Page 74 - Science Course 3 (Book 1)

Mo2-L4a: How Do Organisms in an Ecosystem Interact?

A symbiotic relationship in which one organism Symbiosis
benefits but the other neither benefits nor is harmed
is commensalism. Interaction Species A Species B
Receives
Moss growing on the bark of a tree benefits by commensalism benefit Not Affected
having somewhere to grow, and the tree is neither Receives Receives
benefited nor harmed. mutualism benefit benefit

Receives
parasitism Harmed
benefit

SUMMARY

How Do Organisms in an Ecosystem Interact?

Each species that shares a habitat has a
A symbiotic relationship in which one organism separate niche.
benefits while the other is harmed is parasitism.
Overpopulation occurs when a population
A parasitic wasp lays its eggs in a caterpillar’s body. becomes so large that it causes damage to
The larvae develop and eventually chew their way out the environment.
of the caterpillar and kill it.
Symbiosis usually involves obtaining energy.

Mo2-L4: Vocabulary Review

Direction: Each of the sentences below is false. Make the sentence true by replacing the underlined word
with a term from the list below. Write your changes on the lines provided.
NOTE: You may need to change a term to its plural form.

commensalism competition mutualism niche overpopulation
parasitism predation symbiosis

1. Overpopulation occurs when two or more organisms interact to obtain the same
biotic or abiotic factor at the same time.

2. Parasitism occurs when one organism kills and eats another organism.

3. When moss grows on tree bark, the moss benefits; the tree does not benefit and
is not harmed. This is an example of mutualism.

4. Although two or more species can share the same habitat, they do not share the
same symbiosis.

5. Mutualism, commensalism, and parasitism are types of predation.

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