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Question 1

The anomeric carbon of a sugar is …

Answer 1

an invertible epimer

Question 2

The oxidation of succinate via the citric acid cycle produces one NADH and one FADH2 molecule. What is the ratio of succinate molecules entering the citric acid cycle to the number of ATP molecules formed?

knowing that :
NADH –> 10 protons pumped by ETC / molecule –> 2.5 ATP pumped per proton

FADH2 –> 6 protons pumped by ETC / molecule –> 1.5 ATP pumped per proton

a) 1: 1.5
b) 1:2.5
c) 1: 4
d) 1:5

Answer 2

Answer C is correct. There are a total of 16 protons (10 from NADH and 6 from FADH2) that are pumped back across the inner mitochondrial membrane by the ETC. The NADH molecule produces an average of 0.25 ATP per proton, so the 10 protons pumped per NADH molecule will produce approximately 2.5 ATP molecules. Similarly, the 6 protons pumped due to the FADH2 molecule will produce 1.5 ATP molecules. Together, that is 4.0 ATP molecules per oxidized succinate molecule, or a ratio of 1:4.

Question 3

Oxytocin is a mammalian hormone with the primary amino acid sequence CYIQNCPLG. The tertiary structure of oxytocin is primarily stabilized by:
A) hydrophobic interactions. B) hydrogen bonds. C) charge-charge interactions. D) disulfide bonds.

Answer 3

d) Oxytocin is a short peptide hormone that is critical during childbirth and other important mammalian processes. Looking at the primary structure, CYIQNCPLG, one can see that there are both polar and non-polar amino acids. But, more importantly, there are two cysteine residues. Answer D is correct because, with two cysteines in close proximity (especially as part of a small peptide with very little additional protein structure) it is very likely that a disulfide bond will form. A disulfide bond in a peptide that is only 9 amino acids long will be the primary source of stabilization.

Question 4

A new bacteria is discovered that utilizes a novel nucleotide, designated as H. The H nucleotide replaces guanine in the bacteria’s genome and base pairs with cytosine. This bacteria is likely to be highly successful at evading host immune system responses because the:
A) bacteria’s genome will not be recognized by antibodies in the host’s immune system.
B) bacteria will produce new proteins which cannot be detected by the host’s immune system.
C) H nucleotide will disrupt restriction endonucleases that target non-self DNA molecules to degrade them.
D) H nucleotide will make the bacterial surface proteins more similar to human surface proteins.

Answer 4

Answer C is correct. The newly discovered bacterium has a genome that uses ATCH instead of ATCG, but no other changes are described. We are told that H base pairs with C, so one can assume that it behaves in most respects just like G does. Answer C is the best answer because one way that organisms fight foreign invaders is through restriction endonucleases that recognize ‘non-self” DNA sequences. These endonucleases have very specific restriction sites (It would be very dangerous to have endonucleases without specific sites, since they could cleave any DNA). Answer A is incorrect because antibodies are generated against proteins, not DNA molecules. Answer B is incorrect because there is nothing to indicate that new proteins are being generated. If H base pairs with C, tRNA should interact with codons the same way whether H or G is being used. Answer D is incorrect for the same reason, there is no reason to believe the bacteria will produce new proteins, or that those proteins will be more like host surface proteins because of the H for G transition.

Question 5

A typical blood bicarbonate concentration is 26 mM. Based on Equation 1, what must the carbonic acid concentration be to achieve a pH of 7.0 if the Ka for carbonic acid at physiological temperature is 9.9 ×10–7?

A)2.6 mM
B) 519 mM
C) 20 mM
D) 7.1 mM

Answer 5

Answer A is correct; The Henderson-Hasselbalch equation is given in the passage as Equation 1: pH = pKa + log([HCO3]/[H2CO3]). To solve, we must first convert the Ka given to pKa. pKa = -logKa. First, round the pKa to 10 x 10-7. pKa = -log(10 x 10-7) = -log(1 x 10-6) = 6. Substituting into Equation 1 gives: 7.0 = 6.0 + log(26mM/x). Subtracting 6.0 from both sides yields: 1.0 = log(26mM/x), or 26mM/x = 1 x 101, or 26mM/x = 10. Therefore, x = 26mM/10, and x = 2.6. This is Answer A. Answers B, C and D are obtained through making various calculation errors.

