MCAT 2

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Which of the following processes do NOT occur at the placenta? I. Diffusion of amino acids from fetal blood to maternal blood II. Mixing of maternal and fetal blood and gas exchange III. Exchange of CO2 and O2 between fetal and maternal blood

Item I does not occur: Amino acids are charged and cannot cross the placental and fetal capillary membranes. Item II does not occur: Fetal and maternal blood do not mix, so the only way substances can cross the placental barrier is if they are lipid soluble or if they are actively transported. Item III is correct: CO2 and O2 are lipid soluble and easily cross the barrier.

The following measurements were obtained by an investigator who observed a light ray that propagated across a boundary between air and Material X: speed of light in air = 3.0 × 108 m/s frequency of light in air = 5.0 × 1014 Hz angle of incidence = 30.0° angle of refraction = 23.5° density of Material X = 5.0 g/cm3 At what speed does light propagate through Material X? (Note: sin 23.5° = 0.4)

Snell's Law gives n1 sin θ1 = nX sin θX → (1) sin30° = nX sin(23.5°) → 0.5 = nX(0.4) → nX = 5/4. Since the index of refraction of Material X is 5/4, then, by definition, the speed of light is reduced by a factor of 5/4 from its speed in vacuum (or air). Thus, vX = (4/5)c = (4/5)(3 × 108 m/s) = 2.4 × 108 m/s. (Note that choice D can be eliminated immediately since it is greater than c = 3 × 108 m/s.)

adaptation hypothesis

The adaptation hypothesis proposes that interactions between bacteria and virus produce viral resistance. The more interactions that occur, or the denser the mixture of virus and bacteria, the more resistance that will be observed.

The trimerization of adenovirus protein fiber monomers is an example of what type of protein structure? A. Primary B. Secondary C. Tertiary D. Quaternary

Trimerization implies the interaction of multiple protein subunits to form a complex, which is an example of quaternary structure (choice D is correct and choices A, B, and C are wrong).

How many chiral centers does (+)-fructose contain?

Distillation

A process that separates the substances in a solution based on their boiling points

zona pellucida

A thick, transpartent coating rich in glycoproteins that surrounds an oocyte.

Nucleophilic substitution

A type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

A researcher proposed to block the leptin receptor in order to treat hypertension in obese patients. Which of the following detection methods would work best to identify the receptor in the different tissues affected by leptin? A. Northern blot B. Western blot C. Southern blot

B Western blot Snow drop Southern=DNA Northen=RNA Western= Protein

HPLC (high performance liquid chromatography)

Most widely used liquid chromatography Fractionation of drugs, hormones, lipids, carbohydrates, and proteins

low Ksp means

Precipitate

Stearic acid (or octadecanoic acid) is a saturated fatty acid with the formula CH3(CH2)16COOH After undergoing β-oxidation, it will generate: A. 9 acetyl-CoA, 9 NADH and 9 FADH2. B. 9 acetyl-CoA, 8 NADH and 8 FADH2. C. 8 acetyl-CoA, 8 NADH and 8 FADH2. D. 8 acetyl-CoA, 7 NADH and 7 FADH2.

Stearic acid has 18 carbons and so will undergo 8 rounds of β-oxidation. This will generate 9 molecules of acetyl-CoA (eliminate choices C and D), 8 molecules of NADH and 8 molecules of FADH2 (choice B is correct, eliminate choice A).

Trimerization

The formation of a trimer.

corona radiata

The layer of granulosa cells taht surround an oocyte after is has been ovulated.

If φcrit for a glass-air interface is 42°, which of the following best approximates nglass? (Note: sin 42° = 0.67.) A. 1.25 B. 1.50 C. 1.67 D. 1.75

Using nb = 1 for the index of refraction of air, Snell's Law gives sin φb = nasin φa. If nasinφa> 1, then there is no φb; that is, the beam experiences no refraction (total internal reflection). The cut-off, then, is determined by nasin φa= 1, that is, by nglass sin φcrit = 1, so 1/.67=1.5

androcentric

centered around male interests

Resistance physics

dissipate some of the electrical energy that flows through them as heat

Low Kd means

high affinity and high stability

Volts =

kg·m2·s−3·A−1

Transformation

process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

Speciation

the formation of new and distinct species in the course of evolution. The factors that contribute to speciation -Geographic isolation of population -Genetic diversity -natural selection

synapsis

the fusion of chromosome pairs at the start of meiosis.

hydride shift

the migration of a hydrogen with its two bonding electrons

T3, T4, calcitonin

thyroid hormones and steroid

If the distance of an object from a converging lens is x and the distance of the real image from the lens is also x, what is the focal length of the lens? A. x / 2 B. x C. 2x D. 3x

x/2

Which of the following salts, when dissolved in water, would produce the solution with the highest pH? A. Na2CO3 B. NH4Cl C. NaCl D. AlBr3

A . The most basic salt will produce the solution with the highest pH. The carbonate ion from Na2CO3 is the conjugate base of bicarbonate, which is itself weakly basic in aqueous solution; choice A is the most basic salt listed. NaCl is a neutral salt as neither of its ions are reactive with water (eliminate choice C). Both NH4Cl and AlBr3 are acidic salts because both cations will interact with water to increase the [H+] in solution (eliminate choices B and D).

An individual's description of her behavior at work earlier that day is an example of retrieval from: A. episodic memory. B. semantic memory. C. procedural memory. D. olfactory memory.

A. Episodic memory refers to memory of one's personal experiences (choice A is correct). Semantic memory is memory of concepts and information (choice B is wrong), while procedural memory is memory of how to execute motor tasks (choice C is wrong). Olfactory memory is not a term associated with models of long-term memory. In the context of short-term memory, it would refer to a sensory store from which one could recall what a given stimulus smelled like. It would not have relevance to recall of one's behavior (choice D is wrong).

A scientist wants to separate a mixture of amino acids in a solution buffered to pH 6.0 by using electrophoresis. The mixture is composed of lysine, glycine, and aspartic acid, which have isoelectric points of 9.7, 6.0, and 3.0, respectively. The expected order of the amino acids I, II, and III is: A. lysine, glycine, aspartic acid. B. lysine, aspartic acid, glycine. C. aspartic acid, glycine, lysine. D. aspartic acid, lysine, glycine.

A. First, it is clear that glycine will be amino acid II on the electrophoresis gel since its isoelectric point matches the pH of the solution. This eliminates choices B and D. Since opposite charges attract each other, the positively-charged amino acid at pH 6.0 will be amino acid I since it will be attracted to the minus charge. Lysine, with an isolelectric point of 9.7, is the positively-charged amino acid at pH 6.0, so the answer is A.

TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) is a method for detecting DNA fragmentation by labeling the terminal end of nucleic acids. BrdU (5-bromo-2'-deoxyuridine) can also be used in staining protocols, as this synthetic nucleoside can be incorporated into nucleic acids during replication instead of thymidine. Tumor cells have: A. minimal TUNEL staining due to their low apoptotic rate, but strong BrdU staining due to active genome replication. B. strong TUNEL staining due to their high apoptotic rate, and strong BrdU staining due to active genome replication. C. strong TUNEL staining due to their high apoptotic rate, but weak BrdU staining due to minimal genome replication. D. minimal TUNEL staining due to their low apoptotic rate, and weak BrdU staining due to minimal genome replication.

A. Genome fragmentation is one of the hallmarks of apoptosis and tumor cells generally evade apoptosis. This means tumor cells will have minimal TUNEL staining (eliminate choices B and C). Tumor cells have high proliferation rates and so will be actively replicating the genome. This means they will likely display strong BrdU staining (choice A is correct, eliminate choice D).

The inhibition of hexokinase by glucose-6-phosphate is best classified as: A. feedback inhibition. B. a proteolytic cleavage. C. enzymatic catalysis. D. positive feedback.

A. Glucose-6-phosphate is a product of the reaction catalyzed by hexokinase (the phosphorylation of glucose to produce glucose-6-phosphate) and also inhibits the enzyme. This is a classic example of feedback inhibition (choice A is correct). Proteolytic cleavage refers to the cleavage ("cutting") of a protein to regulate its activity. This is commonly seen in the activation of zymogens to their active form, but is not the case here (choice B is wrong). Since glucose-6-phosphate is not an enzyme, the inhibition of hexokinase by glucose-6-phosphate is not an enzymatic catalysis (there is no enzyme catalyzing a reaction, choice C is wrong). If positive feedback were occurring, then glucose-6-phosphate would stimulate hexokinase to produce more glucose-6-phosphate (choice D is wrong).

O 2 saturation vs. O 2 concentration for fetal hemoglobin (HbF) and maternal (or adult) hemoglobin (HbA)?

A. Hemoglobin binds oxygen cooperatively, and so has a sigmoidal binding curve (choices C and D are wrong). Fetal hemoglobin must have a higher oxygen affinity than maternal hemoglobin to be able to bind oxygen at lower partial pressures than maternal hemoglobin (choice A is correct and choice B is wrong).

Suppose a parent group accuses a school of maintaining a hidden curriculum that gives boys an advantage in subjects requiring mental rotation, such as geometry. The school makes changes that are later characterized by a local paper as tokenism. Which of the following scenarios is most illustrative of this vignette? A. The school hired one female geometry teacher to join an existing staff of 9 male geometry teachers. B. The school required its geometry teachers to disclose curriculum expectations at the start of the school year. C. The school instituted a reward system to provide incentives to female students to improve their geometry scores. D. The school rewarded geometry teachers who ensured that boys and girls received equal time to ask questions in class.

A. Hidden curriculum refers to social messages conveyed in schools that may impact performance of different groups. Through teachers' language, test formats, classroom procedures, or other factors, implicit messages about the value, abilities, or importance of different groups may be internalized by students. An example of a hidden curriculum may be a disproportionate number of male geometry teachers versus female teachers. In such a case, students may "learn" that men are typically better at geometry than women. By hiring a single female teacher, however, the school may be engaging in tokenism. Tokenism refers to an organization's inadequate remediation of problems of inequality while exploiting minimal improvements. Such an approach is likened to giving a low-cost token to equality advocates in order to quell their demands for substantial reform. Thus, emphasizing its hiring of a female geometry teacher despite a disproportionate number of male geometry teachers could be characterized as "tokenism" (choice A is correct). Hidden curriculum does not pertain to maintaining secrecy about curriculum objectives (choice B is wrong). The institution of a system of tangible rewards in exchange for desired behavior is known as a "token economy," not "tokenism" (choices C and D are wrong).

In humans, the fusion of the plasma membranes of a sperm and an ovum is followed first by which of the following? A. Release of the second polar body from the fertilized ovum B. Implantation in the uterus C. The first cell division of the zygote D. Gastrulation

A. Human ova do not complete the second meiotic cell division, including the formation of the second polar body, until after fertilization (choice A is correct). This process occurs immediately after fertilization and is a prerequisite for the first cell division of the zygote (choice C is wrong). Implantation happens a few days later, and gastrulation occurs at a stage many cell divisions after the first cell division (choices B and D are wrong).

In order to maintain the maximum yield of ammonia when raising the temperature of the reaction, scientists should: A. maintain N2 and H2 at high pressure. B. allow N2 and H2 to expand with the increased kinetic energy. C. increase the volume in the reaction chamber to favor the forward reaction. D. carefully control the temperature to avoid runaway heating by the forward reaction.

A. In order to maximize the yield of the reaction while increasing temperature, the pressure should be kept as high as possible. Maintaining the compression of the gases (choice A) will maintain a high pressure. However, increasing the volume (choices B or C) would decrease the pressure and lower the overall yield. Since the reaction is exothermic, its forward progress might heat the reaction, hindering the formation of products. Controlling the temperature would eliminate this (choice D).

The average age of participants in this meta-analysis was about 62 years old. That would place the average participant in which psychosocial crisis stage according to Erik Erikson's eight-stage theory of development? A. Integrity vs. Despair B. Generativity vs. Stagnation C. Identity vs. Role Confusion D. Trust vs. Mistrust

A. Integrity vs. Despair asks whether one can come to terms with the approach of one's own death or does one feel despair over the disappointments of one's life, the "natural" feelings of old age (choice A is correct). Generativity vs. Stagnation describes the period between one's 30s to one's 50s when a person struggles between building a career and family and getting stuck in routine (choice B is wrong). Identity vs. Role Confusion is the period between the ages of 12-19 when a teenager is finding him- or herself in the world (choice C is wrong). Trust vs. Mistrust is the period of the first year of life when a baby is deciding whether to trust his or her caregivers and environment (choice D is wrong).

Human T-cell lymphotropic virus (HTLV) is very similar to HIV. Which of the following would be true regarding HTLV? I. HTLV exhibits a lysogenic life cycle. II. HTLV is a retrovirus. III. HTLV destroys the antibody-producing cells. A. I and II only B. I and III only C. II and III only D. I, II, and III

A. Item I is true: HIV exhibits a lysogenic life cycle since it integrates into the host's genome. If HTLV is similar to HIV, then it must also be lysogenic (choice C can be eliminated). Item II is true: If HTLV is similar to HIV, then it must also be a retrovirus (choice B can be eliminated). Item III is false: HIV and HTLV infect the host's T-cells. The B-cells are the antibody-producing cells of the body. There is no discussion of HIV infecting B cells (choice D can be eliminated and choice A is correct).

Which of the following statements is true regarding self-schemata? I. Self-schemata contain information about one's experiences II. Self-schemata can be activated even when one is unconscious III. Self-schemata are not influenced by culture

A. Item I is true: according to the passage, self-schemata contain information about one's experiences (choice B can be eliminated). Item II is false: self-schemata are cognitive structures, which implies that one must be conscious in order to access them (choice C can be eliminated). Item III is false: according to the passage, self-schemata are influenced by culture (choice D can be eliminated and choice A is correct).

According to Lawrence Kohlberg, what is the highest level of morality that the average adult tends to achieve? A. She or he will acknowledge a sense of duty to uphold the laws of the land and maintain basic social conventions. B. He or she will strive for social justice—the greatest good for the greatest number. C. He or she will focus on the approval (or disapproval) of others, acting in accordance with the views of his or her community or peer group. D. She or he will act in such a way as to avoid punishment at all costs.

A. Lawrence Kohlberg postulated six stages of moral development, but said that the average person generally does not pass beyond the fourth stage, in which he or she acknowledges a sense of duty to uphold the law and maintain social conventions (choice A is correct). Striving for social justice, wherein one acts for the greatest good for the greatest number, is the fifth stage in Kohlberg's schema and one that he proposed that few people reach (choice B is wrong). A focus on receiving approval from one's peers along with a need to conform is the third stage of development, usually seen in older children and adolescents (choice C is wrong). Acting to avoid punishment is the earliest stage of moral development, typical of very young children (choice D is wrong).

If Trial 2 were performed with 25.0 mL of NaOH instead of 50.0 mL, the resulting solution would have: A. pH < 1 B. T = 71°C C. [H3O+] = [OH-] D. the same ΔH

A. Only 0.05 mol of NaOH is added (instead of 0.1 mol). Therefore, only half of the HCl will be neutralized (so [H3O+] > [OH-], eliminate choice C), less heat is liberated (eliminate choice D), and the temperature will not increase as much (eliminate choice B). Although not necessary to answer the question, here's the calculation to show that choice A is indeed correct: 0.05 mol of HCl remains active—in 0.075 L of solution—after the addition of the (reduced amount of) NaOH; since HCl is a strong acid, this means [H+] = (0.05 mol)/(0.075 L) = 2/3 M, which is greater than 0.1 M. As a result, -log[H+] will be less than 1.

Overdosing on acetylsalicylic acid can cause a metabolic acidosis as well as hyperventilation. Which of the following is true? A. Blood pH will likely be 7.2. B. Little compensation is needed to correct the acid-base disturbance. C. Blood pH will likely be 7.6. D. The kidneys will need to secrete more HCO3- to compensate for the acid-base disturbance.

B. A metabolic acidosis is caused by a decrease in HCO3- concentration, resulting in a comparatively higher than normal H+ concentration. Hyperventilation causes a decrease in CO2 concentration. Remembering that CO2 is acid (see Equation 1 and the formation of H+), hyperventilation creates a respiratory alkalosis. The combination of both respiratory alkalosis (which results in a higher blood pH) and metabolic acidosis (which results in a lower blood pH) would result in a near normal blood pH. As a consequence, there will be little compensation required to maintain a normal level pH in the blood (choice B is correct). A pH of 7.2 indicates acidemia, typically caused by an acidosis, or potentially two acidoses (respiratory and metabolic, choice A is incorrect). A pH of 7.6 represents an alkalemia, caused by one or two alkaloses (choice C is incorrect). If the kidneys secreted HCO3-, then the blood pH would become lower since the body is ridding itself of HCO3-, a base. This compensation would only be necessary if there was an alkalemia to correct (choice D is incorrect).

All of the following are true about photoreceptors in the retina EXCEPT: A. rods function best in reduced light. B. rods are highly sensitive to visual detail. C. cones process color information in bright light. D. cones are the only photoreceptor found in the fovea.

B. Although rods are more sensitive to lower levels of light than are cones, rods are not sensitive to detail and instead are generally involved in peripheral vision in normal or bright light (choice B is false and therefore correct). Due to their sensitivity to photons, rods do most, if not all, of their photoreception in dark situations (choice A is true and therefore wrong). Cones process color information in all settings, including bright light (choice C is true and therefore wrong). The fovea, the middle section of the retina on which images are generally focused, contains only cones (choice D is true and therefore wrong).

According to the laws of thermodynamics, an endothermic reaction is most likely to be spontaneous if the: A. change in entropy is positive and the temperature is low. B. change in entropy is positive and the temperature is high. C. change in entropy is negative and the temperature is high. D. change in entropy is negligible and the temperature is low.

B. An endothermic reaction has a positive ΔH (eliminate choices C and D). Since a reaction is spontaneous if ΔG = ΔH - TΔS is negative, an endothermic reaction is spontaneous when ΔS is positive and the temperature is high (eliminate choice A and choice B is correct).

Which of the following would be increased the most in an individual with uncontrolled diabetes? A. Acetyl-CoA B. Ketone bodies C. Lactic acid D. NADH

B. An individual with uncontrolled diabetes would have hyperglycemia and a relative (or complete) deficiency of insulin. This means that glucose levels would be elevated in the blood and unable to get inside of insulin-responsive tissues. Thus, any molecule that is produced mainly through glucose catabolism and cannot be made from alternative pathways (such as lactic acid), would be decreased, not increased (choice C is incorrect). In addition to being produced during cellular respiration, NADH can be made in the Krebs cycle and acetyl-CoA can be made from fatty acid oxidation would enter the Krebs cycle; however the greatest increase would be in the production of ketone bodies (choices A and D are eliminated, choice B is correct). Ketone bodies represent an alternate energy molecule in the absence of glucose.

All of the following statements regarding enzymes are true EXCEPT that they: A. can be stereospecific in substrate recognition. B. alter reaction equilibria. C. are often regulated by feedback inhibition. D. reduce the activation energy of reactions.

B. Enzymes lower the activation energy of reactions to speed them up (choice D is true and eliminated), but they do not alter the potential energy of reactants and products or the reaction equilibrium, only the rate at which equilibrium is reached (choice B is false and the correct response). Enzymes do have great stereospecificity in the reactions they catalyze (choice A is true and eliminated) and are frequently regulated by feedback inhibition by products (choice C is true and eliminated).

