Bio 20
Stephens
Relationships in Ecosystems
Name ____________________
An observant Grade 11 Biology student was doing a study of the relationship
between organisms. One June, the student wandered through a Sweet Clover
field and observed the following organisms and their activities:
Read each of the following descriptions of an interaction within the ecological community and
answer each of the questions in order to identify the types of ecological relationship(s that exist
within the community.
The main producers were Sweet Clover plants, Wild Oats, Canada Thistle and
Blue Burr. These species were growing and photosynthesizing, intermingled in
the same field.
1. Which two of the following best describe the relationships that exist between the plants?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
Upon digging up a clover plant, the student observed an average of 8 nodules on
the roots of each clover plant (Nodules contain bacteria which have the ability to
convert atmospheric nitrogen into nitrates and release them into the soil. Plants
utilize nitrates to manufacture proteins.)
2. Which of the following best describes the ecological relationship that exists between the
bacteria and the clover plant?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
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Bio 20
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Small green aphids were sucking the juices from clover stems. Further
investigation found some aphids being eaten by an army of ants.
3. What type of ecological relationship exists between the aphids and the clover?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
4. What type of ecological relationship exists between the ants and the aphids?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
A considerable number of clover and wild oat plants had been cut down and
partially eaten by a colony of lined squirrels that made their home in an adjacent
pasture.
5. Which of the following describes the relationship between the squirrels and the clover
plants?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
6. What is the ecological relationship that exists between the squirrels?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
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The squirrels had lice.
7. What ecological relationship exists between the lice and the squirrels?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
a. interspecific competition
Some clover plants had withered and died. A white fungus was found on the
roots and lower stems, which was identified as root rot.
8. What ecological relationship exists between the lice and the squirrels?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
A colony of Leaf Cutters bees was feeding on the nectar and pollinating flowers.
9. What ecological relationship exists between the flowers and the bees?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
A bee keeper was setting out a hive of honey bees.
10. What ecological relationship exists between the bee keeper and the bees?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
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Several butterflies and moths were flitting over the field. Some could be
observed landing on flowers, others were landing on leaf axils, and the students
thought they were laying eggs.
11. What ecological relationship exists between the butterflies and the leaves?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
Nearby, a Red Fox was dozing in the sun, contented after his recent kill, a Jack
Rabbit. Several Blue Burr seeds were stuck in his coat.
12. What ecological relationship exists between the fox and the rabbit?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
13. What is the relationship between the seeds and the fox?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
Hundreds of soil insects were burrowing in and out of the soil, pausing to feed on
dead plant leaves. Several species of insects were involved.
14. Which of the following best describes the ecological relationship that exists between the
various species of insects?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
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A Mallard hen brooded her clutch, hidden from the watchful eyes by the dense
clover foliage.
15. What is the ecological relationship between the hen and the foliage?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
Blackbirds from a nearby slough picked caterpillars from clover stems.
16. What is the ecological relationship between the blackbirds and the caterpillars?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
17. What is the ecological relationship between the blackbirds and the clover stems?
a. Mutualism
b. Parasitism
c. Commensalism
d. Predation
e. intraspecific competition
f. interspecific competition
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