Question

which mechanism requires energy?
diffusion of oxygen into a red blood cell
diffusion of ions through a potassium channel
osmosis
exocytosis

Explanation:

• Diffusion of oxygen into a red blood cell is a passive process (simple diffusion) that does not require energy. It occurs down the concentration gradient.
• Diffusion of ions through a potassium channel is facilitated diffusion (a form of passive transport). It uses a channel protein but no energy as it moves ions down their concentration gradient.
• Osmosis is the diffusion of water across a semi - permeable membrane. It is a passive process and does not require energy.
• Exocytosis is an active process. In exocytosis, vesicles fuse with the plasma membrane to release substances out of the cell. This process requires energy (usually in the form of ATP) to form vesicles, move them to the membrane, and fuse them.

Answer:

exocytosis