Question 6

what does an anhydrase enzyme do?

Answer 6

removes water from a single substrate

Question 7

What equation has reagents responsible for maintaining homeostasis of blood pH?

Answer 7

H2CO3 (aq) + H2O (l) ⇌ H3O+ + HCO3– (aq)

Question 8

when is pH = pKa?

Answer 8

According to Henderson Hasselbach equation, when the base concentration = acid concentration

Question 9

Suppose the RNA strand shown below is a segment of viral genomic RNA. Using this RNA as a template, the enzyme reverse transcriptase would produce which of the following nucleotide polymers?

5’ GGAUCCUGAAC 3’

A) 3’ CCUAGGACUUG 5’
B) 5’ GGATCCTGAAC 3’
C) 5’ GUUCAGGAUCC 3’ 3’ CAAGUCCUAGG 5’
D) 5’ GTTCAGGATCC 3’

Answer 9

d
To answer this question, one must remember that reverse transcriptase is an RNA-dependent DNA polymerase and, as such, it will generate a DNA molecule. This means that the answer must contain “T” instead of “U”. It must also be complimentary to the genomic DNA given in the question, 5’ GGAUCCUGAAC 3’.

Question 10

A normal adult human has approximately 80 mg of copper in their body. Ammonia is normally converted to urea by the liver. Inadequate liver function can result in ammonia reacting with copper (II) ions to form an octahedral complex with which formula?
A) Cu(NH4)24+ 
B) Cu(NH3)42+ 
C) Cu(NH3)62+
D) Cu(NH3)82+

Answer 10

Answer C is correct. The octahedral shape has six positions occupied by coordinated atoms, so only choice C can be correct. Choice A is a complex that can exist at lower ammonia concentrations, but it is not octahedral. Choice B does not have six coordinated ammonia ligands.

Question 11

When the muscles of the diaphragm contract, the volume of the lungs is:

Answer 11

increased, and the pressure inside the lungs is decreased.

Question 12

for a first oder reaction, what are axis on graph?

Answer 12

y axis is Ln (concentration of reagent that is to first order)
x- axis is time

Question 13

If a patient’s original lung volume (V1) is decreased by 33% (V2), what is the relationship between the total pressure in the patient’s lungs before (P1) and after (P2) this change?

A) P2 = 1/3P1
B) P2 = 2/3P1
C) P2 = 3P1
D) P2 = 3/2P1

Answer 13

The Ideal Gas Law demonstrates that pressure and volume are inversely related. Therefore, if the volume of the lungs is decreased, the pressure inside the lungs must increase. This immediately eliminates answers A and B because they both indicate that the pressure after the change was less than the pressure before the change. Answer C is incorrect because for the pressure after the change to be three-fold larger than the pressure before the change (P2 = 3P1), the lung volume would have had to decrease by a factor of three (a 66% decrease). Because lung volume decreased by only 33%, Answer D is the only possible answer. A simple way to calculate the exact change in pressure is to convert the percentage change in volume to a fraction. A decrease in volume of 33% is equivalent to multiplying V1 by 2/3. Therefore, because pressure is inversely related to volume, P1 must be multiplied by 3/2 (the inverse of 2/3) to give P2. This is Answer D.

Question 14

what is electrophilic addition?

Answer 14

a reaction where a π (double/triple) bond is broken and two sigma (single) bonds are formed.

Question 15

what’s ionization energy?

Answer 15

amount of energy required to take a valence electron away from atom- it increases as you go to the right on periodic table because it gets harder to remove a valence electron as you go to non metals and closer to halogens.