If 99% of the H+ ions in a solution of pH 1.3 were neutralized, what would be the final pH? A. 0.3 B. 3.3 C. 5.3 D. 6.9

B. If only 1% = 1/100 of the H+ ions remained, then the number of H+ ions would drop by a factor of 102. Therefore, the pH would increase by log(102) = 2 units. In this case, the pH would rise from 1.3 to 1.3 + 2 = 3.3.

PDC deficiency is a rare genetic disease. Which of the following conditions would be expected in patients with the disease? A. Metabolic alkalosis B. Lactic acidosis C. Hyperglycemia D. Hypolipidemia

B. In PDC deficiency, the pyruvate cannot be converted to acetyl-CoA and therefore, the cells can only undergo glycolysis and anaerobic respiration. The end product of anaerobic respiration in humans is lactic acid. Thus, patients with PDC deficiency have lactic acidosis (choice B is correct). Glucose is still being utilized for energy so there is no reason to assume its circulating levels would increase (eliminate choice C) and PDC does not play a role in processing lipids (eliminate choice D). A lack of PDC activity would not increase the body's pH (eliminate choice A).

In a facultative anaerobe, which of the following processes occurs under both aerobic and anaerobic conditions? A. Fermentation B. Krebs cycle C. Glycolysis D. Oxidative phosphorylation

C. A facultative anaerobe can survive through fermentation when oxygen is not available but will use oxidative respiration when oxygen is available. Glycolysis will occur under both aerobic conditions (in which case the pyruvate will go on to enter the Krebs cycle as acetyl-CoA) and under anaerobic conditions (fermentation reduces pyruvate to alcohol or lactate), so choice C is correct. Fermentation occurs only in anaerobic conditions (choice A is wrong), while the Krebs cycle and oxidative phosphorylation can occur only in aerobic conditions (choices B and D are wrong).

Researchers found that people with graduate or professional degrees were divorced less often than were those with other levels of education. Therefore, it is possible that the success of a marriage depends on: A. economic capital. B. political capital. C. cultural capital. D. social capital.

C. According to social reproduction theory, inequality is transmitted from one generation to the next through various forms of "capital". Education is a classic example of cultural capital, which includes non-financial social assets such as knowledge, skills, and experience (choice C is correct). Education may be related to economic and political success; however, this is not supported by the information provided (choices A and B are wrong). The other choice, social capital, is also an important mechanism of social reproduction. It includes relationship-based social assets, like influence and "connections" with people in one's social network (choice D is wrong). It is important to note that the question stem states that cultural capital "might" determine marital success, as correlation does not necessarily imply causation.

Decreased secretion of aldosterone has all of the following effects EXCEPT: A. increased loss of Na + in urine. B. decrease in extracellular fluid volume. C. increase in arterial pressure. D. increase in urine volume.

C. Aldosterone causes increased sodium reabsorption, and because of the rise in systemic Na+, there will be decreased water loss, increased extracellular fluid volume and increased blood pressure. Decreased secretion of aldosterone would cause the opposite: increased loss of sodium (choice A is true and eliminated), a decrease in the extracellular fluid volume (choice B is true and eliminated), and an increase in urine volume (choice D is true and eliminated). It will not cause an increase in blood pressure, however, since more urine is formed and extracellular fluid volume lost (choice C is false and thus the correct answer choice).

Which of the following best justifies the use of DNA, as opposed to RNA, for generating aptamers? A. DNA is double-stranded. B. RNA is single-stranded. C. DNA lacks a 2' hydroxyl group. Correct Answer D. RNA contains uracil instead of thymine.

C. As aptamers are single-stranded, the stability of the oligonucleotides is important. DNA lacks the 2' hydroxyl group on RNA that leads to self-cleavage, making DNA more stable than RNA and better suited as an aptamer (choice C is correct). According to the passage, the DNA aptamers used are single stranded, making the strandedness of the original nucleotide irrelevant (choices A and B are wrong). Uracil and thymine are essentially identical except for a methyl group but that would not significantly affect the binding capability of the oligonucleotides (choice D is wrong).

What is the pH of a solution containing equal concentrations of acetic acid and acetate ion? A. 1.8 B. 3.5 C. 4.7 D. 5.2

C. As the passage states, when the concentration of the acid (acetic acid) is equal to the concentration its conjugate base (acetate ion), the pH of the solution will be equal to the pKa of the acid. So pH = pKa = -log Ka = -log (1.8 × 10-5) = 5 - log 1.8 ≈ 4.7.

An object is floating in a fluid of 1.5 specific gravity. If the volume of the fluid displaced by the floating object is 5 × 10-3 m3, what is the object's mass? A. 2.5 kg B. 5.0 kg C. 7.5 kg D. Cannot be determined from the information given

C. Because the object is floating, the object's weight is balanced by the buoyant force; that is, mg = ρfluidVsubg, or, after canceling the g's, m = ρfluidVsub. With ρfluid = 1.5ρH2O = 1500 kg/m3 and Vsub = 5 × 10-3 m3, we find that m = ρfluidVsub = (1500 kg/m3)(5 × 10-3 m3) = 7.5 kg

Sociologists refer to women's role as family caregivers in addition to their role as professionals as the "second shift". How might the "second shift" be interpreted as a psychosocial stressor? A. It increases women's sense of self-efficacy in the workplace. B. It results from prejudice against working women. C. It may lead to identity interference. D. It is a function of the "glass ceiling", which leads to a lower standard of living.

C. By definition, women's "second shift" refers to an ongoing duality of roles (the role of a working professional and the role of the family caregiver). When the demands of these roles conflict in terms of time and energy, tension results. Identity interference is the principle that states that people experience stress when two aspects of their identity are in conflict. Thus, the "second shift" could be understood as a cause of identity interference, which then constitutes a psychosocial stressor (choice C is correct). There is nothing to indicate that the "second shift" is the result of prejudice against working women (choice B is wrong). Self-efficacy is Albert Bandura's term for an individual's feelings of capability regarding the accomplishment of a given task; compounding one's roles would not increase self-efficacy in the workplace (choice A is wrong). The "glass ceiling" refers to unofficial limits on women's advancement in the workplace and does not directly relate to their additional roles outside the workplace (choice D is wrong).

Hydrolysis of the phosphocreatine bond releases 43.1 kJ/mol of energy. What is the standard free energy of hydrolysis for ATP? A. -87.4 kJ/mol B. -43.1 kJ/mol C. -30.5 kJ/mol D. +6.7 kJ/mol

C. The passage says that creatine kinase can transfer a phosphate group from phosphocreatine to ADP via a spontaneous reaction. In other words, phosphocreatine dephosphorylation can be coupled to ADP phosphorylation and the net overall reaction is spontaneous, or has a -ΔG. If phosphocreatine dephosphorylation releases 43.1 kJ/mol, ADP phosphorylation must use less energy than this (choice C is correct). If ATP hydrolysis released 87.4 kJ/mol or 43.1 kJ/mol, the transfer of a phosphate group from phosphocreatine to ADP would not be a spontaneous reaction (choices A and B are wrong). ATP hydrolysis releases energy to the cell, so must have a negative standard free energy (choice D is wrong).

What is the FRC for an individual with the following lung volumes: total lung capacity (TLC) = 5700 mL, vital capacity (VC) = 4700 mL, inspiratory reserve volume (IRV) = 3000mL and tidal volume (VT) = 500 mL? A. 3500 mL B. 1000 mL C. 2200 mL D. 1200 mL

C. The passage states that FRC = ERV + RV. TLC = VC + RV RV= TLC - VC = 5700 mL - 4700 mL = 1000 mL VC = VT + IRV + ERV ERV = VC - VT - IRV = 4700 mL - 500 mL - 3000 mL= 1200 mL FRC = ERV + RV= 1200 mL + 1000 ml = 2200 mL Thus choice C is correct and choices A, B and D are eliminated.

(R)-2-Methylcyclohexanone was placed in a flask containing 0.9 equivalents of LDA at −78°C. The flask was then warmed to 0°C and benzaldehyde was added to the solution. How many stereoisomeric products can be isolated from the mixture? A. 4 B. 3 C. 2 D. 1

A. (R)-2-Methylcyclohexanone contains a single stereocenter. When the ketone is added to LDA, the less substituted carbon is deprotonated generating the kinetic enolate. This does NOT affect the stereocenter on the more substituted carbon. However, there is more ketone than base, and as a result not all of the ketone is deprotonated. Thus when the solution is warmed to 0°C, the kinetic enolate tautomerizes to the more stable thermodynamic enolate. This racemizes the stereocenter of the enolate as it adds to the benzaldehyde. Since both the top and bottom of the π system of the enolate can react with either the top or bottom of the π system of the benzaldehyde, the products formed will each have two stereocenters, and all possible combinations of configurations will be produced. Therefore, four possible stereoisomeric products can be isolated.

What is the effect of adding a small amount of a strong acid to the equilibrium shown in Equation 1? A. The equilibrium shifts to the left. B. The pH shifts to 7. C. The pH decreases dramatically. D. The concentration of HCO3- increases.

A. According to Le Châtelier's principle, adding a small amount of acid (H+) to this solution will shift the equilibrium to the left (choice A). This will result in a decrease in the concentration of acetate ion, making choice D incorrect. In addition, since the solution is buffered, it will resist changes in pH, making choices B and C incorrect.

In the semantic network model, what determines the strength of a connection between a node and an association? A. How frequently and deeply connections are made B. How closely the node and association are explicitly related C. How many links there are between the node and the association D. How many state-dependent cues have been created between the node and the association

A. According to the semantic network model, the strength of a connection between a node and an association is related to how frequently and how deeply the connections are made (choice A is correct). The explicit relationship between the node and the association is meaningless unless that connection is constantly reinforced (choice B is wrong). Separate links between the node and the association—suggesting a more circuitous route—are indicative of the spreading activation pattern (choice C is wrong). State-dependent cues, in which familiar locales are used to trigger memories, do not determine the strength of the connection between a node and an association unless, once again, they are used with great frequency (choice D is wrong).

In which of the following are the acrosomal enzymes synthesized? A. Rough endoplasmic reticulum B. Cytoplasm C. Golgi apparatus D. The nucleus, since sperm have no cytoplasm

A. Acrosomal enzymes are located inside a membrane-bound vesicle and are going to be secreted. It is likely that they are processed through the secretory pathway, and to do so they must be synthesized in the rough ER (choice A is correct), not the cytoplasm (choice B is wrong). Proteins are never synthesized in the Golgi (choice C is wrong). It is true that sperm have very little cytoplasm, but during spermatogenesis they did originally have all normal cell structures. Also, protein synthesis never occurs in the nucleus (choice D is wrong).

Similarities that exist between protists and bacteria include all of the following except: A. Organelles B. Double-stranded DNA C. Unicellularity D. Flagellar motility

A. Bacteria do not have organelles while protists exhibit the organelles typical of animal cells (answer choice A is correct). While bacterial store genetic information in circular DNA and protists have linear chromosomes, both forms of DNA are double-stranded and, thus, this is a similarity between bacteria and protists (answer choice B is incorrect). Bacteria are unicellular and protists typically are, as well (answer choice C is wrong). Some protists exhibit amoeboid movement but both protists and bacteria often exhibit flagellar movement (answer choice D is wrong).

All of the following apply to mitotic prophase EXCEPT: A. recombination between homologous chromosomes. B. formation of spindle fibers. C. nuclear envelope breakdown. D. condensation of chromosomes.

A. Both meiosis and mitosis share B, C, and D in common. Recombination only occurs in meiosis, however, and not mitosis (A is false and the correct answer choice).

It has been observed that when an alpha particle and a beta particle are given equivalent initial kinetic energies, the beta particle will travel a significantly greater distance in air before losing its energy. Of the following, which is the most likely explanation for this observation? A. The alpha particle's greater size and charge results in a greater number of interactions, which cause it to dissipate its energy faster. B. Beta particles have greater momentum. C. The beta particle's smaller size causes it to have more elastic collisions with air molecules, allowing it to travel farther. D. The greater velocity of the alpha-particle relative to the beta-particle results in an erratic, shorter mean free path for the alpha particle.

A. Choice B is false since the equation relating momentum, p, to kinetic energy, K, is p =. Since the alpha and beta particles have the same K, the one with the smaller mass (the beta particle) has the lower momentum. Choice C is false since a smaller particle would tend to have fewer collisions, not more. Choice D can be eliminated because the greater mass of the alpha particle means it has a lower velocity than a beta particle of equal kinetic energy.The alpha particle would experience a greater electric force and a greater gravitational force than an equally-energetic beta particle, not because of its lower velocity, but because of its greater charge and its greater mass. [In fact, it can be shown the energy lost per unit distance for a particle of charge q and mass m moving through matter is proportional to q2m / K.] Choice A is correct and describes why alpha particles have shorter ranges than beta particles.

(+)-Ginkgolide B is a diterpenoid trilactone with six five-membered rings, and is extracted from the root bark and leaves of the Ginkgo biloba tree. This molecule has blood-brain barrier permeability, the molecular formula C20H24O10 and a molecular weight of 424.4 g/mol. This molecule must contain: A. four isoprene units, additional functional groups and is able to perform simple diffusion through endothelial cells connected by tight junctions. B. four isoprene units, no additional functional groups and is able to perform simple diffusion through endothelial cells connected by tight junctions. C. four terpene units, additional functional groups and is able to perform simple diffusion through neurons connected by tight junctions. D. four isoprene units, additional functional groups and is able to perform simple diffusion through endothelial cells connected by gap junctions.

A. Diterpenoids contain four isoprene units (eliminate choice C) and additional functional groups (eliminate choice B). The blood-brain barrier is a highly selective permeability barrier that separates the circulating blood from the central nervous system. It is formed by endothelial cells (another reason to eliminate choice C), which are connected by tight junctions (eliminate choice D). Choice A is correct because it accurately describes the composition of the molecule.

The first daughter nucleus in the 238U decay series is thorium-234. If the next four decays are two β- and two α decays, what is the resulting radionuclide? A. Radium-226 B. Polonium-226 C. Radon-228 D. Thorium-230

A. Each β- decay increases the number of protons by 1, but leaves the total number of protons and neutrons unchanged. Each α decay decreases the number of protons by 2 and decreases the total number of protons and neutrons by 4. Thus, after two β- and two α decays, thorium-234 becomes radium-226:

Media representations of Planned Parenthood often center on their abortion practices. Planned Parenthood is responsible for an annual total of 300,000 abortions. However, this accounts for a mere three percent of the services provided. This misrepresentation of Planned Parenthood is an example of: A. institutional discrimination. B. the McDonaldization of society. C. a coercive organization. D. symbolic interactionism

A. Planned Parenthood experiences the effects of prejudice as a result of practices, such as abortion, that conflict with the beliefs of some groups, and this prejudice, in some cases, contributes to institutional discrimination. Mass media is a powerful institution in the United States, and the media executives with higher socioeconomic status are able to set the agenda for their programs. This can lead to institutional discrimination in situations when the media presents a specific group in a negative light for its own purposes (e.g., the anti-abortion movement; choice A is correct). The McDonaldization of society described when a culture adopts the characteristics of a fast-food restaurant, such as efficiency, calculability, standardization, and control. While aspects of mass media are certainly a good example of McDonaldization, the misrepresentation of Planned Parenthood by the media is not an example of this (choice B is wrong). A coercive organization is one where members have no choice in joining; for example, a prison is an example of a coercive organization. While Planned Parenthood has little choice in what the media portrays about them, as an organization, Planned Parenthood is not a part of the media - these are two separate organizations. Therefore, this is not an example of a coercive organization (choice C is wrong). Symbolic interactionism is a major sociological theory that suggests that people create symbolic meanings about objects, events, and behaviors. For example, a handshake is a symbol in society that conveys many different meanings—and everyone in society pretty much acts toward this symbol in agreed-upon ways. Symbolic interactionism is a micro-level theory of society, which focuses on interactions between individuals. Therefore, even if the interaction between the media and Planned Parenthood neatly conveyed something symbolic, it still could not be an example of symbolic interactionism because these are two social structures, which is a macro-level view of society (choice D is wrong).

They found that after controlling for factors such as status, cultural similarity, and physical attractiveness, approximately 75% of respondents rated members of their own race and/or ethnicity as "more romantically desirable" than members of other races and ethnicities. Moreover, marriage data demonstrate that, as of 2010, approximately 92% of all marriages are between couples of the same race and/or ethnicity. This best demonstrates: A. prejudice in romantic desirability ratings and discrimination in marriage partner selection. B. discrimination in romantic desirability ratings and class inequality in marriage partner selection. C. class inequality in romantic desirability ratings and social exclusion in marriage partner selection. D. social exclusion in romantic desirability ratings and prejudice in marriage partner selection.

A. Prejudice involves biased opinions and thoughts about members of another group (such as a racial/ethnic out-group), but does not involve acting on those thoughts; since same-race mate preference involves an opinion about desirability, prejudice best explains the fact that approximately 75% of respondents rated members of their own race and/or ethnicity as "more romantically desirable" than members of other races and ethnicities. Discrimination, on the other hand, is prejudicial treatment of an individual by another individual based on perceived membership in a certain social group; same-race mate discrimination best explains the fact that approximately 92% of all marriages are between couples of the same race and/or ethnicity (choice A is correct; choice D is wrong). Class inequality refers to processes in society that limit a social group's status or opportunities for advancement; this does not best explain same-race romantic desirability ratings or marriage preferences. Similarly, social exclusion, or marginalization, describes social structures that leave certain groups at the fringes of society, rather than allowing them access to equal rights, opportunities, and resources; again, this does not best explain same-race romantic desirability ratings or marriage preferences (choices B and C are wrong).

Retinal isomerase is used to alter the conformation of retinal. Retinal isomerase is most likely manufactured by: A. dehydration synthesis. B. hydrolytic synthesis. C. oxidation. D. glycosidic anabolism.

A. Retinal isomerase, an enzyme, is a protein, and proteins are synthesized by the condensation of amino acids. Condensation involves dehydration.

Unlike humans, in birds the females are the heterogametic gender (produce two different gametes with respect to the sex chromosomes). The sex chromosomes are denoted Z and W, and the W chromosomes carries very little genetic information compared to the Z chromosome. If a sex-linked gene in birds has two different alleles, A and a, that display classical dominance, which of the following represents the possible avian genotypes? A. Females: ZAW or ZaW Males: ZAZA, ZAZa, or ZaZa B. Females: ZAZA, ZAZa, or ZaZa Males: ZAW or ZaW C. Females: ZAW or ZaW Males: ZAW or ZaW D. Females: ZAZA, ZAZa, or ZaZa Males: ZAZA, ZAZa, or ZaZa

A. Since female birds are the heterogametic gender, their gender genotype must be ZW (choices B and D are wrong), and the male bird genotype must be ZZ (choice C is wrong). The key words are "unlike humans."

1-Methylcyclohexanol reacts with HBr to form 1-bromo-1-methylcyclohexane. The mechanism for this reaction is likely to be an: A. SN1 reaction. B. SN2 reaction. C. Nucleophilic addition. D. Addition-elimination.

