own. This is known as the house money effect.

Given the procedure outlined in the passage, what must be true about SP peptide synthesis?

The protein is synthesized from C-terminal to N-terminal Unlike ribosome protein synthesis, solid-phase peptide synthesis proceeds in a C-terminal to N-terminal fashion because the C-terminus is bound to the linker throughout the synthetic process. In the absence of a permanent support at one end — as in SP synthesis — amino acids could be added to either terminus.

Which statement best explains why the lung volume in Figure 1 never drops below 15 ml/kg?

The residual volume is such that the lungs are at their minimum volume under maximum intrapleural pressure The best way to approach this question is by process of elimination. It can be helpful to first eliminate answers that are untrue, and then to eliminate true choices that do not answer the question. Reasoning for how to eliminate each option is shown below. Once we eliminate options A, B, and D, we see that choice C is both accurate and relevant to the question stem: this 15 mL/kg of air is the residual volume, which is the minimum volume the lungs can have, and which is attained at maximum intrapleural pressure.

Two known competitive inhibitors were studied to analyze their effects on the reaction rate catalyzed by the enzyme lysozyme. Equimolar amounts of inhibitor A (hydronium ion) and inhibitor B (hydroxide ion) were mixed in a beaker before being added into the reaction mixture containing the substrates. Then, lysozyme was also added into the reaction mixture. Based on Figure 1, where would the resulting enzyme kinetics curve for this experiment fall?

The same as line 1 Be sure to read the question stem carefully! Inhibitor A is a strong acid (H3O+) and inhibitor B is a strong base (OH-). Since these inhibitors are mixed together before being added to the reaction mixture, they would simply neutralize each other and become water before having any effect at all. Thus, the enzyme kinetics would not be affected, and the curve would fall along line 1.

If research continues to indicate that the SAT is biased against students from low socioeconomic backgrounds and does not reflect their knowledge or skills, what does that mean for the test's psychometric properties?

The test may still have high reliability but low validity. A test can be reliable but not valid - think of a bathroom scale. If you step on it every day and the weight is the same but wrong, the test has high reliability (consistency) but low validity (accuracy). Students may be getting reliable, consistent scores over time, but if the test isn't a true measure of their ability and skills, then it is not valid. Background* For an experiment or test to have value, it must be both reliable and valid. Reliability refers to how consistent and repeatable an experiment or assessment is. Test-test reliability refers to the fact that a good test should give stable results over time Validity is a measure of how well a given experiment actually measures what it sets out to measure. If a study has internal validity, then the study has internally been well constructed, using things like large random samples, safeguards against confounding variables, reasonable and reliable processes and instruments, etc. If a study is internally valid, we can then assess whether it has external validity—can the results of the experiment be generalized to other settings? After all, if a study only shows that X is related to Y for this experimental group, then it's not very valuable for drawing conclusions about the larger population. To have external validity, an experiment must tightly control any situational variables in the execution of the study. Finally, construct validity refers to how well a given assessment (a survey, a test, etc.) actually measures what it claims to measure— whether it has been properly constructed to measure the relevant thing.

Fluid pressure changes with depth are assumed to be linear. Which statement best explains why this does not hold true for atmospheric pressure changes?

The volume of a mass of air is not constant. Hydrostatic pressure for liquids is linear because as depth changes, the density of the liquid remains constant. Gases, however, have densities that change according to the forces applied to them. Gases are compressible, while liquids and solids are not (lack a fixed volume) Higher temps --> more ideal molecules in air are non polar but that doesn't answer question

Key Psychologist and Experiments:

Zimbardo's Stanford prison experiment focused on the effects of power and authority on individuals. Participants designated as "guards" were given power over participants designated as "prisoners," and over time, the guards began to exhibit progressively more abusive and problematic behavior. Milgram's electric shock experiment also relates to authority. This experiment indicated that participants were willing to administer painful stimuli to others if instructed to do so by an authority figure. In reality, the "others" in the study were actors who were simply pretending to be shocked. Abraham Maslow famously developed Maslow's hierarchy of needs, a schematic of human needs in order from the most basic (food, water, etc.) to the most high-level (self-actualization).

