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MCAT daily question

Terms in this set (67)

Simultaneous processing of conscious emotions and physiological activation is the defining feature of which theory of emotion?

a) Schachter-Singer theory
b) James-Lange theory
c) Incentive theory
d) Cannon-Bard theory
d) Cannon-Bard theory (of emotion is based on the premise that conscious feelings and physiological components of emotion are experienced at exactly the same time)

Schachter-Singer theory - in which nervous system arousal occurs and then is labeled based on the context provided by the environment
Becoming a college graduate requires hard work and diligence in academics. As such, being a college graduate could be considered a(n):

a) ascribed status
b) achieved status
c) master status
d) pigeonhold status
b) achieved status (is one that is acquired through personal efforts)

ascribed status - in which the status is involuntarily given based on race, ethnicity, gender, family background, and so on

master status - is one that influences all aspects of an individual's life
A stroke patient comprehends speech but cannot move her mouth to form words. Which of the following brain areas is likely affected?

a) Broca's area
b) Wernicke's area
c) arcuate fasciculus
d) superior temporal gyrus
a) Broca's area (governs the motor function of language; receptive language intact, but word formation will be affected)

Wernicke's area - the individual is unable to comprehend speech

arcuate fasciculus - an inability to repeat words heard but spontaneous language production is intact

superior temporal gyrus - where Wernicke's area is located
Each individual in a group of teenagers is asked to estimate the height of a tree. One individual estimates the height to be 25 feet, but after discussing with the group is convinced that the height is likely closer to 40 feet. Which type of conformity is seen here?

a) obedience
b) identification
c) internalization
d) compliance
c) internalization (Internalization refers to the type of conformity in which an individual changes her outward opinion to match the group and also personally agrees with those ideas)
Which of the following neurotransmitters is associated with both schizophrenia and Parkinson's disease?

a) GABA
b) serotonin
c) dopamine
d) enkephalins
c) dopamine (Schizophrenia is associated with high levels of dopamine, or high sensitivity to dopamine. Parkinson's disease is associated with destruction of the dopaminergic neurons in the basal ganglia.)
Primary groups differ from secondary groups in that:

a) primary groups are shorter-lived than secondary groups
b) primary groups are larger than secondary groups
c) primary groups are formed of stronger bonds than secondary groups
d) primary groups are assigned while secondary groups are chosen
c) primary groups are formed of stronger bonds than secondary groups

(Primary groups have direct and close bonds between members, providing warm, personal, and intimate relationships to its members. Secondary groups, in contrast, form superficial bonds and tend to last for a shorter period of time.)
A student is volunteering in a hospital with a stroke center. When asked what he believes is the prevalence of stroke among those greater than 65 years old, the student states that it is probably about 40% even though data analysis indicates that it is significantly lower. What accounts for this error?

a) deductive reasoning
b) representativeness heuristic
c) confirmation bias
d) base rate fallacy
d) base rate fallacy (The base rate fallacy occurs when prototypical or stereotypical factors are used for analysis rather than actual data. Because the student is volunteering in a hospital with a stroke center, he sees more patients who have experienced a stroke than would be expected in a hospital without a stroke center. Thus, this experience changes his perception and results in base rate fallacy.)

Deductive reasoning- refers to drawing conclusions by integrating different pieces of evidence.

representativeness heuristic- involves categorization and classification based on how well an individual example fits its category.

Confirmation bias- occurs when a person only seeks information that reinforces his or her opinions.
Why are triacylglycerols used in the human body for energy storage?

a) They are highly hydrated, and therefore can store lots of energy.
b) They always have short fatty acid chains, for easy access by metabolic enzymes.
c) The carbon atoms of the fatty acid chains are highly reduced, and therefore yield more energy upon oxidation.
d) Polysaccharides, which would actually be a better energy storage form, would dissolve in the body.
c) The carbon atoms of the fatty acid chains are highly reduced, and therefore yield more energy upon oxidation. (The fatty acid chains produce twice as much energy as polysaccharides during oxidation because they are highly reduced. The fatty acid chains vary in length and saturation.)

Triacylglycerols are highly hydrophobic and therefore not highly hydrated (which would add extra weight from the water of hydration, taking away from the energy density of these molecules), eliminating choice (A).
Prolonged vitamin B12 deficiency can be associated with subacute combined degeneration of the spinal cord. Patients with this disease have difficulty walking because they lose the ability to feel where their feet are in space. This represents a loss of:

a) vestibular sense
b) kinesthetic sense
c) parallel processing
d) feature detection
b) kinesthetic sense (Kinesthetic sense, or proprioception, refers to the ability to tell where body parts are in three-dimensional space. The sensors for proprioception are found predominantly in the muscles and joints.)

