Food Web QuestionsFood Web QuestionsPage 46 and 47Page 46 and 47

Draw five food chains based on the Draw five food chains based on the food web shown in fig. 2.10food web shown in fig. 2.10

Seeds- mouse- snakeSeeds- mouse- snake

Food Web versus Food ChainFood Web versus Food Chain Food chains are Food chains are one model one model of food of food

relationships. Each producer is eaten relationships. Each producer is eaten by more than one primary consumer by more than one primary consumer and so on. Therefore the food and so on. Therefore the food relationships, in an ecosystem, looks relationships, in an ecosystem, looks more like a web than a chainmore like a web than a chain

Energy FlowEnergy Flow In an ecosystem, energy always In an ecosystem, energy always

flows from what is being eaten to the flows from what is being eaten to the organism that is eating. For organism that is eating. For example, if a robin eats a caterpillar, example, if a robin eats a caterpillar, the energy flow is directed from the the energy flow is directed from the caterpillar to the robin.caterpillar to the robin.

This is indicated in a food chain by an This is indicated in a food chain by an arrowarrow

BiomassBiomass Biomass is the total mass of Biomass is the total mass of

organisms in an ecosystemorganisms in an ecosystem Biomass is related to food chains Biomass is related to food chains

because it takes a greater number of because it takes a greater number of organisms at the lower levels to feed organisms at the lower levels to feed the organisms at the higher levels. the organisms at the higher levels.

The result is that energy flow in an The result is that energy flow in an ecosystem looks like a pyramid ecosystem looks like a pyramid

AssignmentAssignment Draw your own food chain using things Draw your own food chain using things

that you eat.that you eat. Label it with: producer, primary consumer, Label it with: producer, primary consumer,

secondary consumer, tertiary consumersecondary consumer, tertiary consumer Use arrows to indicate the flow of energyUse arrows to indicate the flow of energy Question: Some people have a limited food Question: Some people have a limited food

source. What might happen if their food source. What might happen if their food supplies were damaged by a hurricane, or supplies were damaged by a hurricane, or war.war.