Question 16

The pyruvate dehydrogenase complex (PDH) is naturally inhibited by ATP because:
A) ATP mimics pyruvate, acting as a competitive inhibitor for the ATP synthase enzyme.
B) pyruvate is converted to ATP in a subsequent oxidation step, leading to feedback inhibition.
C) enzymes of this class utilize ADP, rather than ATP, to dehydrogenate substrates.
D) the PDH product generates ATP via the citric acid cycle, leading to feedback inhibition.

Answer 16

D

Question 17

what’s 1 pascal?

Answer 17

1 n/m^2

Question 18

One of the bone-resorbing enzymes secreted by osteoclasts requires a covalently bound zinc ion to exhibit normal enzyme function. In this scenario, zinc is acting as:

I. a coenzyme.
II. an allosteric effector.
III. a prosthetic group.

Answer 18

III
Because the question states that the zinc is covalently bound and is necessary for normal function, the zinc is an example of a prosthetic group; which is a non-protein cofactor that is tightly bound to an enzyme and is necessary for its function.

coenzyme are loosely bound
and allosteric effector are bound to a part that is NOT active site.

Question 19

Which physiological process prevents cross-species fertilization among hominids?
A) Social constraints that prevent interspecies mating. B) Eggs fertilized with sperm from another species are always unviable. C) Cross-species fertilization results in polyspermy and death of the zygote. D) Species-specific receptors on the egg bind species-specific ligands on the sperm.

Answer 19

D-
The mechanism that prevents cross-species fertilization is species-specific receptors expressed on the outside of the egg, which are bound by species-specific ligands expressed on the outside of the sperm. Answer D is therefore the correct answer. Social constraints may be a tempting answer because human beings would logically express social opposition to interspecies mating, but this is neither a physiological process, nor would it prevent fertilization if mating did occur contrary to social constraints. Eggs fertilized with sperm from another species do not always die, if the genetic material is almost identical. An example is the ability of a horse and a donkey to mate and produce a mule. Therefore, Answer B is incorrect. Answer C is incorrect because there is no reason to believe that polyspermy, or the fusion of more than one sperm with the egg, would automatically occur if a sperm and an egg were from two different species. It may also be helpful to note that only Answers A and D would actually prevent fertilization. Answers B and C allow for fertilization, but the fertilized egg or zygote is unviable. Because the questions stem asks for something that PREVENTS fertilization, this is another reason to dismiss choice B and C.

Question 20

Which physiological mechanism is LEAST likely to result in a significant decrease in blood acidity?
A) Exhalation of carbon dioxide
B) Release of H3PO4 into the blood stream
C) Conversion of bicarbonate to carbon dioxide in the blood
D) Excretion of protons into the urine by the kidneys

Answer 20

Choice B is the best answer. The major physiological mechanisms used to control blood pH include exhalation of carbon dioxide, conversion of carbon dioxide into bicarbonate in the blood, and the excretion of protons through the kidneys. In the precise way they are stated here, all three mechanisms will decrease blood acidity (i.e., increase blood pH). Answer A will decrease blood acidity according to Le Chatelier’s Principle as it is applied to the following equation:
CO2 + H2O ⇄ H2CO3 ⇄ H+ + HCO3-

Question 21

Calcium is a necessary structural or functional component in which of the following processes?

  I. Bone tissue formation
 II. Blood clotting
III. Muscle contraction
IV. Nerve signal transmission
A) I and IV only B) III and IV only C) I, III, and IV only D) I, II, III, and IV

Answer 21

Choice D is correct. Calcium combines with phosphate and hydroxide in hydroxyapatite, the major component of the extracellular bone matrix.

Question 22

An experiment focused on anaerobic respiration in muscles under hypoxic conditions should focus on which cellular compartment?
A) Mitochondrial matrix B) Mitochondrial intermembrane space C) Cytoplasm D) nucleus

Answer 22

Choice C is the correct answer. In mammalian cells, anaerobic respiration is the alternative pathway taken when oxygen is not available for oxidative phosphorylation, such as during the oxygen debt created during extended periods of exercise. Glycolysis occurs in the cytoplasm and the products from that pathway will be the final electron acceptors to produce lactic acid. Because this occurs in the cytoplasm rather than the mitochondria, Answer C is correct.