Vestibular sense- Loss of vestibular sense, would also cause difficulty walking, but this would be due to a sense of dizziness or vertigo, not an inability to feel one's feet.
Which of the following is/are function(s) of NADPH in the cell?
I. Antimicrobial resistance via bacterial destruction by bleach within lysosomes.
II. Involvement in the production of the precursors to steroid hormones.
III. Functional carriage of energy across organelle membranes for use within the mitochondria

a) I and II only
b) I only
c) II and III only
d) I, II, and III
a) I and II only

NADPH has three primary functions: involvement in biosynthesis of lipids and cholesterol (the precursor to steroid hormones), production of bactericidal bleach in the lysosomes of certain white blood cells, and maintenance of a supply of reduced glutathione for protection against free radical damage. Energy carriage is an important function of NADH, not NADPH.
Increases in which of the following hormones causes sleepiness?

a) cortisol
b) growth hormone
c) oxytocin
d) melatonin
d) melatonin (As light diminishes throughout the day, the pineal gland increases secretion of melatonin, resulting in sleepiness.)

cortisol - increase throughout the early morning, resulting in wakefulness.

Growth hormone- peaks during slow-wave sleep.

Oxytocin- is associated with uterine contractions in childbirth, milk letdown, and bonding behavior.
How does the inner mitochondrial membrane differ from the outer mitochondrial membrane?

a) The inner mitochondrial membrane is more permeable and lacks cholesterol.
b) The inner mitochondrial membrane is less permeable and lacks cholesterol.
c) The inner mitochondrial membrane is more permeable and has cholesterol.
d) The inner mitochondrial membrane is less permeable and has cholesterol.
b) The inner mitochondrial membrane is less permeable and lacks cholesterol.

The outer mitochondrial membrane is very permeable while the inner membrane is highly impermeable. The inner mitochondrial membrane is unique within the cell because it lacks cholesterol.
Some cellular membranes sequester hydrogen ions on one side in order to create an acidic or basic environment. For example, the membrane of lysosomes contains proton pumps that move hydrogen ions into the lysosome. For a cell with the following half-reactions:

Anode: SO2 + 2H20 ---> SO4 2- + 4H+ + 2e-
Cathode: Pd2+ + 2e- ---> Pd

How would decreasing the pH of the solution inside the cell affect the electromotive force (emf)?

a) The emf would decrease.
b) The emf would increase.
c) The emf would become zero.
d) The emf would remain the same.
a) The emf would decrease.

A change in pH has a direct correlation to the hydrogen ion (H) concentration. Decreasing the pH increases the H+ concentration, which means the concentration of products has increased in the oxidation of sulfur dioxide. This means it would be harder to liberate electrons, thus decreasing the emf. One could also view this decrease in oxidation potential as an increase in reduction potential.

If E°red, anode increases, then E°cell must decrease according to
E°cell = Ered,cathode - E°red,anode
Which of the following is true regarding bipolar disorders?
I. They have little, if any, genetic heritability.
II. They are associated with increased levels of serotonin in the brain.
III. They all require at least one depressive episode for diagnosis.

a) I only
b) II only
c) I and III only
d) I and II only
b) II only

Bipolar disorders have been shown to be highly heritable and are associated with increased levels of norepinephrine and serotonin in the brain. Bipolar I disorder can be diagnosed with a single manic episode and does not require a major depressive episode. Bipolar II disorder requires at least one hypomanic episode and one major depressive episode. Cyclothymic disorder contains at least one hypomanic episode and dysthymia.
While on the phone, a friend says: "A good friend would let me borrow the bike." This friend is using which impression management strategy?

a) managing appearances
b) alter-casting
c) ingratiation
d) self-disclosure
b) alter-casting

Imposing a role on another person (in this case, "good friend") is the hallmark of altercasting. This example is also the opposite of ingratiation, choice (C), because the implication behind the statement is that one is a "bad friend" if he or she does not lend the bike; ingratiation is the use of flattery or conformity to win over someone else.
A woman notices that her father has started to move his fingers in such a way that it looks like he is rolling something, despite nothing actually being there. She also notes slowed movement and a shuffling gait. Which neurotransmitter is likely to be present in decreased levels in her father's brain?

a) epinephrine
b) histamine
c) dopamine
d) serotonin
c) dopamine

The symptoms indicate that the woman's father likely has Parkinson's disease. This disease is caused by decreased dopamine production in the substantia nigra.
While cleaning your house, you notice a large spider on the wall by your head and feel your heart rate jump up and your skin temperature grow warm. Which stage of stress response are you experiencing?

a) alarm
b) resistance
c) exhaustion
d) homeostasis
a) alarm

The initial reaction to stress, which is activation of the sympathetic nervous system, is the alarm stage of stress response.
Which of the following terms refers to the burden or degree of disease associated with a given illness?

a) morbidity
b) mortality
c) second sickness
d) chronicity
a) morbidity

Morbidity refers to the burden of illness, or the severity or degree of illness.

Mortality, choice (B), refers to deaths caused by a given illness.

Second sickness, choice (C), is a term used to describe the exacerbation of health outcomes due to social injustice.