A. Since no double bonds are formed or broken, this must be a substitution reaction (eliminate choices C and D). Since the hydroxyl in the starting material is on a tertiary carbon atom, the mechanism cannot occur by a bimolecular pathway (eliminate choice B.) The protonated OH group (under acidic conditions) will leave as water to yield a tertiary carbocation, which will be attacked by the bromide ion to give the product.

The standard potential for the reaction K+ + e- K(s) equals -2.93 V, as referenced against 2H+ + 2e- H2(set to 0.0 V by definition). If solid potassium is placed into an aqueous solution of HCl, then: A. H2(g) and KCl(aq) are produced. B. Cl2(g) and KCl(aq) are produced. C. Cl2(g), H2(g), and KCl(aq) are produced. D. no reaction occurs.

A. Since the reduction of K+ as given in the question has a potential more negative than the reduction of H+, the oxidation of K(s) to K+ with transfer of electrons to H+ will have a positive potential and be spontaneous. This eliminates choice D. Hydrochloric acid (HCl, a strong acid) will dissociate nearly completely in water into H+ and Cl-. In the presence of a reducing agent (K), H+ ions can accept electrons and be reduced to H2, and K+ and Cl- will remain in solution. Since there is no oxidant which can accept the extra electron from Cl-, Cl2 will not be formed, eliminating choices B and C.

Addition of which of the following to a 100 mL solution of aqueous HI at pH = 1 would result in a new solution with a pH closest to 7? A. 230 mg of solid Na B. 100 mL of a 1 M solution of Ni(NO3)2 C. 420 mg of solid NaF D. 100 mL of a 0.01 M solution suspension of Zn0

A. The H+ in the HI solution can be eliminated electrochemically or through an acid base reaction to achieve a pH = 7. Neither the Ni2+ nor the Zn0 in choices B and D, respectively, have the capacity to reduce H+. Such a reaction with Zn0 has a negative voltage, and Ni2+ is simply not reductive. The NaF (MW = 42) in choice C does have the capacity to neutralize H+ after dissociating into Na+ and F-, and 420 mg of the compound does represent the correct 0.01 moles of compound needed to neutralize the 0.01 moles of acid in 100 mL of a 1 M solution. However, this constitutes adding a weak base to a strong acid, and will hence have a residual pH somewhere below 7. 230 mg of solid Na is 0.01 moles of Na. Since the reaction 2Na + 2H+ → H2 + 2Na+ is clearly electrochemically spontaneous, all of the H+ will be neutralized, leaving only a spectator ion in Na+. This makes choice A correct.

The amphoteric character of amino acids best explains their ability to: A. form dipolar ions. B. form peptide bonds. C. contribute directly to a protein's secondary structure. D. dissolve in nonpolar solvents.

A. The amphoteric character of amino acids describes their ability to do two things: accept a proton or donate a proton. In other words, amino acids can act as either an acid or a base. When the amino portion of an amino acid deprotonates its own carboxylic acid, a dipolar ion (or zwitterion) forms. This is a direct result of the amphoteric character of the amino acid.

If the alcohol in the Pitot tube were replaced with water, then the height difference of the liquid in the U-tube for a given air speed would be: A. smaller. B. the same. C. greater. Your Answer D. impossible to predict.

A. The equation given in the passage can be rearranged to show that y = v2ρgas / (2gρliquid) → y ∝ 1 / ρliquid. Since ρwater is greater than ρalcohol ρliquid increases causing y to decrease.

The levels of processing theory would be supported by a finding that: A. participants in the low coherence condition performed better on a task assessing long-term memory of the material than did participants in the high coherence condition, regardless of intelligence-theory orientation. B. participants in the high coherence condition performed better on a task assessing long-term memory of the material than did participants in the low coherence condition, regardless of intelligence-theory orientation. C. entity theorists in the high coherence condition performed better than incremental theorists in the same condition on a problem-solving task. D. incremental theorists in the high coherence condition showed lower emotional arousal in response to the text than did entity theorists in the same condition

A. The levels of processing theory posits that people remember information better when they process it more deeply. For example, people who are made to answer questions about material they read will remember the material better than those who simply read it. Since participants in the low coherence condition must think more deeply about the text in order to understand it, it follows that they will remember the material better and thus perform better on a long-term memory task. Additionally, while the researchers expected differences in perceived comprehension between the two types of theorists, no expected differences in depth of processing or actual comprehension is indicated by the passage (choice A is correct; choice B is wrong). The passage did not suggest that entity and incremental theorists would differ regarding problem-solving ability (choice C is wrong) or emotional arousal (choice D is wrong). Further, neither problem solving nor emotional arousal is relevant to the levels of processing theory.

Networks built of copper wiring experience signal degradation. This occurs because copper wires: A. dissipate some of the electrical energy that flows through them as heat. B. must be surrounded by insulation, which interferes with copper's conduction properties. C. are often bent in networks, and mechanical deformation of the copper interferes with its conduction properties. D. experience thermal expansion in hot environments, which adversely affects their conducting ability.

A. The passage states that "due to their resistivity, copper wires attenuate [i.e., degrade the amplitude of] signals." Resistivity of a current-carrying component immediately implies dissipation of heat, so choice A is best.

Which of the following amino acids found in ARFGAP1 is most likely to contribute to the protein's stabilization of GTP in the myrARF1 GTPase active site? A. Lys B. Val C. Asp D. Asn

A. The passage states that the activity of ARFGAP1 is in part due to its stabilization of the myrARF1 GTPase active site. Due to the negative charge of GTP at physiological pH, a basic amino acid residue which will be positively charged in a protein under the same conditions would provide the greatest stabilizing effect. Since lysine is the only basic amino acid given, it is the correct answer (choice A is correct). Val is a nonpolar amino acid (eliminate choice B). Asp is an acidic amino acid (eliminate choice C). Asn is a polar, non-ionizable amino acid (eliminate choice D).

The results of the manipulation check for the "no difference condition" are evidence of: A. in-group favoritism. B. out-group favoritism. C. a primary group. D. out-group discrimination.

A. The passage states that, in the "no difference condition," a majority of girls guessed that excellent performance was associated with a girl, while a majority of boys guessed that excellent performance was associated with a boy. An individual's positive bias towards his/her own group in known as "in-group favoritism" (choice A is correct; choice B is wrong). Primary groups are groups composed of members who interact frequently and on an intimate, long-term basis. Primary groups are typically composed of family members and very close friends; guessing a "girl" or a "boy" in the "no difference condition" is not an example of a primary group (choice C is wrong). While the students' responses on the manipulation check reflect a negative out-group bias, they are not considered an example of discrimination. The term discrimination describes when members of a group are denied access to resources or other privileges on the basis of their membership in that group (choice D is wrong).

Rank the following bonds in order of increasing polarity: I. C—Cl III. Cl—ClII. Si—Cl IV. P—Cl A. III < I < IV < II B. III < IV < II < I C. I < II < IV < III D. II < IV < I < III

A. The polarity of a bond depends on the difference in electronegativity between the two bonding atoms: The larger the difference, the more unequal the sharing of electrons, and the more polar the bond. Thus, the Cl—Cl bond is completely nonpolar, eliminating choices C and D. To find the final answer, look at the other extreme of the ranking problem for the remaining answer choices. Carbon is more electronegative than Si, therefore Cl, which is the most electronegative element depicted, will show the greatest electronegativity difference with Si. Therefore, of the four bonds, the Si—Cl bond should be the most polar (eliminate choice B).

Misoprostol is a synthetic analog of prostaglandin E. Which of the following is true regarding the use of misoprostol in a patient with PUD? A. Misoprostol inhibits cAMP and calcium release mechanisms, and promotes ulcer healing. B. Misoprostol promotes cAMP and calcium release mechanisms, and promotes ulcer healing. C. Misoprostol inhibits cAMP and calcium release mechanisms, and prevents ulcer healing. D. Misoprostol promotes cAMP and calcium release mechanisms, and prevents ulcer healing.

A. This is a two-by-two question. The passage states that prostaglandin E helps protect the intestinal lining from acid. Thus misoprostol, a prostaglandin E analog, would be expected to do the same thing. Protecting the intestinal lining from acid would promote ulcer healing (choice C and D are wrong). From the figure, the cAMP and calcium release mechanisms are involved in promoting acid secretion; to have a protective effect, misoprostol would have to inhibit these signal cascades (choice A is correct and choice B is wrong).

One of the modifications that Milgram made to his original shock experiment was to test the possible effects of conformity on obedience. The basic experiment tests the conditions under which a research subject, the "teacher", will administer an electric shock to the "learner" (a confederate member of the research team). The teacher receives instructions from an authoritative "experimenter" (a research team member) to administer the shock under certain circumstances. Which of the following experimental modifications would in fact test for the effects of conformity on obedience? I. Adding another teacher (a confederate) to the shock administration room II. Adding a window to the room so that the teacher can see the learner III. Increasing the proximity of the teacher to the learner A. I only B. II only C. I and II only D. II and III only

A. To assess the possible effects of conformity on obedience, one must determine whether and to what extent subjects conform their behavior to the actions of others who appear to be similarly situated (i.e., other "teachers") when determinig whether or not to obey the experimenter who instructs them to administer shocks. Item I is true: adding another confederate teacher to the shock administration room would test whether the naive subject would conform to the actions of the other "teacher" when determining whether or not to obey. Item II is false: adding a window to the room wherein the learner will receive the shock would not test for the effects of conformity on obedience because it would not include a similarly situated figure (choices B and C can be eliminated). Item III is false: similarly, merely increasing the proximity of the teacher to the learner would only test obedience, as there is no other person present to whose behavior the subjects might conform their actions (choice D can be eliminated, choice A is correct).

Which of the following is NOT true regarding stereotype threat? A. Telling a group of females that "females tend to perform more poorly on this math test than males" before the math test results in lower average scores for the females. B. White males are unaffected by stereotype threat because they are the majority group to which other groups are often compared. C. Emphasizing students' race before a standardized test often produces lower scores for ethnic and racial minorities. D. Females tend to score higher on math-based tests when testing in a group of all females (rather than a mixed group of females and males).

B. Any group can be subject to stereotype threat, regardless of if the group is a majority or minority group. For example, when a group of white male students, who scored high in math on the SAT, were told that they were taking a test to "determine why Asian students typically outperform other students in math," they performed much worse in math. Stereotype threat can cause anyone to perform worse when they believe the negative stereotype could be true or worry about confirming a stereotype about a group to which they belong (choice B is correct). Numerous studies have shown that emphasizing the stereotype that males are better at math than females will produce lower math performance for females; this is one of the classic stereotype threat examples (choice A is wrong). Similarly, emphasizing an individual's race will also often lead to poorer academic performance, since the stereotype for most racial and ethnic minorities is that they do not perform as well on standardized tests as white people do; this is also a classic stereotype threat example (choice C is wrong). When females perform math-based assessments in all-female groups, stereotype threat is not activated, because they are less aware of their female-ness while taking the exam, so they do tend to perform much better; this is also a classic stereotype threat example (choice D is wrong).

Which of the following inhibitors would have no effect on the slope of a Lineweaver-Burk plot? A. Competitive Inhibitor B. Uncompetitive Inhibitor C. Noncompetitive Inhibitor D. Mixed Inhibitor

B. As the slope of the Lineweaver-Burk plot is Km/Vmax, the correct answer is an inhibitor that has the same effect on both Km and Vmax. An uncompetitive inhibitor leads to an equal decrease in the both the Km and Vmax, leading to a series of parallel lines on a Lineweaver-Burk plot (choice B is correct). Competitive, noncompetitive, and mixed inhibitions would all affect the slope of a Lineweaver-Burk plot (choices A, C, and D are wrong).

All of the following are involved in proprioception, EXCEPT: A. muscle spindles. B. baroreceptors. C. Golgi tendon organs. D. joint capsule receptors.

B. Baroreceptors are a type of mechanoroceptor located within the blood vessels sensitive to the stretch of the vessel itself. Baroreceptors detect changes in blood pressure, and are not involved in proprioception (choice B is correct). Muscle spindles are mechanoreceptors sensitive to the stretch of muscles, and are thus involved in movement and proprioception (choice A is wrong). Similarly, the Golgi tendon organs monitor the amount of tension in the tendons and are also involved in movement and proprioception (choice C is wrong). Joint capsule receptors sense pressure, movement, and tension in the joints and are also involved in movement and proprioception (choice D is wrong).

Which of the following equilibria could be present in a buffered solution? A. HCl( aq ) H + ( aq ) + Cl - ( aq ) B. H 2 CO 3 ( aq ) H + ( aq ) + HCO 3 - ( aq ) C. H2O 2 ( aq ) + 2KI( aq ) 2KOH( aq ) + I 2 ( aq ) D. CaCl 2 ( aq ) Ca 2+ ( aq ) + 2 Cl - ( aq )

B. Buffered solutions are commonly made with weak acids and their conjugate bases. The only weak acid given is carbonic acid (choice B). HCl (choice A) is a strong acid and CaCl 2 (choice D) is a salt. Choice C is a redox reaction.

the forward direction, Reaction 1 may be considered: A. favorable, because both steps of the reaction are favorable. B. favorable, because the negative ΔG° for Reaction 2 more than compensates for the positive ΔG° for Reaction 3. C. unfavorable, because the positive ΔG° for Reaction 3 more than compensates for the negative ΔG° for Reaction 2. D. unfavorable, because the negative ΔG° for Reaction 2 more than compensates for the positiveΔG° for Reaction 3.

B. Choice A is false since Reaction 3 is unfavorable (its ΔG° is positive). Choice D is false since ΔG°2 + ΔG°3 < 0, so the overall reaction would be favorable. Choice C is false for the same reason (and, furthermore, ΔG°3 is less than the magnitude of ΔG°2).

HIV, the virus that causes AIDS, is a retrovirus. Retroviruses have an RNA genome that, after entry into the host cell, is reverse transcribed to DNA, then incorporated into the host genome. RNA copies of the viral genome are produced using the normal host machinery, then packaged into viral capsid proteins for release. Which one of the following is most likely to contribute to the development of drug-resistant HIV? A. Mutation of the virus after insertion into the host-cell genome B. Frequent random errors in transcription by host-cell enyzmes C. Viral proteins folding differently in the presence of drug than in its absence D. Changes in the tertiary structure of viral RNA by drug

B. Drug resistance develops as mutant versions of the virus are produced and begin infecting new host cells. The change must be able to be passed on to viral progeny. If the viral proteins fold differently in the presence of drug than in its absence, this might account for the mechanism of action of the drug, but does not explain how drug resistance develops, nor could this be a heritable change (choice C is wrong). Changes in the tertiary structure of the viral RNA by the drug is another temporary, non-heritable change (choice D is wrong). Choices A and B are both plausible mechanisms for creating new, heritable versions of the virus. However, mutation of the virus after insertion into the host-cell genome would require that an error in DNA replication be made—a rather unlikely event, given the proofreading ability of DNA polymerase. Viral progeny are produced through transcription (creating a new RNA viral genome off the permanent DNA version inserted into the host-cell genome), and the question states that this occurs using the normal host machinery. Since the normal host RNA polymerases have no proofreading function, it is more likely that errors will occur here, leading to mutant virus (choice B is better than choice A).

If the conversion of tyrosine to epinephrine were monitored by IR spectroscopy, the spectrum would show which of the following: I. Disappearance of a band near 3200 cm-1 II. Appearance of a band near 3200 cm-1 III. Disappearance of a band near 1720 cm-1

B. During the transformation indicated, a carboxylic acid group is lost. Since the carbonyl group (C=O) is the only bond type present in the reactant that is not present in the product, it is the only band lost. C—O double bond bands appear near 1700 cm-1, so item III is true (eliminate choice A). Since both the reactant and products have O—H bonds in them, the band at 3200 cm-1 that represents the hydroxyl group will neither disappear or appear, making both items I and II false (eliminate choices C and D).

In transposition of the great arteries, a congenital birth defect, the aorta of the newborn is connected to the right ventricle and the pulmonary artery is attached to the left ventricle. This would result after birth in circulation of: A. oxygenated blood through the systemic vasculature and deoxygenated blood through the pulmonary vasculature. B. deoxygenated blood through the systemic vasculature and oxygenated blood through the pulmonary vasculature. C. oxygenated blood through both the systemic and pulmonary vasculature. D. deoxygenated blood through both the systemic and pulmonary vasculatur

B. In the normal circulation, the right ventricle pumps blood through the pulmonary artery to the lungs. Blood returns from the lungs to the left atrium and is pumped by the left ventricle through the aorta to the rest of the body. If blood from the left ventricle passes to the pulmonary artery instead of the aorta and is then returned to the left atrium, oxygenated blood will loop around through the pulmonary system without passing to the rest of the body. At the same time, the deoxygenated blood from the systemic circulation will pass to the right atrium, then back out to the systemic circulation through the aorta rather than the pulmonary artery, causing deoxygenated blood to loop through this system (choice B is correct and choice A is wrong). Choices C and D are wrong since they have all blood either oxygenated or deoxygenated.

Increased intermolecular attractions cause the ratio PV/(RT) to decline because individual molecules: A. eventually combine with other molecules, decreasing the number of particles in the container. B. lose kinetic energy to potential energy and strike the side of the container with less force. C. increase in speed due to electron repulsion and strike the side of the container with increased force. D. transfer electrons during collisions with other molecules in the container.

B. Intermolecular attractions increase the potential energy between molecules, decreasing their kinetic energy. Note that the molecules do not undergo any reactions, eliminating choices A and D. Choice C is incorrect because intermolecular attractions do not result in electron repulsion.

Goiter development resulting from iodine deficiency is most likely due to: A. accumulation of T3 and T4 in the thyroid gland. B. high levels of TSH. C. the build-up of lipids in thyroid hormone-producing cells. D. low levels of TRH.

B. Iodine is required for thyroid hormone production, so in the absence of sufficient iodine, thyroid hormone levels will fall, and feedback inhibition will not occur. TSH and TRH levels will increase, causing goiter (choice B is correct, and choice D is wrong). In the absence of iodine, T3 and T4 cannot be made, so they will not accumulate (choice A is wrong). There is no reason to believe that lipids build up in these cells (choice C is wrong).

Researchers used a probability-based sample to recruit non-physician participants, which lead to a non-physician sample representative of the national population. Therefore, even though demographic information is not presented in the passage, it is still possible to conclude that: the most common religious affiliation reported is Christian (as compared with Muslim, Jewish, Hindu, and Buddhist). the least common socioeconomic status reported is lower class (as compared with upper class, middle class, and working class). for married participants, the most common relationship structure reported is monogamous (as compared with polygamous). A. I and II only B. I and III only C. II and III only D. I, II, and III

B. Item I is true: the most common religion in the United States is Christianity (choice C can be eliminated). Christianity is the largest religion in the world, and in the United States 80% of the people identify as Christian. Item II is false: the least common socioeconomic status in the United States is upper class, not lower class (choices A and D can be eliminated). In the United States, the top 3% of the population is considered upper class, while roughly a quarter of the population is considered lower class. Item III is true: the most common form of marriage in the United States is monogamy. The social norm in the U.S. is monogamous marriages, in which the partners are married only to each other. Furthermore, this convention is reinforced through legislation, as polygamous marriages are illegal in the United States (choice B is correct).

