Energy Flow in an Ecosystem

Contributed by:

Sharp Tutor Thu, Jan 27, 2022 07:32 AM UTC

DISCUSSION POINTS:
How does energy flow in an ecosystem?
What is an energy pyramid?
What is a trophic level?

1. ENERGY FLOW IN ECOSYSTEM
How does energy flow in an ecosystem?
What is an energy pyramid?
What is a trophic level?

2. ENERGY ENTERS ECOSYTEM
 All energy in
ecosystem comes
from the sun
 First law of
Thermodynamics:
Energy cannot be
created or destroyed
(but it can be
transformed into
stored energy & heat)

3. ENERGY LEAVES ECOSYSTEM
 Second law of
thermodynamics:
Energy is lost as
energy is transformed
 In ecosystem, when
energy is
transformed, some
energy is lost as
HEAT

4. ENERGY PATHS
3 ways to 1. Food Chain: Single path
illustrate
energy flow
2. Food Web: many paths 3. Food Pyramid

5. FOOD CHAINS
 A food chain shows the path of
energy from one organism to
the next
 energy flows from producers
to consumers
 arrows point to who is eating
(plant is eaten by herbivore)
 Usually decomposers are left
out

6. FOOD WEBS
 A food web shows all feeding relationships in
an ecosystem (made of many food chains)

7. FOOD WEBS
 Typically, food webs go like this: remember:
decomposers
CONSUMER receive energy
from all other
(CARNIVORE) organisms in
an ecosystem
CONSUMER CONSUMER
DECOMPOSER
(OMNIVORE) (HERBIVORE)
PRODUCER

8. FOOD CHAINS AND WEBS
 Practice! Draw a food
CONSUMER
chain that includes the (CARNIVORE)
following organisms:
 grasshopper
 mouse CONSUMER
(CARNIVORE)
 grass
 owl
CONSUMER
 Now label the organisms (HERBIVORE)
as producers, consumers
(which type?), or
decomposers PRODUCER

9. FOOD CHAINS/WEBS & ENERGY PYRAMIDS
 Food chains/webs can be
written as a pyramid:
 Producers form the base
of the pyramid
 Consumers form the
upper layers

10. ENERGY PYRAMIDS
The energy pyramid shows
energy flow in an ecosystem: Top
Consumer
 A level of the
energy pyramid is
called a TROPHIC Energy stored by
Secondary Consumers
LEVEL
Energy stored by
Primary Consumers
 Each trophic level
represents the
ENERGY STORED
energy for those BY PRODUCERS
organisms

11. TROPHIC LEVELS
 Energy is lost with each trophic
 ~90% is released to the environment as heat
 ~10% of the energy is used
Only about
10% of the
energy from
one level is
passed on to
the next level

12. QUICK REVIEW
 Practice!
If 100% of the energy is available at the first trophic
level, what percentages of the energy are available at
the second and third trophic levels?
1%
10%
100%

13. QUICK REVIEW!
All organisms in an ecosystem need _______
energy
from food to live. An energy ________
pyramid shows
how much food energy is passed from one
organism to another through food chains.
Producers have the largest spot at the base
of the pyramid. Altogether, only about _____
10% of
the food energy at each level gets passed up to
the next level.

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