MCAT Biology Question — Action Potential
- Aug 15, 2014
- MCAT Question of the Day
Which ions are primarily responsible for repolarization of a neuron following an action potential?
a) K+ out of the neuron
b) K+ in to the neuron
c) Na+ out of the neuron
d) Na+ in to the neuron
An action potential and accompanying depolarization results from Na+ ions rushing down their concentration gradient in to the cell. The repolarization is caused predominantly by a rush of K+ ions down their concentration gradient out of the cell.
a) K+ out of the neuron, correct.
b) K+ in to the neuron, incorrect, This would require K+ ions to flow contrary to their concentration gradient.
c) Na+ out of the neuron, incorrect, The Na+/K+ ATPase pumps Na+ out of the neuron, Na+ will not spontaneously flow out of the neuron.
d) Na+ in to the neuron, incorrect, Na+ in to the neuron accompanies depolarization, not repolarization.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Search the Blog
Free ConsultationSchedule Now
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More