Case Study on Relationships in Ecosystems:

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Case Study on Relationships in Ecosystems
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An observant 11th grade biology student was doing
a study on the relationships between organisms.
One June, the student wandered through a Sweet
Clover field and observed the following organisms
and their activities
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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.
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1. Which two of the following best describe the
relationships that exist between the plants?

• mutualism
• parasitism
• commensalism
• predation
• competition

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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.)
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2. Which of the following best describes the
ecological relationship that exists between the
bacteria and the clover plant?

• mutualism
• parasitism
• commensalism
• predation
• competition

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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.
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3. What type of ecological relationship exists
between the aphids and the clover?

• mutualism
• parasitism
• commensalism
• predation
• competition

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4. What type of ecological relationship exists
between the ants and the aphids?

• mutualism
• parasitism
• commensalism
• predation
• competition

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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.
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5. Which of the following describes the
relationship between the squirrels and the clover
plants?

• mutualism
• parasitism
• commensalism
• predation
• competition

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6. What is the ecological relationship that
exists between the squirrels?

• mutualism
• parasitism
• commensalism
• predation
• competition

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The squirrels had lice.
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. What ecological relationship exists between the
lice and the squirrels?

• mutualism
• parasitism
• commensalism
• predation
• competition

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Some clover plants had withered and died. A
white fungus was found on the roots and lower
stems, which was identified as root rot.
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8. Which of the following best describes the
ecological relationship between the clover plant
and the fungus?

• mutualism
• parasitism
• commensalism
• predation
• competition

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A colony of Leaf Cutters bees was feeding on the
nectar and pollinating flowers.
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9. What ecological relationship exists between
the flowers and the bees

• mutualism
• parasitism
• commensalism
• predation
• competition

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A bee keeper was setting out a hive of honey bees.
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10. What ecological relationship exists between
the bee keeper and the bees?

• mutualism
• parasitism
• commensalism
• predation
• 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.
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11. What ecological relationship exists between
the butterflies and the leaves?

• mutualism
• parasitism
• commensalism
• predation
• competition

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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.
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12. What ecological relationship exists between
the fox and the rabbit?

• mutualism
• parasitism
• commensalism
• predation
• competition

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13. What is the relationship between the seeds
and the fox?

• mutualism
• parasitism
• commensalism
• predation
• competition

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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.
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14. Which of the following best describes the
ecological relationship that exists between the
various species of insects?

• mutualism
• parasitism
• commensalism
• predation
• competition

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A Mallard hen brooded her clutch, hidden from the
watchful eyes by the dense clover foliage.
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15. What is the ecological relationship between
the hen and the foliage?

• mutualism
• parasitism
• commensalism
• predation
• competition

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Prairie birds from a nearby slough picked
caterpillars from clover stems.
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16. What is the ecological relationship between
the blackbirds and the caterpillars?

• mutualism
• parasitism
• commensalism
• predation
• competition

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17. What is the ecological relationship between
the blackbirds and the clover stems?

• mutualism
• parasitism
• commensalism
• predation
• competition