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Unit 8 Lesson 3 Interactions in Communities
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Unit 8 Lesson 3 Interactions in Communities
Florida Benchmarks
• SC.7.N.1.1 Define a problem from the seventh
grade curriculum, use appropriate reference
materials to support scientific understanding, plan
and carry out scientific investigations of various
types, such as systematic observations or
experiments, identify variables, collect and
organize data, interpret data in charts, tables, and
graphics, analyze information, make predictions,
and defend conclusions.
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Unit 8 Lesson 3 Interactions in Communities
Florida Benchmarks
• SC.7.L.17.2 Compare and contrast the
relationships among organisms such as
mutualism, predation, parasitism, competition,
and commensalism.
• LA.6.2.2.3 The student will organize information
to show understanding (e.g., representing main
ideas within text through charting, mapping,
paraphrasing, summarizing, or
comparing/contrasting).
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 8 Lesson 3 Interactions in Communities
Florida Benchmarks
• LA.6.4.2.2 The student will record information
(e.g., observations, notes, lists, charts, legends)
related to a topic, including visual aids to organize
and record information and include a list of
sources used.
• SC.7.L.17.3 Describe and investigate various
limiting factors in the local ecosystem and their
impact on native populations, including food,
shelter, water, space, disease, parasitism,
predation, and nesting sites.
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Unit 8 Lesson 3 Interactions in Communities
Feeding Frenzy!
How do predator and prey interact?
• The feeding relationships of organisms establish
the structure of a community.
• In a predator-prey relationship, one animal eats
another animal for energy and nutrients.
• The predator eats another animal. The prey is
the animal that gets eaten.
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Unit 8 Lesson 3 Interactions in Communities
How do predator and prey interact?
• Predators and prey have adaptations that can help
them survive.
• Some predators have talons, claws, or sharp
teeth.
• Some have camouflage to help them blend in with
the environment.
• Some prey animals, such as skunks, defend
themselves with chemicals.
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Unit 8 Lesson 3 Interactions in Communities
How do predator and prey interact?
• The sizes of predator and prey populations are
linked very closely.
• If one population grows or shrinks, the other
population is affected.
• For example, if most of an antelope population is
killed, a population of lions might have less to eat.
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Unit 8 Lesson 3 Interactions in Communities
Living Together
What are the types of symbiotic
relationships?
• A close long-term relationship between different
species in a community is called symbiosis.
• In symbiosis, the organisms in the relationship
can benefit from, be unaffected by, or be harmed
by the relationship.
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Unit 8 Lesson 3 Interactions in Communities
What are the types of symbiotic
relationships?
• A symbiotic relationship in which both organisms
benefit is called mutualism.
• An example of mutualism is the relationship
between bees and flowering plants. The
interaction benefits both organisms.
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Unit 8 Lesson 3 Interactions in Communities
What are the types of symbiotic
relationships?
• A symbiotic relationship in which one organism
benefits while the other is unaffected is called
commensalism.
• For example, lichens use tree bark for a living
space, and the tree bark is unaffected.
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Unit 8 Lesson 3 Interactions in Communities
What are the types of symbiotic
relationships?
• Parasitism is a relationship in which one
organism benefits and the other is harmed.
• The organism that benefits is the parasite, and
the one that is harmed is the host.
• Some parasites live on the host and feed on its
blood. Other parasites live in the host’s body.
They can weaken their host so much that the host
dies.
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Unit 8 Lesson 3 Interactions in Communities
Let the Games Begin!
Why does competition occur in
communities?
• In a biological community, organisms compete for
resources.
• Competition occurs when organisms fight for the
same limited resource, such as food, sunlight, and
mates.
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Unit 8 Lesson 3 Interactions in Communities
Why does competition occur in
communities?
• Sometimes competition happens among
individuals of the same species, such as different
groups of lions competing for mates.
• Competition can also happen among individuals of
different species, such as the competition between
lions and cheetahs for the same food.
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Unit 8 Lesson 3 Interactions in Communities
Strange Relationships
• Organisms in an extreme cave community interact
in ways that help them meet their needs.
• Predators have special adaptations that help them
hunt their prey in the darkness of the cave.
• Some cave dwellers never have to leave the cave
because they eat bird dung dropped by birds in
the cave.
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