In oxidative phosphorylation, H⁺ ions from the intermembrane space of mitochondria to the mitochondrial matrix, which type of membrane transport is this?

Describe the concentration of the solution outside the cell as hypertonic or hypotonic if that solute is being transported across the cell membrane by

(b) facilitated transport.

Which process requires energy—passive or active transport? Why is energy sometimes required to move solute across the cell membrane?

During respiration, oxygen gas diffuses into cells spontaneously. Which type of transport is this?

How would you expect an H⁺ ion to move out of the cell if [H⁺] inside the cell is lower than extracellular fluid?

As noted earlier (Section 22.3), he first step in glycolysis, which occurs within cells, is phosphorylation of glucose to glucose 6-phosphate. Why does this step prevent passive diffusion of glucose back out of the cell?

Identify the type of transport described by each of the following:

a. A molecule moves through a protein channel.

Identify the type of transport described by each of the following:

b. O₂ moves into the cell from a higher concentration outside the cell.

Identify the type of transport described by each of the following:

a. An ion moves from low to high concentration in the cell.