Muscle fibers are composed of small contractile units called sarcomeres. During contraction, which of the following occurs within a sarcomere? Myosin filaments shorten. Actin filaments shorten. Overlap between actin and myosin filaments increases. A. I only B. III only C. II and III only D. I, II, and III

B. Items I and II are false: During contraction, neither myosin nor actin filaments get shorter. The overlap between them increases to make the sarcomere shorter (eliminate choices A, C and D). Item III is true: The overlap between the fibers increases as part of contraction.

Research has also considered the salaries of medical professionals and the effects of compensation on overall life satisfaction. Reports of average earnings range from $156,000 to $315,000, with pediatricians reporting the lowest salaries and orthopedic surgeons and radiologists reporting the highest salaries. Based on this information, models of social stratification in the United States would consider the average anesthesiologist to be a member of which social class? A. Upper class B. Middle class C. Working class D. Lower class

B. Most sociologists consider socioeconomic status (SES) when discussing social stratification. This measure is often defined in terms of power, prestige, and wealth owing to the common interrelationship among these factors. The reported salaries of specialists range from $157,000 to $316,000 for the lowest and highest earners listed, respectively. The average anesthesiologist is then expected to earn an intermediate amount (the research reports an annual average of approximately $310,000). While estimates differ, this earning potential alone suggests that anesthesiologists are middle class, perhaps upper middle class (choice B is correct). Middle class annual incomes range from $46,000 to the minimum earnings representing the upper class (this definition varies); 40% of the population is considered middle class. Despite the high earnings of these medical specialists in comparison to the national average, it is a common misconception that these professionals are "upper class". According to most models of social stratification, the income range for upper class is much higher. Upper class annual incomes range from millions to billions of dollars; a mere 3% of the population is considered upper class (choice A is wrong). There are medical professionals who earn comparable amounts when accounting for additional income and wealth (e.g., famous doctors who host their own medically-themed television shows can earn several million dollars each year). However, the information provided considers the average anesthesiologist. Working class annual incomes range from $19,000 to $45,000; 30% of the population is considered working class (choice C is wrong). Lower class annual incomes range from no income to $18,000; 27% of the population is considered lower class (choice D is wrong).

The following characteristics are shared between skeletal and smooth muscle with the exception of: A. Upstroke in action potential is secondary to inward Na+ current B. Potential exhibits a plateau C. Action potential opens voltage gated Ca2+ channels D. Ca2+ is the primary substrate for triggering contraction

B. Neither skeletal nor smooth muscle contraction is initiated by an action potential with a plateau; this feature is only characteristic of cardiac action potentials (answer choice B does not indicate a similarity and is the correct answer). The upstroke in the action potential for both skeletal and smooth muscle is triggered by an inward Na+ current (answer choice A states a similarity and is not the correct answer). Once received by either skeletal or smooth muscle, the action potential does, indeed, cause voltage-gated Ca2+ channels to open; in skeletal muscle, these channels are located on the sarcoplasmic reticulum while, in smooth muscle, they are located in the cell membrane (answer choice C is wrong). Indeed, Ca2+ is the molecular substrate for triggering contraction in both skeletal and smooth muscle; binding with troponin triggers skeletal muscle contraction and calmodulin binding activates myosin light-chain kinase in smooth muscle (answer choice D is wrong).

Nevirapine is an example of a non-nucleoside reverse transcriptase inhibitor. Which of the following is true of nevirapine? A. It is a competitive antagonist of reverse transcriptase. B. It is a noncompetitive antagonist of reverse transcriptase. C. It is an uncompetitive antagonist of reverse transcriptase. D. Its effect on reverse transcriptase can be reversed with increasing concentrations of adenine, thymine, cytosine, and guanine.

B. Nevirapine is a non-nucleoside antagonist. As the passage states, the non-nucleosides are allosteric inhibitors. As a result, they must be noncompetitive inhibitors of reverse transcriptase (choice B is correct and choices A and C are eliminated). Noncompetitive inhibitors cannot be reversed by increasing the concentration of substrate; that would work only for a competitive inhibitor (choice D is eliminated

A semipermeable membrane separates an aqueous solution of 0.003 MNaCl from an aqueous solution of 0.0025 MBaF2. With this apparatus, one would observe that water crosses the membrane: A. from the BaF 2 solution to dilute the NaCl solution. B. from the NaCl solution to dilute the BaF 2 solution. C. from the BaF 2 solution to concentrate the NaCl solution. D. from the NaCl solution to concentrate the BaF 2 solution.

B. Osmotic pressure is a colligative property, which means it depends only on the concentration of solute particles, and not their identity. Therefore, a 0.003 M solution of NaCl will have an effective molality of 0.006 M (since NaCl is composed of two ions) and a 0.0025 M solution of BaF2 will have an effective molality of 0.0075 M (since BaF2 is composed of three ions). Osmotic pressure will drive movement of water from the lower concentration solution (NaCl) to the higher concentration solution (BaF2). Note that this movement of water acts to dilute the BaF2 solution.

Which of the following describes how the brain uses parallel processing to process a visual stimulus? A. A different area of the brain is activated by each type of image (images, letters, etc.). B. Visual areas V1-V5 are utilized to analyze different aspects of an image simultaneously. C. Images are simultaneously processed using both top-down and bottom-up processing. D. Visual areas V1-V5 are utilized to analyze each aspect of an image in succession.

B. Parallel processing describes the simultaneously processing of different aspects of a stimulus (choice B is correct), instead of analyzing the pieces of a stimulus step-by-step (choice D can be eliminated). Choice A is the definition of feature detection theory, and can be eliminated. Top-down and bottom-up processing are elements of gestalt psychology; the simultaneous use of both top-down and bottom-up processing is characteristic of most sensory processing, but is not the definition of parallel processing (choice C can be eliminated).

The tertiary structure of a hydrophilic sodium-hydrogen transport channel would best accommodate which of the following substances? A. Anions B. Cations C. Phosphoric acids D. Neutral compounds

B. Proteins transporting ions through the plasma membrane are typically highly selective in the ions they transport. Both H+ and Na+ are cations, so choice B is the best option.

According to self-determination theory, which proposes that people will seek autonomy, competence, and relatedness throughout their lifespans, the oldest participants in the study would most likely: A. determine on their own that they are unfit to drive, regardless of their objective driving performances. B. emphasize that any decisions to limit their respective driving privileges are self-endorsed. C. strive to achieve a sense of acceptance regarding their individual life histories. D. enhance their driving skills at the expense of social relationships.

B. Self-determination theory maintains that, throughout the lifespan and especially in older age, people seek autonomy, competence, and relatedness. Autonomy refers to viewing one's circumstances as self-endorsed, while competence refers to the expression of one's talents. Finally, relatedness refers to a sense of being cared about by other people. Therefore, according to this theory, one of the oldest participants in this study would emphasize that a decision to limit his or her driving is self-endorsed (choice B is correct). A determination of being unfit irrespective of driving skill is not implied by self-determination theory (choice A is wrong). Enhancing one's skills at the expense of social relationships contradicts the theory's principle of relatedness (choice D is wrong). Finally, achieving a sense of acceptance of one's personal life history is associated with Erikson's developmental conflict of integrity versus despair, not with self-determination theory (choice C is wrong).

The Whorfian hypothesis suggests that our perception of the world is based on our availability of language with which to describe it. If a language's only color words were white, black, red, and green, which of the following would a supporter of the Whorfian hypothesis believe? A. There is nothing purple in the environment of the native speakers of this language. B. Native speakers of this language perceive grass and the ocean as being the same color. C. It is evolutionarily important for native speakers of this language to identify the color red (e.g., to avoid poisonous berries). D. Native speakers of this language are most likely colorblind.

B. Since the Whorfian hypothesis states that language drives cognition, a supporter would believe that the only distinctions among colors that a native speaker of this language would perceive are among black, white, red, and green. Therefore, they would not see a difference between the green of the grass and the blue of the ocean (choice B is correct). Whorfian supporters would not necessarily believe that other colors are not present in this environment; the native speakers would simply accept that particular wavelength as one of the colors for which they have a term (choice A is wrong). The Whorfian hypothesis does not speak to why certain color terms are used as opposed to others, although there is a standard pattern described by Berlin and Kay (1969). It would therefore be irrelevant to the supporter whether or not the word red is an evolutionarily useful tool (choice C is wrong). If native speakers were colorblind and only used terms for the colors that they could see, this would contradict the Whorfian hypothesis, as cognition would be determining language and not the other way around (choice D is wrong).

After asking the opinions of several medical students about raising the voting age, a researcher then asked those participants who were against such a proposal to write a brief essay in support of raising the voting age. As an incentive, he paid half of the medical students $1 and the other half $50. Next, he reassessed their opinions on the topic to see if writing the essay had made an impact. Which group was more likely to change opinions? A. Students paid $50 were more likely to change their opinions because of the conditioning. B. Students paid $1 were more likely to change their opinions because of cognitive dissonance. C. The two groups of students were equally likely to change opinions as the result of exposure to new information. D. No students would change their opinions because this was not a personal topic.

B. Students who are paid to advocate a given position are more likely to support that position when asked about their opinions if the incentive received was minimal, as they are more likely to attribute their opinion change to internal reasons rather than to an external circumstance (i.e., the compensation). Thus, cognitive dissonance causes a shift in opinion (choice B is correct). With respect to answer choice A, when students are given a substantial incentive (in this case $50) to advocate a conflicting position they are able to attribute their advocacy to the large reward given, rather than to internal factors; the pressure of cognitive dissonance is thus removed. Moreover, neither classical nor operant conditioning principles apply to this scenario. Classical conditioning requires the pairing of a neutral stimulus with an unconditioned stimulus until the two stimuli become associated, which is not pertinent to this situation. Operant conditioning involves increasing or decreasing the frequency of a certain behavior by repeatedly rewarding or punishing it, respectively, which did not occur in this case (choice A is wrong). There would be a greater cognitive dissonance effect on students without the external motivation to modify their positions (the group paid $1) than on those with an external explanation for the change (those paid $50). Moreoever, no new information was provided (choice C is wrong). The personal nature of the topic would not be relevant; so long as the students did not have an external factor to which to attribute their advocacy, they would experience cognitive dissonance and would be less supportive of their previous positions (choice D is wrong).

f an organic nerve toxin (acting at the neuromuscular junction) renders the ion channel of postsynaptic acetylcholine receptors permanently open, the toxin would be most likely to: A. cause prolonged hyperpolarization of the postsynaptic membrane. B. cause prolonged depolarization of the postsynaptic membrane. C. block the release of vesicles containing acetylcholine. D. prevent muscle contraction.

B. The acetylcholine receptor in the neuromuscular junction is a ligand-gated sodium channel. When it binds acetylcholine, it opens to allow sodium to flow down a gradient into the cell, depolarizing the muscle cell. The more that the channel is open, the greater the depolarization (B is correct). Hyperpolarization would require positive charges to leave the cell, not enter (A is wrong). The toxin acts on the acetylcholine receptor, so there is no reason to believe that it will block acetylcholine release (C is wrong). The result of prolonged depolarization will be excessive excitation of skeletal muscle, not a block on contraction (D is wrong).

The bicarbonate buffering system protects the blood against large pH swings from its normal level at 7.4 and is based in the following equilibria: H2O(l) + CO2(g) H2CO3(aq) H+(aq) + HCO3-(aq) If a subject were to be placed in an environment enriched in CO2, which of the following is a reasonable expectation for his/her blood pH? A. 7.4 B. 7.1 C. 8.6 D. 7.9

B. The question details the fact that H2O and CO2 react to form H2CO3. Assuming the hypothetical test subject was equilibrated in a normal environment, his/her blood would have a normal pH of 7.4. If the concentration of CO2 inhaled by the subject was increased, all of the equilibria would shift to the right, slightly increaing the [H+] of the blood and thus slightly decreasing the pH of the blood. The only answer possible is choice B.

Which of the following best describes how the brain determines the location of a sound? A. The angle of the sound wave, with respect to the eardrum, allows the brain to determine the location of the sound. B. Sound waves reach the ear closest to the source of the sound first, and this difference in timing allows the brain to determine the location of the sound. C. The angle of the sound wave, with respect to the auditory hair cells, allows the brain to determine the location of the sound. D. Sound waves closer to the source have a higher frequency, and this difference in frequency allows the brain to determine the location of the sound.

B. The angle of the sound wave with respect to the ear is not pertinent to determining the location of the sound (choices A and C can be eliminated). Sound waves reach the ear closest to the source of the sound first, and the further ear second. This time gap allows the brain to determine the location of the sound (choice B is correct). Choice D is incorrect; the frequency of the sound is not relevant to determining the location, nor is there a difference from one ear to the next.

Which of the following statements might be a reasonable expectation based on the data shown in Figure 2? A. Ongoing administration of GBP would reduce afferent pain signaling to the brain from the ipsilateral paw only. B. Ongoing administration of GBP would reduce afferent pain signaling to the brain from both the ipsi- and contralateral paws. C. Ongoing administration of saline would reduce afferent pain signaling to the brain from the ipsilateral paw only. D. Ongoing administration of saline would reduce afferent pain signaling to the brain from both the ipsi- and contralateral paws.

B. The data shown in Figure 2 demonstrate that, while the effect is more dramatic for the ipsilateral paw, the withdrawal threshold increases for both ipsi- and contralateral paws (choice B is correct). While it is unlikely that the contralateral paw exhibits mechanical allodynia in this experiment, the data suggest that the threshold for withdrawal is increased with GBP administration (eliminate choice A). Saline has no effect on the paw withdrawal threshold (eliminate choices C and D).

DNA from resistant bacteria in Dish 6 is extracted and placed on agar with phage-sensitive E. coli. After incubation it is determined that these E. coli are now insensitive to phage T1 infection. The most likely mechanism for their acquisition of resistance is: A. transduction. B. transformation. C. sexual reproduction. D. conjugation.

B. The definition of transformation is the process in which naked DNA, not a virus, is taken into a cell and changes the genetic characteristics of that cell. That is the case in this experiment, with extracted DNA making cells resistant to the virus (choice B is correct). Transduction is mediated by a virus, conjugation involves direct transfer of DNA between bacteria, and sexual reproduction does not apply to bacteria (choices A, C, and D are wrong).

A scientist is experimenting with enzymes found in the human body. Of the following, which would make the most appropriate buffer for such work? A. C6H5COOH (Ka = 6.5 × 10-5) B. HClO (Ka = 3.5 × 10-8) C. HCN (Ka = 4.9 × 10-10) D. H3CNH3+ (Ka = 2.2 ×10-11)

B. The human body has a pH of 7.4. It is best to choose a buffer whose pKa value is close to the pH that one is trying to maintain. Since HClO has a Ka value of 3.5 × 10-8, we know that its pKa is a little less than 8 (in fact, it's about 7.5). Therefore, of the choices listed, HClO (choice B) would be the best here.

In the study described in the final paragraph, what is/are the independent variable(s)? Neuroticism Socioeconomic status (SES) Coronary heart disease incidence A. I only B. I and II only C. I and III only D. II and III only

B. The independent variable is the variable that the experimenter controls or manipulates, or which is already fixed in advance; the independent variable is thought to have some effect on the dependent variable. The study described in the final paragraph contains two independent variables and one dependent variable. Item I is true: Neuroticism is an independent variable because it is fixed prior to the experiment (subjects are either high or low in neuroticism) and this variable is used to place the individuals into groups. In other words, neuroticism is a personality characteristic of each individual that can be measured by the researchers, although not assigned or controlled (choice D can be eliminated). Item II is true: SES is an independent variable because it is also used to place individuals into groups and is a demographic characteristic of each individual that can be measured by the researchers (choices A and C can be eliminated). Item III is false: coronary heart disease is a dependent variable because it is the response measured by the researchers, who hypothesize that neuroticism and SES somehow impact this variable (choice B is correct).

T3 and T4 most likely exert their effect on target cells by: A. binding to a transmembrane protein and activating a second messenger system B. diffusing across the cell membrane and binding to a nuclear receptor. C. entering the cell via facilitated transport and binding to a nuclear receptor. D. entering the cell via iodine channels and binding to a cytosolic receptor.

B. The passage states that T3 and T4 are lipid soluble; in fact, although they are peptide hormones, T3 and T4 have the same mechanism of action as the steroid hormone, diffusing through the plasma membrane to bind to an intracellular receptor that goes into the nucleus to regulate transcription (choice B is correct and choice A is wrong). They do not require a protein to cross the plasma membrane, so facilitated transport is not involved (choices C and D are wrong).

A possible contributor to Alzheimer's disease is the clumping of amyloid proteins formed from the degradation of larger proteins in the fatty tissues surrounding nerve cells. This degradation could be a result of: A. formation of more peptide linkages via the condensation of amino and carboxylic acid functional groups attached at the ends of the larger protein unit. B. hydrolysis of some of the amide peptide linkages, creating smaller polypeptide units. C. the destabilizing effects of 2° structures in the proteins. D. oxidative cleavage of the disulfide linkages between cysteine units of the proteins.

B. The question states that the degradation of a larger protein is responsible for generating smaller amyloid protein segments. Proteins are polypeptides with an amide linkage holding adjacent amino acids together. These peptide bonds will break when hydrolyzed and form smaller chains (choice B is correct). Condensation reactions result from the combination of two molecules with the removal of water (the opposite of hydrolysis) and will only lead to larger molecules not smaller ones (eliminate choice A). The 2° structures of proteins are α-helices and β-sheets. These structures are energetically favorable, thus stabilizing, as they are held together by hydrogen bonds (eliminate choice C). Cleavage of the disulfide bond in the 4° structure of a protein can lead to smaller subunits. However, that process is a reduction, not an oxidation (eliminate choice D).

The tumor suppressor gene p53 contains a number of lysine residues that can be acetylated to stabilize the protein and facilitate its activation. All of the following could be the result of acetylation of p53 EXCEPT: A. activation of DNA repair pathways. B. progression in the cell cycle from G1 to S phase. C. initiation of apoptosis. D. Increasing transcription of the cell cycle inhibitor CDKN128.

B. The question stem states that acetylation of p53 enhances its activity. p53 is a tumor suppressor gene that prevents movement through the cell cycle in the event of DNA damage (thus giving time for the DNA to be repaired), or that triggers apoptosis in the even that DNA damage is too severe to be repaired. Choices A, C, and D are all consistent with the idea of halting the cell cycle, repairing DNA, or committing cell suicide. However, choice B is an enhancement of the cell cycle, not a halting (choice B is not a result of acetylation of p53 and is the correct answer choice).

Antibodies specific to the mitotic spindle apparatus would most likely recognize products of: A. transcription. B. translation. C. transformation. D. replication.

B. The spindle is composed of microtubules, which are polymers of tubulin protein monomers. Antibodies against the spindle would recognize proteins, which are produced during translation (choice B is correct). Choices A, C, and D are wrong because these processes do not produce proteins.

