Question

select the true statements. diffusion is a form of passive transport. carbon dioxide only crosses the cell membrane in one direction. the unassisted diffusion of molecules directly through the phospholipid bilayer is called simple diffusion. carbon dioxide can move across cell membranes via simple diffusion because it is large and polar.

Explanation:

1. Diffusion is a passive - transport process where substances move from high to low concentration without energy input, so the first statement is true.
2. Carbon dioxide can cross the cell membrane in both directions depending on the concentration gradient, so the second statement is false.
3. Simple diffusion is the unassisted diffusion of molecules directly through the phospholipid bilayer, so the third statement is true.
4. Carbon dioxide is small and non - polar, which allows it to move across cell membranes via simple diffusion, so the fourth statement is false.

Answer:

Diffusion is a form of passive transport.
The unassisted diffusion of molecules directly through the phospholipid bilayer is called simple diffusion.