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Module 1 - Student Quiz Answers
Question: 1
A. Sorry, try again. The higher concentration of ethanol must be in the gut, right after drinking it. The
ethanol moves down its concentration gradient into the bloodstream, and the concentration gradient is the
driving force. No energy is required.
B. You are right! The higher concentration of ethanol must be in the gut, right after drinking it. The
ethanol moves down its concentration gradient into the bloodstream, and the concentration gradient is the
driving force. No energy is required.
C. Wrong answer. There is no pressure forcing the ethanol from the gut into the bloodstream. The higher
concentration of ethanol is in the gut, right after drinking it. The ethanol moves down its concentration
gradient into the bloodstream, and the concentration gradient is the driving force. No energy is required.
D. Sorry, that is incorrect. There is no pressure forcing the ethanol from the bloodstream into the gut.
The higher concentration of ethanol is in the gut, right after drinking it. The ethanol moves down its
concentration gradient into the bloodstream, and the concentration gradient is the driving force. No energy
is required.
Question: 2
A. Yes, you are correct! More fat means less water in the female body. Alcohol is dissolved in water and
reaches higher concentrations in the smaller volume of water (including the bloodstream) present in the
female body.
B. Close, but not quite. The second half of this statement is true, but females have more fat relative to
water in their bodies, so there is a smaller space into which the ethanol will distribute.
C. Close, but not quite. The first half of this statement is true, but ethanol distributes into a smaller
space (water) compared to males. This produces a higher concentration of alcohol in the blood, which is
mostly water.
D. Sorry, this is incorrect. Females have more fat relative to water in their bodies so ethanol distributes
into a smaller space (water) compared to males. This produces a higher concentration of alcohol in the blood,
which is mostly water.
Question: 3
A. Incorrect. They become less soluble in water. As chain length of carbons in the alcohol increases the
molecule becomes increasingly non-polar or hydrophobic (water fearing).
B. Half right. They do become less soluble in water. As chain length of carbons in the alcohol increases
the molecule becomes increasingly non-polar or hydrophobic (water fearing).
C. Half right. They become less soluble in water. As chain length of carbons in the alcohol increases the
molecule becomes increasingly non-polar or hydrophobic (water fearing).
D. Great! They become less soluble in water. As chain length of carbons in the alcohol increases the
molecule becomes increasingly non-polar or hydrophobic (water fearing).
Question: 4
A. Nope. Actually alcohol promotes urination, but the alcohol in the kidney moves back into the blood
down its concentration gradient. The alcohol accumulates in the bloodstream (and the brain) because the
alcohol molecules outnumber the enzyme molecules. They just can't keep up to perform the metabolism. As
alcohol levels rise in the blood (and brain), the person gets intoxicated.
B. Not quite. The enzymes don't work overtime—they become outnumbered by the alcohol molecules and
just can't keep up to perform the metabolism. As alcohol levels rise in the blood (and brain), the person gets
intoxicated.
C. Correct! The alcohol accumulates in the bloodstream (and the brain) because the alcohol molecules
outnumber the ADH enzyme molecules. The ADH molecules just can't keep up to perform the metabolism.
As alcohol levels rise in the blood (and brain), the person gets intoxicated.
D. Sorry, you are incorrect. The enzymes keep working, but they can't keep up with all the extra alcohol
molecules around. As alcohol levels rise in the blood (and brain), the person gets intoxicated.
Question: 5
A. Correct-but there's more! Oxidation of ethanol involves the donation of 2 electrons in the form of H
atoms to an acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes
reduced, because its charge is now reduced by the acceptance of the 2 electrons.
B. No-you got it backwards. Oxidation of ethanol involves the donation of 2 electrons in the form of H
atoms to an acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes
reduced, because its charge is now reduced by the acceptance of the 2 electrons.
C. Correct-but there's more! Oxidation of ethanol involves the donation of 2 electrons in the form of 2 H
atoms to an acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes
reduced, because its charge is now reduced by the acceptance of the 2 electrons.
D. No-you got it backwards. Oxidation of ethanol involves the donation of 2 electrons in the form of 2 H
atoms to an acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes
reduced, because its charge is now reduced by the acceptance of the 2 electrons.