A man is accidentally exposed to a toxin which binds irreversibly and noncompetitively to pyruvate dehydrogenase. A likely consequence of this ingestion is

a decrease in the level of Krebs cycle activity within the exposed cells Pyruvate dehydrogenase is the enzyme that mediates pyruvate decarboxylation. This step is the critical link between anaerobic and aerobic respiration. With this link broken, cells would be limited to anaerobic respiration. Thus, a decrease in aerobic respiration makes sense in this context The pyruvate dehydrogenase complex converts pyruvate (a three-carbon molecule that is produced by glycolysis) into acetyl-CoA, a two-carbon molecule that is fed into the citric acid cycle for further metabolism The conversion of pyruvate to acetyl-CoA is accompanied by the production of 1 molecule of NADH, which can eventually enter the electron transport chain to generate ATP, and 1 molecule of carbon dioxide. In eukaryotes, the pyruvate dehydrogenase complex is located within the mitochondrial matrix

In the proposed structures shown in Figure 2, bonds are formed to metal ions at neutral pH through all of the following donor atoms EXCEPT:

a nitrogen atom of a primary amine

An additional experiment on the bovine extracts using a known ADAMTS inhibitor would serve as:

a positive control A positive control is a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect. The scientists wished to test the effect of the analogs on enzyme activity. Using a known inhibitor is an example of comparing the expected effects of this inhibitor to those of the analog treatment. Thus, it is a positive control. A negative control group is a control group that is not exposed to the experimental treatment or to any other treatment that is expected to have an effect.

The most appropriate way to explain the impact of the short-term stress exposure used in the experiment on individual decision-making would be to cite:

general adaptation syndrome This is a classic MCAT question where we need to match the general activity/details of the passage to some psychological or sociological concept. We need to find the answer that encompasses the effects of short-term stress on the psychological state of the individual (since the Q asks about impact on decision making). General adaptation syndrome is a term created by Hans Selye to describe the body's short-term and long-term reactions to stress. Selye thought that the general adaptation syndrome involved two major systems of the body, the nervous system and the endocrine system. He then went on to outline what he considered as three distinctive stages in the syndrome's evolution. He called these stages the alarm reaction (AR), the stage of resistance (SR), and the stage of exhaustion (SE).

If researchers conducted a new version of this study in which they controlled for participants' prior condom use, that would improve its:

internal validity Internal validity refers to the degree to which causal conclusions can be drawn from a study, which can include accounting for potential confounding variables. Adding the additional measurement point of pre-intervention condom use and controlling for that variable statistically would considerably improve the degree to which one could make conclusions about how Truvada use affected participants' behavior.

Scientists who wished to study the metabolic function of cells with balanced translocations while preventing cell replication would be best served by arresting the cells during which phase of the cell cycle

interphase If the scientists wanted to prevent cellular replication, they would need to halt cell division (mitosis). Interphase is the stage of the cell life cycle (shown below) that occurs between rounds of division

Air is bubbled through distilled water. The solution will have a pH:

less than 7, because carbon dioxide undergoes hydrolysis. Air contains elemental nitrogen as its major component, but elemental nitrogen is essentially inert and is neither an acid nor a base. On the other hand, carbon dioxide can undergo a hydrolysis reaction in liquid water to produce carbonic acid, a weak acid that produces a solution whose pH is less than the pH of water (pH = 7) -hyperventilating leads to excel CO2 and cause blood pH to go up

If the children in the follow-up study included both 4-year-olds and 8-year-olds, researchers would likely observe:

more examples of parallel play among the 4-year-olds Parallel play is a normal part of the behavior of preschool children, in which they will play by themselves but observe another child playing and adjust their behavior in response. Parallel play does not entail direct interaction between the children. As children reach school age, they are much more likely to engage in forms of play together. *Go over The Piaget's and Erikon's Stage*

A shopper behaves very aggressively towards another shopper and, in response, the store manager refuses to sell a coveted toy to the shopper. This experience would most likely serve as:

negative punishment Here, something is being taken away from the shopper - the opportunity to purchase a particular item - which makes this a negative reaction. Remember that positive responses in operant condition involve adding something (giving a food pellet, giving a shock) but negative ones involve removing somethings (removing a noxious noise, removing food). Since the action is something the shopper would not want, it is more likely that the aggressive behavior would decrease rather than increase, making it a punishment.