Chronicity, choice (D), refers to the duration of a disease, not its severity or significance for the patient.
A child has experienced nervous system damage and can no longer coordinate the movements to dribble a basketball, although she can walk. Which region of the central nervous system was most likely affected?

a) forebrain
b) midbrain
c) hindbrain
d) spinal cord
c) hindbrain

The hindbrain is responsible for balance and motor coordination, which would be necessary for dribbling a basketball.

The midbrain, choice (B), manages sensorimotor reflexes that also promote survival.

The forebrain, choice (A), is associated with emotion, memory, and higher-order cognition.

The spinal cord, choice (D), is likely not damaged as the child can still walk.
A researcher uses a partial-report procedure after presenting participants with an array of nine numbers for a fraction of a second. Which of the following is the most likely result of this procedure?

a) The participant will be able to recall any of the rows or columns in great detail but only immediately after presentation.
b) The participant will only be able to recall the first few numbers in the array due to the serial position effect.
c) The participant will be able to recall approximately seven of the numbers for a few seconds following presentation of the stimulus.
d) The participant will not be able to recall any of the numbers verbally, but will be able to draw the full array under hypnosis.
a) The participant will be able to recall any of the rows or columns in great detail but only immediately after presentation.

Partial-report procedures, in which the individual is asked to recall a specific portion of the stimulus, are incredibly accurate, but only for a very brief time. This is a method of studying sensory (specifically, iconic) memory.

Both the serial position effect, choice (B), and the 7 ± 2 rule, choice (C), are characteristics of short-term memory.
An α-helix is most likely to be held together by:

a) disulfide bonds
b) hydrophobic effects
c) hydrogen bonds
d) ion attractions between side chains
c) hydrogen bonds

The α-helix is held together primarily by hydrogen bonds between the carboxyl groups and amino groups of amino acids.

Disulfide bridges, choice (A), and hydrophobic effects, choice (B), are primarily involved in tertiary structures, not secondary.

Even if they were charged, the side chains of amino acids are too far apart to participate in strong interactions in secondary structure.
Ingested acetic acid is a common source of biochemical acetyl groups, including those that form acetyl-CoA. Acetic acid dissociates in solution according to the following equation:

CH3COOH ---> CH3COO- + H+

If sodium acetate is added to a solution of acetic acid in excess water, which of the following effects would be observed in the solution?

a) decreased pH
b) increased pH
c) decreased pKeq (pKa)
d) increased pKeq (pKa)
b) increased pH

Adding sodium acetate increases the number of acetate ions present. According to Le Châtelier's principle, this change will push this reaction to the left, resulting in a decrease in the number of free H+ ions. Because pH is determined by the hydrogen ion concentration, a decrease in the number of free protons will increase the pH.

An acid's Ka (which is simply the Keq for acid dissociation) will remain constant under a given temperature and pressure, eliminating choices (C) and (D).
A patient comes in with a tumor of the pituitary gland, which grows upwards into the optic chiasm and causes a visual field defect. The most likely defect from compression of the optic chiasm is:

a) complete blindness in one eye.
b) loss of the upper visual fields in both eyes.
c) loss of the nasal visual fields in both eyes.
d) loss of the temporal visual fields in both eyes.
d) loss of the temporal visual fields in both eyes.

The optic chiasm houses the crossing fibers from each optic nerve. Specifically, the fibers coming from the nasal half of the retina in each eye cross in the chiasm to join the optic tract on the opposite side. Remember that the lens of the eye causes inversion, so images on the nasal half of the retina actually originate in the temporal visual field. This condition is called bitemporal hemianopsia.
A student is trying to determine the type of membrane transport occurring in a cell. She finds that the molecule to be transported is very large and polar, and when transported across the membrane, no energy is required. Which of the following is the most likely mechanism of transport?

a) active transport
b) simple diffusion
c) facilitated diffusion
d) exocytosis
c) facilitated diffusion

We are asked to identify the type of transport that would allow a large, polar molecule to cross the membrane without any energy expenditure. This scenario describes facilitated diffusion, which uses a transport protein (or channel) to facilitate the movement of large, polar molecules across the nonpolar, hydrophobic membrane. Facilitated diffusion, like simple diffusion, does not require energy, which explains why no ATP was consumed during this transport process.
Which of the following is true about cholesterol?

a) Cholesterol always increases membrane fluidity in cells.
b) Cholesterol is a steroid precursor.
c) Cholesterol is a precursor for vitamin A, which is produced in the skin.
d) Cholesterol interacts only with the hydrophobic tails of phospholipids.
b) Cholesterol is a steroid precursor.

Cholesterol is a steroid precursor that has variable effects on membrane fluidity depending on temperature, eliminating choice (A).

It interacts with both the hydrophobic tails and the hydrophilic heads of membrane lipids, nullifying choice (D).

