Exchange systems 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.

Roots absorb water from the soil through osmosis and dissolve mineral oins from the soil by active transport

To maximise the absorbtion, roots have specialised cells called root hair cells (found in the tips of the roots)

They have several adaptations

• 'Tube like' structure provides a larger surface area across which water and mineral ions can be exchanged.
• 'Tube like' structure can penertrate between soil particles, ruducing distance in which water and mineral ions must move
• the root hair cell contains lots of mitochondria, which release energy fromglucose during respiration in order to provide the energy needed for active transport

One of the main jobs of the leaves is a major site of photosynthsis to produce glucose from water and carbon dioxide with the input of energy from sunlight.

To perform this function effectively, leaves are adapted to maximising the absorption of carbon dioxide and sunlight.

Adaptation

Purpose

Flattened shape

Larger surface area to absorb light and carbon dioxide

Thin

Short diffusion distance for carbon dioxide to diffuse into leaf cells, and oxygen to diffuse out of leaf cells

Stomata

Can open to allow diffusion of carbon dioxide into the leaf from the atmosphere, and the diffusion of oxygen and water vapour out of the leaf