Unit 8
Nervous and Immune System Quiz
Chap. 43 and 48

1) A nervous system can alter activities in its target cells in muscles and glands because	

A) they are electrically coupled by gap junctions.
B) the target cells each have an internal neural network connected to the nervous system.
C) the target cells that become disconnected from the nervous system rapidly die.
D) the target cells have receptor proteins for the signals released by the nervous system.
E) the nervous system releases signals into the blood to control the target cells.

2) In the communication link between a motor neuron and a skeletal muscle,	

A) the motor neuron fires action potentials but the skeletal muscle is not electrochemically excitable.
B) the motor neuron is considered the presynaptic cell and the skeletal muscle is the postsynaptic cell.
C) action potentials are possible on the motor neuron but not the skeletal muscle.
D) the motor neuron is considered the postsynaptic cell and the skeletal muscle is the presynaptic cell.
E) action potentials are possible on the skeletal muscle but not the motor neuron.

3) The "threshold" potential of a membrane	

A) is the minimum hyperpolarization needed to prevent the occurrence of action potentials.
B) is the point of separation from a living from a dead neuron.
C) is the minimum depolarization needed to operate the voltage-gated sodium and potassium channels.
D) is the peak amount of depolarization seen in an action potential.
E) is the lowest frequency of action potentials a neuron can produce.

4) The operation of the sodium-potassium "pump" moves	
A) sodium and potassium ions into the mitochondria.
B) sodium ions out of the cell and potassium ions into the cell.
C) sodium and potassium ions out of the cell.
D) sodium ions into the cell and potassium ions out of the cell.
E) sodium and potassium ions into the cell.

5) For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in	

A) the replacement of potassium ions with calcium ions.
B) depolarization of the neuron.
C) hyperpolarization of the neuron.
D) the replacement of potassium ions with sodium ions.
E) the neuron switching on its sodium-potassium pump to restore the initial conditions.

6) After the depolarization phase of an action potential, the resting potential is restored by	

A) the opening of more voltage-gated sodium channels.
B) the opening of voltage-gated potassium channels and the closing of sodium activation gates.
C) the opening of sodium activation gates.
D) a brief inhibition of the sodium-potassium pump.
E) a decrease in the membrane's permeability to potassium and chloride ions.

SHORT ANSWER.  Write the word or phrase that best completes each statement or answers the question.
For the following questions, refer to the graph of an action potential in Figure 48.1 and use the letters to indicate your answer.

Figure 48.1

7) The membrane potential is closest to the equilibrium potential for potassium at label

8) The cell is not hyperpolarized, but repolarization is in progress, as the sodium channels are closing or closed, and many potassium channels have opened, at label

9) Saltatory conduction is a term applied to conduction of impulses	
A) an action potential that skips the axon hillock in moving from the dendritic region to the axon terminal.
B) jumping from one node of Ranvier to the next in a myelinated neuron.
C) rapid movement of an action potential reverberating back and forth along a neuron.
D) jumping from one neuron to an adjacent neuron.
E) across electrical synapses.

10) In the sequence of permeability changes for a complete action potential, the first of these events that occurs is	

A) the activation of the sodium-potassium "pump."
B) the inhibition of the sodium-potassium "pump."
C) the opening of voltage-gated potassium channels.
D) the opening of voltage-gated sodium channels.
E) the closing of voltage-gated potassium channels.

11) The observation that the acetylcholine, a neuritransmitter, released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of	

A) a ligand-gated sodium channel.
B) a voltage-gated sodium channel.
C) a chemical that inhibits action potentials.
D) a second-messenger-gated sodium channel.
E) a voltage-gated potassium channel.

12) The steps below refer to various stages in transmission at a chemical synapse:

1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.
2. Calcium ions rush into neuron's cytoplasm.
3. An action potential depolarizes the membrane of the axon terminal.
4. The ligand-gated ion channels open.
5. The synaptic vesicles release neurotransmitter into the synaptic cleft.
Which sequence of events is correct?	

A) 1 → 2 → 3 → 4 → 5
B) 5 → 1 → 2 → 4 → 3
C) 3 → 2 → 5 → 1 → 4
D) 4 → 3 → 1 → 2 → 5
E) 2 → 3 → 5 → 4 → 1

13) What happens when a neuron's membrane depolarizes?	
A) There is a net diffusion of Na+ out of the cell.
B) The inside of the cell becomes more negative relative to the outside.
C) The equilibrium potential for K+ (EK) becomes more positive.
D) The neuron's membrane voltage becomes more positive.
E) The neuron becomes less likely to generate an action potential.

14) These cells are involved in cell-mediated immunity and destroy virally infected cells:	
A) cytotoxic T cells
B) macrophages
C) natural killer cells
D) helper T cells
E) B cells

15) Which cells and which signaling molecules are responsible for initiating an inflammatory response?	

