Biological Communities Chapter 17 Pre AP Biology Spring ‘13.

Biological Communities

Chapter 17

Pre AP Biology

Spring ‘13

Relationships within an ecosystem

• No one organism can survive by itself. Organisms depend on each other.

Predator-Prey• Predation is a relationship between 2 organisms in which

one is being consumed so that the other can gain energy.• The predator does the eating, the prey gets eaten.

Symbiotic Relationships

• Symbiosis – when two or more species live together in a close, long-term association.

• Three major kinds of symbiosis:

1. Parasitism

2. Mutualism

3. Commensalism

Parasitism

• One organism feeds on another.• Usually lives on or in another larger

organism which is called a “host”• Parasites don’t kill their host.

Mutualism

• Mutualism is a relationship in which both species benefit.

Commensalism

• Commensalism is a relationship in which one species benefits and the other is neither harmed nor hurt.