Page 32 - Science Coursebook

2.5 Decomposers

The food chains and food webs that we have looked
at so far are made up of living organisms. But what
happens to dead organisms, and the waste material
that they produce? What happens to parts of an
organism that don’t get eaten – such as that apple
core you throw away, or those left-over fries that
you put into the waste bin?

All of these substances contain organic matter.
And, as you may remember from Stage 7, many
micro-organisms can break down (decompose)
organic matter. This is where they get their energy. These earthworms have been decomposing

Organisms that get their energy by breaking down dead leaves and food waste. They are turning
dead bodies and waste from animals and plants are it into compost that can be used to help new
plants grow.
called decomposers. Earthworms, fungi, some
insect larvae and bacteria are decomposers.

How do decomposers feed?
Inside your digestive system, you produce
enzymes that break down large molecules – such
as starch and protein – in your food into small ones.
The small molecules can then be absorbed through
the walls of your digestive system, and get into
your blood.

Decomposers also produce enzymes. But many Mouldy bread seen through a microscope.
decomposers do not have digestive systems.

The diagram shows how a fungus breaks down
bread. The fungus is made of many tiny thread-like
structures, called hyphae. The hyphae produce
enzymes that digest the starch and protein in the
bread around them. The small molecules that are

produced can then diffuse into the hyphae. The
fungus can use them for energy, or for making new 1 Thread-like
cells for growth. hyphae grow
through the bread.
Questions

1 Draw a food chain that ends with 2 Hyphae produce
a fungus. enzymes that break
2 Give two similarities between the way down the starch in
that a fungus feeds, and the way that the bread to sugar.
you feed. 3 Sugar diffuses

3 Describe the differences between the into the hyphae.
way that a fungus feeds, and the way
that you feed.
How a fungus digests bread.

30 2 Living things in their environment