Question 23

how do protein based vaccines work? what do they recognize?

Answer 23

Vaccines that are protein-based work because the antigens they contain resemble the antigens of the invading pathogen. For example, viral vaccines usually contain viral capsid proteins, and bacterial vaccines contain surface proteins. This allows the host immune system to initiate a primary immune response and prepare for a secondary immune response without an actual pathogen infection.

Question 24

Although the average pKa of the Glu side chain is approximately 4.2, the enolase enzyme contains a glutamate in its active site that is protonated at physiological pH. This Glu residue is protonated because:
A) it is buried in the center of the protein, inhibiting proton dissociation.
B) enolase functions inside of lysosomes, where the pH is naturally much lower.
C) the local environment lacks a basic molecule to act as a proton acceptor.
D) the local environment increases the pKa of the Glu side chain.

Answer 24

D- Choice D is the correct answer. The local environment causes the pKa of the Glu side chain to become more basic, causing the proton on the Glu side chain to remain bound. Answer A is not correct since the active site of most enzymes is on or near the surface of the protein, making it accessible to the surrounding solvent, not buried inside the core of the protein (which is usually almost exclusively hydrophobic). Answer B is incorrect since enolase is one of the enzymes of glycolysis, which occurs in the cytoplasm, not in lysosomes. Further, a lower pH doesn’t change the pKa of the side chain; rather, the pKa value tells us the approximate pH at which the proton will be 50% dissociated. Answer C is not correct since the active site is exposed to the aqueous cellular fluid and water is a common proton acceptor.

Question 25

A study reports that women spend an average of 18 hours per week doing housework, while men spend an average of 10 hours per week doing housework. How can social conflict theory be used to explain this finding?
A) Men, on average, work more hours outside the home, which balances out women’s household work.
B) Women do more household work because most women do not work outside of the home.
C) Some women are not married, and therefore their inclusion in the study skews the data.
D) The housework performed by women is an example of the “second shift” experienced by working women.

Answer 25

Choice D is the correct answer. The term “second shift” is a concept used within the conflict theory perspective to explain the unequal division of labor in the household between women and men. Answer A is wrong because, although this observation could be true, it does not explain the observation in the stem from a conflict theorist perspective. Answer B is wrong because research shows that women do work outside the home more today and this explanation does not suggest a conflict over the division of labor as social conflict theory would. Answer C is wrong because a skew in the data might explain the gender discrepancy in household work, but it is not related to social conflict theory.

Question 26

A dramatic change in which variable is most likely to improve health outcomes in countries where mortality rate is high and life expectancy is low?
A) Average income
B) Healthcare access 
C) Medical technology 
D) Physicians per capita

Answer 26

Answer A is correct. Multiple sociology studies, as well as reports by the World Health Organization, suggest that increased income is the single change that has the greatest impact on health outcomes in developing countries. Answer B is wrong because many developing countries have universal healthcare but it is underfunded or ineffective. Even in industrialized nations with universal healthcare the health of citizens in lower socioeconomic strata lags behind that of wealthier citizens. Answer C is wrong because, while better medical technology is helpful in realizing some positive health outcomes, higher income has a greater impact. Answer D is incorrect because the number of doctors alone does not necessarily improve individual health outcomes. Citizens need wealth either to access a physician at all, or to access the best care. Finally, a higher income is associated with a variety of other behaviors that impact health. For example, wealthier people have access to more nutritious food options and are less likely to smoke.

Question 27

If the Social Gender Theory is true, one would expect gender differences in the level of depressive symptoms to:
A) increase during gender socialization processes and remain unchanged when a woman adopts a socially accepted gender role.