It is also a precursor for vitamin D (not vitamin A), which can be produced in the skin in a UV-driven reaction, eliminating choice (C).
A rat is trained to press a lever to obtain food under a fixed-interval schedule. Which of the following behaviors would the rat most likely exhibit?

a) Pressing the lever continuously whenever it is hungry.
b) Pressing the lever exactly once and waiting for the food pellet before pressing it again.
c) Pressing the lever slowly at first, but with increasing frequency as the end of the interval approaches.
d) None of the above; the association formed by fixed-interval schedules is too weak to increase behavior.
c) Pressing the lever slowly at first, but with increasing frequency as the end of the interval approaches.

In a fixed-interval schedule, the desired behavior is rewarded the first time it is exhibited after the fixed interval has elapsed. Both fixed-interval and fixed-ratio schedules tend to show this phenomenon: almost no response immediately after the reward is given, but the behavior increases as the rat gets close to receiving the reward.
Aerobic respiration ends at the electron transport chain, where protein complexes are reduced and oxidized in turn as electrons make their way to join O2 to form H2O.

Consider the following equation:
6Na + 2NH3 ---> 2Na3N + 3H2

Which species acts as an oxidizing agent?
a) Na
b) N in NH3
c) H in NH3
d) H2
c) H in NH3

The oxidizing agent is the species that is reduced in any given equation. In this problem, six hydrogen atoms with +1 oxidation states in NH3 are reduced to three neutral H2 molecules.
Biochemical reactions that involve the transfer of electrons produce an electromotive force.

Given the following standard reduction potentials:
Zn2+ + 2e- ---> Zn2 Ecell= -0.763
Ag+ + e- ---> Ag Ecell= +0.337

What is the standard electromotive force of the following reaction?
Zn2+ + 2Ag ---> 2Ag+ + Zn2

a) -2.2V
b) -1.1V
c) +1.1V
d) +2.2V
b) -1.1V

To determine the standard electromotive force of a cell, simply subtract the standard reduction potentials of the two electrodes. In this case, the cathode is zinc because it is being reduced; the anode is silver because it is being oxidized.
Thus, E°cell = E°red,cathode - E°red,anode = -0.763 - 0.337 = -1.10 V. While we must multiply the silver half-reaction by two to balance electrons, the actual value for the reduction potential does not change. Remember that the standard reduction potential is determined by the identity of the electrode, not the amount of it present.
What stage of protein synthesis does NOT require energy?

a) initiation
b) elongation
c) termination
d) all stages of protein synthesis require energy.
d) all stages of protein synthesis require energy

All three stages of protein synthesis (initiation, elongation, and termination) require large amounts of energy.
The formation of α-d-glucopyranose from β-d-glucopyranose is called:

a) glycosidation
b) mutarotation
c) enantiomerization
d) racemization
b) mutarotation

Mutarotation is the interconversion between anomers of a compound. Enantiomerization and racemization, choices (C) and (D), mean the same thing as each other: the formation of a mirror-image or optically inverted form of a compound. Glycosidation, choice (A), is the addition of a sugar to another compound.
Which of the following correctly indicates the response of CD8+ T-cells when activated?

a) secretion of cytotoxic chemicals
b) causing isotope switching
c) presentation of antigens
d) activation of B-cells
a) secretion of cytotoxic chemicals

CD8+ T-cells are largely responsible for the cytotoxic immune response. By releasing toxic chemicals into virally infected cells, CD8+ T-cells are able to kill these cells in an effort to contain viral infections. Isotype switching refers to changes in the isotype of antibody produced, which is not caused by CD8+ cells, eliminating choice (B). Antigens are presented by macrophages, dendritic cells, certain epithelial cells, and some B-cells, eliminating choice (C). B-cells are not activated by cytotoxic T-lymphocytes, eliminating choice (D).
Which of the following trends regarding healthcare disparities has NOT been documented?

a) Females are more likely to be insured than males.
b) Primary care use is more likely among males than females.
c) Low-income individuals have more difficulty accessing care than high-income individuals.
d) LGBT individuals have more barriers to healthcare than heterosexuals.
b) Primary care use is more likely among males than females.

In comparison to females, males visit primary care doctors less frequently. All of the other trends listed here have been documented.
A double-stranded RNA genome isolated from a virus was found to contain 15% uracil. What percentage of guanine should exist in this virus''s genome?

a) 15%
b) 35%
c) 70%
d) 85%
b) 35%

The percentage of uracil must equal that of adenine due to base-pairing. This accounts for 30% of the genome. The remaining 70% must be split evenly between guanine and cytosine, so they each account for 35% of the genome.
Some people with anxiety disorders respond to stress by hyperventilating. It is recommended that these people breathe into a paper bag and then re-breathe this air. Why is this treatment appropriate?

a) Hyperventilation causes an increase in blood carbon dioxide, and breathing the air in the bag helps to readjust blood levels of carbon dioxide.
b) Hyperventilation causes a decrease in blood carbon dioxide, and breathing the air in the bag helps to readjust blood levels of carbon dioxide.
c) Hyperventilation causes an increase in blood oxygen, and breathing the air in the bag helps to readjust blood levels of oxygen.
d) Hyperventilation causes a decrease in blood oxygen, and breathing the air in the bag helps to readjust blood levels of oxygen.
b) Hyperventilation causes a decrease in blood carbon dioxide, and breathing the air in the bag helps to readjust blood levels of carbon dioxide.

