Ch.1 Nerve Cells and Nerve Impulses (Practice Questions)

Question 1

Santiago Ramon y Cajal was responsible for which of these discoveries?
A. The human cerebral cortex has many specializations
to produce language.
B. The brain’s left and right hemispheres control different functions.
C. The nervous system is composed of separate cells.
D. Neurons communicate at specialized junctions called
synapses.

Answer 1

C. The nervous system is composed of separate cells.

Question 2

Which part of a neuron has its own genes, separate from those of the nucleus?
A. The ribosomes
B. The mitochondria
C. The axon
D. The dendrites

Answer 2

B. The mitochondria

Question 3

What is most distinctive about neurons, compared to other cells?
A. Their temperature
B. Their shape
C. Their internal components, such as ribosomes and
mitochondria
D. Their color

Answer 3

B. Their shape

Question 4

Which of these do dendritic spines do?
A. They synthesize proteins.
B. They increase the surface area available for synapses.
C. They hold the neuron in position.
D. They metabolize fuels to provide energy for the rest of the neuron.

Answer 4

B. They increase the surface area available for synapses.

Question 5

What does an efferent axon do?
A. It controls involuntary behavior.
B. It controls voluntary behavior.
C. It carries output from a structure.
D. It brings information into a structure.

Answer 5

C. It carries output from a structure.

Question 6

Which of the following is a function of astrocytes?
A. Astrocytes conduct impulses over long distances.
B. Astrocytes build myelin sheaths that surround and insulate axons.
C. Astrocytes create the blood–brain barrier.
D. Astrocytes synchronize activity for a group
of neurons.

Answer 6

D. Astrocytes synchronize activity for a group
of neurons.

Question 7

Which of the following is a function of microglia?
A. Microglia remove dead cells and weak synapses.
B. Microglia build myelin sheaths that surround and insulate axons.
C. Microglia dilate blood vessels to increase blood supply to active brain areas.
D. Microglia synchronize activity for a group of neurons.

Answer 7

A. Microglia remove dead cells and weak synapses.

Question 8

Which of these can easily cross the blood–brain barrier?
A. Fat-soluble molecules
B. Chemotherapy drugs
C. Proteins
D. Viruses

Answer 8

A. Fat-soluble molecules

Question 9

Which of these chemicals cross the blood–brain barrier by active transport?
A. Oxygen, water, and fat-soluble molecules
B. Glucose and amino acids
C. Proteins
D. Viruses

Answer 9

B. Glucose and amino acids

Question 10

What is the brain’s main source of fuel?
A. Glucose
B. Glutamate
C. Chocolate
D. Proteins

Answer 10

A. Glucose

Question 11

For the brain to use its main source of fuel, what does it also need?
A. Steroid hormones
B. Vitamin C
C. Thiamine
D. Acetylsalicylic acid

Answer 11

C. Thiamine

Question 12

When the neuron’s membrane is at rest, where are the sodium ions and potassium ions most concentrated?
A. Sodium is mostly outside and potassium is mostly inside.
B. Sodium is mostly inside and potassium is mostly outside.
C. Both ions are mostly inside the cell.
D. Both ions are mostly outside the cell.

Answer 12

A. Sodium is mostly outside and potassium is mostly inside.

Question 13

When the membrane is at rest, what are the forces acting on sodium ions?
A. Both the concentration gradient and the electrical gradient tend to move sodium ions into the cell.
B. Both the concentration gradient and the electrical gradient tend to move sodium ions out of the cell.
C. The concentration gradient tends to move sodium ions into the cell, and the electrical gradient tends to move them out of the cell.
D. The concentration gradient tends to move sodium ions out of the cell, and the electrical gradient tends to move them into the cell.

Answer 13

A. Both the concentration gradient and the electrical gradient tend to move sodium ions into the cell.

Question 14

When the membrane is at rest, what are the forces acting on potassium ions?
A. Both the concentration gradient and the electrical gradient tend to move potassium ions into the cell.
B. Both the concentration gradient and the electrical gradient tend to move potassium ions out of the cell.
C. The concentration gradient tends to move potassium ions into the cell, and the electrical gradient tends to move them out of the cell.
D. The concentration gradient tends to move potassium ions out of the cell, and the electrical gradient tends to move them into the cell.

Answer 14

D. The concentration gradient tends to move potassium ions out of the cell, and the electrical gradient tends to move them into the cell.

Question 15

Which direction does the sodium–potassium pump move ions?
A. It moves both sodium and potassium ions into the cell.
B. It moves both sodium and potassium ions out of the cell.
C. It moves sodium ions into the cell and potassium ions out of the cell.
D. It moves sodium ions out of the cell and potassium ions into the cell.

Answer 15

D. It moves sodium ions out of the cell and potassium ions into the cell.

Question 16

Under what conditions does an axon produce an action potential?
A. Whenever the membrane is hyperpolarized
B. Whenever the membrane’s potential reaches the threshold
C. Whenever the membrane is depolarized
D. Whenever the membrane’s potential reaches zero

Answer 16

B. Whenever the membrane’s potential reaches the threshold

Question 17

If a membrane is depolarized to twice its threshold, what happens?
A. The neuron produces an action potential at twice as much strength as usual.
B. The neuron produces an action potential that travels twice as fast as usual.
C. The neuron produces an action potential slightly stronger and slightly faster than usual.
D. The neuron produces the same action potential it would at the threshold.

Answer 17

D. The neuron produces the same action potential it would at the threshold.

Question 18

To which part or parts of a neuron does the all-or-none law apply?
A. Axons
B. Dendrites
C. Both axons and dendrites
D. Neither axons nor dendrites

Answer 18

A. Axons

Question 19

During the rising portion of the action potential, which ions are moving across the membrane and in which direction?
A. Sodium ions move out.
B. Sodium ions move in.
C. Both sodium and potassium ions move in.
D. Potassium ions move in.

Answer 19

B. Sodium ions move in.

Question 20

After the action potential reaches its peak, the potential across the membrane falls toward its resting level. What accounts
for this recovery?
A. The sodium–potassium pump removes the extra sodium.
B. Sodium ions move out because their channels are open and the concentration gradient pushes them out.
C. Potassium ions move out because their channels are open and the concentration gradient pushes them out.
D. Potassium ions move in.

Answer 20

C. Potassium ions move out because their channels are open and the concentration gradient pushes them out.

Question 21

What does the myelin sheath of an axon accomplish?
A. It enables an axon to communicate with other axons.
B. It enables action potentials to travel in both directions along an axon.
C. It enables nutrients to enter the axon.
D. It enables action potentials to travel more rapidly.

Answer 21

D. It enables action potentials to travel more rapidly.

Question 22

What causes the refractory period of an axon?
A. The sodium–potassium pump becomes inactive.
B. The sodium–potassium pump increases its activity.
C. The potassium channels are closed.
D. The sodium channels are closed.

Answer 22

D. The sodium channels are closed.

Question 23

About what percentage of the brain does an average person use?
A. 10 percent
B. 30 percent
C. 50 percent
D. 100 percent

Answer 23

D. 100 percent