During oxidative stresses, HbS can cause the affected red blood cells to sickle. The spleen is very vascular and is responsible for removing old or damaged red blood cells. Recurrent sickling can cause blockage of blood flow in the spleen, resulting ultimately in death of splenic cells. Which of the following would result from destruction of the spleen? A. Impaired ability to synthesize red blood cells B. Impaired ability to fight off encapsulated bacteria C. Impaired digestion D. Increased red blood cell destruction

B. The spleen is one of the major organs of the immune system. It is rich with lymphocytes, both B and T, and serves a major resource in the body's natural defenses against pathogens, especially encapsulated bacteria (choice B is correct). The spleen is not the site of red blood cell synthesis; the bone marrow is (choice A is incorrect). The spleen is not involved in digestion (choice C is incorrect). The spleen also removes damaged or old red blood cells. If the spleen is damaged, or infarcted, then there will be less destruction of red blood cells (choice D is incorrect).

Synthesis of creatine requires: A. Glycine, arginine and cysteine B. Glycine, arginine and methionine C. Alanine, lysine and cysteine D. Alanine, lysine and methionine

B. The two amino acids pictured on the left side of Figure 1 are glycine and arginine (choices C and D are wrong). The passage says that the third amino acid required in the synthesis of creatine has a thioether group. Only methionine has this functional group (choice A is wrong; choice B is correct).

Can glucogenic amino acids be converted into glucose? A. Yes: pyruvate and oxaloacetate can be converted directly into glyceraldehyde-3-P, which is a major intermediate in both gluconeogenesis and glycolysis. B. Yes: pyruvate and Krebs cycle intermediates can be converted into oxaloacetate, then phosphoenolpyruvate, which can enter gluconeogenesis. C. No: pyruvate and Krebs cycle intermediates are formed as part of glucose breakdown and this process is important to generate ATP for the cell. D. No: glucose is obtained from the diet and stored in the liver; it cannot be made as a new molecule because cellular respiration has several steps with a -ΔG.

B. This is a typical two by two question. The passage says that glucogenic amino acids are broken down into citric acid cycle intermediates or pyruvate. The Krebs cycle regenerates oxaloacetate (OAA), and in the first step of gluconeogenesis, pyruvate is also converted into OAA (by the enzyme pyruvate carboxylase). OAA is converted into phosphoenolpyruvate (PEP) by the enzyme phosphoenolpyruvate carboxykinase (or PEPCK). Gluconeogenesis can then continue to run, and will generate glucose from these non-carbohydrate precursor molecules (choice B is correct). Although glyceraldehyde-3-P is a major intermediate in both gluconeogenesis and glycolysis, pyruvate and oxaloacetate cannot be converted directly into this molecule (choice A is incorrect). Both choices C and D are incorrect because they start with "No"; as discussed above, glucogenic amino acids can be converted into glucose (choices C and D are wrong).

Suzanne was in the middle of deep sleep and was suddenly jolted awake and alert by her alarm clock. Suzanne's brain wave state has most likely quickly shifted from: A. alpha wave to delta wave. B. delta wave to beta wave. C. theta wave to alpha wave. D. beta wave to theta wave.

B. This question calls for knowledge of four brain wave states. Beta waves are associated with alert wakefulness, while alpha waves are associated with relaxed wakefulness or drowsiness. Theta waves are active during drowsiness or sleep, and delta waves are associated with deep sleep. The question described Suzanne as being jolted from deep sleep to alert wakefulness, which corresponds to a shift from delta wave to beta wave activity (choice B is correct; choices A, C, and D are wrong).

Positive cognitive biases in marital satisfaction forecasts would lead to: A. more severe declines in marital satisfaction, according to the first theoretical perspective. B. unpredictable changes in marital satisfaction, according to the second theoretical perspective. C. no changes in marital satisfaction, according to the second theoretical perspective. D. less severe declines in marital satisfaction, according to the third theoretical perspective.

B. This question tests one's understanding of the three theoretical perspectives presented in paragraph 2 and can be answered using the process of elimination. The first theoretical perspective suggests a positive correlation between predicted and actual marital satisfaction; positive forecasts are described as a strength, which can benefit, rather than harm, the relationship (choice A is wrong). The second theoretical perspective does not suggest a correlation between predicted and actual marital satisfaction; positive forecasts are described as random errors, and thus their effects on the relationship cannot be predicted (choice B is correct). Despite the fact that this perspective cannot predict specific changes, it does not predict the absence of changes (choice C is wrong). The third theoretical perspective suggests a negative correlation between predicted and actual marital satisfaction; positive forecasts are described as a form of self-protection when circumstances are stressful, which can harm, rather than benefit, the relationship (choice D is wrong).

Research indicates that professional burnout can result in thoughts of suicide. Suicidal ideation is most often associated with a psychological disorder in which broad category? A. Anxiety disorders B. Mood disorders C. Personality disorders D. Psychotic disorders

B. Thoughts of death or suicide are most often associated with major depressive disorder, which is a mood disorder characterized by persistent feelings of sadness and hopelessness (choice B is correct). Mood disorders involve disturbances in mood or affect. Anxiety disorders involve excessive worrying and include generalized anxiety disorder, panic disorder, and obsessive-compulsive disorder (choice A is wrong). Research does not show a significant association between these disorders and suicidal ideation, with the exception of post-traumatic stress disorder. Personality disorders involve enduring maladaptive patterns of behavior and cognition and include antisocial personality disorder, avoidant personality disorder, and borderline personality disorder (choice C is wrong). Psychotic disorders involve a loss of contact with reality and include schizophrenia and delusional disorder (choice D is wrong).

Creatine phosphate is a high-energy buffer that helps maintain the level of available high-energy phosphates such as ATP. During intense muscular exertion, creatine phosphate replenishes the muscle's ATP by releasing a relatively larger amount of energy in transferring its phosphate group to ADP. ATP is able to accept this phosphate group from creatinine phosphate and serve as a convenient carrier of energy because: A. it releases more energy upon hydrolysis than any other molecule in the body. B. it has phosphate groups with an intermediate transfer potential. C. it has such a specific and limited role. D. it is present in selected cells.

B. What makes ATP a particularly good energy carrier is that it has an intermediate transfer potential. This allows higher energy phosphate carriers (like creatine phosphate) to drive the synthesis of ATP by transferring their phosphate groups to ADP (choice B is correct). ATP's hydrolysis does not release the largest amount of energy of any molecule in the body, since creatine phosphate can drive ATP synthesis (choice A is wrong). ATP has a varied role in the body, as an energy carrier and also as a nucleotide for RNA and DNA (choice C is wrong), and ATP is present in every cell in the body (choice D is wrong)

The passage states that gabapentin is an effective mediator for neuropathic pain. Which of the following provides the best explanation of the direct effect of GBP on transmission of pain signals? A. GBP blocks the influx of Ca2+ into the pre-synaptic terminal, decreasing glutamate release. B. GBP decreases influx of Ca2+ into the axon, inhibiting propagation of the action potential. C. GBP decreases the capacity of the pre-synaptic terminal to allow Ca2+ influx, decreasing glutamate release. D. GBP decreases the influx of Ca2+ into the pre-synaptic terminal, decreasing glutamate release.

C. By preventing the transport and expression of Ca2+ channels on the pre-synaptic membrane, GBP effectively decreases the capacity of the terminal to allow Ca2+ influx; therefore, preventing a crucial step in the classical model of neurotransmission and decreasing release of glutamate (choice C is correct). GBP does not directly block the influx of Ca2+ into the pre-synaptic terminal (eliminate choice A). GBP does not block Ca2+ influx and does not inhibit the action potential (eliminate choice B). While GBP does effectively decrease the influx of Ca2+ into the pre-synaptic terminal, its most direct action is decreasing expression of Ca2+ channels on the pre-synaptic membrane, thereby decreasing the capacity of the membrane to facilitate Ca2+ influx (eliminate choice D).

The spontaneity of Reactions 1 and 2 suggests which of the following? A. The group 11 metals tend toward neutral configurations with all valence s and d orbitals completely filled. B. Zinc is stable with an oxidized 4s2 3d8 electron configuration. C. A completely filled set of d-orbitals denotes a particularly stable configuration. D. The reaction Zn( s) + Au2+ (aq) → Zn2+ (aq) + Au(s) will have a negative value of Ecell.

C. Choice A can be ruled out as the neutral coinage metals in group 11 only have 11 valence electrons, while 12 would be required to completely fill their valence s and d sets. Choice B may be eliminated as Zn2+ has a configuration of 4s0 3d10, since ionized electrons are removed first from the s orbitals when transition metals are oxidized. Choice D may be eliminated as the spontaneity of the reactions of the coinage metals in Reactions 1 and 2 would suggest that a similar reaction with Au (the last coinage metal) should also be spontaneous. The answer choice, however, states that the value of the standard voltage is negative, and therefore non-spontaneous. Choice C is correct, as both Zn2+ and the neutral group 11 atoms have filled d-shells. Recall that the neutral group 11 metals promote one electron from their s orbital to a d orbital to completely fill their d subshell.

Eukaryotic cells use reciprocal regulation to make sure β-oxidation and fatty acid biosynthesis do not occur at the same time. This is accomplished by malonyl CoA, which inhibits the carnitine shuttle required to transfer activated fatty acids from the cytoplasm to the mitochondrial matrix. Each of the following is a true statement EXCEPT: A. both β-oxidation and fatty acid biosynthesis occur in four steps; fatty acid biosynthesis involves elongation, two redox reactions and a dehydration. B. β-oxidation involves the reduction of both FAD and NAD+; fatty acid biosynthesis oxidizes two NADPH (generated by the pentose phosphate pathway) to two NADP+. C. because of this reciprocal regulation, both β-oxidation and fatty acid biosynthesis occur in the mitochondrial matrix. D. β-oxidation generates acetyl CoA, while fatty acid biosynthesis uses malonyl CoA, which is made from acetyl CoA by acetyl CoA carboxylase.

C. Choices A, B and D are true statements. Choice C is false (and the correct answer); β-oxidation occurs in the mitochondrial matrix and fatty acid biosynthesis occurs in the cytoplasm.

if one woman in a small and isolated Korean village fell ill with shin-byung, and then her close friend also began experiencing similar symptoms, claiming that she too was being pursued by spirits, which of the following might explain this occurrence regarding the friend? A. Compliance followed by obedience B. Conformity followed by compliance C. Conformity followed by private acceptance D. Obedience followed by conformity

C. Conformity, obedience, and compliance are related but distinct terms. Conformity involves changing one's behavior in order to fit in with the norms of a particular social group, most typically a group that has a certain level of social importance. Obedience involves changing one's behavior in response to the direct command or order of a person who is in authority or is of higher social status. Compliance involves changing one's behavior in response to a request from another person who is of equal or lower status (thus differing from obedience). Private acceptance is an attitude change that can occur in a person due to the social influence of others. Thus, it is most likely that the friend first conformed to the behavior of the woman initially affected by shin-byung symptoms, then privately accepted the possibility of spirit possession after modifying her behavior (choice C is correct). One could comply with a request from a peer and then obey a command from a leader, but that would not explain the situation described (choice A is wrong). Similarly, changing one's behavior in accordance with a group norm and then responding to a request from a peer would not fit the described situation either (choice B is wrong). Finally, following the orders of an authority figure and then the norms of a desired social group would not explain the shin-byung symptoms in this scenario (choice D is wrong).

Which of the following experimental findings would best confirm that a patient's type II diabetes was caused by a genetic defect and not a poor diet? A. Elevated patient blood glucose levels three hours after consumption of a concentrated glucose solution B. Discovery of an antibody in the patient's bloodstream that marks pancreatic beta cells for destruction C. Isolation of one of the patient's insulin receptors reveals a lysine-histidine substitution in the insulin-recognition site D. Detection of a virus that selectively targets and lyses insulin receptor expressing cells

C. Detection of an amino acid substitution in the insulin receptor insulin recognition site would be a strong indicator that a genetic malformation resulted in the production of an ineffective receptor (choice C is correct). Elevated blood glucose levels hours after consuming glucose is a hallmark of diabetes in general and does not indicate the specific cause of diabetes (choice A is wrong). The presence of an antibody that targets pancreatic beta cells is not indicative of type II diabetes but of type I diabetes (choice B is wrong). The presence of a virus that selectively targets insulin receptor expressing cells does not demonstrate that the cause of the patient's type II diabetes is a genetic defect (choice D is wrong).

All of the following processes occur during the conduction of a nerve impulse across the synapse of two neurons EXCEPT: A. the release of vesicles from the presynaptic cell. B. the opening of postsynaptic ion channels. C. a retrograde depolarization of the presynaptic cell. D. the depolarization of the postsynaptic cell.

C. During the conduction of an action potential across a chemical synapse, neurotransmitter is released by the presynaptic cell, it diffuses across the synapse, binds to receptors on the postsynaptic cell, opens ion channels on the postsynaptic cell, and depolarizes (or hyperpolarizes) the postsynaptic cell. Thus, choices A, B, and D are all part of the normal conduction of an action potential across a synapse and can be eliminated. The presynaptic cell does not normally transmit a retrograde action potential, however (choice C is false and the correct response here). This is usually prevented by the refractory period after an action potential passes, causing action potentials to propagate in only one direction along an axon.

If the students had used propylamine in Experiment 2 in place of piperidine, what functional group would they synthesize in Step 1? A.Enamine B. Amide C. Imine D. Lactam

C. Enamines form from the combination of an aldehyde or ketone with a secondary amine (like piperidine). Since propylamine is a primary amine (eliminate choice A), an imine is formed instead (choice C is correct). Amides are carboxylic acid derivatives and form from the reaction of an amine with any other derivative (eliminate choice B). A lactam is a cyclic amide, so choices B and D are effectively the same answer (eliminate choice D).

The idea that foreign-born students might be negatively affected by native-born students' cultural norms and values can best be explained by: A. cultural relativism. B. prejudice. C. ethnocentrism. D. discrimination

C. Ethnocentrism is the tendency to believe that one's own ethnic or cultural group is the most important one, and that all other groups are measured against one's own. Ethnocentric thinking typically involves making false or negative assumptions about a minority ethnic or cultural group (choice C is correct). Cultural relativism is seen as the opposite of ethnocentrism, as cultural relativism is the principle of viewing aspects of a different culture from the viewpoint of that culture, rather than from one's own viewpoint (choice A is wrong). Prejudice is a negative and often unjustified attitude or stereotypical belief about an individual or a group, and it is not specific to race or culture (choice B is wrong). Discrimination is actual behavior, typically negative, towards an individual or group (choice D is wrong).

Glucose-6-phosophate dehydrogenase (G6PDH) deficiency is an inheritable metabolic disorder that can result in the destruction of red blood cells, and in severe cases, can lead to kidney and liver failure. Which of the following best describes the reason why G6PDH deficiency can result in premature red blood cell destruction? A. G6PDH deficiency results in a buildup of glucose-6-phosphate, increasing the solute concentration in the intracellular environment, causing the cell to swell and lyse. B. G6PDH deficient cells are recognized as abnormal and are targeted for destruction by macrophages. C. G6PDH deficiency results in a deficiency of NADPH, which results in increased damage from reactive oxygen species and causes premature cell death. D. G6PDH deficiency results in an increased intracellular pH, which denatures proteins and triggers apoptosis.

C. Glucose-6-phosphate dehydrogenase (G6DPH) catalyzes the first step in the pentose phosphate pathway, where NADPH is produced. NADPH plays a major role in preventing damage due to oxidative stress/reactive oxygen species. A deficiency of G6PDH prevents the production of NADPH, thus individuals with this deficiency would experience increased damage from reactive oxygen species (choice C is correct). G6PDH deficiency would not be expected to alter the intracellular osmolarity (choice A is incorrect) or to increase the intracellular pH (choice D is also incorrect). Choice B is incorrect: macrophages are not involved in the death of red blood cells in G6PDH cells.

Which of the following statements best supports why two equivalents of hydroxide are used in the basic hydrolysis of dichorine monoxide in Reaction 1? A. The second hydroxide is necessary to neutralize the HCl produced in situ during the course of the reaction. B. Adding a second equivalent of hydroxide will double the rate of reaction. C. Adding only one equivalent will lead to the formation of a buffer solution of hypochlorous acid and its conjugate base, and therefore an incomplete reaction. D. Chlorine in the +1 oxidation state is highly reactive, and only stable in highly basic environments.

C. In Reaction 1, chlorine is in the +1 oxidation state throughout, and there is no redox reaction available to take it to the -1 state it would require to form HCl (eliminate choice A). Choice B is a true statement only if the hydroxide ion is part of the overall rate law for the reaction and is first order in hydroxide. Regardless, this statement doesn't address the exact stoichiometric amount in question (eliminate choice B). Choice D is false because Cl+ should find no problem with an acidic environment where the most active species is H+. One equivalent of hydroxide will hydrolyze the dichlorine monoxide as follows: Cl2O + OH- HOCl + OCl-. Since this reaction forms a weak acid and its conjugate base in equal amounts, a buffer solution is produced. When the second equivalent of OH- is added, it will undergo another acid/base reaction to deprotonate the hypochlorous acid to the hypochlorite ion, giving the products in Reaction 1 of the passage.

Which of the following would be the most effective method to determine if transcription of a gene had been silenced? A. DNA fingerprinting B. ELISA C. RT-PCR D. DNA sequencing

C. RT-PCR uses reverse transcriptase to make cDNA from mRNA. The cDNA can then amplified, and then tested for. This is the only method listed that can be used to test for the presence of mRNA and determine if transcription of the gene is occurring or not (choice C is correct). Both DNA Fingerprinting and DNA Sequencing are methods used to analyze DNA sequences; this does not provide information about transcription (choices A and D can be eliminated). While ELISA could be used to test for the presence of a protein product, it would not be the best test to use in this situation (choice B is incorrect). The absence of a protein could be due to a variety of reasons, including problems with translation, protein degradation, etc. Thus, RT-PCR would be a better method to specifically test for gene expression (i.e., transcription).

Brown fat will increase energy expenditure in the form of heat better than any other adipose tissue in the body. In brown fat, leptin indirectly activates uncoupling protein 1 (UCP-1) located in the inner mitochondrial membrane. UCP-1 activation will dissipate the proton gradient across the inner mitochondrial membrane and STOP which of the following reactions in mitochondria? A. Electron transport chain B. Krebs cycle C. Oxidative phosphorylation D. NAD+ reduction

C. In the absence of the proton gradient across the inner mitochondrial membrane no electrochemical gradient has been built and oxidative phosphorylation, i.e. the formation of ATP by ATP synthase, will not proceed (C is correct). The electron transport chain will continue and pass electrons along the transport chain, but the pumped protons will return to the matrix of the mitochondria with the help of UCP-1 activation (choice A will continue and can be eliminated). The Krebs cycle provides NADH and FADH2 as substrates to the electron transport chain and receives NAD+ and FAD for continuation of its chemical cycle. This action can proceed unhindered during UCP-1 activation and choice B can be eliminated. Reduction of NAD+ in the mitochondria takes place in the Krebs cycle and the pyruvate dehydrogenase complex reaction and occurs prior to the action of events induced by UCP-1 (choice D will continue and can be eliminated).

Trivalent arsenite prevents the regeneration of S-S form of lipoamide. This would immediately block which of the following processes? Oxidation of lipoamide Reduction of FAD Reduction of CoA A. I only B. II only C. I and II only D. I, II, and III

C. Item I is correct: arsenite is blocking the formation of S-S form of lipoamide, thereby blocking the oxidation of lipoamide. Eliminate choice B. Item II is correct: The reduction of FAD is linked to oxidation of lipoamide, thus, it will be blocked. Eliminate choice A. Item III is incorrect: Oxidation, not reduction, of CoA is linked to the series of reactions. Eliminate choice D and choice C is correct.

