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AP Biology
Saturday Study Session 2
Information Transfer
Student Packet
Session 2 – Cell Signaling (Nervous and Immune)
Multiple Choice Questions
1) Action potentials originate from an energy stimulus causing depolarization within a neuron. The
rising phase of an action potential is due to the:
A)
B)
C)
D)
closing of K+ channels.
Closing of voltage-gated Ca2+ channels
Opening of voltage-gated Na+ channels
Spread of positive current along the plasma membrane
2) A single inhibitory postsynaptic potential has a magnitude of -0.5mV at the axon hillock and a
single excitatory postsynaptic potential has a magnitude of 0.5 mV. What will be the membrane
potential at the hillock after the spatial summation of 6 IPSPs and 2 EPSPs, if the initial membrane
potential is -70 mV?
A)
B)
C)
D)
-68 mV
-69 mV
-71 mV
-72 mV
3) Nerve impulses have to cover a large distance in very little time. Which animal movement could be
used to represent impulse conductance along a myelinated axon?
A)
B)
C)
D)
A person out on a power walk.
An amoeba extending pseudopodia.
A moth moving toward light.
A frog leaping between lily pads.
4) Given the steps shown below, which of the following is the correct sequence for transmission at a
chemical synapse?
1. neurotransmitter binds with receptor on post synaptic neuron membrane
2. calcium ions rush into neuron’s cytoplasm and push the vesicles to the membrane
3. action potential depolarizes the presynaptic membrane
4. ion channel opens to allow a particular ion to enter the post synaptic neuron
5. synaptic vesicles release neurotransmitter into the synaptic cleft
A) 1, 2, 3, 4, 5
B) 3, 2, 5, 1, 4
C) 5, 1, 2, 4, 3
D) 4, 3, 1, 2, 5
5) Cell signaling is important in understanding immune system function. The following events occur
when a mammalian immune system first encounters a pathogen. Place them in the correct
sequence, and then choose the answer that indicates that sequence.
1. Pathogen is destroyed or neutralized.
2. Lymphocytes secrete antibodies.
3. Antigenic determinants from pathogen bind to antigen receptors on T helper lymphocytes.
4. Lymphocytes specific to antigenic determinants from pathogen become numerous.
5. Only memory cells remain to fight future potential infections.
A)
B)
C)
D)
3, 4, 2, 1, 5
1, 2, 3, 4, 5
2, 1, 4, 3, 5
4, 2, 3, 1, 5
6) Helper T cells are perhaps the most important immune system cells in your bodies, next to the
neutraphil. They are responsible for activating not only the humoral response; but also the cellmediated response. Which of the following is NOT true about helper T cells?
A)
B)
C)
D)
They respond to reception of Interleukin-1 (IL-1).
They recognize polysaccharide fragments presented by class II MHC molecules.
They can be subject to infection by the HIV virus.
When activated, they secrete Interleukin-2 (IL-2) and other cytokines.
Math Grid In
Cells of the human body come in various shapes and sizes. Suppose a cell is rectangular in the following
dimensions. Find the total surface area for the given dimensions.
6 mm
10 mm
20mm
Perform calculations here:
Short Free Response
1) Structure equals functions is an important theme in Biology. Cells have evolved to have specific
shapes to enhance their specific function. For example, neurons have a specific shape that has
often been compared to a funnel. Describe the structure of a neuron and explain the function of
each part.
2) The innate immune system, also known as non-specific immune system, comprises the cells and
mechanisms that defend the host from infection by other organisms in a non-specific
manner.
Choose TWO different types of innate defenses present in plants and explain how each
defense either prevents the entry or prevents establishment of a pathogen.
Long Free Response
The defenses of the human body to the entry and establishment of a pathogen (disease-causing
organism) can be divided into nonspecific responses and specific responses.
(a) Explain how THREE types of nonspecific defenses can prevent the entry and/or establishment
of a pathogen in a person’s body.
(b) Discuss how the immune system responds to an initial pathogenic exposure, and how this
initial exposure can lead to a quicker response following a second exposure to the same pathogen.
(c) Explain the biological mechanisms that lead to the rejection of transplanted organs.