Chapter 3: Cell Structure and Function

Chapter 3: Cell Structure and Function

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

MULTIPLE CHOICE
1. Glycolysis is the metabolic process of breaking down a glucose molecule to form
a. CO2 and H2O.
b. 2 ATP and 2 pyruvate.
c. 30 ATP.
d. oxygen.
ANS: B
Glycolysis produces a net gain of 2 ATP molecules and breaks down glucose modules to produce two pyruvate molecules.
Oxidative phosphorylation produces CO2 and H2O. Oxidative phosphorylation produces 30 ATP molecules. Oxygen is not
produced by glycolysis, but it is necessary for oxidative phosphorylation.
REF: Pg. 34
2. The benefit of glycolysis is that this phase supplies
a. ATP to meet energy needs of the body.
b. pyruvate to the citric acid cycle.
c. energy for oxidative phosphorylation
d. lactate during anaerobic conditions.
ANS: B
The benefit of glycolysis is to supply pyruvate to the citric acid cycle of cellular metabolism, which then produces much ATP.
Glycolysis only produces 2 ATP modules, which is insufficient for energy needs. Glycolysis does not supply energy for oxidative
phosphorylation. Lactate produced during prolonged anaerobic conditions builds up and can lead to lactic acidosis, which is an
undesirable outcome.
REF: Pg. 34
3. Repolarization of a neuron after a depolarizing action potential is due to
a. activation of the Na+-K+ pump.
b. influx of calcium.
c. efflux of potassium.
d. influx of sodium.
ANS: C
Repolarization is due to efflux of potassium from the cell. The Na+-K+ pump maintains cellular volume via osmotic pressure and
helps to maintain resting membrane potential. Calcium influx prolongs the action potential. Influx of sodium initiates
depolarization.
REF: Pg. 45
4. Excitable cells are able to conduct action potentials because they have
a. receptors for neurotransmitters.
b. tight junctions.
c. ligand-gated channels.
d. voltage-gated channels.
ANS: D
Voltage-gated channels respond to changes in membrane potential and are responsible for conducting action potentials. Receptors
for neurotransmitters allow neurotransmitters to bind to the cell membrane but are not directly responsible for action potentials in
excitable cells. Tight junctions are intercellular connections that help segregate proteins on the cell membrane and are not involved
in conducting action potentials. Ligand-gated channels respond to binding of a signaling molecule such as a neurotransmitter, but
are not directly responsible for action potentials in excitable cells.
REF: Pgs. 42-44
5. The resting membrane potential in nerve and skeletal muscle is determined primarily by
a. extracellular sodium ion concentration.
b. the ratio of intracellular to extracellular potassium ions.
c. activation of voltage-gated sodium channels.
d. activity of energy-dependent membrane pumps.
ANS: B
The major determinant of the resting membrane potential is the difference in potassium ion concentration across the membrane.
Extracellular sodium helps to maintain cell volume and resting membrane potential but it is not the primary determinant. Activation
of voltage-gated sodium channels help to initiate an action potential. Channels are not linked to an energy source; ions flow
passively across the cell membrane.