Active Transport in Plants

Mineral absorption in plants

Active transport in the root hairs of plants allows plants to absorb mineral ions, which are necessary for healthy growth, even though the concentration of minerals is usually lower in the soil than in the root hair.

Active transport

Active transport is the net movement of particles against a concentration gradient. Energy is therefore required. During active transport, molecules are transported from a low concentration to a high concentration.

Passive transport

Osmosis and diffusion are examples of passive transport. Passive transport does not need energy. The particles move randomly, with a net movement towards an area of lower concentration. Passive transport is a naturally occurring phenomenon and does not require the cell to expend energy to accomplish the movement.

Osmosis

Osmosis is a special case of diffusion where only water molecules move. It requires a partially permeable membrane.

Example

Osmosis would take place if the blackcurrant squash was trapped inside a membrane. The water moves instead of the squash molecules. To equalise the concentration, the water moves into the membrane: The water moves from the dilute solution (outside the membrane) to the concentrated solution (where the squash is).

Diffusion

Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration.

Example

When you add blackcurrant squash to water, the particles in squash spread out, so that the strength of its flavour is the same throughout the whole drink. The squash molecules move from the high concentration of squash molecules to the low concentration. This is diffusion, not osmosis.