Energy Transfer Within EcosystemsAPES~Mr. Plowman

How do organisms grow?

What determines the productivity of an ecosystem?

Food chains, food webs, and trophic level pyramids

How Do Organisms Grow?

Photosynthesis builds biomass

Biomass: the dry weight of an organism.• No water weight

Energy flow and nutrient cycling

Primary Productivity Gross Primary Production (GPP)

Rate at which an ecosystem’s producers convert solar energy into biomass.

Rate of photosynthesis

Net Primary Production (NPP) NPP = GPP - R

Primary Productivity

Food Chains

Primary Producer

Primary Consumer

Secondary Consumer

Tertiary Consumer

Food Webs

Trophic Levels

Energy transfer is inefficient

Pyramid of Numbers• Shows the number of organisms at each trophic level in a food chain.

Pyramids of Biomass

Final Thought If humans have a limited amount of land and

resources, what do you think is more sustainable: Eating plants Eating animals