Questions: The cell membrane has many functions. One of the most important is facilitating the passage of molecules into and out of the cell. Some molecules can freely pass through the membrane, while others require a channel in order to enter or leave. Which of the following molecules will pass most freely through the cell membrane? Oxygen Glucose Insulin Water Na+

The cell membrane has many functions. One of the most important is facilitating the passage of molecules into and out of the cell. Some molecules can freely pass through the membrane, while others require a channel in order to enter or leave.

Which of the following molecules will pass most freely through the cell membrane?
Oxygen
Glucose
Insulin
Water
Na+

Transcript text: 19 The cell membrane has many functions. One of the most important is Attempt facilitating the passage of molecules into and out of the cell. Some molecules can freely pass through the membrane, while others require a channel in order to enter or leave. Which of the following molecules will pass most freely through the cell membrane? Oxygen Glucose Insulin Water $\mathrm{Na}+$

Solution

The answer is the first one: Oxygen.

Explanation for each option:

Oxygen: Oxygen is a small, nonpolar molecule, which allows it to pass freely through the lipid bilayer of the cell membrane by simple diffusion.
Glucose: Glucose is a large, polar molecule that cannot pass freely through the cell membrane. It requires a specific transport protein to facilitate its passage.
Insulin: Insulin is a large protein hormone and cannot pass through the cell membrane freely. It requires receptor-mediated endocytosis or other mechanisms to enter cells.
Water: Water is a small polar molecule that can pass through the cell membrane, but its passage is facilitated by aquaporins, which are channel proteins.
Na+ (Sodium ion): Sodium ions are charged particles and cannot pass freely through the hydrophobic core of the lipid bilayer. They require specific ion channels or transporters.