Which of the following are determinants of the G2/M checkpoint? Ensure that genomic replication is complete Take inventory of nucleotide levels Check for mutations or DNA instability A. II only B. I and II only C. I and III only D. I, II, and III

C. Item I is true: Before the cell divides, it must check the integrity of the genome it is passing to the daughter cells. This includes making sure DNA replication is complete. Choice A can be eliminated. Item II is false: Checking the levels of nucleotides in the cell is part of the G1/S checkpoint (the other major checkpoint pathway mentioned in the passage), since these building blocks are required for DNA replication (choices B and D can be eliminated). Item III is true: Before the cell divides, mutations have to be repaired. Choice C is correct.

Which of the following could cause metabolic acidosis? I. Anaerobic metabolism II. Vomiting III. Ethylene glycol A. III only B. I and II only C. I and III only D. I, II, and III

C. Item I is true: anaerobic metabolism results in the formation of lactic acid and this creates a metabolic acidosis (choice A can be eliminated). Item II is false: vomiting causes the loss of hydrochloric acid from the stomach. This in turn causes the parietal cells to avidly take H+ from the blood-side of the cell to create new HCl. By removing H+ from the blood, an imbalance between H+ and HCO3- exists, with greater HCO3- than normal. This results in a metabolic alkalosis (choices B and D can be eliminated, and choice C is correct). Note that Item III is in fact true: the passage states that ethylene glycol (antifreeze) can cause a metabolic acidosis.

In gastroesophageal reflux disease (GERD), gastric secretions exit the stomach via the lower esophageal sphincter and come in contact with the lower part of the esophagus. How would this affect the esophageal epithelium? Increased proliferation of the stratified squamous epithelium Conversion to columnar epithelium similar to that in the stomach Introduction of bicarbonate-secreting cells A. I only B. II only C. I and II only D. I, II, and III

C. Item I is true: in the short term, gastric acid would corrode the outermost layer of epithelium in the lower esophagus, increasing the production of cells (choice B can be eliminated). Item II is true: over time, the acid will destroy the epithelium and expose the submucosa. Columnar epithelium found in the stomach will gradually encroach on this area and become the dominant form of epithelium, since it is not sensitive to acid (choice A can be eliminated). Item III is false: There are specialized areas known as Brunner's glands in the proximal duodenum that produce bicarbonate to neutralize the acidic chyme as it passes from the stomach to the duodenum. However, there is no reason to assume that these cells would traverse the stomach to the lower esophagus (choice D can be eliminated and choice C is correct).

Measurements of which of the following would be sufficient to calculate the usable work performed by a mechanical engine? A. The rate at which energy is consumed by the engine and the amount of time the engine was running B. The heat produced by the engine and the amount of time the engine was running C. The power output of the engine and the amount of time the engine was running Correct Answer D. The energy consumed by the engine and the amount of time the engine was running

C. Power is defined as work divided by time: P = W / t. Therefore, if the power output P and the time t are known, the work performed can be calculated by the equation W = Pt. Since we want the usable work produced by the engine, which presumably is not 100% efficient, the output power is needed, which will be less than the input power.

Which of the following statements primarily differentiates between schizophrenic behavior and schizoid affect? A. Schizophrenics hear voices and schizoids have delusions. B. Schizophrenics have delusions and schizoids have thought disorders. C. Schizophrenics exhibit psychotic behaviors and schizoids withdraw from interactions with others. D. Schizophrenics exhibit flat affect and schizoids have bursts of wild behavior.

C. Schizophrenia is classified as a brain disorder that may include any combination of the following symptoms: positive symptoms (familiarly known as psychotic symptoms such as delusions, hallucinations, thought disorders, or movement disorders) and negative symptoms (a flat affect, a loss of pleasure in everyday life or previously pleasurable activities, and a lack of interest in beginning or continuing with activities or in interacting with others). Cognitive symptoms include poor executive functioning (e.g., decision-making) and trouble with focusing or remembering (choices A, B, C, and D all accurately describe schizophrenic symptoms). "Schizoid" refers to a personality disorder, which is a different diagnostic category, and is characterized primarily by an unwillingness to interact with others. Those with schizoid personality disorder may seem aloof or to be loners, and may or may not prefer that state of being (choice C is correct). Typically schizoid individuals do not have delusions (choice A is wrong), do not have thought disorders (choice B is wrong), and do not demonstrate bursts of wild behavior (choice D is wrong).

Aβ peptides can negatively regulate various steps of acetylcholine (ACh) synthesis, release, and signaling. Which of the following would be the best target for pharmacological intervention? A. A drug that inhibits postsynaptic ACh receptors B. A drug that blocks voltage-gated Na+ channels C. An allosteric inhibitor of acetylcholinesterase D. A drug that inhibits choline reuptake by cholinergic neurons

C. Since the Aβ peptides negatively regulate ACh synthesis, release, and signaling, any kind of pharmacological intervention should be targeted at increasing ACh or its activity. An inhibitor of acetylcholinesterase (AChE) would prolong the life of ACh in the synaptic cleft, thus increasing its effect on the postsynaptic cell (choice C is correct). Drugs that inhibit postsynaptic ACh receptors would be a poor choice because they would inhibit ACh signaling (choice A is wrong). Blocking voltage-gated Na+ channels would have severe consequences throughout the body, as virtually all nervous system and muscular activity would be inhibited (choice B is wrong). Inhibition of choline reuptake by cholinergic neurons would reduce or prevent ACh synthesis (choice D is wrong).

A bus is traveling at 25 m/s, and a cyclist is traveling at 5 m/s behind the bus, in the same direction. The frequency of a sound coming from the bus is observed by the cyclist to be 1000 Hz. Approximately what is the frequency of the sound as perceived by the bus driver? A. 950 Hz B. 1000 Hz C. 1060 Hz D. 2100 Hz

C. Since the bus is traveling away from the cyclist faster than the cyclist is traveling toward it, there is a steady increase in the distance between the source and detector. Motion "away" always corresponds to a frequency decrease. Thus, if the cyclist (detector) hears a frequency of 1000 Hz, the actual source frequency must be higher than 1000 Hz; this eliminates choices A and B. No calculation is really necessary to decide between choices C and D, because for detector and source speeds much less than the speed of sound, the change in frequency due to the Doppler Effect will always be a percentage much less than 100%. Thus choice D is too high a frequency to be correct here.

Which of the following is NOT true regarding somnambulism (sleepwalking), a type of parasomnia? A. Sleepwalking tends to occur during slow-wave sleep B. Typically individuals will engage in sleepwalking during the first third of the night C. Individuals will often act out the dreams they are concurrently having while sleepwalking D. While somnambulism tends to affect many children, most will grow out of it by adulthood

C. Somnambulism, or sleepwalking, occurs during slow-wave non-REM sleep (choice A is wrong), typically during the first third of the night (which corresponds to the fact that more slow-wave, deep sleep occurs early in the night; choice B is wrong); therefore, since it occurs during non-REM sleep, it is not possible for sleepwalkers to be concurrently dreaming (which only occurs during REM sleep), so sleepwalkers cannot be acting out the dreams they are having (choice C is correct). Somnambulism is common in children and studies suggest that up to 20-25% of all children have experienced at least one sleepwalking episode. Sleepwalking usually disappears by adolescence (choice D is wrong).

Which of the following is the most likely origin in the afferent sensory neuron of the α2δ-1 Ca2+ channels implicated in the inhibitory mechanism of GBP on signal transmission? A. Dorsal post-synaptic terminal B. Proximal pre-synaptic terminal C. Dorsal root ganglion D. Proximal portion of the axon

C. The dorsal root ganglion is the location of the neuron cell body where protein production occurs; thus, this is the most likely origin for channel proteins that would subsequently become embedded in the neuron cell membrane (choice C is correct). Since the afferent neuron begins in the periphery and ends in the CNS, the dorsal post-synaptic terminal of the afferent neuron would be located in the tissues from which the sensory signal is being sent making it a less likely source for channel proteins (eliminate choice A). As channel proteins are stored in vesicles in the proximal pre-synaptic terminal, it is likely that these proteins will be found here; however, the terminal itself is an unlikely origin due to the fact that protein synthesis typically does not occur in the terminal (eliminate choice B). Again, the proximal portion of the axon is a likely place to find channel proteins being transported to the terminal via anterograde transport by dynein but it is an unlikely origin (eliminate choice D).

The vestibular sense detects motion and is involved in balance by way of what mechanism? A. Control of autonomic functions by the pons B. The endolymph in the cochlea contains hair cells that detect motion and rotation of the head C. The endolymph in the utricle, saccule, and ampullae contain hair cells that detect motion and the rotation of the head D. Coordination of motion in cerebellum

C. The endolymph in the utricle, saccule, and ampullae—the semicircular canal of the inner ear—contain hair cells that detect motion and the rotation of the head. This aids in the sense of balance (choice C is correct). The pons in the hindbrain controls some autonomic functions and coordinates movement and thus is related to the sense of balance but that control of autonomic functions on its own is not the vestibular sense (choice A is wrong). The endolymph in the cochlea contains hair cells that are designed to transmit auditory vibrations for the sense of hearing, not proprioception or balance (choice B is wrong). The cerebellum coordinates complex movements and damage to that area results in difficulties in movement and balance, but again this is not the specific mechanism of the vestibular sense (choice D is wrong).

Which of the following accurately lists the composition of the endoplasmic reticulum, phosphofructokinase and alanine, respectively? A. Double membrane surrounding a lumen, amino acids linked together by covalent proteolytic bonds, four different groups on a chiral carbon. B. Single membrane surrounding a lumen, amino acids linked together by hydrogen bonds, four different groups on a chiral carbon. C. Single membrane surrounding a lumen, amino acids linked together by covalent peptide bonds, four different groups on a chiral carbon. D. Single membrane surrounding a lumen, amino acids linked together by covalent peptide bonds, three different groups on a chiral carbon.

C. The endoplasmic reticulum is an organelle with a single membrane surrounding a lumen (eliminate choice A). Phosphofructokinase is an enzyme of glycolysis, and so is a protein made of amino acids linked together by covalent peptide bonds (choice B is wrong). Alanine is a chiral amino acid, and so has four different groups on a chiral carbon (another reason to eliminate choice D). Choice C provides an accurate description and is correct.

Which of the following accurately lists the composition of the endoplasmic reticulum, phosphofructokinase and alanine, respectively? A. Double membrane surrounding a lumen, amino acids linked together by covalent proteolytic bonds, four different groups on a chiral carbon. B. Single membrane surrounding a lumen, amino acids linked together by hydrogen bonds, four different groups on a chiral carbon. C. Single membrane surrounding a lumen, amino acids linked together by covalent peptide bonds, four different groups on a chiral carbon. Correct Answer D. Single membrane surrounding a lumen, amino acids linked together by covalent peptide bonds, three different groups on a chiral carbon.

The function of the electron transport chain is to transfer the energy stored in electrons. The primary source of high-energy electrons is: A. ATP. B. the mitochondrial pH gradient. C. NADH. D. NADPH.

C. The high-energy electrons that enter electron transport originate from the NADH produced in the Krebs cycle (choice C is correct). The electron transport chain creates the mitochondrial pH gradient (choice B is wrong), which is used to make ATP in turn (choice A is wrong). NADPH is structurally almost identical to NADH but has very different functions. NADPH is used as a source of biosynthetic energy in processes like fatty acid biosynthesis, but it is not used as a source of high-energy electrons by the electron transport chain (choice D is wrong).

An object with a height of 6 cm is placed at a distance of 20 cm from a concave mirror with a focal length of 12 cm. If the mirror produces a real, inverted image at a distance of 30 cm, the height of the image is: A. 4 cm. B. 6 cm. C. 9 cm. D. 12 cm.

C. The linear magnification m is given by the expression -i/ o. In this case, m = -(30 cm) / (20 cm) = -1.5, so the image is 1.5 times taller than the object. Therefore, if the object is 6 cm tall, then the image is 1.5(6 cm) = 9 cm tall. (Note: The minus sign on msimply signifies that the image is inverted, as stated in the question.)

The melting temperature of the 15-mer oligonucleotide 5'-GACTGCGGTTTTAAC-3' is 42 °C. Which of the following oligonucleotides would be found primarily in a random coil state at 42 °C? A. 5'-GACTGCGGCGCGAAC-3' B. 5'-GCCTGAGGTTTTAGC-3' C. 5'-GACTGTAATGGTAAC-3' D. 5'-GACTGCGGCCCCAAC-3'

C. The melting temperature is the temperature at which half of the DNA strands are in the random coil or single-stranded state. As the given oligonucleotide has a melting temperature of 42°C, then the correct answer must be an oligonucleotide with a melting temperature with a lower melting temperature in order to be primarily in the random coil state at 42°C. In order to have a lower melting temperature, the oligonucleotide must contain fewer GC nucleotides than the given oligonucleotide (Choice C is correct; Choices A, B, and D are wrong). This is because GC base pairing involves three hydrogen bonds while AT only involves two.

he percentage of "Ba" responses is what type of variable in the research study above? A. Regression coefficient B. Predictor variable C. Dependent variable D. Independent variable

C. The percentage of "Ba" responses is the outcome variable for the research study in the passage. This means that the percentage of "Ba" responses is the dependent variable of this study, which is the variable that the researchers do not manipulate and simply measure (choice C is correct). The independent variable is the variable that the researchers manipulate, which is also called the predictor variable. In this study the independent/predictor variable is the delay of the acoustic stimulus (choices B and D are wrong). A regression coefficient is a way to characterize the relationship between the independent and dependent variables, and graphically is represented by the slope of the line that represents the rate of change of one variable as a function of changes in the other (choice A is wrong).

This study factored in perceptions of support as well as actual support. If both factors were found to be equally valuable in increasing the odds of survival, we might consider this outcome the most analogous to: A. a bimodal distribution. B. a type II error. C. the placebo effect. D. confirmation bias.

C. The placebo effect describes when the control group in a study receives a fake drug or treatment (one that is not meant to produce any changes or improvements in the subjects) and despite this, the subjects in the control group still experience/report changes or improvements. The perception of support is somewhat analogous to receiving a fake drug, and the fact that those who perceive support experience as much benefit as those who actually have support demonstrates a change or improvement that is most analogous to the placebo effect (choice C is correct). A bimodal distribution occurs in statistics when, instead of the characteristic one hump in a normal distribution, there are two distinct humps. While it is possible that some variable or outcome in this study might be bimodally distributed, there is not enough information in the passage or the question stem to reach this conclusion; therefore, this principle is not analogous to the finding that both real and perceived social support are equally valuable in increasing the odds of survival (choice A is wrong). In statistics, a type II error is the failure to reject a false null hypothesis; in signal detection theory, a type II error occurs when the signal is present, but the receiver fails to detect it (also known as a miss). Either way, a type II error is not analogous to the finding that both real and perceived social support are equally valuable in increasing the odds of survival (choice B is wrong). Confirmation bias occurs when an individual only looks for evidence to support his/her beliefs; this also is not analogous to the finding that both real and perceived social support are equally valuable in increasing the odds of survival (choice D is wrong).

Compared to sensitive bacteria, phage-resistant bacteria are most likely to display which of the following characteristics? A. Increased sensitivity to antibiotics that disrupt the cell wall B. The presence of plasmid DNA absent in sensitive cells C. Alteration in the amino acid sequence of a specific protein found in sensitive cells D. Increased expression of lysosomal enzymes

C. The results of the experiment are most consistent with the mutation hypothesis, since the initial number of phage and bacteria were held constant, but variable numbers of resistant bacteria were observed. If a mutation is responsible, then this will result in a protein with an altered amino acid sequence, or else the mutation would have no effect (choice C is correct). There is no relationship to antibiotic sensitivity implied (choice A is wrong). A plasmid is not likely to be responsible since the plasmid would have to spontaneously appear in resistant cells where none was present in sensitive cells (choice B is wrong). Bacteria do not express lysosomal enzymes since they would lyse themselves (choice D is wrong).

During the blastula stage, neighboring cells are in close contact with each other. The formation of the blastula is contemporaneous with the formation of tight junctions. The function of tight junctions is to: A. provide a means through which induction occurs. B. act as pores connecting the cytoplasm of adjacent cells. C. seal off the blastocoel and unite connected cells into a tissue. D. transmit action potentials between cells.

C. Tight junctions hold cells together and can form a seal so that fluid does not leak between cells (choice C is correct). Induction involves communication between cells but can be performed by secreted factors and does not require tight junctions for the communication to happen (choice A is wrong). Tight junctions do not, however, form a junction between the cytoplasm of cells (choice B is wrong), nor do they allow the transmission of action potentials (choice D is wrong).

While walking the tightrope, the youngest Maaza brother carries a long heavy pole as shown in Figure 2. What is the most likely reason for this? A. The extra mass of the pole stabilizes the cable by creating more tension. B. The extra mass of the pole lowers his center of gravity making balance easier. C. The long pole increases his rotational inertia making balance easier. D. The long pole decreases his rotational inertia making balance easier.

C. While the extra mass does create more tension in the cable, it is not clear how this "stabilizes" it or makes balancing on it any easier, so A is not the best choice. Since Figure 2 shows the young Maaza holding the pole at roughly the level of his own center of mass, the additional mass of the pole would not change the overall center of mass by very much, so B is not the best choice. As for C and D, the pole can only increase his rotational inertia, so D is eliminated. Choice C is indeed the best choice here since the increase in rotational inertia will imply less tendency to rotate (that is, less tendency to topple off the cable), thus making balancing easier.

What is the correct relationship between the first ionization energies of the elements mercury, thallium, and lead? A. Hg > Tl > Pb B. Tl > Pb > Hg C. Pb > Tl > Hg D. Hg > Pb > Tl

D. According to periodic trends, as you move from left to right within a row, ionization energy should increase due to increased effective nuclear charge. However, these three elements (Hg, Tl, and Pb—atomic numbers 80, 81, and 82, respectively) provide an example of an exception to that rule. The electron configurations of these atoms are as follows: Hg: [Xe] 4f14 5d10 6s2 Tl: Xe] 4f14 5d10 6s2 6p1 Pb: [Xe] 4f14 5d10 6s2 6p2 In Hg, all orbitals are full, which is relatively stable. It is the least likely atom to give up any electrons, and therefore it has the highest ionization energy (eliminate choices B and C). Tl is the opposite. If Tl gives up a single electron, it would result in the electron configuration of Hg, which is more stable. Therefore, Tl has the lowest ionization energy of the three, making the answer choice D.

What is the correct relationship between the first ionization energies of the elements mercury, thallium, and lead? A. Hg > Tl > Pb B. Tl > Pb > Hg C. Pb > Tl > Hg D. Hg > Pb > Tl

D. According to periodic trends, as you move from left to right within a row, ionization energy should increase due to increased effective nuclear charge. However, these three elements (Hg, Tl, and Pb—atomic numbers 80, 81, and 82, respectively) provide an example of an exception to that rule. The electron configurations of these atoms are as follows: Hg: [Xe] 4f14 5d10 6s2 Tl: [Xe] 4f14 5d10 6s2 6p1 Pb: [Xe] 4f14 5d10 6s2 6p2 In Hg, all orbitals are full, which is relatively stable. It is the least likely atom to give up any electrons, and therefore it has the highest ionization energy (eliminate choices B and C). Tl is the opposite. If Tl gives up a single electron, it would result in the electron configuration of Hg, which is more stable. Therefore, Tl has the lowest ionization energy of the three, making the answer choice D.

