1) Energy from the sun is absorbed by producers like plants through photosynthesis and converted into chemical energy in sugars. 2) Consumers obtain this energy by eating producers or other consumers. 3) Decomposers break down dead organisms, releasing nutrients back into the environment and completing the energy cycle.

1. Energy Flow in Ecosystems

2. Energy Flow in Ecosystems
Terms to know:
Producers (autotrophs):
Organisms, like green plants, that
produce organic compounds
from inorganic compounds.
Consumers (heterotrophs):
Organisms that obtain nutrients
from other organisms.
Decomposers:
Organisms that break down the remains
of dead animals and plants, releasing the
substances that can be used by other
members of the ecosystem.

3. Energy Flow in Ecosystems
Almost all energy on
Earth comes from
radiant energy – the
energy from our sun.

4. Energy Flow in Ecosystems
Radiant energy that is
absorbed by land and
water is called thermal
energy. It keeps Earth
at its present
temperature range.

5. Energy Flow in Ecosystems
The portion of radiant energy we can see is called light
energy.

6. Energy Flow in Ecosystems
Producers can collect this energy and turn it into
chemical energy.

7. Energy Flow in Ecosystems
This process is called photosynthesis:
carbon dioxide + water + light energy  sugar + oxygen
Sugar is a source of high energy.

8. Energy Flow in Ecosystems
When a consumer eats a producer, it releases the energy
from the sugar in a process called cellular respiration:
sugar + oxygen  carbon dioxide + water + energy

9. Food Chains
"There's always a bigger fish."
– Qui-Gon Jinn

10. Food Chains
A food chain is a diagram which shows how organisms
are linked together by feeding relationships.
seed  mouse  cat

11. Food Chains
A food chain is a diagram which shows how organisms
are linked together by feeding relationships.

12. Food Chains
They always begin with a producer.

13. Food Chains
The arrows point in the direction of energy (food) flow.

14. Food Chains
Other Abiotic
Components

15. When organisms die, they are eaten by scavengers
(ex. vultures, crabs, hyenas).
Food Chains

16. Then they are
broken down by
decomposers
and detritivores
(bacteria and
fungi).
Food Chains

17. Food Chains
Other Abiotic
Components

18. Food Webs

19. - the connection of several
food chains.
- more realistic view of
energy transfer.
- show organisms as part of
an interlocking relationship.
Food Webs:

20. Food Webs

21. Food Webs

22. Trophic Levels

23. Trophic Levels
Are the feeding levels that describe the positions of
organisms along a food chain.

24. Trophic Levels

25. 1st
tropic 
level
2nd
tropic 
level
3rd
tropic 
level
4th
tropic 
level
Producer primary
consumer
secondary
consumer
tertiary
consumer
secondary

26. Name an organism that:
- eats rabbits
- is on trophic level 2
- is an autotroph
- is a top carnivore
Think. Pair. Share.

27. Impacts on Food Webs
What would happen if an organism in a food chain
suddenly has a drastic change in population?

28. Think. Pair. Share.
What would happen if all
of the mangroves in this
ecosystem were cut down
by humans?
There would be no food
for the fish or crabs to
eat, so they would all die
off.
After the fish and crabs die,
the seabirds and pied
oyster catchers would also
starve.

29. What would happen
if a virus invaded
this ecosystem and
killed-off all of the
seabirds?
There would be no
predators to eat the
fish and the fish
population would
become very large.
If there are too many
fish in the ocean, they
may out-compete the
pied oyster catchers
for crabs and drive
them to starvation.
Think. Pair. Share.

30. Ecological Pyramids

31. Ecological Pyramids
No organism EVER receives all of the energy
from the organism they just consumed.

32. Ecological Pyramids
Only 10% of the energy from one trophic level is
transferred to the next (most of the energy is
lost as heat)

33. Ecological Pyramids
An ecological pyramid shows the relationship between
producers and consumers at different trophic levels in
an ecosystem by relative amounts of energy or matter

34. 1) Pyramid of Numbers:
- show number of organisms in each trophic level
- usually numbers decrease as one moves up food chain
10 000 grass
900 ants
5 birds
Ecological Pyramids

35. Sometimes, it does not produce a proper pyramid in all
cases
1500 lice
4000 caterpillars
1 tree
5 birds
Ecological Pyramids

36. 2) Pyramid of Biomass:
- The total mass of the organic matter at each trophic
level is called biomass
- Biomass is just another term for potential energy –
energy that is to be eaten and used.
Ecological Pyramids
2 kg lice
15 kg birds
200 kg caterpillars
2000 kg apple tree

37. 10 kJ birds
100 kJ caterpillars
1000 kJ apple tree
1 kJ lice
3) Pyramid of Energy:
- show the total energy of organisms in a food chain
- this is the best way to show flow of energy through a
food chain
approx. 90% energy is lost with each transfer in the food web
Ecological Pyramids

38. Ecological Pyramids