E. Great! Oxidation of ethanol involves the donation of 2 electrons in the form of 2 H atoms to an
acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes reduced,
because its charge is now reduced by the acceptance of the 2 electrons.
F. No-you got it backwards. Oxidation of ethanol involves the donation of 2 electrons in the form of 2 H
atoms to an acceptor molecule (sometimes this is oxygen, but not always). The acceptor molecule becomes
reduced, because its charge is now reduced by the acceptance of the 2 electrons.
Module 2 - Student Quiz Answers
Question: 1
A. Sorry, try again. While most capillaries in the body have fenestrae (pores) through which water, ions,
and small solutes move, the brain capillaries do not have these fenestrae.
B. Terrific! The brain capillaries have endothelial cells that are tightly packed together and do not have
the fenestrae (pores) found in capillaries elsewhere in the body. But, it's small size and relatively non-polar
character allows ethanol to cross the brain capillary endothelial cell membrane by simply diffusing across with
its concentration gradient (in either direction).
C. Sorry, try again. The brain capillaries have endothelial cells that are tightly packed together unlike
endothelial cells found in capillaries elsewhere in the body. The packing is tight enough to exclude the
passage of ethanol between the endothelial cells.
D. Sorry, that is incorrect. Ethanol is not transported by special proteins across membranes. It's
relatively non-polar character enables is to diffuse passively through the endothelial cell membrane, with the
concentration gradient.
Question: 2
A. Sorry, you got it wrong. Slurred speech occurs after one has had several drinks because it takes more
alcohol to suppress motor control.
B. Sorry, try again. The loss of balance occurs at blood levels of alcohol that are higher than those that
produce incoordination.
C. Not likely. Impaired memory in the form of a blackout occurs when people drink a lot of alcohol in a few
hours—this is called binging. Or, impaired memory results from repeated use of smaller amounts of ethanol.
D. Yes, you are correct! One of the first areas of the brain to be affected by alcohol is the cerebral cortex.
Judgment is governed by the frontal part of the cerebral cortex, along with thinking and decision-making.
Risky and impulsive behavior is also under the control of the frontal cortex.
Question: 3
A. Well, only part is true. Alcohol decreases the firing rate of neurons wherever in the brain alcohol has
access (i.e., everywhere!). It increases chloride ion entry through GABA receptors and blocks sodium ion
entry through glutamate receptors. Either way, the more negative interior of the cell reduces the flow of an
electrical impulse.
B. Fantastic! Alcohol decreases the firing rate of neurons wherever in the brain alcohol has access (i.e.,
everywhere!). It increases chloride ion entry through GABA receptors and blocks sodium ion entry through
glutamate receptors. Either way, the more negative interior of the cell reduces the flow of an electrical
impulse.
C. Sorry. Alcohol decreases the firing rate of neurons wherever in the brain alcohol has access (i.e.,
everywhere!), but the actual symptoms are due to alcohol's actions in specific brain regions. It increases
chloride ion entry through GABA receptors and blocks sodium ion entry through glutamate receptors. Either
way, the more negative interior of the cell reduces the flow of an electrical impulse.
D. You're close, but not perfect. Alcohol decreases the firing rate of neurons wherever in the brain alcohol
has access (i.e., everywhere!), but the actual symptoms are due to alcohol's actions in specific brain regions.
It increases chloride ion entry through GABA receptors and blocks sodium ion entry through glutamate
Question: 4
A. Great! People develop tolerance to alcohol when they drink it repeatedly—this means they need more
alcohol to produce the same effect they had originally. Tolerance is due, in part, to a down-regulation of
GABA receptors in the brain, the target of ethanol's action.
B. Sorry, it's backwards. People develop tolerance to alcohol when they drink it repeatedly—this means
they need more alcohol to produce the same effect they had originally. Tolerance is due, in part, to a
down-regulation of GABA receptors in the brain, the target of ethanol's action.
C. Not quite. Actually, this is a trick question. People develop tolerance to alcohol when they drink it
repeatedly—this means they need more alcohol to produce the same effect they had originally. There are two
reasons for the tolerance development; 1) there is a down-regulation of GABA receptors in the brain, the
target of ethanol's action and 2) people metabolize alcohol faster after drinking repeatedly, so they need
more of it.
