Answers 2024/2025
1. All of the following are true statements about the action potential EXCEPT:
a) Opening of the voltage-gated Na-channels will move the membrane potential to the equilibrium
potential of Na.
b) Opening of voltage-gated K-channels will move the membrane potential to the equilibrium potential
of K.
c) The Hodgkin cycle causes the fast change in membrane potential during the rising phase of the action
potential.
d) The falling phase of the AP is mainly due to the movement of K+ ions.
e) Voltage-gated Na-channels stay open longer than voltage-gated K-channels. - ANSWERSe) Voltage-
gated Na-channels stay open longer than voltage-gated K-channels. ***
2. Scientists discovered a new animal species with nerve cells physiologically similar to nerve cells found
in other animals. The membrane potential when only sodium ions can move across the membrane was
measured at +116 mV. What is the sodium concentration outside the nerve cell if the sodium
concentration inside the cell is 1 mM?
a) 1 M
b) 0.232 M
c) 0.116 M
d) 0.58 M
e) 0.1 M - ANSWERSe) 0.1 M ***
3. Which neurotransmitter binds to the nicotinic ACh receptor?
a) muscarine
b) atopine
c) norepinephrine
d) glutamate
e) None of the above - ANSWERSe) None of the above ***
, 4. The period of excitability of neuron during which both Na+ and K+ activation can occur is called the
a) interphase period.
b) relative refractory period.
c) absolute refractory period.
d) hyperexcitable period.
e) latent period - ANSWERSb) relative refractory period. ***
5. Excitation of the cone cell by blue light results in the production of an action potential in the
connected bipolar cell.
a) true
b) false - ANSWERSb) false ***
6. Which concept is the defining feature of the discipline of physiology?
a) Descent with modification
b) Homeostasis
c) Evolution
d) Equilibrium
e) Differentiation - ANSWERSb) Homeostasis ***
7. Stimulation of a hair cell results in changes in the hair cell membrane such as
a) opening of voltage-gated Na+ channels.
b) opening of voltage-gated K+ channels.
c) answers a and b.
d) none of the above. - ANSWERSd) none of the above. ***
8. What is the general purpose of positive feedback mechanisms?
a) To maintain a constant internal environment
b) To anticipate changes in the environment