Osmosis Flashcards
What is osmosis?
Movement of water from an area of higher water potential to an area of lower water potential down a water potential gradient across the phospholipid bilayer OR via protein channels (aquaporins)
What does water potential mean?
Measure of the ability of water molecules to move freely in solution
High = lots of free water molecules
Low = few free molecules
What’s is water molecules measure in
Kilopascals (KPa)
What is the highest water potential?
0kPa (pure water)
Does adding solutes to water make the water potential lower or higher?
Lower (less than zero, so negative)
What are the types of solutions for osmosis?
1) hypertonic
2) isotonic
3) hypotonic
What is a hypertonic solution?
Have a lower water potential
i.e lower conc of free water molecules than in the cell cytoplasm
What is an isotonic solution?
Have the same water potential as the cell
Therefore no net movement of water molecules
What is a hypotonic solution?
Has a higher water potential
ie a higher conc of free water molecules than in the cell cytoplasm
What is the effect of a hypotonic solution on an animal cell?
Water molecules move from a higher water potential in the solution to a lower water potential in the cell down a water potential gradient by osmosis and cause cell lysis (burst)
What is the effect of a hypotonic solution on an plant cell?
Water molecules move from a higher water potential in the solution to a lower water potential in the cell down a water potential gradient by osmosis and cause the vacuole to increase in size, pushes against the cell wall which prevents it from bursting. The cell becomes turgid
What is the effect of a hypertonic solution on an animal cell?
Water molecules move from a higher water potential in the cell to a lower water utensil in the solution by osmosis and cause cell to shrink/shrivel - crenates
What is the effect of a hypertonic solution on a plant cell?
Water molecules move from a higher water potential in the cell to a lower water playable in the solution by osmosis and cause the vacuole to shrink, pulling cell surface membrane away from the cell wall - cell becomes plasmolysed
What does more moles mean when it comes to water potential
More moles (m) = lower water potential
How can you make up a concentration by finding the scale factor?
Method 1:
Starting conc x starting vol = final conc x final volume
Method 2:
What is the formula for concentration of a solution?
Common exam question:
