Standard LS.9
Community Interactions
VDOE - Revised 2003 Standards

Standard LS.9
The student will investigate and understand interactions among populations in a biological community. Key concepts include
a) the relationships among producers, consumers, and decomposers in food webs;
b) the relationship between predators and prey;
c) competition and cooperation;
d) symbiotic relationships; and
e) niches.

Overview / Key Concepts

In a community, populations interact with other populations by exhibiting a variety of behaviors that aid in the survival of the population.

Organisms or populations that rely on each other for basic needs form interdependent communities.

Energy resources of a community are shared through the interactions of producers, consumers, and decomposers. (identify the populations of producers, consumers, and decomposers and describe the roles they play in their communities.)

The interaction between a consumer that hunts for another consumer for food is the predator-prey relationship. (Generate predictions based on graphically represented data of predator-prey populations)

Populations of one species may compete with populations of other species for resources. (Predict the effect of population changes on the food web of a community.)

Populations of one species may also cooperate with populations of other species for resources. (Generate predictions based on graphically represented data of competition and cooperation between populations.)

A symbiotic relationship may exist between two or more organisms of different species when they live and work together.

Symbiotic relationships include mutualism (in which both organisms benefit), commensalism, in which one organism benefits and the other is unaffected, and parasitism, in which one organism benefits and the other is harmed. (Differentiate between the types of symbiosis and explain examples of each.)

Each organism fills a specific role or niche in its community. (Infer the niche of organisms from their physical characteristics.)