25) The movement of potassium into an animal cell requires
A) low cellular concentrations of sodium.
B) high cellular concentrations of potassium.
C) an energy source such as ATP or a proton gradient.
D) a cotransport protein.
E) a gradient of protons across the plasma membrane.

Question

25)  The movement of potassium into an animal cell requires 
A) low cellular concentrations of sodium. 
B) high cellular concentrations of potassium. 
C) an energy source such as ATP or a proton gradient. 
D) a cotransport protein. 
E) a gradient of protons across the plasma membrane.

alphadxg · Answer

It is C, because it doesn't let big molecules like that diffuse down the gradient so it needs energy in order to do so.