Osmosis Flashcards
Define osmosis
Passage of water molecules down their water potential gradient, across a partially permeable membrane.
Define water potential
Measure of the tendency of water molecules to diffuse from one region to another.
True or false? Polar molecules have a greater effect on osmosis than non polar molecules.
True. Because they split into two separate ions for example, sodium chloride disassociates into sodium ions and chloride ions this doubles the amount of solute making the water potential lower. Causing more water molecules to diffuse by osmosis through the partially permeable membrane.
Define water potential.
A measure of the tendency of water molecules to diffuse from one region to another.
What is the unit for measuring water potential?
Kilopascals kPa
How does the water potential of a solution lower?
As more solute molecules are added the water potential of the solution is lowered.
Is the water potential of cells higher or lower than pure water? And why?
It is lower as there are solutes in solution in the cytoplasm and in the large vacuole of plant cells.
What is the name of the consequence of an animal cell absorbing too much water?
Cytolysis
What does turgid mean?
Turgidity is when a plant cell has been surrounded by a large amount of water. This water has diffused by osmosis into the cell as it has a lower water potential than outside the cell. Because the plant cell wall is stronger due to cellulose they swell and this is when a clef becomes turgid.
Why is turgidity important?
It’s important because it helps to support plants
What happens if an animal cell is aced in a solution of low water potential?
They are described as crenated.
What happens when a plant cell is placed in a solution of low water potential?
They become plasmolysed.
Why can plasmolysed cells metabolisms not function?
The enzyme catalysed reactions need to be in solution.
