Question

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

A. Hemoglobin
B. DNA
C. Sodium ion
D. Carbon dioxide
E. Glucose

Answer 1

Carbon dioxide is the molecule most likely to passively diffuse across the plasma membrane.

Step-by-step explanation:

The plasma membrane is made up of phospholipid bilayer. The fatty acid tails of the phospholipids make the cell membrane hydrophobic.

Due to the hydrophobic nature of the cell membrane, larger molecules like sodium ion, glucose ions, etc cannot enter through the cell by passive transport, when dissolved in water. Simple, non- polar molecules like carbon dioxide and oxygen can pass through the cell membrane easily by passive diffusion.