B) decrease during gender socialization processes and remain unchanged when a woman adopts a socially accepted gender role.
C) remain unchanged during both gender socialization processes and during a woman’s normal aging process. D) remain unchanged during gender socialization processes and increase when a woman adopts a socially accepted gender role.

Answer 27

Choice A is the correct answer. If females’ disadvantaged social status creates strain, this would be most active during a period of socialization when they are being socialized to accept traditional roles for women. Once they have adopted the socially accepted roles for their gender, strain may continue, but would not increase or decrease because they are maintaining a constant role. This eliminates Answer D because it suggests that depression would increase after a woman accepts a socially defined gender role. Answer B can be eliminated because depression should increase during gender role socialization if gender role strain is the cause of depression and would be unlikely to change once a woman attains a socially accepted gender role. Answer C suggests that gender role strain and depression would not change under any circumstance, which is not logical, and it also introduces aging as a variable, which was not discussed in the passage. For these reasons, Answer C should be eliminated.

Question 28

Which term most accurately describes the motives of a person who is driven to perform tasks for their own sake, or because they enjoy the performance of the task itself?
A) Extrinsic 
B) Intrinsic
C) Needs-based 
D) Drive-reduction

Answer 28

Choice B is the correct answer. Extrinsic motivation (Answer A) occurs when a person is motivated by external factors such as money, while intrinsic motivation (Answer B) occurs when the activity itself is motivating. The scenario described in the stem is an example of intrinsic motivation. Needs-based motivation (Answer C) is a theory of motivation that suggests people are motivated by the desire to satisfy their most urgent needs. Drive reduction (Answer D) is a motivational theory characterized by some extant physiological need such as hunger or sexual arousal.

Question 29

After beginning to read online news articles daily, a man has developed a fear of terrorist attacks. He is now convinced that more people die in terrorist attacks than in automobile accidents. Which decision-making framework is most likely responsible for this erroneous belief?
A) Representativeness heuristic 
B) Negative illusions bias 
C) Availability heuristic
D) Anchoring bias

Answer 29

Choice C is the correct answer. The availability heuristic is a mental shortcut whereby one gives precedence to the most immediate examples that come to mind. In this case, the terrorist attacks reported in the news are readily available and supersede historical information about the actual frequency of terrorists incidents relative to automobile accidents. Answer A, the representativeness heuristic, is a mental shortcut based on reasoning that is related to how representative something seems to be of a category (e.g., how likely is a woman to be a librarian based on how similar she seems to the idea one has of a typical librarian). Answer B, negative illusions bias, is not a recognized decision-making framework. However, it may be a tempting distractor because it is similar in structure to the term positive illusions bias. The positive illusions bias involves having an exaggerated or inflated assessment of one’s own abilities, how good the future will be, or how much control one has over life events. Answer D, anchoring bias, occurs when one uses an initial piece of information (the anchor, e.g., an original price for an item) to make judgements about subsequent pieces of information (e.g., a sale price for the item).

Question 30

Neuroticism and extroversion are both concepts described by which model of personality?
A) The Social-Cognitive Model 
B) The Humanist-Existential Model 
C) The Psychodynamic Model 
D) The Big Five Factor Model

Answer 30

Choice D is the correct answer. Neuroticism and extroversion are both components of the Big Five theory of personality. Answers A, B and C must be eliminated because none of these personality theories are considered ‘trait’ models of personality. The neuroticism and extroversion-introversion measures mentioned in the passage are personality traits, and therefore they are only logically explained by a trait theory of personality.

Question 31

in psychology what are the two recognized aspects of arousal? what do they represent?

Answer 31

Most theories of emotion recognize two dimensions or aspects of emotion: valence and arousal. In psychology, valence describes the inherent attractiveness or aversiveness of a stimulus, event or situation. Attractive stimuli are labeled as having a positive valence and aversive stimuli are labeled as having a negative valence. Therefore, the researchers were contrasting two extremes of emotional valence: anger and happiness.

