What is photosynthesis?

All the trees in a forest grow from tiny seeds and, over the years, they grow

bigger and taller. Unlike most animals, plants continue to grow throughout

their lives. The extra material organisms make is called biomass.

People used to think that plants got all the things they needed to grow from

soil. However, if this were true, then all the soil in a forest would soon be used

up and this obviously does not happen!

Today we know that plants need carbon dioxide from air as well

as water from the soil to make their own food. The process that

they use to make their food is called photosynthesis. A green

substance in the leaves, called chlorophyll, absorbs light energy

from the Sun to make photosynthesis happen. Carbon dioxide

and water are the raw materials (reactants) for photosynthesis.

The food made is a sugar. There are many different sorts of

sugar but the one made in photosynthesis is called glucose.

Oxygen is also made in photosynthesis.

Fruits and vegetable can be grown year after

year in the same soil

Plants can also be grown without

soil

Even very large

trees grow from

tiny seeds. The most

massive organism

on Earth is thought

to be this sequoia

tree (nick-named

‘General Sherman’)

Photosynthesis mainly occurs in leaves. Plants do not

grow properly

if they cannot

get enough

light, like the

plant on the

center of the

photograph