Mean of Transport Flashcards
Diffusion, facilated diffusion and active transport
Means of transport across cell
Diffusion facilitated diffusion and active transport.
Diffusion
The movement of molecules from the region of lower concn without involving semi permeable membrane.
- along concn featuring
- passive transport
- no energy is utilized
Rate of diffusion
Maximum in gas
Gas>liquid>solid
Depends on kinetic energy
Factors affecting diffusion
1) temperature: increase, increase rate of diffusion and vice versa
2) diffusion pressure gradient: greater, greater is the rate of diffusion.
3) density of difusion substance: inversely proportional to the square root of the density of the diffusion substances..
4) diffusing medium: high concn of diffusion medium lower the rate of diffusion.
Role of diffusion
1) gas exchange during the process of photosynthesis and respiration.
2) transpiration of plants.
3) absorbtion of minerals.
4) translocation of food materials.
5) movement of water molecule in plant cell.
6) distribution of hormone.
Facilitated diffusion
The movement of molecules across the cell membrane with the help of molecule protein or carrier, but without the expenditure of energy.
- along concn gradient
- passive transport
- no energy is utilized
- through fixed membrane transport proteins.
Osmosis
Movement of solvent molecules from the lower concnd solution higher concentrated solution through a semi permeable membrane
Permeable membrane
Membrane which allows passing both solute and solvent particles across it.
Eg cell wall.
Impermeable membrane
Does not allows the free movement of both solute and solvent molecules.
Semi permeable membrane
Allows passing only solvent molecules but not solute molecules.
Eg. Egg membrane
Selectively permeable membrane
Which allows passing ply selected substance through them.
Eg cell membrane
Active transport
Transport of substance with the utilisation of energy.
