Question

11.describe how each of the following molecules travel through the cell membrane.

• oxygen:
• carbon dioxide:
• potassium:
• sodium:
• water (2 methods):
• enzymes:

Explanation:

Oxygen and carbon dioxide are small, non - polar molecules that pass through the cell membrane by simple diffusion, moving from an area of high concentration to an area of low concentration. Potassium and sodium ions are transported across the cell membrane through ion channels (passive transport) and by the sodium - potassium pump (active transport which requires energy). Water can pass through the cell membrane by simple diffusion and also through aquaporins (water - specific channels). Enzymes are large proteins. They are usually synthesized inside the cell and may be secreted out of the cell through exocytosis or remain inside the cell.

Answer:

Oxygen: Simple diffusion.
Carbon dioxide: Simple diffusion.
Potassium: Ion channels (passive) and sodium - potassium pump (active).
Sodium: Ion channels (passive) and sodium - potassium pump (active).
Water: Simple diffusion, through aquaporins.
Enzymes: Synthesized inside the cell, may be secreted by exocytosis or remain inside.