Name________________________________________Period__________Date____________________
Food Web Review
The flow of matter 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
eagle
snake
1. Put the following 10 labels in the correct spaces above:
herbivore
top carnivore
omnivore
producer
first
carnivore
tertiary
consumer
quaternary
consumer
primary
consumer
secondary
consumer
producer
2. At each level in this food chain, energy is lost. Approximately 90% of the energy consumed by the
grasshopper is used in its day-to-day metabolism, and only 10% can be passed on to the frog that
eats it. Fill in the chart below with the units of energy available to each organism if the grass begins
with 1000 units of energy.
grass
grasshopper
frog
snake
1000 units
3. Food chains rarely go beyond 5 trophic levels. Using energy in your answer, explain WHY.
eagle
4. Complete each of the following food chains with an appropriate animal:
a. In a wood lot:
Leaves →
Worm →
b. In a pond:
Algae →
Insect →
c. In a forest:
Grass →
Rabbit →
5. Consider a food chain that is common in Ontario:
sapling
deer
wolf
a. If the deer population increases, what will happen to the sapling population?
b. If the deer population increases, what will happen to the wolf population?
c. The resulting changes in the sapling and wolf population (a & b) will cause a new change in the
number of deer. What happens to the deer population as a result?
d. As a result of the change in (c) what will now happen to the sapling population?
e. As a result of the change in (c) what will now happen to the wolf population?
6. 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?
7. 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:
The food web represents a more realistic situation. In the above food chain;
a. What are the two foods that the deer eats?
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:
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.
8. 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?
9. Consider the food chain pictured below:
a. Identify all the producers.
b. Construct a food chain that has four (4) trophic levels.
c. Identify three (3)
herbivores.
d. Identify three (3) secondary
consumers.
e. Identify all omnivores (if
there are any).
10. List all the organisms that are
affected if a disease
dramatically reduces the hare
population.
a. Describe what might
happen to the producers
you listed.
b. Describe what might happen to the top level carnivores you listed.
11. Draw a food web for the following ecosystems. Label each organism as one of the following:
 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.