Paper 1 - Cell Transport

Question 1

Simple diffusion

Answer 1

The movement of small, uncharged and lipid soluble molecules across the phospholipid bilayer, passively. E.g. oxygen

Question 2

Facilitated diffusion

Answer 2

The movement of molecules through channel or carrier proteins, passively.

Question 3

Osmosis

Answer 3

The movement of water molecules from a high water potential to a low water potential, through a partially permeable membrane.

Question 4

Active transport

Answer 4

The movement of molecules from a low concentration to a high concentration, through a carrier protein using ATP.

Question 5

Co-transport - absorption of glucose in gut

Answer 5

1. Na+ is actively transported out of epithelial cell into blood using Na+/K+ pump.
2. This lowers the conc of Na+ inside the epithelial cells
3. Na+ moves down its conc gradient from the ileum into the epithelial cell via the carrier protein, by facilitated diffusion.
4. Glucose moves out of the cell via facilitated diffusion into the blood,