Neurons contain a high concentration of potassium ions relative to the fluids surrounding them. How could a neuron acquire even more potassium?
A. active transport
B. osmosis
C. endocytosis
D. diffusion
Choose A, B, C or D as your solution.
The correct answer is A. This question is asking how to move a potassium ion (which is small) from an area that has a low concentration to an area with a relatively higher concentration. In this case we are moving against the concentration gradient. The transport type that could do this is active transport, using energy to move the ions against their concentration gradient.