Question

Which of the following pairs of characteristics is more likely to make a substance diffuse through the cell membrane?

A) large, non-polar molecule

B) small, non-polar molecule

C) large, polar molecule

D) large, amphipathic molecule

E) small, polar molecule

Answer 1

A small, non-polar molecule is more likely to diffuse through the cell membrane because the plasma membrane is permeable to nonpolar, uncharged molecules and small size facilitates diffusion.

Step-by-step explanation:

The substance more likely to diffuse through the cell membrane is a B) small, non-polar molecule. This is because the plasma membrane is permeable to nonpolar and uncharged molecules. Moreover, small size facilitates diffusion through the lipid bilayer.

Larger polar or charged molecules cannot easily cross the hydrophobic interior of the phospholipid bilayer without the assistance of transport proteins. Amphipathic molecules, which contain both polar and nonpolar regions, may have different rates of diffusion depending on their size and the polarity of the substance.