1. Unit 3 Ecosystems
Chapter 6 & 7

2. Part 1
The Web Of Life p. 92
&
Food Relationships p. 93
Questions #3-9 in the book

3. Define Ecosystem
Ecosystem = the network of relationships
(interactions) among living (plants, animals) and
the non-living parts (soil, climate, water etc.) in an
environment.

4. Differentiate the terms producers, consumers
decomposers. P. 93
Other examples:
Grasses
Trees shrubs
Water lilies
Flowers
Vegetables
Fruits
Producer = a plant which can synthesize carbohydrates
using carbon dioxide and the sun’s energy.
Actually “produce” their own food and food for the rest of
the ecosystem

5. Differentiate the terms producers, consumers,
decomposers. P. 93
Consumers = All those organisms that have
to eat (consume) plants or animals to obtain
their food.

6. Types of consumers
Primary Consumers: Animals that eat
producers. Also called 1st. order consumers.
(Ex. Rabbit, squirrels, grouse, insects)
Secondary Consumers: Animals that eat
primary consumers. Also called 2nd. order
consumers. (fox, owl, mink )
Tertiary Consumers: Animals that eat
secondary consumers. Also called 3 rd. order
consumers. (Wolf, coyote, hawk)

8. Differentiate the terms producers, consumers,
decomposers. P. 94
Examples:
Worms
Bacteria
Fungi
Protozoa
• Decomposers = Simple organisms that obtain
their food from dead/decaying organisms and
wastes.

9. Differentiate the terms food chain & food
web. P. 94
Food chain = linear Food web = a series
sequence of interconnecting
representing the food chains in an
nutrition of various ecosystem.
species Food web is more
from the simplest complex and is
plant to the top composed of several
carnivore. food chains
Food web is a more
realistic picture of an
ecosystem.

10. Food Chain vs Food Web

11. Identify ALL examples of each trophic level.
Producers
Shrubs, grass, trees
Primary Consumers
Grasshopper, rabbit, deer,
squirrel
Secondary Consumers
Mountain lion, snake, shrew,
insect-eating bird, hawk
Tertiary Consumers
Hawk, snake, mountain lion
Decomposers
Bacteria, fungi

12. Give an example
of a food chain
from fig. 6.4. P.
95
Tree insect insect eating hawk
→ → bird →
Producer Primary 2nd order 3rd order
consumer consumer consumer
Note: The arrows indicate the flow of energy & nutrients
from one level to the next

13. Sample Food Chain

14. Draw an example of a food web
containing humans. P. 94
Mosquito
Hawk
Cow
Grass
Man
Decomposer
Phytoplankton
Fish

15. Draw an example of a food web containing
humans. P. 94
Hawk
Mosquito
Cow
Man fish
Grass Decomposer Phytoplankton

16. What happens to energy? (Handout)

17. What happens to energy?
85-90% is LOST 10-15% is
or USED up: stored:
Available or
maintaining transferred to
the organism other animals
(Ex. when it is
metabolism, eaten.
reproduction
etc.)
And as heat!!!
IF NOT EATEN:
Energy is
transferred to
the
decomposers
.

18. What happens to the energy at the
decomposer level?
Same thing….ALMOST !?
Most is lost or used up through heat and maintaining
the organism.
If eaten (Ex. A mushroom) energy gets passed on.
HOWEVER, once a decomposer dies….
The energy is LOST FOREVER!!!

19. Summary – Energy & Food Webs
The ultimate source of energy (for most ecosystems) is the
sun
The ultimate fate of energy in ecosystems is for it to be lost
as heat, metabolism, reproduction, etc..
Energy and nutrients are passed from organism to
organism through the food chain as one organism eats
another.
Decomposers remove the last energy from the remains of
organisms.
Inorganic nutrients are cycled, energy is not.

20. Summary – Energy & Food Webs
Question #14, 15 & #16 p. 98 make perfect review
questions for the test.