18th Feb '26

Photosynthesis

Unlike animals, plants are able to make their own using a chemical reaction called photosynthesis. That is why plants are found at the bottom of all food , making them vitally important to all to provide their food as well.

Sunlight is captured by in the chloroplasts. This energy powers the reaction. The reactants are water (H₂0) from the , and carbon dioxide (CO₂) from the . The energy breaks up these molecules to make two new products: (C₆H₁₂O₆) and (O₂).

The oxygen can be released as a waste product, or used by the plant for - another chemical reaction which takes place in every living cell.

A limiting factor is something that stops a reaction go any quicker. For photosynthesis to occur the plant needs:

and as with all reactions the rate will depend on

If there is an infinite concentration of CO₂, unless there is enough light it can not be used. In this case light would be the limiting factor.

Copy Graph on P67

Water is transported from the roots to the leaves through a vein structure known as the Xylem. Water and minerals are 'sucked up' as water evapourates from the leaves of plants in a process known as Transpiration.

The sugars produced through photosynthesis are transported around the plant through another vein structure called the Phloem.