Create an account to track your scores
and create your own practice tests:
Test: MCAT Biology
In humans, nerve impulses are transmitted with the coordinated action of sodium and potassium ion channels. These channels open in a specific sequence, to allow for membrane potential changes to take place in a directional manner along the length of an axon.
Figure 1 depicts a single phospholipid layer of a cell membrane, and three transmembrane channels important to action potential propagation.
1. | The refractory period is the period of time after action potential that a neuron is unable to "refire" if another stimulus is present. If protein 1 is a voltage-gated sodium channel, protein 2 is a voltage-gated potassium channel, and protein 3 is a leak channel, which channel contributes most to the absolute refractory period? |
Potassium channel, because its lacks an activation gate
Protein 3, due to its lack of an inactivation gate
Protein 2, due to its activation gate
Leak channel, due to its inactivation gate
Protein 1, due to its inactivation gate
Certified Tutor
Certified Tutor