Exchange system in plants

Like all living organisms, plants must exchange materials with their environment. These exchanges include absorbing water and minerals from the soil and absorbing carbon dioxide from the air for photosynthesis. Therefore plants have specialised exchange surfaces which maximise the efficiency of these exchanges.

Exchanges in the roots

The role of the roots is to absorb water from the soil by osmosis and dissolve mineral ions from the soil by active transport.

The mineral ions are transported around the plant where they serve a variety of functions, whilst the water is transported to be used as a reactant in photosynthesis, as well as to cool the leaves by evaporation and support the leaves and shoots by keeping cells rigid.

To maximise the efficiency of absorption, roots have specialised cells called root hair cells which are found just behind the tip of the root.

Root hair cells have several adaptations:

• the tube-like protrusion provides a greatersurface areaacross which water and mineral ions can be exchanged

• the tube-like protrusion can penetrate between…