Question

by which method does the following occur: movement of oxygen, carbon dioxide, and other small uncharged molecules across the cell membrane?

Explanation:

To determine the correct method for the movement of oxygen, carbon dioxide, and other small uncharged molecules across the cell membrane, we analyze each option:

• Receptor - mediated endocytosis: This is a process for taking in specific macromolecules, not small uncharged molecules like oxygen and carbon dioxide.
• Simple diffusion: Small, uncharged, non - polar molecules (such as oxygen and carbon dioxide) can pass through the lipid bilayer of the cell membrane via simple diffusion, moving from an area of high concentration to low concentration without the need for energy or a transport protein.
• Phagocytosis: It is a type of endocytosis where cells engulf large particles or whole cells, not small molecules.
• Active transport mechanisms: These require energy (usually ATP) to move molecules against their concentration gradient. Oxygen and carbon dioxide move down their concentration gradients, so active transport is not involved.
• Osmosis: Osmosis is the diffusion of water across a selectively permeable membrane, not the movement of gases like oxygen and carbon dioxide.

So, the correct method is simple diffusion.

Answer:

B. Simple diffusion (assuming the second option is labeled B, as per the standard multiple - choice labeling where the first option is A, second B, etc. and the selected option in the image corresponds to simple diffusion)