When people hyperventilate, their respiratory rate increases. When the respiratory rate increases, more carbon dioxide is blown off. This causes a shift to the left in the bicarbonate buffer equation, and the blood becomes more alkaline. Breathing into the bag allows some of this carbon dioxide to be returned to the bloodstream in order to maintain the proper pH.
The body's pH is tightly regulated because specific enzymes function best within a narrow pH range. What is the approximate pH of a 1.2 × 10-5M aqueous solution of NaOH?

a) 4.92
b) 7.5
c) 9.08
d) 12.45
c) 9.08

NaOH is a strong base; as such, there will be 1.2 × 10-5 M OH- in solution. Based on this information alone, the pOH must be between 4 and 5, and the pH must be between 9 and 10. Using the shortcut, pOH ≈ 5 - 0.12 = 4.88. pH = 14 - pOH = 9.12 (actual = 9.08).
Which of the following is NOT a difference that would allow one to distinguish a prokaryotic and a eukaryotic cell?

a) Ribosomal subunit weight
b) Presence of a nucleus
c) Presence of a membrane on the outside surface of the cell
d) Presence of membrane-bound organelles
c) Presence of a membrane on the outside surface of the cell

The main differences between prokaryotes and eukaryotes include: prokaryotes do not have a nucleus, while eukaryotes do, eliminating choice (B); prokaryotes have ribosomal subunits of 30S and 50S, while eukaryotes have ribosomal subunits of 40S and 60S, eliminating choice (A); and prokaryotes do not have membrane-bound organelles, whereas eukaryotes do, eliminating choice (D). The presence of a membrane on the outer surface of the cell could not distinguish a prokaryotic cell from a eukaryotic one because both gram-negative bacteria and animal cells share this feature. Thus, choice (C) is the correct answer.
Consider a biochemical reaction A → B, which is catalyzed by A-B dehydrogenase. Which of the following statements is true?

a) The reaction will proceed until the enzyme concentration decreases.
b) The reaction will be most favorable at 0 °C.
c) A component of the enzyme is transferred from A to B.
d) The free energy change (ΔG) of the catalyzed reaction is the same as for the uncatalyzed reaction.
d) The free energy change (ΔG) of the catalyzed reaction is the same as for the uncatalyzed reaction.

Enzymes catalyze reactions by lowering their activation energy, and are not changed or consumed during the course of the reaction. While the activation energy is lowered, the free energy of the reaction, ΔG, remains unchanged in the presence of an enzyme. A reaction will continue to occur in the presence or absence of an enzyme; it simply runs slower without the enzyme, eliminating choice (A). Most physiological reactions are optimized at body temperature, 37 °C, eliminating choice (B). Finally, dehydrogenases catalyze oxidation-reduction reactions, not transfer reactions, eliminating choice (C).
The swimming times for all members of a swim team are tracked over a six-month period in team-only practices and at public meets. For 14 of the 16 members, top times were clocked at the meets. What social phenomenon does this evidence support?

a) Social facilitation
b) Peer pressure
c) Identification
d) Group polarization
a) Social facilitation

For 14 out of the 16 members, the record times were obtained during public meets. The fact that the team members performed better when in front of a crowd supports the notion of social facilitation.
Which ion channels are responsible for maintaining the resting membrane potential?

a) ungated channels
b) voltage-gated channels
c) ligand-gated channels
d) No ion channels are involved in maintenance of the resting membrane potential.
a) ungated channels

The resting membrane potential is displayed by cells that are not actively involved in signal transduction. Ungated or "leak" channels permit limited free flow of ions, while the sodium-potassium pump is also active and corrects for this leakage. Ligand-gated and voltage-gated channels are involved in cell signaling and in the pacemaker potentials of certain cells, but cause deviation from—not maintenance of—the resting membrane potential.
A woman is at a restaurant and orders a spicy entreé. After the first bite, she experiences burning in her mouth and becomes concerned that her food is too hot for her. The next few bites are similarly uncomfortable, but after a while the spiciness seems to subside somewhat, and by the end of the meal, she doesn't notice the spice level. The end of the meal experience is best described as:

a) adaptation
b) signal detection
c) a difference threshold
d) pain perception
a) adaptation

The spicy food can be considered an extreme stimulus because it eclipses what the woman believes she can handle in terms of heat. However, after experiencing the stimulus over and over, the experience of spice drops to barely perceptible. This is sensory adaptation: a reduction in response to a stimulus over time.
How do chylomicrons and VLDLs differ?

a) Chylomicrons contain apoproteins, VLDLs do not.
b) Chylomicrons are synthesized in the intestine, VLDLs are synthesized in the liver.
c) Chylomicrons transport triacylglycerol, VLDLs transport cholesterol.
d) VLDLs are another term for chylomicron remnants; they differ in age.
b) Chylomicrons are synthesized in the intestine, VLDLs are synthesized in the liver.

