(Here you will find answer keys for homework
or quizzes as well as unedited responses on exams from your classmates)
QUIZ 1
1. The K ion channel is an example of how molecules
are transferred across the phospholipid bilayer by the process of
a. simple
diffusion
b. facilitated
transport
c. secondary
active transport
d. primary
active transport
ANSWER: b.
2. If you placed one of your cheek cells (given:
The ICF = 170 mM NaCl ) in a solution of 300 mM glucose, and you assume neither
compound could permeate the PL bilayer, through the process of osmosis your
cell would
a. crenate
b. lyse
c. be happy as a clam (normal cell volume)
d. cannot
determine by the provided information
ANSWER: b.
3. The Na/K ATPase pump uses a method called
__________________ __________________
or successive
phosphorylation/dephosphorylation cycles to change its configuration and pump
ions against their concentration gradients.
ANSWER: Molecular Peristalsis
4. T or F
(please circle)
If a cell has an electrical
disturbance of at least 30 mV, it will always fire an action potential because
of the ALL-or-NONE principle.
ANSWER: F
5. Which of the following physiological processes
requires no ATP expenditure?
a. endocytosis
b. exocytosis
c. osmosis
d. facilitated diffusion
e. two of the above
ANSWER: e.
6. Which of the following organic molecules
would be classified as a protein?
a. molecules that are formed from dehydration
reactions
b. molecules that contain free fatty acids
c. molecules that are produced from
peptide bond formations
d. steroids
e. DNA
f. glycogen
g. ketone bodies
ANSWER: c.
7. If a cell had the following ionic
concentrations and permeabilities, about at what voltage would you predict an
action potential would change polarity (peak of the action potential spike)?
HINT: You can decide whether
to use Nernst or Goldman.
PK = 10
PNa = 10,000
Assume mammalian temperature
of 37 degrees.
[K+]o = 40 mM
[K+]i
= 365 mM
[Na+]o = 420 mM
[Na+]i
= 65 mM
Please show all
calculations.
Answer: ______________________________
ANSWER: You can use either Nernst or Goldman, but of
course the former is less time consuming.
ENa = 60 log (420/65) = 49 mV
Em = 60 log[ [(10,000)420 + 10(40)]/[(10,000)65
+ 10(365)] = 49 mV
8. If the resting potential of the cell in #7
was -85 mV, at what voltage would this action potential begin to fire
fully? HINT: Threshold.
Please show all calculations. Answer: _________________________________
ANSWER: Th = 0.15 (Amplitude)
Amplitude = -85 mV to 49
mV = a delta of 134 mV
134 * 0.15 = 20 mV
If the resting potential is
-85 mV and you have to calculate the voltage
at which the AP would fire fully, then
add 20 mV to -85 mV = -65 mV
9. Write one sentence describing the importance
of the phospholipid bilayer for the physiologist =
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
ANSWER: Many things here!
10. T or F (please circle)
According to Fick’s Law of
Diffusion, the diffusion rate or flux is greatest when the molecule to be
transported has a high molecular weight and has to traverse a large
cross-sectional area.
ANSWER: F
11. If an action potential (AP) reaches
threshold, where in the neuron will the AP “spike” be initiated?
a. the dendrite
b. the soma
c. the axon hillock
d. the
synaptic terminals
e. the
sodium/potassium ATPase pump
ANSWER: c.