i-How: Science - How does Photosynthesis work


How do plants make their food?


Plants produce their own food by Photosynthesis. The food they produce is called Glucose. To make this, plants use light energy from the Sun, water from roots and Carbon Dioxide from the air.  Photosynthesis take place in the leaves of all green plants.

Photosynthesis can be explained using the following equation:


carbon dioxide + water (+ light energy) glucose + oxygen


Conditions required for photosynthesis to happen:

Light - provided by the Sun onto the leaves.

Water - comes from the soil, absorbed by root hairs, up the stem and into the leaves.

Chlorophyll - 'green stuff' found in the chloroplasts which makes the leaves look green and absorbs sunlight.

Carbon Dioxide - enter the leaves from the surrounding air.



Photosynthesis image courtesy of science-resources.co.uk


Structure of a leaf

structure of a leaf

Leaf Structure image courtesy of science-resources.co.uk


  • Epidermis: Protective layer coated with a waxy surface (cuticle) which protects the leaf and prevents excess water loss.

  • Palisade cells: Contain many Chloroplasts which contain lots of Clorophyll to absorb all the available light.

  • Spongy layer: Have many air spaces to allow Carbon Dioxide to diffuse through the leaf.

  • Stomata: Allows water vapour and other gases to enter and leave the leaf.

  • Leaf vein: Helps support the leaf and contains Xylem and Phloem tubes to carry food and water.



Stomata image courtesy of science-resources.co.uk


Tags: How does Photosynthesis work; How do plants make their food; Structure of a leaf



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