Chylomicrons and VLDLs are very similar. Both contain apolipoproteins and primarily transport triacylglycerol, eliminating choices (A) and (C). The only major difference between them is the tissue of origin. Chylomicrons transport dietary triacylglycerol and originate in the small intestine, while VLDLs transport newly synthesized triacylglycerol and originate in the liver.
What role does peptidyl transferase play in protein synthesis?

a) It transports the initiator aminoacyl-tRNA complex.
b) It helps the ribosome to advance three nucleotides along the mRNA in the 5′ to 3′ direction.
c) It holds the proteins in its tertiary structure.
d) It catalyzes the formation of a peptide bond.
d) It catalyzes the formation of a peptide bond.

Peptidyl transferase is an enzyme that catalyzes the formation of a peptide bond between the incoming amino acid in the A site and the growing polypeptide chain in the P site. Initiation and elongation factors help transport charged tRNA molecules into the ribosome and advance the ribosome down the mRNA transcript, as in choices (A) and (B). Chaperones maintain a protein's three-dimensional shape as it is formed, as in choice (C).
Which of the following concepts are LEAST likely to coincide?

a) Hazardous waste facilities and low-income neighborhoods
b) Tuberculosis and poor living conditions
c) Environmental pollution and high minority population
d) Globalization and global equality
d) Globalization and global equality

Globalization does not typically lead to global equality; rather, globalization tends to create further global inequalities. In regard to environmental justice, higher numbers of hazardous waste facilities tend to be found in low-income neighborhoods, choice (A). Poor living conditions tend to be associated with greater health problems, including tuberculosis, choice (B). Finally, environmental pollution is more prevalent in areas with minority populations, especially low-income minority populations, choice (C).
Which of the following is NOT a method by which enzymes decrease the activation energy for biological reactions?

a) modifying the local charge environment
b) Forming transient covalent bonds
c) Acting as electron donors or acceptors
d) Breaking bonds in the enzyme to provide energy
d) Breaking bonds in the enzyme to provide energy

Enzymes are not altered by the process of catalysis. A molecule that breaks intramolecular bonds to provide activation energy would not be able to be reused.
Elephant seal males mate with multiple females each mating season, while females only have one mate each. What type of mating system is this?

a) Polyandry
b) Polygyny
c) Monogamy
d) Promiscuity
b) polygyny

Polygamy involves a male having exclusive relationships with several females (polygyny) or a female having exclusive relationships with several males (polyandry), choice (A). Monogamy, choice (C), consists of exclusive mating relationships. Promiscuity, choice (D), refers to a member of one sex mating with any member of the opposite sex.
Some enzymes require the presence of a nonprotein molecule to behave catalytically. An enzyme devoid of this molecule is called a(n):

a) holoenzyme
b) apoenzyme
c) coenzyme
d) zymoenzyme
b) apoenzyme

An enzyme devoid of its necessary cofactor is called an apoenzyme and is catalytically inactive.
Which of the following would be most likely to be stored in long-term memory?

a) A list of nonsense words
b) A list of the dates of birth of 15 randomly selected people
c) A list of the names of musicians in an individual's favorite bands
d) A list of the dates of battles in the Peloponnesian War
c) A list of the names of musicians in an individual's favorite bands

The self-reference effect indicates that information that is most meaningful to an individual is the most likely to be memorized. Choice (C) is the most personally relevant to the individual memorizing the list.
Which process is expected to begin earliest in a prolonged fast?

a) Ketone bodies are used by the brain.
b) Glycogen storage is halted.
c) Proteins are broken down.
d) Enzyme phosphorylation and dephosphorylation.
d) Enzyme phosphorylation and dephosphorylation.

A prolonged fast is characterized by an increase in glucagon, which accomplishes its cellular activity by phosphorylating and dephosphorylating metabolic enzymes. Glycogen storage, choice (B), is then halted, but this requires enzyme regulation by glucagon to occur. Later in the postabsorptive state, protein breakdown, choice (C), begins. Eventually, in starvation, ketone bodies, choice (A), are used by the brain for its main energy source.
For the most part, biological pH is slightly basic. However, the stomach is very acidic, and its contents must be swiftly neutralized by basic bicarbonate ions upon entering the small intestine, which has a basic pH. How many liters of 2 M Ba(OH)2 are needed to titrate a 4 L solution of 6 M H3PO4?

a) 1.33 L
b) 12 L
c) 18 L
d) 56 L
c) 18 L

Use the equivalence point equation:

NaVa = NbVb

Ba(OH)2 can dissociate to give two hydroxide ions, so its normality is 2 M × 2 = 4 N. H3PO4 can dissociate to give three hydronium ions, so its normality is 6 M × 3 = 18 N. Plugging into the equation, we get (18 N)(4 L) = (4 N)(Vb). Therefore, Vb is 18 L.
Which of the following INCORRECTLY pairs a digestive hormone with its function?