A) dendritic cells: interferons
B) lymphocytes: interferons
C) mast cells: histamines
D) phagocytes: chemokines
E) phagocytes: lysozymes

16) What are antigens?	
A) foreign molecules that trigger the generation of antibodies
B) proteins embedded in B cell membranes
C) proteins found in the blood that cause foreign blood cells to clump
D) proteins released during an inflammatory response
E) proteins that consist of two light and two heavy polypeptide chains

17) A person exposed to a new cold virus would not feel better for one to two weeks because	
A) it takes up to two weeks to stimulate immunologic memory cells.
B) antigen receptors are not the same as for a flu virus to which she has previously been exposed.
C) no memory cells can be called upon, so adequate response is slow.
D) specific B cells and T cells must be selected prior to a protective response.
E) V-J gene rearrangement must occur prior to a response.

Use the graph in Figure 43.1 to answer the following questions.

Figure 43.1

18) When would memory cells be produced?	
A) between 0 and 7 days
B) between 35 and 42 days
C) between 28 and 35 days
D) between 7 and 14 days
E) both A and C

19) When would you find antibodies being produced?	
A) between 3 and 7 days
B) between 14 and 21 days
C) between 28 and 35 days
D) 14-21 and 42-56 days
E) both A and C

20) Which of the following cell types are responsible for initiating a secondary immune response?	
A) macrophages
B) B cells
C) stem cells
D) memory cells
E) T cells

21) In which of the following situations will helper T cells be activated?	
A) when a cytotoxic T cell releases cytokines
B) when B cells respond to T-independent antigens
C) in the bone marrow during the self-tolerance test
D) when an antigen is displayed by a dendritic cell
E) when natural killer (NK) cells come in contact with a tumor cell

22) Which of the following is accounted for by immunological memory?	
A) the ability of the immune system to present antigen fragments in association with MHC antigens
B) the human body's ability to distinguish self from nonself
C) the observation that some strains of the pathogen that causes dengue fever cause worse disease than others
D) the ancient observation that someone who had recovered from the plague could safely care for those newly diseased
E) the ability of a helper T cell to signal B cells via cytokines

23) Both lysozyme and cytotoxic T cells	
A) kill cells by generating a membrane attack complex.
B) are part of innate immunity.
C) kill cells by inducing apoptosis.
D) are involved in cell-mediated immune responses.
E) kill cells through chemical interactions.

24) These cells are involved in innate immunity, and a person lacking these cells may have a higher than normal chance of developing malignant tumors:	

A) macrophages
B) natural killer cells
C) B cells
D) cytotoxic T cells
E) helper T cells

25) Which of the following is the last line of defense against an extracellular pathogen?	
A) phagocytosis by neutrophils
B) lysis by natural killer cells
C) antibody production by plasma cells
D) histamine release by basophils
E) lysozyme production

26) Which cell type interacts with both the humoral and cell-mediated immune pathways?	
A) cytotoxic T cells
B) natural killer cells
C) plasma cells
D) helper T cells
E) CD8 cells

27) Which of the following are T cells of the immune system?	
A) cytotoxic and helper cells
B) class I MHC, class II MHC, and memory cells
C) plasma, antigen-presenting, and memory cells
D) CD4, CD8, and plasma cells
E) lymphocytes, macrophages, and dendritic cells

28) Phagocytosis of microbes by macrophages is enhanced by which of the following?	
A) the binding of antibodies to the surface of microbes.
B) antibody-mediated agglutination of microbes.
C) the release of cytokines by activated B cells.
D) A and B only
E) A, B, and C

29) What is the primary function of humoral immunity?	
A) It is responsible for transplant tissue rejection.
B) It primarily defends against fungi and protozoa.
C) It primarily defends against bacteria and viruses that have already infected cells.
D) It produces antibodies that circulate in body fluids.
E) It protects the body against cells that become cancerous.

30) Naturally acquired passive immunity would involve the	
A) placental transfer of antibodies.
B) absorption of pathogens through mucous membranes.
C) ingestion of interferon.
D) injection of antibodies.
E) injection of vaccine.

31) Which of the following is true of active but not passive immunity?	
A) requires secretion of interleukins from macrophages.
B) proliferation of lymphocytes in bone marrow.
C) acquisition and activation of antibodies.
D) transfers antibodies from the mother across the placenta.
E) requires direct exposure to a living or simulated pathogen.

32) Jenner successfully used cowpox virus as a vaccine against the virus that causes smallpox. Why was he successful even though he used viruses of different kinds?	

A) The cowpox virus made antibodies in response to the presence of smallpox.
B) The immune system responds nonspecifically to antigens.
C) There are some antigenic determinants common to both pox viruses.
D) Cowpox and smallpox are antibodies with similar immunizing properties.

33) Which of the following is true of the successful development of a vaccine to be used against a pathogen?	
A) It is dependent on the pathogen having only one epitope.
B) It requires a rearrangement of the B cell receptor antibodies.
C) It is dependent on the surface antigens of the pathogen not changing.
D) It is not possible without knowing the structure of the surface antigens on the pathogen.
E) It is dependent on MHC molecules being heterozygous.

1) D
2) B
3) C
4) B
5) C
6) B
7) D
8) C
9) B
10) D
11) A
12) C
13) D
14) A
15) C
16) A
17) C
18) E
19) E
20) D
21) D
22) D
23) E
24) B
25) C
26) D
27) A
28) D
29) D
30) A
31) E
32) C
33) C