D. Wrong. People develop tolerance to alcohol when they drink it repeatedly—this means they need more
alcohol to produce the same effect they had originally. There are two reasons for the tolerance development;
1) there is a down-regulation of GABA receptors in the brain, the target of ethanol's action and 2) people
metabolize alcohol faster after drinking repeatedly, so they need more of it.
Question: 5
A. True, but there's more to the answer. Her liver enzyme alcohol dehyrogenase or ADH metabolized the
alcohol into acetaldehyde, a toxic compound that produces the symptoms described. See the other answers
for the reason why this happens.
B. True, but there's more to the answer. Her liver enzyme acetaldehyde dehyrogenase or ALDH was not
very active, so it couldn't metabolize the acetaldehyde very well. The acetaldehyde, a toxic compound,
accumulated in her blood to produce the symptoms described. See the other answers for the reason why
this happens.
C. Great! Because she carried a polymorphism for the acetaldehyde dehydrogenase (ALDH) gene, she
synthesized a poorly active form of the ALDH enzyme. Thus, her liver couldn't metabolize the acetaldehyde
very well. The acetaldehyde, a toxic compound, accumulated in her blood to produce the symptoms
described. See the other answers for the reason why this happens.
D. Perfect! See the answers to 1-3.
Module 3 - Student Quiz Answers
Question: 1
A. Sorry, try again. It's OK if neurons are crowded together. The branch-like structure increases the
surface area for synapses and communication between neurons.
B. That's right! The branch-like structure increases the surface area for synapses and communication
between neurons.
C. Sorry, that is incorrect. Myelin only surrounds the axon, where the major electrical impulse (action
potential) travels. The branch-like structure increases the surface area for synapses and communication
between neurons.
D. You're close, but that's not quite right. The branch-like structure increases the surface area for
synapses and communication between neurons.
Question: 2
A. Great! Electrical signals travel down the axon to the terminal, but can't cross the synaptic space.
Instead, the electrical impulse triggers a chemical to be released and carry the message across to another
neuron.
B. Not quite. There are fast and slow ways for neurons to communicate, but that is not the reason.
Electrical signals travel down the axon to the terminal, but can't cross the synaptic space. Instead, the
electrical impulse triggers a chemical to be released and carry the message across to another neuron.
C. Incorrect. The chemical signals cause new electrical signals in the receiving neuron. The problem is
that the electrical signals that reach the terminal can't jump cross the synaptic space.
D. Sorry, that is incorrect. The electrical signal doesn't degrade. Once it reaches the axon's terminal it
stops because it can't cross the synaptic space. Instead, the electrical impulse triggers a chemical to be
released and carry the message across to another neuron.
Question: 3
A. Not quite right. Alcohol does damage the hippocampus, but this occurs over a period of time. The
memory loss during a blackout is immediate.
B. Sorry, try again. Alcohol reduces electrical firing of neurons in the hippocampus responsible for setting
the initial stages of memory. So, events can't be recalled later.
C. That's right! Alcohol reduces electrical firing of neurons in the hippocampus responsible for setting
the initial stages of memory. So, events can't be recalled later.
D. Sorry, try again. Alcohol can shrink the hippocampus, but this occurs over a period of time. The
memory loss during a blackout is immediate.
Question: 4
A. Incorrect. Alcohol actually interrupts the cell cycle in phase G1 of neural stem cell growth, thereby
decreasing neurogenesis.
B. Sorry, try again. Alcohol actually interrupts the cell cycle of neural stem cell growth, thereby
decreasing proliferation of neural stem cells and neurogenesis.
C. No. Alcohol can dehydrate the body in general by promoting "peeing," but this doesn't explain why the
hippocampus shrinks. Alcohol interrupts the cell cycle of neural stem cell growth, thereby decreasing
proliferation of neural stem cells and neurogenesis.
D. Great! Alcohol decreases neurogenesis in the hippocampus either by preventing neural stem cell
proliferation or promoting neural stem cell death.
Question: 5
A. Great! H atoms make up about 63% of the atoms in our bodies; they are abundant in water and fat.
The sheer number provides an excellent signal for the MRI scanner to detect when they spin.
B. Incorrect. There's a lot more to it! The reason is that H atoms make up about 63% of the atoms in our
bodies; they are abundant in water and fat. The sheer number provides an excellent signal for the MRI
scanner to detect when they spin.
