MCAT practice questions
A stroke patient comprehends speech but cannot move her mouth to form words.
Which of the following brain areas is likely affected?
■Broca's area
■Wernicke's Area
■Arcuate fasciculus
■Superior temporal gyrus - CORRECT ANSWER-Broca's area (Broca's area
governs the motor function of language. A stroke that affects Broca's area will leave
receptive language intact, but word formation will be affected. A stroke affecting
Wernicke's area, choice (B), will make it so the individual is unable to comprehend
speech. A stroke affecting the arcuate fasciculus, choice (C), will result in an inability
to repeat words heard but spontaneous language production is intact. The superior
temporal gyrus, choice (D), is 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?
■Obedience
■Identification
■Internalization
■Compliance - CORRECT ANSWER-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?
■GABA
■Serotonin
■Dopamine
■Enkephalins - CORRECT ANSWER-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. - CORRECT
ANSWER-C (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?
■Deductive reasoning
■Representativeness heuristic
■Base rate fallacy
■Confirmation bias - CORRECT ANSWER-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, choice (A), refers to drawing
conclusions by integrating different pieces of evidence. The representativeness
heuristic, choice (B), involves categorization and classification based on how well an
individual example fits its category. Confirmation bias, choice (D), 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. - CORRECT ANSWER-C (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). 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.)
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:
■vestibular sense.
■kinesthetic sense.
■parallel processing.
■feature detection. - CORRECT ANSWER-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. Loss of vestibular sense, choice (A), 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 only
B) I and II only
C) II and III only
D) I, II, and III - CORRECT ANSWER-B (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?
■Cortisol
■Growth hormone
■Melatonin
■Oxytocin - CORRECT ANSWER-Melatonin (As light diminishes throughout the day,
the pineal gland increases secretion of melatonin, resulting in sleepiness. Cortisol
levels, choice (A), increase throughout the early morning, resulting in wakefulness.
Growth hormone secretion, choice (B), peaks during slow-wave sleep. Oxytocin,
choice (D), 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. -
CORRECT ANSWER-B (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:
