3. Topic 2: Ecosystems
2.1.2: Trophic Levels
The big idea
The starting point of all energy in ecosystems is the
sun.
4. Topic 2: Ecosystems
2.1.2: Trophic Levels
The big idea
The starting point of all energy in ecosystems is the
sun.
But only organisms which photosynthesize can obtain
energy directly from the sun.
5. Topic 2: Ecosystems
2.1.2: Trophic Levels
The big idea
The starting point of all energy in ecosystems is the
sun.
But only organisms which photosynthesize can obtain
energy directly from the sun.
All other organisms obtain energy by eating
6. Topic 2: Ecosystems
2.1.2: Trophic Levels
It is possible to classify the way organisms obtain energy into two
categories.
7. Topic 2: Ecosystems
2.1.2: Trophic Levels
It is possible to classify the way organisms obtain energy into two
categories.
Producers or Autotrophs: These manufacture their
own food from simple inorganic substances (plants)
8. Topic 2: Ecosystems
2.1.2: Trophic Levels
It is possible to classify the way organisms obtain energy into two
categories.
Producers or Autotrophs: These manufacture their
own food from simple inorganic substances (plants)
Consumers or Heterotrophs: Feed on autotrophs
or other heterotrophs to obtain energy (herbivores,
carnivores, omnivores, detrivores and decomposers
9. Topic 2: Ecosystems
2.1.2: Trophic Levels
It is possible to classify the way organisms obtain energy into two
categories.
Producers or Autotrophs: These manufacture their
own food from simple inorganic substances (plants)
Consumers or Heterotrophs: Feed on autotrophs
or other heterotrophs to obtain energy (herbivores,
carnivores, omnivores, detrivores and decomposers
But within the consumers their is a feeding hierarchy of
feeding
12. Topic 2: Ecosystems
2.1.2: Trophic Levels
Plants capture the suns energy and convert it to glucose
Herbivores eat plants
13. Topic 2: Ecosystems
2.1.2: Trophic Levels
Plants capture the suns energy and convert it to glucose
Herbivores eat plants
Carnivores eat herbivores
14. Topic 2: Ecosystems
2.1.2: Trophic Levels
Plants capture the suns energy and convert it to glucose
Herbivores eat plants
Carnivores eat herbivores
This creates different feeding levels or Trophic levels
(Greek for food is trophe)
18. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of
feeding relationships .
19. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
20. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of Trophic Level 4 Tertiary Consumer
feeding relationships .
The energy flow in the ecosystem Trophic Level 3 Secondary Consumer
can be illustrated as a Food chain.
Trophic Level 2 Primary Consumer
The arrows show the direction
that energy flows
Trophic Level 1 Producer
21. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of Trophic Level 4 Tertiary Consumer
feeding relationships .
The energy flow in the ecosystem Trophic Level 3 Secondary Consumer
can be illustrated as a Food chain.
Trophic Level 2 Primary Consumer
The arrows show the direction
that energy flows
Trophic Level 1 Producer
22. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of Trophic Level 4 Tertiary Consumer
feeding relationships .
The energy flow in the ecosystem Trophic Level 3 Secondary Consumer
can be illustrated as a Food chain.
Trophic Level 2 Primary Consumer
The arrows show the direction
that energy flows
Trophic Level 1 Producer
23. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Ecosystems have an hierarchy of Trophic Level 4 Tertiary Consumer
feeding relationships .
The energy flow in the ecosystem Trophic Level 3 Secondary Consumer
can be illustrated as a Food chain.
Trophic Level 2 Primary Consumer
The arrows show the direction
that energy flows
Trophic Level 1 Producer
26. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Food chains are an
oversimplification
They only show direct feeding
relationships within one
hierarchy
31. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Simpli ed Boreal Forest Food Web
The reality is that there is
a complex network of
interrelated food chains
which create a food web
34. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Food chains contain both
transfers and
transformations
Solar energy (light) is
transformed into stored
chemical energy by
photosynthesis
35. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
This transformation is
not very efficient. Only
about 2% of the solar
energy is converted to
sugars (chemical store of
energy)
36. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
98% used during
This transformation is photosynthesis
not very efficient. Only
about 2% of the solar
energy is converted to
sugars (chemical store of Light energy
energy) from the sun
2% converted
to sugars
38. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
When the zebra eats grass
matter is transferred. Not
all the available matter is
transferred. E.g. Bone
To make use of the stored
Transfer of
energy, respiration has to material
transform the matter to
energy. The total efficiency
is only about 10%.
39. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Some gets transformed straight
When the zebra eats grass to usable energy and lost as heat
matter is transferred. Not
all the available matter is
transferred. E.g. Bone
To make use of the stored
Transfer of
energy, respiration has to material
transform the matter to
energy. The total efficiency Some passes
straight through
is only about 10%.
40. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
The transfers and
transformations carry
on up the food chain with
less energy and material
being passed from one
level to the next
41. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
The transfers and
transformations carry
on up the food chain with
less energy and material
being passed from one
level to the next
42. Topic 2: Ecosystems
2.1.3: Food Chains and Food Webs
Because of the Trophic Level 4 Tertiary Consumer Sparrow Hawk
inefficiency of energy
transfer food chains are
rarely longer than four Trophic Level 3 Secondary Consumer House Sparrow
connections
Trophic Level 2 Primary Consumer Banded snail
Trophic Level 1 Producer Dandelion
