3 If O2 is found in high concentration on the outside of a c

3. If O2 is found in high concentration on the outside of a cell: a) energy will be expended to pump it inside the cell. b) it will move inside the cell through a protein channel. c) it will form a shell around the outside of the cell. d) it will passively diffuse out of the cell. e) none of the above

4. Which of the following lipid bilayers would have the greatest fluidity and permeability (at room temperature)? a) A bilayer constructed of saturated phospholipids and fewer cholesterol molecules. b) A bilayer constructed of unsaturated phospholipids and more cholesterol molecules. c) A bilayer constructed of saturated phospholipids and more receptor proteins. d) A bilayer constructed of unsaturated phospholipids and less cholesterol molecules. e) A bilayer constructed of unsaturated phospholipids, more cholesterol molecules, and more receptor proteins.

Solution

(3) e) none of the above

Oxygen is a small polar molecule which can easily diffuse into the cell.

(4) e) A bilayer constructed of unsaturated phospholipids, more cholesterol molecules, and more receptor proteins.

greatest fluidity is obtained when membrane is composed of more unsaturated lipids and cholesterol. More number of receptors and channels further increase the permeability