Plant+transport+notes

= Transport in Plants =

**Homework and readings for this note:** Pp. 541-550.

1. Transpiration pull (evapotranspiration)

 * water evaporates from leaves and creates negative pressure which pulls water up from the roots
 * minerals dissolved in water distributed around plant

2. Translocation

 * movement of sugar and other nutrients around the plant through phloem
 * does not have to be in only one direction

3. Osmosis

 * a form of diffusion
 * water moves from areas of high water concentration to low water concentration
 * this movement happens through the phloem

Osmosis is "the diffusion of water through a semi-permeable membrane. The semi-permeable membrane only allows water to pass through, not substances (solutes) dissolved in the water."


 * membrane** - barrier
 * permeable membrane** - allows all substances through
 * semi-permeable membrane** - allows only some substances through
 * impermeable membrane** - nothing passes


 * solute** - a substance dissolved in a solvent
 * solvent** - a liquid in which solutes dissolve


 * diffusion** - movement of a substance from an area of high concentration to an area of low concentration. No energy involved.
 * passive transport** - movement of substances through a membrane along a diffusion gradient. No energy involved.
 * active transport** - a pump. Requires chemical energy in the form of ATP. The movement of substances through a semi-permeable membrane with the use of energy. Active transport can be used to speed up diffusion **or** work against the diffusion "gradient" by pumping molecules from a low concentration to a high concentration.