C. Wrong answer. Protons don't get destroyed by the scanner, but that's not the reason. H atoms make
up about 63% of the atoms in our bodies; they are abundant in water and fat. The sheer number provides
an excellent signal for the MRI scanner to detect when they spin.
D. Sorry, you're wrong. The magnet is not detecting the charge of the proton. The reason is that H
atoms make up about 63% of the atoms in our bodies; they are abundant in water and fat. The sheer
number provides an excellent signal for the MRI scanner to detect when they spin.
Module 4 - Student Quiz Answers
Question: 1
A. You are partly right. Before entering the lungs, red blood cells carrying carbon dioxide in the veins
must first return to the right side of the heart. Oxygenated blood from the lungs returns to the left side of
the heart for distribution to the rest of the body, including the brain.
B. Terrific! Red blood cells carrying carbon dioxide in the veins must first return to the right side of the
heart. The right side of the heart pumps the blood into the lungs where carbon dioxide is exchanged for
oxygen in the capillaries. Oxygenated blood from the lungs returns to the left side of the heart for
distribution to the rest of the body, including the brain.
C. Sorry, you got it backwards. Red blood cells carrying carbon dioxide in the veins must first return to
the right side of the heart. The right side of the heart pumps the blood into the lungs where carbon dioxide
is exchanged for oxygen in the capillaries. Oxygenated blood from the lungs returns to the left side of the
heart for distribution to the rest of the body, including the brain.
D. Sorry, that is incorrect. Before entering the lungs, red blood cells carrying carbon dioxide in the veins
must first return to the right side of the heart. Oxygenated blood from the lungs returns to the left side of
the heart for distribution to the rest of the body, including the brain.
Question: 2
A. You are right! The oxygen atom in ethanol has only 3 bonds available for hydrogen bonding. Individual
water molecules may be held together with as many as 4 hydrogen bonds. Fewer hydrogen bonds to break
makes it easier to vaporize.
B. Sorry, that is incorrect. The oxygen atom in ethanol has only 3 bonds available for hydrogen bonding.
Individual water molecules may be held together with as many as 4 hydrogen bonds.
C. Sorry, try again. Although ethanol does have 2 carbon atoms, they do not participate in hydrogen
bonding.
D. Sorry, try again. Nitrogen atoms can participate in hydrogen bonding, however neither ethanol nor
water contain a nitrogen atom.
Question: 3
A. Sorry, many people get this wrong. In a state of equilibrium, the ratio of the ethanol concentration in
the blood relative to the alveoli achieves a constant value.
B. Sorry, many people get this wrong. In a state of equilibrium, the ratio of the ethanol concentration in
the blood relative to the alveoli achieves a constant value.
C. Sorry, many people get this wrong. In a state of equilibrium, ethanol molecules still move back and
forth, but there is no net flow. The ratio of the ethanol concentration in the blood relative to the alveoli
achieves a constant value.
D. Yes, you are correct! In a state of equilibrium, the ratio of the ethanol concentration in the blood
relative to the alveoli achieves a constant value. Ethanol molecules still move back and forth, but there is no
net flow.
Question: 4
A. Sorry, not quite. The small molecular size makes it easy for ethanol to cross a membrane, but it is not
a force that drives it across.
B. Sorry, try again. Proton pumps require energy to move molecules across a membrane.
C. Sorry, you have it backwards. Molecules passively diffuse across a biological membrane from an area of
high concentration (in the gut) to an area of low concentration (in the blood).
D. Yes, you got it right! Molecules passively diffuse across a biological membrane from an area of high
concentration (in the gut) to an area of low concentration (in the blood).
Question: 5
A. Correct! Hydrogen is an electron acceptor and gains an oxygen (is oxidized), while oxygen gains a
hydrogen (is reduced).
B. No, you got it backwards. Hydrogen is an electron acceptor and gains an oxygen (is oxidized), while
oxygen gains a hydrogen (is reduced).
C. Sorry, you are incorrect. Hydrogen is an electron acceptor and gains an oxygen (is oxidized), while
oxygen gains a hydrogen (is reduced).
D. Sorry, you are incorrect. Hydrogen is an electron acceptor and gains an oxygen (is oxidized), while
oxygen gains a hydrogen (is reduced).