Osmosis Flashcards
What is osmosis?
The movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane.
What is water potential?
The pressure created by water molecules.
What is water potential measured in?
kPa
What symbol represents water potential?
ψ
What is the water potential of pure water?
0
When solutes are dissolved in water, what happens to their water potential?
It becomes more negative.
What does it mean if the water potential is more negative?
More solute must be dissolved in it.
What is meant by isotonic?
An isotonic solution is when the water potential is the same in the solution and the cell within the solution.
What is meant by hypertonic?
Hypertonic is when the water potential of a solution is more positive (closer to zero) than the cell.
What is meant by hypotonic?
Hypertonic is when the water potential of a solution is more negative than the cell.
What happens if an animal cell is put in a hypotonic solution such as pure water?
A lot of water will move into the cell by osmosis. As animal cells don’t have a cell wall, the pressure will cause the cell to burst.
What would happen to a plant cell placed in a hypotonic solution?
They become turgid as they have a strengthened cell wall.
What happens if a plant or animal cell is placed in a hypertonic solution?
They’ll shrink and become shrivelled due to large volumes of water leaving the cell by osmosis.
Describe how movement across membranes occur by osmosis.
Water moves from an area of high water potential to low water potential down a water potential gradient through a partially permeable membrane. This is a passive process as it doesn’t require energy from ATP or respiration only kinetic energy of substances.
