Movement of Molecules Flashcards
Define ‘diffusion’
The random net movement of molecules from an area of high concentration to an area of low concentration
What are the four main factors affecting diffusion?
Temperature
Concentration gradient
Surface area
Volume
Describe how temperature affects the rate of diffusion
At higher temperatures molecules have more kinetic energy, and so move faster, increasing the rate of diffusion
Describe how concentration gradient affects the rate of diffusion
If there is a large difference in concentration in two areas, molecules will diffuse from the higher to lower concentration quickly, the larger the concentration difference, the higher the rate of diffusion
Describe how surface area affects the rate of diffusion
A larger surface area speeds up the rate of diffusion, the larger the surface area, the higher the rate of diffusion
Describe how volume affects the rate of diffusion
The larger the volume, the slower the rate of diffusion as the whole volume has to be filled
Describe how the surface are to volume ratio affects the rate of diffusion
The larger the SA to V ratio, the higher the rate of diffusion as there will be a larger surface are, and a smaller volume
Define ‘osmosis’
The movement of free water particles from an area of high concentration to a area of low concentration over a semi permeable membrane
Define ‘free water particle’
When water molecules are not bonded with another molecule
Define ‘semi permeable membrane’
A membrane that only allow particle of a certain size through
Define ‘water potential’
A measure of the concentration of free water particles in a solution
Define ‘isotonic solution’
The solution outside the cell has an equal water potential to inside the cell, no net movement
Define ‘hypotonic solution’
The solution outside the cell has a higher water potential to inside the cell, net movement of water particles into the cell
Define ‘hypertonic solution’
The solution outside the cell has a lower water potential to inside the cell, net movement of water particles out of the cell
Define ‘active transport’
The movement of molecules from an area of low concentration to an area of high concentration using energy
