The movement of dissolved molecules into or out of a cell through the cell membrane, from a region of lower concentration to a region of higher concentration
Active transport
Uses energy released during respiration
Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient
Examples of active transport
Uptake of glucose by epithelial cells in the villi of the small intestine
Uptake of ions from soil water by root hair cells in plants
Anything that prevents oxygen or glucose uptake by the cell
Will also prevent respiration
Without respiration
Energy is not released from glucose and active transport cannot occur
Diffusion is the movement of dissolved substances down a concentration gradient
Osmosis is the movement of water through a partially permeable membrane from a region of lower concentration to a region of higher concentration
Active transport is the movement of dissolved substances against a concentration gradient, using energy
Comparison of diffusion, osmosis and active transport
Diffusion: Down a concentration gradient, Noenergy needed, Dissolvedsolutes moved
Osmosis: Down a concentration gradient, No energy needed, Water moved
Active transport: Against a concentration gradient, Energy needed, Dissolvedsolutes moved
