Download Name: Class: Date: Community Interactions Reinforcement Answer

Name: _____________________________ Class: __________________ Date: __________________
Community Interactions
Reinforcement
Answer Key
1. food, access to mates, territory
2. mutualism, commensalism, parasitism
3. predation is the process by which one
organism captures and feeds on another
organism; parasitism is like predation in that
it involves feeding on another organism, but
parasitism also involves two species having
a very close relationship with one another,
predation does not necessarily require a
close relationship
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
1
Interactions in Ecosystems
Name: _____________________________ Class: __________________ Date: __________________
Community Interactions
Reinforcement
KEY CONCEPT Organisms interact as individuals and as populations.
Similar to how the interactions between you and your friends shape your
relationships, the way organisms interact in nature determines the dynamics of an
ecosystem. Two major interactions occur in nature:
• Competition occurs when two organisms fight over the same limited resources.
Competition can occur between individuals of the same species or between
individuals of two different species.
• Predation is the process by which one organism captures and feeds upon
another organism. Predation plays an important role in the adaptations of
organisms to their habitat.
In some cases, two species may have a very close relationship and interact with
one another very frequently. Symbiosis is a close ecological relationship between
two or more organisms that live in direct contact with one another. There are three
main types of symbiosis:
• Mutualism is an interaction in which both organisms get some kind of benefit.
A bee and a flower is an example of a mutualism. The bee receives food in the
form of nectar, and the flower is getting its pollen carried to another flower.
• Commensalism is an interaction in which one organism benefits, while the
other neither benefits nor is harmed. Small fish called remoras attach themselves
to the sides of sharks, and when the shark feeds, the remora eats the scraps the
shark cannot eat.
• Parasitism is a relationship in which one organism benefits while the other
organism is harmed. A leech may attach itself to a fish and suck the blood from
the fish. Eventually the fish will die, but the leech has kept itself alive on the
fish’s blood long enough to reproduce.
1. What types of resources might organisms compete for?
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2. What are the three types of symbiosis?
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3. What is the difference between parasitism and predation?
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Copyright by McDougal Littell, a division of Houghton Mifflin Company
Biology
2
Interactions in Ecosystems