Question 32

A woman involved in a violent riot explains to the police that the vandalism in which she participated was a complete departure from her normal pattern of behavior. Such a change in behavior while participating in a large group activity could be the result of which phenomenon?

A) Group think B) Deindividuation
C) Social obedience D) Heuristic decision making

Answer 32

Answer B is the correct choice. Deindividuation occurs when people in a group cease to act as individuals with an individual sense of responsibility. Rather, they take on a mob mentality dictated by the group. Answer A is incorrect because group think is a different phenomenon whereby individuals value group cohesion over individual responsibility. This causes individuals to adopt the views of the rest of group even when contrary to their own views. Answer C, social obedience, occurs when individuals obey orders which may be contrary to their own values. While it is possible that a group leader could have ordered the woman to participate, this cannot be assumed when nothing in the stem suggests this specific circumstance. Answer D, heuristic decision making, is a cognitive shortcut individuals use when making decisions. This concept is not directly related to the scenario described in the stem.

Question 33

In the human auditory system, which cell type is responsible for transduction of an auditory signal?
A) Inner hair cells of the cochlea

B) Outer hair cells of the cochlea
C) Hair cells of the semicircular canals
D) Cranial nerve cells with synapses in the inner ear

Answer 33

Answer A is correct. The inner hair cells of the cochlea are the sensory receptors for the human auditory system. Answer B is false because the outer hair cells of the cochlea are used for mechanical amplification. Answer C is false because the hair cells of the semicircular canals transduce vestibular information regarding balance and orientation. Answer D is false because cranial nerve endings do not receive auditory signals directly from the inner ear. The auditory branch of the vestibulocochlear nerve synapses with the inner hair cells.

Question 34

A person suffering from insomnia would receive the greatest short-term benefit from which type of therapy?
A) Cognitive-behavioral therapy
B) Group therapy 
C) Electroconvulsive therapy 
D) Aversion therapy

Answer 34

Choice A is the correct answer. Cognitive-behavioral therapy would be the most beneficial to someone who is suffering from insomnia, as this form of therapy is a short-term therapy that focuses on helping clients deal with a specific problem, such as insomnia, smoking cessation, or weight loss. During this form of therapy, clients learn how to identify and change patterns that negatively influence behavior. Answer B is incorrect because group therapy would not be particularly beneficial to someone suffering from insomnia. Group therapy is focused primarily on group dynamics such as support, interpersonal relationships, and group cohesion. Answer C is incorrect because electroconvulsive therapy is a procedure, performed under general anesthesia, in which small electric currents are passed through the brain, intentionally triggering a brief seizure. This treatment is rarely employed, and only after other therapeutic options have been exhausted. Answer D, aversion therapy, is a form of behavior therapy in which an aversive (causing a strong feeling of dislike or disgust) stimulus is paired with an undesirable behavior in order to reduce or eliminate that behavior. This form of therapy might be used to assist with something like alcohol or drug addiction, or to eliminate an undesirable habit such as nail biting, but could not be used to treat insomnia. The desired remedy is increased sleep and attempting to pair “awakeness” with an aversive stimulus to reinforce sleep would be extremely problematic.

Question 35

Which hypothetical finding provides the most support for the psychological theories espoused by Abraham Maslow?
A) People with unresolved deficiency needs do not focus on self-actualization.
B) People are motivated to repeat behaviors that are positively reinforced.
C) Individuals are primarily motivated by unresolved childhood conflicts.
D) Individuals achieve self-actualization by mirroring behaviors observed in others.

Answer 35

Choice A is the correct answer. Abraham Maslow is the creator of Maslow’s hierarchy of needs. Maslow stated that the lower, or fundamental needs in this pyramid were “deficiency” or “d-needs.” If these fundamental needs are not satisfied, a person is not motivated to work toward higher-order needs. Answer B is incorrect because this finding would support the theory of behaviorism, or more specifically, operant conditioning. Answer C is false because this finding would support the ideas suggested by psychoanalytic theorists such as Freud. Answer D is false because this finding would support social learning theory.