Question

Polar and charged molecules typically cross the cell membrane by way of:

a) Simple diffusion
b) Facilitated diffusion
c) Active transport
d) Endocytosis

Answer 1

Polar and charged molecules typically cross the cell membrane through facilitated diffusion, which utilizes protein channels or carriers to help these molecules move along the concentration gradient without requiring energy.

Step-by-step explanation:

Polar and charged molecules typically cross the cell membrane by way of facilitated diffusion. This process involves the use of membrane proteins that act as carriers or channels to help these molecules move down a concentration gradient through the membrane. Unlike simple diffusion, which is used by small and nonpolar molecules, facilitated diffusion is necessary for polar and charged molecules because they are unable to pass directly through the hydrophobic lipid bilayer of the cell membrane. Facilitated diffusion does not require energy, as it relies on the inherent concentration gradient of the molecules to drive movement.