1. Food Chain and Food Webs
Ms. McGrath
Science 10

2. Food Chains Grass  grasshopper  robin  hawk
Primary consumer: eat producers
Herbivore: only eat plants
Heterotroph: hetero = others, troph = food
Producer: makes its own food through photosynthesis which uses energy from the sun
Autotroph: auto = self, troph = food
Secondary consumer
Tertiary consumer
Energy transfer (10% passed on at each step)

3. 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

4. Trophic Levels First trophic level = producers (plants)
Second trophic level = primary consumers (herbivores)
Third trophic level = secondary consumers (carnivores)
Fourth trophic level = tertiary consumers

5. 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

6. Energy
What is the primary source of energy for all food chains?

7. 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

8. 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

9. 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

10. 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?

11. 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?

12. 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

13. Definitions
Ecosystem: interactions among organisms and their environment
Sustainable ecosystem: able to handle pressure and support many different organisms

14. Day 2 Questions
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?