a) Trypsin—hydrolyzes specific peptide bonds
b) Lactase—hydrolyzes lactose to glucose and galactose
c) Pancreatic amylase—hydrolyzes starch to maltose
d) Lipase—emulsifies fats
d) Lipase- emulsifies fats

Lipase is involved in the digestion of fats, but its function is not to emulsify fats—this is the job of bile. Rather, lipase chemically digests fats in the duodenum, allowing them to be brought into duodenal cells and packaged into chylomicrons. The other associations given here are all correct.
An EMT sees himself as a bit of a rebel, but is highly sociable and is able to keep calm in an emergency. This person would likely score in the lower range of which of the following traits?

a) Psychoticism
b) Neuroticism
c) Extraversion
d) Conscientiousness
b) Neuroticism

As a rebel and a sociable person, this individual would score highly on both psychoticism and extraversion, respectively. Neuroticism is associated with high emotional arousal in stressful situations, so being able to keep calm in an emergency is a sign of low neuroticism. Conscientiousness, a trait associated with being hardworking and organized instead of impulsive, is not described by the question stem.
Many double-displacement reactions are enzyme-catalyzed via the "ping pong" mechanism, so called because the reactants appear to bounce off the enzyme like a ping pong ball. These reactions typically have two reactants and two products. In a third-order reaction involving two reactants and two products, doubling the concentration of the first reactant causes the rate to increase by a factor of 2. What will happen to the rate of this reaction if the concentration of the second reactant is cut in half?

a) It will increase by a factor of 2.
b) It will increase by a factor of 4.
c) It will decrease by a factor of 2.
d) It will decrease by a factor of 4.
d) It will decrease by a factor of 4

Based on the information given in the question, the rate is first-order with respect to the concentration of the first reactant; when the concentration of that reactant doubles, the rate also doubles. Because the reaction is third-order, the sum of the exponents in the rate law must be equal to 3. Therefore, the reaction order with respect to the other reactant must be 3 - 1 = 2. If the concentration of this second reactant is multi- plied by 1/2, the rate will be multiplied by (1/2)2 = 1/4..
Why is the α-anomer of d-glucose less likely to form than the β-anomer?

a) The β-anomer is preferred for metabolism.
b) The β-anomer undergoes less electron repulsion.
c) The α-anomer is the more stable anomer.
d) The α-anomer forms more in L-glucose.
b) The β-anomer undergoes less electron repulsion.

The hydroxyl group on the anomeric carbon of the β-anomer is equatorial, thereby creating less steric hindrance than the α-anomer, which has the hydroxyl group of the anomeric carbon in axial position.
Your neighbor asks you to check his mail while he is out of town, and you agree. Later that day, he asks you to water his plants as well. What technique for compliance is he using in this scenario?

a) Lowball technique
b) That's-not-all technique
c) foot-in-the-door technique
d) Door-in-the-face technique
c) foot-in-the-door technique

This is a prime example of the foot-in-the-door technique. The neighbor first asks for a small favor and, after receiving commitment, asks for a larger favor.
Photons and other energy sources can exite electrons into higher energy levels, though these excitations are typically short-lived. X-ray imaging succeeds because different tissue types are differently able to absorb the energy of a photon in order to excite an electron. Suppose an electron falls from n = 4 to its ground state, n = 1. Which of the following effects is most likely?

a) A photon is absorbed.
b) A photon is emitted.
c) The electron moves into a p-orbital.
d) The electron moves into a d-orbital.
b) A photon is emitted.

Because the electron is moving into the n = 1 shell, the only subshell available is the 1s subshell, which eliminates choices (C) and (D). There will be some energy change, however, as the electron must lose energy to return to the minimum-energy ground state. That will require emitting radiation in the form of a photon.
In high doses, aspirin functions as a mitochondrial uncoupler. How would this affect glycogen stores?

a) It causes depletion of glycogen stores.
b) It has no effect on glycogen stores.
c) It promotes additional storage of glucose as glycogen.
d) Its effect on glycogen stores varies from cell to cell.
a) It causes depletion of glycogen stores.

Uncouplers inhibit ATP synthesis without affecting the electron transport chain. Because the body must burn more fuel to maintain the proton-motive force, glycogen stores will be mobilized to feed into glycolysis, then the TCA, and finally oxidative phosphorylation.
Many pets will run toward the kitchen when they hear the sound of a can opener opening a can of pet food. The sound of the can opener is a:

a) conditioned response.
b) unconditioned response.
c) conditioned stimulus.
d) unconditioned stimulus.
c) conditioned stimulus.

