【单选题】Crossing a membrane by simple diffusion can be distinguished from facilitated diffusion because:
A.
Simple diffusion does not require energy: facilitated diffusion requires a source of ATP.
B.
Simple diffusion can only move material in the direction of a concentration gradient; facilitated diffusion moves materials with and against a concentration gradient.
C.
Simple diffusion is not saturable; facilitated diffusion rates are limited by the number of functional membrane proteins and can be saturated
D.
Simple diffusion is found only in prokaryotes while facilitated diffusion is found only in eukaryotes.
【单选题】Solutions A and B are separated by a semipermeable membrane that is permeable to K + , but not to Cl - . Solution A is 100 mM KCl, and solution B is 1 mM KCl. Which of the following statements about s...
A.
K + ions will diffuse from solution A to solution B until the [K + ] of both solutions is 50.5 mM
B.
K + ions will diffuse from solution B to solution A until the [K + ] of both solutions is 50.5 mM
C.
KCl will diffuse from solution A to solution B until the [KCl] of both solutions is 50.5 mM
D.
K + will diffuse from solution A to solution B until a membrane potential develops with solution A negative with respect to solution B
E.
K + will diffuse from solution A to solution B until a membrane potential develops with solution A positive with respect to solution B