Movement Of Molecules Flashcards
What is diffusion?
Random movement of molecules from an area of high concentration to an area of lower concentration
What is osmosis?
Movement of free water particles from an area of high concentration to an area of low concentration over a semi permeable membrane
What is active transport?
Movement of molecules from an area of low concentration to and area of high concentration using energy
Used in small intestine and glucose, plants and root hair cells to absorb mineral ions
What factors affect diffusion?
- Temp - high temp = more kinetic energy, faster
- Conc gradient - large difference in conc between 2 areas = faster
- SA - larger SA = faster, e.g alveoli
- Volume - longer to fill bigger area
What is a semi permeable membrane?
A membrane that only allows certain particles through
What affects osmosis?
Water potential (high and low conc) = measure of free water molecules in a solution, e.g pure water has 0 water potential but as a solute is added the water potential falls as there is lower concentration of free water molecules
What is isotonic solution?
The solution outside the cell has the same water potential as inside the cell - no net movement
What is a hypotonic solution?
Solution outside has higher water potential than inside - net movement of water particles into cell
What is a hypertonic cell?
Solution outside has lower water potential then inside - net movement of free water potential out of cell
What is needed for active transport?
Carrier molecule or carrier protein uses energy to pump substance across membrane and against conc gradient
Investigate diffusion and osmosis using non living and living systems
If a plant cannot replace lost water then it becomes plasmolysed, the turgor pressure inside cells falls and plant wilts
