Which one of the following means of transporting substances across cell surface membranes permits movement in both directions?
- A2 only
- B1 and 4 only
- C2 and 3 only
- D1, 2, 3 and 4
Biology 9700 · AS & A Level · Movement into and out of cells
Which one of the following means of transporting substances across cell surface membranes permits movement in both directions?