why do plants need a transport system?

• All living things need to take substrances from and return waste to their environment.
• Larger plants have a smaller surface area to volume ratio, thus they need to have specialised exchange surfaces and a transport system.
• Every cell of a multicellular plant needs a constant and regular supply of oxygen, water, nutrients and minerals.
• Plants are not very active and their respiration rate is low. Therefore the demand for oxygen is low.
• The demand for oxygen in plants can be met via diffusion.
• However, in plants, the demand for water and sugar is still high. They can absorb water and minerals at the roots but they cannot absorb sugars from soil.
• The leaves of a plant can perform gaseous exchange and manufacture sugars via photosynthesis but hey cannot absorb water from the air.
• Plants need a transport system to move:

  water and minerals from the roots up to the leaves

  sugars from the leaves to the rest of the plant