AEA is most accurately categorized as a:

neurotransmitter From the first paragraph of the passage: "Following depolarization, AEA is synthesized from a phospholipid precursor situated within the lipid bilayer of the neuronal membrane ... Following reuptake into the postsynaptic neuron, it is [degraded] by ... FAAH." This, combined with information in the second paragraph that endocannabinoids, such as anandamide, bind CB1 receptors located on neuronal membranes, makes clear that, despite its somewhat unique structure, anandamide is a neurotransmitter. Types: - Glutamate is an excitatory neurotransmitter and is the most common, as 90% of brain cells are responsive to glutamate. In contrast, GABA is the main inhibitory neurotransmitter of the CNS, and it hyper-polarizes cells to reduce action potential firing. - Dopamine is used in reward and motor pathways. It is particularly associated with Parkinson's disease and the loss of dopaminergic neurons in the substantia nigra. -Endorphins suppress pain and can produce euphoria. -Serotonin regulates mood, appetite, and sleep in the brain, with low levels associated with depressive mood disorders Neurotransmitters can also be active in the peripheral nervous system. -- Acetylcholine activates muscle contraction at the neuromuscular junction. It is used in all autonomic outputs from the brain to autonomic ganglia, and in the parasympathetic nervous system for post-ganglionic connections. -Serotonin regulates intestinal movement in the gastrointestinal tract, in addition to its effects in the brain. -Epinephrine stimulates the fight-or-flight response, and norepinephrine is used in post-ganglionic connections in the sympathetic division of the autonomic nervous system

An outspoken skeptic and opponent of automatic writing attends multiple séances where a medium appears to successfully contact someone who has recently died. If the skeptic's views shift over time to view the practice as harmless entertainment, this evolution is best described by:

reciprocal determinism. Reciprocal determinism is the theory set forth by Albert Bandura that a person's behavior both influences and is influenced by personal factors and the environment. In this scenario, the skeptic does not believe in the supernatural power of a medium, but attends multiple séances where they may see evidence that could soften their views. It appears this behavior of attending séances, in conjunction with the social environment of others who attend the séances, caused the skeptic's views on supernatural phenomena to shift.

A public health advocacy group has developed a program to encourage adherence to a Truvada medication regimen using operant conditioning principles. An example of the group using thinning in the program is:

reducing the frequency of rewards for medication compliance In operant conditioning, thinning refers to reducing the frequency of rewards for a given action

Atherosclerosis, a particular type of arteriosclerosis, usually involves either complete blockage or severe restriction of blood flow due to high cholesterol and buildup of plaque in the arteries. In extreme cases, constricted arteries may collapse under pressure from outside the arteries. This can best be explained by:

the necessary increase in fluid velocity through the constricted arterial sections causing a corresponding drop in fluid pressure According to the continuity equation, velocity increases as cross-sectional area decreases. Increasing velocity decreases pressure. If the pressure inside the artery drops far enough, it may fall below the pressure outside the artery, causing it to collapse from external pressure A final important relationship is given by the continuity equation (v1A1 = v2A2). This equation states that within a closed system, the flow rate of a liquid is constant, which indicates that the velocity of the fluid (v) is inversely proportional to the cross-sectional area that it is flowing through.

The acceleration of the gurney during the initial 6 seconds of Experiment 1 is:

zero The passage states that the Fapplied is increased until the gurney moves. This means that while Fapplied is less than its maximum (t = 0-6s), the gurney is not moving. Here, Fnet = 0 N According to Newton's second law Fnet = ma = a = Fnet /m = 0 Friction produces thermal energy, or heat, from the "useful" energy that would have otherwise contributed to the object's motion. This "useful" energy may be kinetic, if the object was already sliding along the surface. Alternatively, it may come from work, if the object was not yet sliding (for example, if you were straining to force a stationary object to start sliding).

Which of the following correctly describes the conversion of AMP to IMP by AMP deaminase?

ΔG < 0 and ATP could be produced A high activation energy barrier usually causes hydrolysis of a "high-energy bond" to be very slow in the absence of an enzyme catalyst. This kinetic stability is essential to the role of ATP and other compounds with these bonds. If ATP would rapidly hydrolyze in the absence of a catalyst, it could not serve its important roles in energy metabolism and phosphate transfer. Phosphate is removed from these molecules only when the reaction is coupled via enzyme catalysis to some other reaction useful to the cell, such as transport of an ion, phosphorylation of glucose, or regulation of an enzyme by phosphorylation of a serine residue. According to the reaction, the Keq > 100. This Keq (>>1), indicates that the free energy change for the reaction is negative. Also, if the reaction is spontaneous, energy (in the form of ATP) is not required to drive it forward. As such, the reaction could be used to generate ATP, a molecule used biologically to store chemical potential energy.