Cells: Exchange across cell membranes - osmosis Flashcards
What is osmosis
The net movement of water molecules from a region of higher water potential to a region of lower water potential across a semi-permeable membrane
Is osmosis a passive process
Yes
What is meant by water potential
Its the tendency of water to move out of a solution and the pressure exerted by water molecules on a membrane
What is water potential measured in
kPa
What is the kPa of pure water
0
Will the kPa of a solution containing solutes be positive or negative
negative
State the relation between concentration of a solution and its water potential
- As concentration of a solution increases water potential decreases
- This means a more concentrated solution has a lower water potential than a less concentrated solution
Name the factors that affect osmosis
- Water potential gradient
- Thickness of the membrane
- Surface area of the membrane
How does the water potential gradient affect osmosis
The lower the water potential gradient, the slower that rate of osmosis
How does the thickness of the membrane affect osmosis
The thicker the membrane, the slower the rate of osmosis
How does the surface area affect osmosis
The smaller the surface area, the slower the rate of osmosis
What would happen to cells in an isotonic solution
Nothing
What is an isotonic solution
Two solutions with the same water potential
What would happen to cells in an hypotonic solution
It will swell as water moves into the cell
What is a hypotonic solution
A solution with a higher water potential compared to the inside of a cell
