MCAT Question A Day - 6/9/14 - Answer!
A cell membrane is normally slightly passively permeable to potassium ions. If a neuronal membrane were to become suddenly impermeable to potassium ions but retain an active Na+/K+-ATPase, the neurons resting potential would:
A. become more positive because potassium ion concentration would increase inside the neuron.
B. become more positive because potassium ion concentration would increase outside the neuron.
C. become more negative because potassium ion concentration would increase inside the neuron.
D. become more negative because potassium ion concentration would increase outside the neuron.
A is correct. The sodium/potassium pump moves potassium inside the membrane. Potassium is positively charged making the inside of the membrane more positive. The resting potential is measured with respect to the inside.
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A is correct. The sodium/potassium pump moves potassium inside the membrane. Potassium is positively charged making the inside of the membrane more positive. The resting potential is measured with respect to the inside.
Want more questions? - Click here to check out our MCAT Question A Day archive