Meperidine is an opioid-like medication used for pain control. Which of the following compensatory effects would be expected after long-term consistent use of meperidine? Knowing the it can induce respiratory acidosis A. Hyperventilation B. Hypoventilation C. Increased HCO3- secretion D. Increased HCO3- reabsorption

D. According to the passage, "the administration of opiate medications...can induce a respiratory acidosis." The passage also states that if the primary cause of acidosis is respiratory, the kidneys will compensate by adjusting secretion of HCO3- (choices A and B can be eliminated). Because the pH is too acidic, increasing reabsorption of HCO3- would be necessary to increase the pH.

The Ka for the first ionization of sulfurous acid (1.7 × 10-2) is significantly larger than the Ka for the second ionization (6.4 × 10-8). A likely explanation for this is that: A. the electronegativity of the remaining hydrogen atom increases after the first hydrogen ion has been removed. B. the second ionization can only take place if the first ionization proceeds to completion. C. neutral hydrogen is difficult to ionize in aqueous solution. D. the remaining hydrogen atom experiences greater electrostatic attraction after the loss of the first hydrogen ion

D. After loss of the first proton, the remaining hydrogen is bound to a negatively-charged molecule. Electrostatic attraction between this remaining hydrogen and the negatively-charged molecule would disfavor loss of the second proton, resulting in a smaller K. Therefore, K2 << K1.

Which of the following reflects the researchers' attempt to minimize adaptation effects during the experiment? A. Using wild mice rather than domesticated mice B. Using sugar water rather than pond water during the training stage C. Rearranging the bottles after a human subject detected sulfur D. Limiting the human subjects' inhalation time to two seconds

D. An adaptation effect is the phenomenon by which an organism becomes accustomed to a sensory stimulus, which results in a higher threshold for detection of that stimulus. Since the experiment in this study was designed to measure detection thresholds, it was necessary to limit participants' inhalation time to two seconds so that they would not become accustomed to the smell of sulfur. Otherwise, their olfactory thresholds for the detection of sulfur may have measured higher than their actual levels (choice D is correct; choices A, B, and C are wrong).

Assuming that Korean culture is androcentric, which of the following statements is most plausible? A. In Korea, women are considered strong and are therefore less susceptible to shin-byung. B. A woman given the diagnosis of shin-byung in the United States would receive the same social prestige as in Korea. C. Korean women have little motivation to seek out attention and prestige by claiming the symptoms of shin-byung. D. A Korean man who seeks help for shin-byung symptoms would most likely receive a different diagnosis.

D. An androcentric culture is one that is male-oriented; the male is considered the norm and is consistently preferred across the various aspects of the culture. As a result, anything that is related to females and the female experience is relegated to a lower tier of importance. If a male claimed to be experiencing symptoms characteristic of shin-byung, it is unlikely that he would be treated the same as a female. He would most likely receive a different diagnosis, particularly because the passage seems to indicate that this condition occurs only in Korean women (choice D is correct). In an androcentric culture, it is less likely that a woman would be seen as strong enough to resist this disorder (choice A is wrong). A culture that neither recognizes this culture-bound disorder nor rewards women for becoming shamans, such as the United States, is unlikely to provide the same social rewards for women with these symptoms (choice B is wrong). If there are limited avenues for women to gain social status in an androcentric society, there is a greater motivation for women to use unusual means in order to gain such status (choice C is wrong).

In a male individual with Down's Syndrome (trisomy 21), how many chromosomes would be visible at metaphase I of spermatogenesis? A. 23 B. 24 C. 46 D. 47

D. An individual with trisomy 21 has an extra copy of chromosome 21 (three total copies). During metaphase I, the developing gametes are still diploid (separation of homologues has not yet occurred), so this individual would have the normal 46 chromosomes plus the extra copy of chromosome 21, for a total of 47 chromosomes (choice D is correct; eliminate choices A, B and C).

Which one of the following plots best illustrates the pH of an acidic buffer solution as it is diluted with H2O?

D. As stated in the passage, the pH of a buffer solution depends on the ratio of the concentrations of acid to base, and not their absolute quantities. Therefore, the dilution of the buffer solution should not affect the pH, as shown in choice D.

The investigators transfected neuronal cells plated in small culture dishes and 48 hours later measured the levels of Aβ peptide. Which of the following procedures should be implemented to measure the levels of Aβ? A. Place the culture dishes under a microscope and directly count the amount of Aβ B. Harvest the cells, break down the cell membrane, and measure the levels of cellular Aβ using a specific antibody. C. Harvest the cells, break down the cell membrane, and measure the levels of cellular Aβ using PCR. D. Harvest the condition media from the dishes and use an ELISA (enzyme-linked immunosorbent assay) coated with anti-Aβ peptide to measure the levels of Aβ released.

D. Aβ peptide is released into the extracellular space so it should be found in the condition media of the culture dishes. ELISA is the preferred method for secreted proteins found in the media, blood or extracellular space, therefore the harvested media can be used with an ELISA coated with anti-Aβ to measure the levels of Aβ (choice D is correct). Since the protein is secreted, any answer that suggests the measurement of cellular Aβ should be eliminated (choices B and C are wrong). Further, it is impossible to visualize and measure any protein or peptide with a microscope (choice A is wrong).

The enzyme lysozyme degrades peptidoglycan. If lysozyme is mixed in blood agar prior to addition of Strep. viridans, which of the following would be observed? A. Colonies surrounded by a clear zone B. Colonies surrounded by a green zone C. Colonies without a zone of hemolysis around them D. No colonies

D. Bacterial cell walls are made of peptidoglycan and are susceptible to degradation by lysozyme. Gram-positive strains (such as Strep. viridans) are particularly vulnerable since their cell wall is unprotected by membrane like the cell walls of Gram-negative strains. Thus the cell wall of the Strep. viridans will be damaged by the lysozyme, so that the bacteria will not survive and no colonies will form (choice D is correct). Note that the hemolysis observed around some colonies is caused by the ability of bacteria to lyse red blood cells and is not related to lysozyme activity (choices A, B, and C are wrong).

Systolic blood pressure approaches 0 mm Hg when it reaches the: A. capillaries. B. arteries. C. aorta. D. right atrium.

D. Blood from the systemic circulation at the end of its circuit through the body enters the heart through the right atrium, and at this point its pressure is near 0 mm Hg (choice D is correct). Although blood pressure is relatively low in the capillaries, it is not 0 mm Hg, or it would never circulate all the way back to the heart (choice A is wrong). Blood leaves the heart through the aorta on its way to the systemic circulation and is at its highest pressure at that point (choice C is wrong); from the aorta the blood travels through many arteries, and the pressure in these vessels is still high (choice B is wrong).

In addition to being used to produce alanine, pyruvate can be used to form: I. Glucose II. Acetyl-coA III. Fatty acids A. I only B. II only C. II and III only D. I, II, and III

D. Item I is correct: pyruvate is a substrate for gluconeogenesis, and can be used to form glucose. This eliminates choices B and C, which do not include glucose. Item II is also correct: pyruvate can be used to make acetyl-coA using the pyruvate dehydrogenase complex (the process between glycolysis and Krebs). This eliminates choice A, which does not include Item II. Item III is also correct: since pyruvate can be converted to acetyl-coA, it can be used to form fatty acids (which are made from acetyl-coA). Thus, choice D is correct.

Why is dimethyl mercury, a nonpolar molecule, more toxic than inorganic mercury salts? A. The interior of cellular membranes is highly hydrophilic, hence is highly permeable to ions. B. Almost all mercury salts, with the exception of Hg(NO3)2, are very soluble, hence are easily purged by the excretory system. C. The solubility of dimethyl mercury is enhanced in the high pH of the stomach. D. Since the interior of cellular membranes is hydrophobic, toxic nonpolar molecules can rapidly accumulate in and damage these sensitive structures.

D. Choice A is a false statement; the interior of cell membranes is hydrophobic (water repelling) and does not facilitate ion transport. Choice B has got reality reversed: All mercury salts, with the exception of mercuric nitrate, are insoluble (all metal nitrate salts are soluble). However, it is true that once dissolved, aqueous phase mercury ions can slowly be purged by the excretory system. Choice C is wrong for at least one reason: Gastric fluids are acidic and have a low pH. Choice D is correct. All hydrophobic compounds accumulate in the hydrophobic crevices of the body. Fat deposition on the interior of arterial walls is but one example.

Respiratory rate is regulated by many factors. Which of the following conditions is most likely to cause a decrease in breathing rate? A. Metabolic acidosis B. Low O2 concentration in the blood C. High CO2 levels in the blood D. High plasma pH

D. Consider the following equilibria: CO2 + H2O ?H2CO3 ? HCO3-. In the blood, CO2 from the tissues is quickly converted to carbonic acid, which then dissociates into hydrogen ions (lowering the pH) and bicarbonate ions. Excess CO2 thus promotes metabolic acidosis, which is quickly compensated for by increasing the respiratory rate. This helps to eliminate CO2 from the blood and restore pH to normal (choices A and C are wrong). Low O2 concentrations in the blood would lead to an increase in respiratory rate (choice B is wrong); furthermore, blood O2 levels affect the respiratory rate only in situations where O2 availability is low, such as at high altitudes (above 7000 feet). Of the choices given, the most likely condition to induce a decrease in respiratory rate is high plasma pH (choice D is correct) since a reduction in respiratory rate would lead to an accumulation of CO2 in the blood, and a corresponding increase in H+.

During the exponential phase of bacterial growth, bacteria are reproducing by: A. sexual reproduction. B. transduction. C. conjugation. D. binary fission.

D. During the exponential phase of bacterial growth, the population is increasing in size. The only choice which allows an increase in population size is choice D, binary fission. Sexual reproduction does not apply to bacteria (choice A is wrong), and while conjugation serves to increase genetic diversity, it does not increase the size of the population (choice C is wrong). Transduction is also a means to create genetic diversity. It occurs when a lysogenic virus excises from the genome and takes a portion of the genome with it. Any new hosts infected by that virus will be given the new genes, however this does not increase the size of the population (choice B is wrong).

During times of starvation: A. triacylglyceride stores in adipocytes are anabolized by lipase. B. fatty acids are broken down via oxidation, hydration and cleavage reactions, to generate NADPH, and to oxidize FADH2. C. glycerol is converted to DHAP, a glycolysis intermediate, which is then used to generate lactate and ethanol via fermentation. D. fatty acids are transported in the blood via binding to blood proteins like albumin, then are broken down via β-oxidation in target tissues.

D. During times of starvation, sugar, protein and fat stores are degraded to provide the body with sufficient energy. Triacylglycerides are catabolized (not anabolized) in adipocytes via lipase (eliminate choice A). The glycerol backbone is converted to DHAP, a glycolysis intermediate, which is then converted to pyruvate and put through Krebs cycle and ETC to make energy, or is used in gluconeogenesis to make glucose-6-phosphate. Fermentation can generate lactate or ethanol, but not both, and is only done in anaerobic conditions (eliminate choice C). Fatty acids are transported in the blood via binding to blood proteins like albumin. Once at the target tissue, they are activated, shuttled into the mitochondria and broken down via β-oxidation. This generates acetyl-CoA (via cleavage of the carbon backbone), as well as NADH and FADH2 (via reduction of NAD+ and FAD respectively, eliminate choice B and choice D is correct). Note that NADPH is made via the pentose phosphate pathway, not during fatty acid oxidation.

During times of starvation: A. triacylglyceride stores in adipocytes are anabolized by lipase. Your Answer B. fatty acids are broken down via oxidation, hydration and cleavage reactions, to generate NADPH, and to oxidize FADH2. C. glycerol is converted to DHAP, a glycolysis intermediate, which is then used to generate lactate and ethanol via fermentation. D. fatty acids are transported in the blood via binding to blood proteins like albumin, then are broken down via β-oxidation in target tissues.

Engagement rings are presented as betrothal gifts, often from men to their partners. These tokens would be of interest to which of the following? A. Conflict theorists B. Dramaturgical theorists C. Functionalists D. Interactionists

D. Engagement rings are presents to prospective spouses, but they are also important for another reason: engagement rings indicate that a person has accepted a marriage proposal. Interactionists are interested in micro-level interactions that create social meanings, thus focusing on communication through language and other important social symbols. Therefore, it is likely that interactionists would be interested in engagement rings because societies use these symbols to communicate that a person has made a formal agreement with his or her romantic partner and is now engaged to be married. These meanings help create our impression of the person wearing the ring, and individuals are thus active in shaping their societies, reflecting the arguments of interactionism. Furthermore, social interactions also regulate the practice of wearing the ring; for example, it is customary for engagement rings to be worn on the left ring finger in most Western countries (choice D is correct). The dramaturgical perspective is a specific form of interactionism that is interested in impression management (e.g., the back-stage and front-stage selves), but this is less applicable to the specific token presented upon engagement (choice B is wrong). The marriage-related interests of conflict theorists might be the internal power relations (or, to continue with the example, perhaps the relationship between socioeconomic status and the ranging qualities of the engagement ring, such as status); the pertinent interests of functionalists might be the contributions of marriage to social order. However, neither conflict theorists nor functionalists would be expected to consider the implications of an engagement ring in social interactions (choices A and C are wrong).

Ghrelin, the "hunger hormone," is released when the stomach is empty. It increases hunger and promotes secretion and motility in the digestive tract. The receptor for ghrelin is found on the same cells in the brain as the receptor for leptin. Which of the following is a true statement? The interaction of leptin and ghrelin can be considered competitive inhibition because they produce antagonistic effects. B. The interaction of leptin and ghrelin is considered to be allosteric inhibition. C. The interaction of leptin and ghrelin is considered uncompetitive because ghrelin only binds when leptin is already bound. D. There is no interaction between leptin and ghrelin because they operate on separate receptors.

D. Even though they bind to the same cells in the brain, the fact that leptin and ghrelin bind to separate receptors means that there cannot be any kind of inhibition or interaction between them (choice D is correct). For competitive inhibition to occur, two things must be trying to bind to one site; for example, if both leptin and ghrelin bound to the same site on the same receptor. The fact that they have separate receptors prevents this (choice A is wrong). Likewise, allosteric inhibition requires that the inhibitor bind to a separate site on the same enzyme or receptor (choice B is wrong), and there is nothing in the question stem or passage to suggest that ghrelin can only bind when leptin is bound (choice C is wrong).

Fe(CO)6Cl dissociates into two species, both charged, when dissolved in water. Which is the most likely expression for the dissociation constant (Ksp)? A. Ksp = [Fe+][CO]6[Cl−] B. Ksp = [Fe+][Cl−] C. Ksp = [Fe(CO)3+][Cl(CO)3−] D. Ksp = [Fe(CO)6+][Cl−]

D. Fe(CO)6Cl is a complex salt. Since CO is a neutral ligand, dissociation of one CO will not result in two ionic particles. Therefore, the dissociation must be Fe(CO)6Cl → Fe(CO)6+ + Cl−. This dissociation is represented well by choice D. Choice A is the equilibrium constant for total dissociation into eight free particles. Choice B can be eliminated as there will be no free Fe+ in solution if only two charged species form. Choice C can be eliminated since ligands like CO coordinate by donation of electron pairs, which anions such as Cl− are incapable of accepting.

Which of the following represents the correct sequence for embryogenesis? A. Fertilization → gastrulation → blastulation → neural tube formation → somite formation B. Fertilization → gastrulation → blastulation → somite formation → neural tube formation C. Fertilization → blastulation → neural tube formation → gastrulation → somite formation D. Fertilization → blastulation → gastrulation → neural tube formation → somite formation

D. Fertilization is the first step, followed by a series of rapid cell cleavages to form a hollow ball of cells called the blastulam (eliminate choices A and B). Next comes the gastrula, in which cells move into the interior of embryo to form the three germ layers (eliminate choice C). Gastrulation is followed by the formation of the neural tube, which will form the nervous system, followed by the formation of other organs and tissues, such as the somites that will differentiate into bones and muscle. This makes choice D the only possible correct order of events.

Hypothetically, if Reaction I was found to be spontaneous at standard state and higher temperatures, but nonspontaneous at low temperatures, the reaction must result in: A. decreasing entropy and decreasing enthalpy. B. decreasing entropy and increasing enthalpy. C. increasing entropy and decreasing enthalpy. D. increasing entropy and increasing enthalpy

D. From the equation ΔG = ΔH - TΔS, we can eliminate choice B since ΔH > 0 and ΔS < 0 would always give ΔG > 0 (nonspontaneous) no matter what the temperature, and we can eliminate choice C since ΔH < 0 and ΔS > 0 would give ΔG < 0 (spontaneous) regardless of temperature. Choice A is false since at sufficiently high temperatures, the T ΔS term would become more negative than ΔH, leading to a positive ΔG, contradicting the statement in the question that the reaction is spontaneous at high temperatures. This leaves choice D.

Which of the following events takes place during Phase 0? A. A decrease in intracellular Ca2+ B. An efflux of intracellular K+ C. Closure of voltage-gated channels D. An influx of extracellular Na+

D. In both cardiac and skeletal muscle, as in neurons, the initial depolarization (Phase 0) is caused by the opening of voltage-gated sodium channels. When the channels open, sodium flows into the cell down the gradient maintained as part of the resting membrane potential (choice D is correct). Calcium and potassium flux do not occur in this period, and voltage-gated channels are opening, not closing (choices A, B, and C are wrong).

It was observed under the microscope that a small section of bone consisted of concentric rings of fibrous material surrounding an open circular region. The bone section was identified as an osteon. The circular region is expected to contain: A. mature osteocytes. B. maturing chondrocytes. C. large blood cell precursors. D. blood vessels.

D. In compact bone, the osteon is the basic unit of structure. Concentric rings surround the central circular region that contains blood or lymph vessels (choice D is correct). Osteocytes can be found in small spaces along channels branching away from the central channel (choice A is wrong). Bone is the site of the marrow in which blood cell precursors are found, but bone marrow is found in spongy bone and not in compact bone where osteons are found (choice C is wrong). Chondrocytes are found in cartilage (choice B is wrong).

During the research period, 16% of wives with moderate forecasts and 12% of wives with positive forecasts divorced. Despite high divorce rates, many couples decided to forgo professional relationship counseling. This can be attributed to a number of factors, including the social stigma surrounding such services. Which of the following is true of stigma? It is applied to deviant character traits rather than external deformities. It is defined as disapproval resulting from actual or perceived social deviance. It can lead to demeaning labels that are applied to entire social groups. A. II only B. III only C. I and II only D. II and III only

D. Item I is false: social stigma is a negative reaction to a person or group. This can result from the perception, correct or incorrect, of the presence of numerous characteristics; these include personal or behavioral traits, such as in certain mental illnesses, or external deformations, such as visible manifestations of eating disorders (choice C can be eliminated). Item II is true: deviance is the violation of social norms, which is seen as unacceptable by the society at large (choice B can be eliminated). Item III is true: labels are often applied to individuals deviating from the social norm, thus perpetuating social stigma (choice A can be eliminated and choice D is the correct answer). For example, social stigma is a widespread problem in mental health; a demeaning label applied in this context might be "crazy" or another related word.

