Transcript Ecosystems Day 2 Energy transfer

Food Chain and Food Webs
Ms. McGrath
Science 10
Food Chains
Grass  grasshopper  robin  hawk
Producer:
makes its own
food through
photosynthesis
which uses
energy from the
sun
Autotroph:
auto = self,
troph = food
Primary
consumer: eat
producers
Herbivore: only
eat plants
Heterotroph:
hetero = others,
troph = food
Energy transfer (10%
passed on at each step)
Secondary
consumer
Tertiary
consumer
Definitions

Omnivore: eats everything (plants and meat)
Example: Humans, brown bears

Carnivore: only eats meat
Example: Lions

Scavengers: eat dead things, don’t kill prey
Example: Vultures, raccoons

Decomposers: consume dead material and
recycle (return) nutrients to the soil
Example: Worms, bacteria, fungi
Trophic Levels

First trophic level = producers (plants)

Second trophic level = primary consumers
(herbivores)

Third trophic level = secondary consumers
(carnivores)

Fourth trophic level = tertiary consumers
In which trophic level do each of
the following organisms belong?
grass
 crow
 coyote
 maple tree
 bacteria
 snake
 mouse
 deer
 porcupine
 red squirrel
 seeds

Producers
Primary
consumers
Secondary
consumers/
Decomposers
Energy

What is the primary source of energy for
all food chains?
Food Web: many food chains interlinked
Identify 3 food chains in the food web below
deer
snake
wolf
mouse
grass
rabbit
frog
shrubs
hawk
insect
Abiotic vs. biotic

Abiotic factors: components of an
ecosystem that are non-living
Example: soil, water, sunlight

Biotic factors: components of an
ecosystem that are, or use to be, living
Example: trees, birds, insects, bacteria
Complete the diagram using the following terms :
primary consumer (herbivore) , secondary consumer (carnivore),
tertiary consumer, decomposers, second trophic level, first trophic
level, producer, fourth trophic level, third trophic level
Transfer of Energy
Food energy ingested by a consumer is used
for many processes.

Only around ____ % is converted into
body mass.

Why do we rarely see more than 4 links
in a food chain?
Organisms are interconnected

Look at the following food chain :
Grass 
Deer

Wolf

If the deer population increases, what
would happen to:


The grass population?
The wolf population?

The grass population would decrease

The wolf population would increase
because:
 More food increases reproductive rates (more
babies)
 Eventually, the wolf population would start to
decrease because food would run out
Definitions

Ecosystem: interactions among
organisms and their environment

Sustainable ecosystem: able to handle
pressure and support many different
organisms
Day 2 Questions
1.
2.
3.
4.
5.
6.
Which type of organism is at the beginning of
all food chains?
Which organisms can eat all other organisms?
In an ecosystem, the abiotic factors include…?
3 examples of decomposers are …?
What is the importance of decomposers in an
ecosystem?
What is the principal source of energy for all
ecosystems?