2. Ecosystems
An ecosystem is a natural unit composed
of living organisms and their non-living
environment, e.g. a woodland.
A habitat is the place where an
organism lives, e.g. greenfly live on the
leaves of the trees.
An organism’s niche is the role it plays
within the ecosystem e.g a tawny owl is
top predator in a woodland.
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4. Ecosystems
A population is the total number of
organisms of one species living in a
habitat, e.g. the total number of
greenfly in the woodland.
A community is made up of all the living
organisms in a habitat, e.g. all the trees,
grass, insects, birds, etc..
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6. Ecosystems
A species is a group of organisms which
can interbreed to produce fertile
offspring.
Donkey Horse
Horses and donkeys can
mate to produce a mule –
but mules are not fertile
so horses and donkeys
are separate species
Mule
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7. Ecosystems
All of the energy required by all living
organisms in an ecosystem comes from
the sun.
Light energy from the sun is converted
to chemical energy by plants in a
process called photosynthesis.
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8. Producers & Consumers
Producers are organisms which can
produce their own food by
photosynthesis – usually green plants.
Consumers are animals which consume
(eat) other organisms. They cannot
make their own food.
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9. Producers & Consumers
A primary consumer is an animal which
eats plants, and is also known as a
herbivore.
A secondary consumer is an animal
which eats primary consumers, and is
also known as a carnivore.
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10. Producers & Consumers
An omnivore can eat both plants and
animals.
Decomposers are bacteria and fungi
which break down dead plants and
animals for energy and release their
nutrients back into the ecosystem.
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11. Producers & Consumers
An animal which hunts other animals for
food is called a predator.
An animal which is hunted by other
animals as food is called prey.
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12. Food Chains & Webs
A FOOD CHAIN shows a feeding
relationship. It is usually written as:
Green plant herbivore carnivore
The arrows in a food chain point from
food to feeder and show the direction
of energy flow.
A food chain always starts with a
producer (green plant).
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13. Food Chains & Webs
Energy is transferred in the form of
chemical energy in food from plants to
animals and then to other animals.
A green plant (producer) can be eaten
by a herbivore.
The herbivore in turn can be eaten by a
carnivore.
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14. Food Chains and Food Webs
ENERGY ENERGY
Rabbit Fox
Green Plant
PRIMARY SECONDARY
PRODUCER
CONSUMER CONSUMER
(HERBIVORE) (CARNIVORE)
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15. Food Chains & Webs
Feeding relationships are more
complicated than food chains suggest.
Food chains interconnect at many
points.
This interconnection of food chains is
called a food web.
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16. Food Chains & Webs
WEASEL OWL
FOX
HEDGEHOG
RABBIT
VOLE
FROG SNAIL
PRIMROSE
PLANT OAK
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17. Energy Flow and Loss
Every time one organism eats another,
energy is transferred from the food to
the feeder.
The arrow indicates the direction of
energy flow.
E.g.
Oak leaf Caterpillar Shrew
Badger
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18. Energy Flow and Loss
Not all the energy available at each step
in a food chain is passed onto the next
step.
Only about 10% is passed on.
90% of the energy is lost e.g. as:
Movement
Heat production
Waste.
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19. Pyramid of Numbers
A pyramid of numbers is a diagram
which represents the number of
organisms at each stage in a food chain.
A pyramid of numbers can look like:
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20. Pyramid of Numbers
Number of Size of
organisms
organisms
decrease
Thrush increase
Ladybird
Greenfly
Grass
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21. Pyramid of Numbers
Thrush
Ladybird
Greenfly
Grass
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22. Pyramids of Energy
A pyramid of energy is a diagram which
represents the amount of energy
available at each level of a food chain.
It is usually measured in kilojoules of
dry mass per square metre per year.
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23. Pyramid of Energy
100 kJ
1 000 kJ
10 000 kJ
100 000 kJ
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24. Pyramid of Biomass
A pyramid of Biomass is a diagram which
represents the total mass of organisms
at each level of a food chain.
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25. Pyramid of Biomass
Sparrows
Caterpillars
Oak leaves
The energy available to the caterpillars is less
than the energy available to the sparrows, and
therefore, the caterpillars produce a greater
biomass than the sparrows.
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26. Vocabulary
ecosystem carnivore
habitat predator
niche prey
population decomposer
community species
producer pyramid of numbers
primary consumer pyramid of biomass
secondary consumer pyramid of energy
herbivore
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