Thirteen amino acids, including methionine, valine and proline, are glucogenic in humans. This means their α-keto acid carbon skeleton is converted to pyruvate during amino acid catabolism. After deamination, valine can therefore: Be converted into CO2 and H2O to generate ATP. Generate at least three NADH and two FADH2. Enter gluconeogenesis to generate glucose. A. I only B. III only C. I and II only D. I and III only

D. Item I is true: Amino acids are catabolized via deamination into α-keto acids and ammonia. Based on the information in the question stem, the α-keto acid formed from valine will be converted to pyruvate. Pyruvate can keep going through cellular respiration to generate CO2, H2O and ATP. Eliminate choice B. Item II is false: Pyruvate is converted into one acetyl-CoA (during which 1 NADH is made), and the acetyl-CoA would then generate three NADH and only one FADH2 as it cycles through the Krebs cycle. Eliminate choice C. Item III is true: Pyruvate can also enter gluconeogenesis to generate glucose. Eliminate choice A and choice D is correct.

Which of the following statements is/are true regarding reproductive health in society? I. Community clinics have a manifest function of providing women's health resources to lower-income citizens. II. A teenager who becomes pregnant is more likely to have children who also end up having babies at a very young age; this is an example of social reproduction. III. Obtaining contraception and pregnancy prevention information is an issue of both accessibility and availability in most lower-income communities. A. I and II only B. I and III only C. II and III only D. I, II, and III

D. Item I is true: a manifest function of a social institution it the intended purpose of that institution; providing women's health resources to lower-income citizens is the manifest function of community clinics, many of which provide free counseling and resources (choice C can be eliminated). Item II is true: social reproduction refers to the structures in society that transmit social inequality from one generation to the next Item. In other words, the lack of knowledge and access to resources which might have made it more likely for a teenager to become pregnant in the first place will also make it more difficult for that teenager to provide a better life to her children, which tends to perpetuate a cycle of poverty and makes it harder for the next generation to rise above their circumstances. Therefore, the fact that women who get pregnant at an early age are more likely to raise children who also end up having babies very young is an example of social reproduction (choice B can be eliminated). Item III is true: most lower-income neighborhoods do not have as many healthcare resources (both contraception and information) available to them. For example, fewer doctors tend to practice in poorer communities, schools may not have the resources to provide sexual education, and community clinics may not have the fund for outreach or free condoms. These are all issues of availability (the needed resources are not available). Similarly, even when resources do exist, there are also issues of accessibility that also prevent individuals in lower-income communities from obtaining the information or resources they need. For example, even if a low-cost clinic is in the neighborhood, it might be so overbooked that it is difficult to get an appointment when needed. Therefore, obtaining contraception and pregnancy prevention information is an issue of both accessibility and availability in most lower-income communities (choice A can be eliminated; choice D is correct). Concepts tested

Which of the following statements demonstrates the idea that mass media are agents of socialization? I. Young people's body image is affected by the bodies depicted in magazines II. News media coverage of sexual assault focuses primarily on the victim III. Social media has become a pervasive aspect of everyday life A. I only B. I and II only C. II and III only D. I, II, and III

D. Item I is true: the mass media present and perpetuate a body image that is glorified by society. Exposure to these glorified images can influence young people to take on these body standards as ideal, and this is a form of socialization (choice C can be eliminated). Item II is true: when news media coverage focuses primarily on the victim of a sexual assault, women learn that it is their job to protect themselves from such assaults, but perpetrators do not learn to stop assaulting women. Emphasizing women's victimhood in mass media is a form of gender socialization that carries with it messages about whom to associate with, how much to drink, and how to dress oneself (choice A can be eliminated). Item III is true: social media can be considered mass media, and because of its pervasiveness, social media has become a powerful socializing force in almost everyones' lives, and has significantly impacted: how people communicate and interact, the types of information individuals and organizations share, how often information is shared, the lexicon, how business is conducted, and other such major phenomenia, both big and small (choice D is correct; choice B can be eliminated).

The serotonin transporter (or SERT) removes serotonin from the synaptic cleft and recycles it back into the presynaptic cell. It thus terminates the effects of serotonin and this mechanism has been targeted in treatments for alcoholism, clinical depression, obsessive-compulsive disorder, and hypertension. SERT spans the plasma membrane 12 times and is also a: A. glycosylated phospholipid, with both hydrophobic and hydrophilic regions. B. peptide chain with at least four levels of protein structure, held together by disulphide and peptide bonds. C. protein with twelve hydrophobic domains, none of which contain the amino acid proline and at least some of which contain -sheets stabilized by covalent bonds. D. protein with twelve transmembrane domains, each of which is an -helix with no proline and external hydrophobic residues, stabilized by hydrogen bonds.

D. Membrane transport is mediated by proteins, not phospholipids (eliminate choice A). All proteins have at least three levels of protein structure, but only some have quaternary structure. There is no information in the question stem to support the fact that SERT contains more than one peptide chain (eliminate choice B). Transmembrane domains are -helices with external hydrophobic residues. They cannot contain proline because of its secondary amine structure. Both -helices and -sheets are stabilized by hydrogen bonds, not covalent bonds (eliminate choice C, choice D is correct).

All of the following biological developmental milestones that change the brain occur during the adolescent years EXCEPT: A. Cell proliferation (particularly in the limbic system and prefrontal lobes) B. Myelination C. Synaptic pruning (of unused or unnecessary connections) D. Codification of neural networks for basic motor skills

D. Neural network development for motor skills is part of early brain development and is essentially complete for basic motor skills (such as crawling, walking, jumping, and writing) before adolescence (choice D does not occur during adolescence and is therefore correct). Cell proliferation, particularly in the prefrontal lobes and in the limbic system, is one of the changes to the brain that occurs during adolescence, as the prefrontal cortex is required for abstract thinking (choice A is wrong). Myelination, the creation of myelin sheaths around neurons in the brain to strengthen connections, is another change that occurs during adolescence (choice B is wrong). Synaptic pruning, which clears the brain of unnecessary connections, is the third major developmental change in the brain during adolescence (choice C is wrong).

Which of the following is the product of reverse transcriptase activity on the following piece of RNA? 5'-AUGGUACAUACUUGC-3' A. 5'-UACCAUGUAUGAACG-3' B. 5'-GCAAGUAUGUACCAU-3' C. 5'-TACCATGTATGAACG-3' D. 5'-GCAAGTATGTACCAT-3'

D. Reverse transcriptase will make DNA from an RNA template. Therefore choices A and B can be eliminated, since they contain uracil. The resultant strand of DNA will be antiparallel and complementary to the template strand. Therefore, the 3' end of the template corresponds to the 5' end of the newly synthesized strand. Cytosine pairs with guanine (choice C can be eliminated and choice D is correct).

If a bisexual female reports feeling social pressure to be either lesbian or straight, which causes her significant stress, what term best describes the stress this subject is feeling about her social role? A. Role conflict B. Master status C. Role exit D. Role strain

D. Role strain is when having a single status results in conflicting expectations; if a bisexual female reports feeling social pressure to be either lesbian or straight, which causes her significant stress, she is experiencing conflicting expectations about her bisexual identity (choice D is correct). Role conflict happens when there are conflicting societal expectations for multiple statuses held by the same person. For example, a male kindergarten teacher—societal expectations for being a man and being a kindergarten teacher easily come into conflict (choice A is wrong). Master status is when one part of someone's identity comes to dominate their identity, to the exclusion of other parts of their identity (choice B is wrong). Role exit is the process of disengaging from one role in order to take up another. An example is the process of disengaging from a "pre-med" identity to take on a "medical student" identity (choice C is wrong).

A chemist prepares a 1 M solution of sulfuric acid. Which of the following gives the relative concentrations of the species in solution? A. [H2SO4] > [HSO4-] > [SO42-] B. [SO42-] > [HSO4-] > [H2SO4] C. [HSO4-] > [H2SO4] > [SO42-] D. [HSO4-] > [SO42-] > [H2SO4]

D. Since sulfuric acid is a strong acid and dissociation of the first proton is complete, undissociated H2SO4 will have the lowest relative concentration, eliminating choices A and C. Since the dissociation constant for the loss of the second proton is well below 1 (~ 10-2), HSO4- will exist in greater concentration than SO42-, making choice D the correct answer.

Lying is often employed as a means of persuasion. Which theoretical model is often used when attempting to determine why someone has been persuaded? A. Yerkes-Dodson B. Cannon-Bard C. Schachter-Singer D. Elaboration-Likelihood

D. The elaboration-likelihood model of persuasion attempts to explain the different ways individuals process stimuli, why they are used, and their outcomes on attitude change. According to the elaboration-likelihood model, there are two major routes to persuasion: the central route and the peripheral route. Under the central route, persuasion will likely result from a person's careful and thoughtful consideration of the persuasive argument; under the peripheral route, the person will focus more on superficial aspects of the argument (catchy-ness, flashy-ness) and spend less time engaging in deep thought about the actual content of the message, so persuasion will occur because of the superficial aspects of the message (choice D is correct). The Yerkes-Dodson Law suggests that performance increases with physiological or mental arousal, but only up to a point. When levels of arousal become too high, performance suffers, which is graphically illustrated as a bell-shaped curve that increases and then decreases with higher levels of arousal (choice A is wrong). The Cannon-Bard and Schachter-Singer theories both attempt to describe how emotion and physiological arousal are related (choices B and C are wrong).

REaction 1 Cl2O + 2 OH→ 2 OCl +H2O Which of the following statements concerning Reaction 1 is FALSE? A. The chlorine atom in the product has a +1 oxidation state. B. The dichlorine oxide starting material has a bent molecular geometry. C. Addition of acid to the reaction mixture would decrease the potency of the bleach solution formed. D. Increasing the partial pressure of Cl2O(g) would increase the equilibrium constant, Keq, of the reaction.

D. The equilibrium constant, K, depends on the temperature only. That is, the ratio of products to reactants (with the appropriate stoichiometric coefficients as exponents on the concentrations) at equilibrium will remain the same at a given temperature. Therefore, choice D is false. Choice A is true since the rules for assigning oxidation states gives the oxygen atom a -2 oxidation state first, leaving chlorine with a +1 oxidation state in the ion OCl-. Choice B is true, since by VSEPR theory we'd predict the two lone pairs on the oxygen create a roughly 109° bond angle between the Cl—O bonds. Choice C is true, since Le Châtelier's Principle tells us that this reaction will go backward if we lower [OH−]; if the reverse reaction is favored, the active bleaching ingredient will be depleted.

What is the configuration of the electrons in the valence shell of a chloride anion? A. 3s2 3p4 B. 3s2 3p4 4s1 C. 3s2 3p4 4s2 D. 3s2 3p6

D. The most common chloride anion is of course Cl-, which has the octet configuration in its valence shell (like the noble gas argon). Choice D gives the octet configuration, ns2np6 (with n = 3 since Cl is in Period 3).

The blood vessel that carries the most highly oxygenated blood in the fetus is the: A. pulmonary vein. B. ductus arteriosus. C. umbilical artery. D. umbilical vein

D. The most highly oxygenated blood would be the blood returning from the point of oxygenation to the systemic circulation. In the adult this would be the pulmonary vein, but the point of oxygenation in the fetus is the placenta, not the lungs (choice D is correct and choice A is wrong). The ductus arteriosus does carry oxygenated blood but is found after the umbilical vein, so it does not carry the most highly oxygenated blood (choice B is wrong). The umbilical artery carries deoxygenated blood from the fetus to the placenta (choice C is wrong).

The ratio of products to reactants at equilibrium for Reaction 1 will change with a change in the: A. concentration of ATP. B. ΔG°. C. pressure. D. temperature.

D. The only way to change a reaction's equilibrium constant is to change the temperature.

To produce the maximum number of ATPs, post-glycolytic pathways in aerobes must receive from glycolysis: A. ADP and NADH. B. ATP and NADH. C. NADH and glucose. D. NADH and pyruvate.

D. The post-glycolytic pathways are the Krebs cycle and electron transport, which require oxygen, NADH, and pyruvate. Pyruvate is converted into acetyl-CoA to enter the Krebs cycle (choice D is correct). The Krebs cycle does not require either ADP or ATP from glycolysis and does not need glucose, only the pyruvate that is derived from glucose.

Which of the following is the most likely sequence of events in the infection of E. coli by phage T1? A. Replication of viral genome, production of viral DNA polymerase, translation of viral lysozyme, assembly of infectious virus B. Production of viral DNA polymerase, replication of viral genome, translation of viral lysozyme, assembly of infectious virus C. Translation of viral lysozyme, production of viral DNA polymerase, replication of viral genome, assembly of infectious virus D. Production of viral DNA polymerase, replication of viral genome, assembly of infectious virus, translation of viral lysozyme

D. The production of viral DNA polymerase must occur prior to replication of the viral genome since the polymerase is needed to do this (choice A is wrong). The last step must be production of lysozyme since this will lyse the cell, bursting it open and stopping any further activities required to produce infectious virus (choices A, B, and C are wrong). The correct events are in choice D: the expression of the viral DNA polymerase must come first to then replicate the genome. Infectious virus can then be assembled, and released by cell lysis induced by viral lysozyme.

Why is the copper(I) catalyst not necessary to link the fluorophore bearing the cyclooctyne to the stem peptide, even though it is required for other alkynes? A. The copper would increase the Ea. B. The reaction is spontaneous. C. The Ea of the reaction is low due to the high reactivity of the azide. D. The Ea of the reaction is low due to the ring strain from the cyclooctyne.

D. The role of any catalyst is to lower the activation energy (Ea) of a reaction (eliminate choice A), thereby increasing the reaction rate. Catalysts cannot, however, force a nonspontaneous reaction to occur, therefore both the reactions that use and do not use the catalyst must be spontaneous (eliminate choice B). The passage indicates that the copper catalyst is needed to link the azide to the non-activated alkyne. This implies that the azide is a stable functional group and therefore unreactive (eliminate choice C). The activation energy of a reaction can be lowered by stabilizing the transition state of the rate-determining step, or by increasing the relative energy of a substrate that is involved in the kinetics of the reaction (less stable molecules are more reactive). The cyclooctyne ring is highly strained due to the linear geometry of the alkyne. Therefore this substrate is highly reactive and will readily react with an azide without the need for a rate increase from the copper(I) catalyst (choice D is correct).

If a teacher remembered a student's unusual name because, coincidentally, it was also the name of the street on which the teacher lived as a child, that teacher's ease in remembering would be an example of: A. explicit memory. B. social learning. C. depth of processing. D. the self-reference effect

D. The self-reference effect describes how it is easier to remember that which is personally relevant or which can be linked to other memories (choice D is correct). Explicit memory is a type of memory in which one can "declare" and clearly articulate what one knows (choice A is wrong). Social learning is not about memory, but rather about learning through observing another and imitating his or her actions (choice B is wrong). Depth of processing concerns how deeply one thinks about the issues to be committed to memory. In other words, meaning is more easily remembered than form because one often ruminates more about the former (choice C is wrong).

Brain-imaging studies on deceit have shown that it leads to an alternate cognitive process when compared to truth-telling, which appears to be the default process of the human brain. In suppressing or inhibiting the truth, and often responding to the resultant stress, the brain becomes more active overall. Multiple areas are involved in the process, which are expected to include which of the following regions? I. The frontal lobes II. The limbic system III. The temporal lobes

D. The two main brain structures expected to be activated as a result of suppressing or inhibiting the truth are the cerebral cortex and the limbic system. The general functions of the cerebral cortex include perception, skeletal muscle movement, memory, attention, thought, language, and consciousness; the general functions of the limbic system include emotion, memory, and learning. The regions of the cerebral cortex expected to be involved in the process described in the question stem are the frontal lobes and the temporal lobes. Item I is true: the frontal lobes are involved in complex reasoning skills and problem-solving, both of which can occur in the process of suppressing or inhibiting the truth (choices A and C can be eliminated). Item II is true: the limbic system is involved in both memory retrieval, which allows the brain to compare the mental images (i.e., the truth versus the lie), and the resulting emotions related to deception (e.g., anxiety; choice B can be eliminated and choice D is the correct answer). Item III is true: the temporal lobes are involved in short-term memory, language comprehension, and emotion; consciously suppressing or inhibiting the truth suggests memory retrieval.

Because researchers chose to use a questionnaire, which of the following was missing from this study? A. Dependent variables B. Scientific method C. Independent variables D. A control group

D. The use of a questionnaire means that the researchers did not utilize a control group and thus did not have two groups participating simultaneously under different circumstances; this would simply not be possible with this methodology (choice D is correct). The dependent variables in this study are the preferences regarding age and gender of the students polled in the questionnaire—what the researchers were looking to study (choice A is wrong). The scientific method, in which hypotheses are empirically tested through the careful and systematic collection of relevant data. was used in this study and is ideally used in all scientific research (choice B is wrong). The independent variable here is the group of students polled (those between the ages of 18 and 30, identifying as either male or female; choice C is wrong)

If a neutralization similar to Trial 2 were performed with the same molar values of NaOH and acetic acid, which of the following results is the most likely to occur? A. A higher temperature due to a larger |ΔH| B. A lower temperature due to a larger |ΔH| C. A higher temperature due to a smaller |ΔH| D. A lower temperature due to a smaller |ΔH|

D. This is a 2 × 2 style question, and in this case two choices can be eliminated for being internally inconsistent. If the ΔH is larger for an exothermic reaction, more energy will be given off, resulting in a larger increase in temperature (eliminate choice B). Similarly, if less energy is given off, the temperature change should be smaller (eliminate choice C). The heat of neutralization is defined as the enthalpy change resulting from 1 mole of water being produced from the reaction H+(aq) + OH-(aq) → H2O(l). Since weak acids (like acetic acid) are only partially ionized, their neutralization by a strong base will not result in an equal production of water molecules compared with a strong acid/strong base neutralization (eliminate choice A).

Which of the following hormones acts on target cells via a second-messenger system? A. Thyroid hormone B. Aldosterone C. Cortisol D. Epinephrine

D. Thyroid hormone, aldosterone, and cortisol are all small hydrophobic molecules that passively diffuse through the plasma membrane to bind to receptors inside the cell in the cytoplasm and nucleus. These receptors then regulate transcription, without the use of second-messenger systems (choices A, B, and C are wrong). A hydrophilic hormone like epinephrine, however, binds to cell-surface receptors and activates adenylate cyclase to make cAMP, a second messenger (choice D is correct). Note that in general, steroid hormones exert their effects by modifying transcription, while protein hormones utilize second-messenger systems. Thyroid hormone, a protein hormone, is an exception.

The sound level of a sound wave that is striking an eardrum is increased from 35 dB to 55 dB. By what factor has the intensity of the sound increased? A. 2 B. 20 C. 100 D. 200

For each increase by 10 in the decibel level, the intensity of the sound increases by a factor of 10. In this case, the decibel level has increased by two units of 10 (since 55 - 35 = 20 = 10 + 10), so the sound intensity increases by two factors of 10, that is, by a factor of 102 = 100.

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