Unit 4: Energy FlowObjective #1: Interrelationships and energy flow within a food chain and food web

Levels of Organization• The biosphere is where all life exists• Ecosystems include living (biotic) and

non-living (abiotic) factors

Levels of Organization• Populations consist of organisms of the

same species living in an area• Communities have several populations in

an area

Energy Flow

• Living things need energy• For growth, reproduction, metabolic

processes• No energy No life!• Where does energy come from?

Energy Flow: Producers

• The SUN provides energy• Producers make food

(autotrophic)• Plants and some bacteria

are photosynthetic• Some bacteria are

chemosynthetic

Energy Flow: Consumers• Heterotrophs rely on other organisms for

their energy • ie: herbivores, carnivores, omnivores,

scavengers, decomposers, and detritivores

Food Chains• Energy is transferred through an

ecosystem when organisms eat or are eaten

Trophic Levels • Feeding levels in a food chain or web• 1st Trophic Level – Producers• 2nd Trophic Level – 1st Order (Primary) Consumer…ETC

• Each consumer depends on the trophic level below it for energy!

Section 3-2

Figure 3-8 A Food Web

Food Web

• Many food chains together form a food web

Pyramid of Energy• 10% of the energy at one trophic level is

available to the organisms at the next level.

Biomass Pyramid• The amount of living tissue and

thus potential food• Typically the greatest biomass is

at the base

Pyramid of Numbers• Relative number of individual

organisms at each level• In certain ecosystems, it is NOT

pyramid shaped