Name
Food Web Assignment
The flow of materials (and energy) in an ecosystem is the result of predator-prey relationships. These relationships
establish a long chain of events. They always begin with a producer and end with consumers.
grass
grasshopper
frog
snake
eagle
For the food chain above, indicate the: A: producer - ______________________
st
nd
B: primary (1 ) consumer - _____________________, C: secondary (2 ) consumer - ________________________
rd
th
D: tertiary (3 ) consumer - ______________________, E: quarternary (4 ) consumer - _______________________
F: herbivore - _________________________________, G: first carnivore - __________________________________
H: top carnivore - ________________________________
1:
2:
Complete each of the following food chains with an appropriate animal:
A: in a woodlot:
leaves
worm
_________________________________________
B: in a pond:
algae
insect
_________________________________________
C: in a forest:
grass
rabbit
_________________________________________
Consider a food chain that is common in Ontario:
sapling
deer
wolf
A: If the deer population increases, what will happen to –
I: the sapling population? (increase or decrease) ________________________________________
II: the wolf population? (increase or decrease) __________________________________________
B: The changes in the sapling and wolf population will cause a change in the number of deer. What happen
To the deer population as a result? (increase or decrease) ______________________________________
C: As a result of the change in (B) what will now happen to:
I: the sapling population? (increase or decrease) ____________________________________________
II: the wolf population? (increase or decrease) ______________________________________________
2: The area of Ontario in which this food chain occurs contains other organisms such as grass, mice, rabbits,
hawks, frogs, snakes, and insects. We can connect all these animals together in a food web as shown on
the next page.
mouse
snake
sapling
grass
deer
wolf
rabbit
hawk
insect
frog
The food web represents a more realistic situation. In the above food chain;
A: What are the two foods that the deer eats? 1: ________________________; 2: _______________________
B: What does the wolf feed on? ________________________________________
C: Why is it advantageous for the deer and the wolf to have more than one food source? _______________
________________________________________________________________________________________
________________________________________________________________________________________
D: Are there any omnivores in the above food web? If so, name them. _________________________________
_________________________________________________________________________________________
E: The above food web contains 16 food chains. Identify 4 of these chains:
i)
ii)
iii)
iv)
F: If the number of rabbits were to increase, what would happen to each of the following populations:
I: grass (increase or decrease) ___________________________________________________
II: hawks (increase or decrease) _________________________________________________
G: Will the changes in (f) have any effect on the number of mice in the area? EXPLAIN. __________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
3:
One important organism omitted from our food chain and food web is the decomposer.
A: What is the role of a decomposer? __________________________________________________________
B: Why are decomposers important? ___________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
4:
Consider the following food chain:
90 kJ LOST
900 kJ LOST
ENERGY
flower
caterpillar
bird
1000 kJ
100 kJ
10 kJ
At each level in this food chain, energy is lost. Approximately 90% of the energy consumed by the caterpillar
is used in its day-to-day metabolism, and only 10% can be passed on to the bird who eats it.
Food chains rarely go beyond 5 trophic levels. Using energy, explain WHY. ______________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Food Chains and Food Webs
Hawk
Mountain Lion
Snake
Owl
Beaver
Squirrel
Rabbit
Trees
Figure 1: A typical food web for a terrestrial ecosystem.
Bird
A: Identify all the producers. ____________________________________________________________________
B: Construct a food chain that has four (4) trophic levels.
C: Identify three (3) herbivores – 1: ________________________________; 2: _____________________________;
3: ______________________________________
D: Identify three (3) secondary consumers - 1: ____________________________; 2: _________________________;
3: ______________________________________
E: Identify all omnivores (if there are any). ___________________________________________________________
F: Identify any organisms that occupy more than one possible trophic level. _________________________________
___________________________________________________________________________________________
G: Explain what might happen to the fox and the hawk populations if a disease dramatically reduced the
mouse population. ____________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Energy Movement in Ecosystems
On a Blank piece of paper, draw a food web for the following ecosystems and identify:




Producers (first trophic level)
Primary consumers (second trophic level)
Secondary consumers (third trophic level)
Tertiary consumers (fourth trophic level)
A. In a pond, floating plants are found on the surface and phytoplankton (algae)
are found just below the
surface. The floating plants serve as food for muskrats, which are eaten by snapping turtles. The
phytoplankton is food for both tadpoles and minnows in the pond. Both the tadpoles and minnows are eaten
by the Kingfisher bird. Snapping turtles also eat the tadpoles.
B. In
a forest ecosystem, land plants act as producers and provide food for mice, bears, insects, and
grouse (a bird). The mice, in turn, are eaten by hawks and snakes. The insects are eaten by both grouse
and spiders. The grouse are eaten by foxes. Black bears in the area feed on plants and fish. The fish eat
crayfish in the streams, while the crayfish eat microscopic plants in the water.