Lesson 3-How Do Organisms Interact?

- Observe how organisms help each otherObserve how organisms help each other- Describe how organisms compete within an Describe how organisms compete within an

ecosystemecosystem- Explain symbiotic relationshipsExplain symbiotic relationships

ObjectivesObjectives

VocabularyVocabulary• CompetitionCompetition• SymbiosisSymbiosis• ParasiteParasite

• HostHost

Lesson 3

A. Limiting Factors – Competition for Resources1. In an ecosystem, organisms compete for space, light,

food, water, air & nutrients.

2. Competition is the struggle among organisms for limited resources in an area.

3. Every ecosystem and species must compete to stay alive

4. A predator is an animal that feeds on other living animals

5. Prey is an animal that gets eaten by the predator.

VocabularyVocabulary• 166-166-Competition Competition – –

The struggle among The struggle among organisms for limited organisms for limited resources in an area.resources in an area.

Write this Question in your books…

Q: Why does an increase in the number of prey Q: Why does an increase in the number of prey affect the number of predators?affect the number of predators?

A: The more prey there are, the more predators A: The more prey there are, the more predators can be supported.can be supported.

Lesson 3

B. Organisms Interact to Meet Their Needs1. Some organisms live together in a relationship called

symbiosis.2. Symbiosis is a close relationship between organisms of

different species in which one or both of them benefit. There are 3 types of Symbiosis (you will learn the 3rd one tomorrow!).

3. Parasitism: one species benefits while the other is harmed

4. Parasite is an organism that lives in or on another organism

5. Host is the organism that the parasite lives on

6. Mutualism: both organisms benefit

VocabularyVocabulary168 - 168 - Symbiosis Symbiosis – –

A close relationship between organisms of A close relationship between organisms of different species in which one or both of the different species in which one or both of the

organisms benefit.organisms benefit.

168 – 168 – ParasiteParasite – – An organism that lives in or on another An organism that lives in or on another

organism.organism.

168 – 168 – HostHost – –The organism that a parasite lives on.The organism that a parasite lives on.

Write this Question in your books…

Q: What effect does mutualisms have on Q: What effect does mutualisms have on organisms?organisms?

A: Both organisms benefit.A: Both organisms benefit.

Insta-LabInsta-LabModel BehaviorModel Behavior

• Think of a relationship between organisms that Think of a relationship between organisms that shows mutualism. Then make a model of this shows mutualism. Then make a model of this

relationship with clay. How does this relationship with clay. How does this relationship benefit both organisms?relationship benefit both organisms?

Lesson 3

C. Neither Help nor Harm1. The third type of Symbiosis Commensalism: one

organism benefits and the other organism is neither helped nor harmed.

Write this Question in your books…

Q: How are the effects of commensalism and Q: How are the effects of commensalism and parasitism different?parasitism different?

A: In commensalism, one organism benefits, and A: In commensalism, one organism benefits, and the other is neither helped nor harmed. In the other is neither helped nor harmed. In

parasitism, one organism benefits, but the other parasitism, one organism benefits, but the other is harmed.is harmed.

Lesson 3 ReviewLesson 3 Review

In your groups, you will work on numbers:In your groups, you will work on numbers:

1, 3-61, 3-6

When you are finished, you may read, draw When you are finished, you may read, draw in one of the illustration books, work on in one of the illustration books, work on

other unfinished work or get on one of the other unfinished work or get on one of the computers if available.computers if available.