Water and dissolved substances:
- move along a concentration gradient
- move from an area of high concentration to low concentration
- move by osmosis and diffusion
Sometimes substances move against the concentration gradient (from an area of low concentration to an area of high concentration) by active transport.
ENERGY IS REQUIRED in active transport - this energy comes from cellular respiration.
The more respiration happening, the faster the rate of active transport.
Cells such as root hair cells have a lot of mitochondria to provide the energy needed for respiration.
Important for plants: plants absorb ions from very dilute solutions
Important for humans: sugar is absorbed from the small intestine into the blood