The sound of a can opener would not normally produce a response on its own, making it a stimulus that must have been conditioned by association with the sound with food.
A young adult male claims to have had sexual relationships mostly with other men, although he has been attracted to women at times. What would be his most likely score on the Kinsey scale?

a) 0
b) 1
c) 5
d) 6
c) 5

This man is describing his sexuality as mostly homosexual, although he has also had some heterosexual attractions. The Kinsey scale scores a 6, choice (D), as exclusively homo-sexual. A score of 3 would equate to bisexuality. Thus, this man would likely score a 4 or 5.
Glucocorticoids have been implicated in stress-related weight gain because:

a) they increase appetite and decrease satiety signals.
b) they increase the activity of catabolic hormones.
c) they increase glucose levels, which causes insulin secretion.
d) they interfere with activity of the leptin receptor.
c) they increase glucose levels, which causes insulin secretion

Short-term glucocorticoid exposure causes a release of glucose and the hydrolysis of fats from adipocytes. However, if this glucose is not used for metabolism, it causes an increase in glucose level which promotes fat storage. The net result is the release of glucose from the liver to be converted into lipids in the adipose tissue under insulin stimulation.
Which of the following is least likely to cause denaturation of proteins?

a) Heating the protein to 100 °C
b) Adding 8 M urea
c) Moving it to a more hypotonic environment
d) Adding a detergent such as sodium dodecyl sulfate
c) moving it to a more hypotonic environment

High salt concentrations and detergents can denature a protein, as can high temperatures. But moving a protein to a hypotonic environment—that is, a lower solute concentration— should not lead to denaturation.
Which of the following characteristics is NOT attributed to antibodies?

a) Antibodies bind to more than one distinct antigen.
b) Antibodies label antigens for targeting by other immune cells.
c) Antibodies can cause agglutination by interaction with antigen.
d) Antibodies have two heavy chains and two light chains.
a) Antibodies bind to more than one distinct antigen.

Antibodies are specific to a single antigen. Each B-cell produces a single type of antibody with a constant region that is specific to the host and a variable region that is specific to an antigen.
A medical student is feeling a high level of stress due to upcoming exams and pressure from his family to engage in activities at home. He chooses to go the gym for a workout to help himself relax. This workout is which type of stress?

a) Hassle
b) frustration
c) eustress
d) distress
c) eustress

A positive stressor creates eustress. Because working out is used to relax, it is considered a eustress. Hassle, choice (A), and frustration, choice (B), are both types of distress, choice (C), or negative stressors.
Where does β-oxidation of fatty acids occur within the cell?

a) Cytosol
b) Mitochondria
c) Smooth endoplasmic reticulum
d) Plasma membrane
d) Plasma membrane

The liver is the major metabolic organ in the body and is responsible for much of the synthesis and interconversion of fuel sources. Most of the triacylglycerols that are synthesized in the liver are transported as VLDL to adipose tissue for storage. Both the adipocytes, choice (A) and dietary intake, choice (B), constitute a minor source of triacylglycerol.
Glen brings cookies to work. Although you have not yet tasted them, you say to another coworker, "Glen is such a great guy; I'm sure these cookies are fantastic!" What type of bias is this?

a) Reliance on central traits
b) direct benefits
c) Halo effect
d) similarity
c) halo effect

The halo effect is a cognitive bias in which judgments of an individual's character can be affected by the overall impression of the individual.
Matt and Cati discuss the reasons why they avoid driving above the speed limit. Matt says that he wants to avoid a traffic fine, while Cati says that speeding is dangerous and, if everyone did it, there would be more accidents and people would get hurt. According to Kohlberg, which of the following describes the phases of moral reasoning demonstrated by Matt and Cati, respectively?

a) Preconventional; conventional
b) Preconventional; postconventional
c) conventional; preconventional
d) Postconventional; conventional
a) Preconventional; conventional

Matt's reasoning reflects a desire to avoid punishment, which reflects stage one in Kohlberg's preconventional phase (obedience). Cati's reasoning takes into account social order, reflecting stage four in the conventional phase (law and order).
A 28-year-old male comes to a clinic concerned that he has pancreatic cancer. Review of his medical records shows that this is the fourth time in the past year that the patient has appeared for medical attention. No identifiable medical problem is found. When confronted with this history, he confesses that he feels relieved after being told that all of the tests are negative, but soon becomes worried again that he has cancer. Based on the information, the most likely diagnosis for this patient would be:

a) major depressive disorder.
b) illness anxiety disorder.
c) conversion disorder.
d) narcissistic personality disorder.
b) illness anxiety disorder.

In illness anxiety disorder, the person is preoccupied with fears that he has—or will come down with—a serious disease, and these fears continue even after medical exams and tests have returned negative results.
How does prokaryotic DNA differ from eukaryotic DNA?
I. Prokaryotic DNA lacks nucleosomes.
II. Eukaryotic DNA has telomeres.
III. Prokaryotic DNA is replicated by a different DNA polymerase.
IV. Eukaryotic DNA is circular when unbound by centromeres.
I, II, and III only

Prokaryotic DNA is circular and lacks histone proteins, and thus does not form nucleosomes. Both prokaryotic and eukaryotic DNA are replicated by DNA polymerases, although these polymerases differ in identity. Eukaryotic DNA is organized into chromatin, which can condense to form linear chromosomes; only prokaryotes have circular chromosomes. Only eukaryotic DNA has telomeres.
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