Which diffuses across cell membranes more easily, oxygen or carbon dioxide?

Question

Hmmm...

I chose this as a test answer to the following question, because the other answers appear to be correct. Perhaps I am wrong?

Here's the question:

Which of the following does not apply to carbon dioxide?

A: It diffuses across membranes much more easily than oxygen.

B. It is carried in blood as carbaminohemoglobin

C. It is converted into bicarbonate ion.

D. It is replaced on hemoglobin as oxygen in the lungs.

I know there are varying rates of O2/CO2 release or adhesion to hemoglobin depending on the partial pressure of O2, pH of plasma and temperature. Am I overlooking something here?

Answer 1

Oxygen, becuase we breathe in oxygen and diffuses before carbon dioxide is breathed out

Answer 2

The lipid bilayer of a cell membrane is permeable to water molecules and a few other small, uncharged, molecules like

oxygen (O2) and carbon dioxide (CO2). These diffuse FREELY (no energy input needed) in and out of the cell. The diffusion of water through the plasma membrane is of such importance to the cell that it is given a special name: osmosis.

Answer 3

Rate of diffusion depends on several factors including the size of the molecule.  Assuming all other factors are equal then oxygen will diffuse quicker since it is smaller than CO2.