EcologyEcologyFood Chains and Food Webs

Standards:Standards:

BI 6.a-Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats.

BI 6.e-Students know a vital part of an ecosystem is the stability of its producers and decomposers.

BI.6.f-Students know at each link in a food web some energy is stored in newly made structures but much energy is dissipated into the environment as heat. The dissipation may be represented in an energy pyramid.

Ecology Standard Ecology Standard ExplanationsExplanations

BI 6.a-Biodiversity is total number of different livings things in an area. Biodiversity is affected by changing habitats.

BI 6.e-Producers and decomposers maintain the stability (balance) of ecosystems. How?

BI.6.f-At each link in a food web some energy is stored, but most energy is lost as heat.

Objectives:Objectives:

SWBAT:Explain the role of biodiversity in

maintaining the balance of an ecosystem.Demonstrate how energy is transferred

and lost in an ecosystem.Explain the various roles of organisms in

maintaining the stability of an ecosystem.Understand the interaction between living

and nonliving factors in an ecosystem.

Review-Key Concepts So FarReview-Key Concepts So Far

Every ecosystem includes both living (biotic) and nonliving (abiotic) factors.

Life in an ecosystem requires a source of energy.

The biodiversity of an ecosystem maintains the stability of an ecosystem, and altering habitats decreases this biodiversity.

What are food chains?What are food chains?

Key Concept: Food chains and food webs model the flow of energy in an ecosystem.

Food chains-A sequence that links species by their feeding relationships.

Follows the connections between one producer and a single chain of consumers.

What are food chains?What are food chains?

Owl

Mouse

Grasshopper

Grass

What are the different types What are the different types of consumers?of consumers?

Herbivores-eat only plants (grasshopper)

Omnivores-eat both plants and animals (kangaroo mouse)

Carnivores-eat only other animals (owl)

What are the different types What are the different types of consumers?of consumers?

Detritivores-organisms that eat only dead or decaying organic matter (detritus). (Millipedes)

Decomposers-Detritivores that break down organic matter into simpler compounds. They return vital nutrients back to the ecosystem. (Fungi)

What are the different types What are the different types of consumers?of consumers?

Herbivores

Omnivores

Carnivores

Detritivores

Decomposers

What are trophic levels?What are trophic levels?

Trophic levels-are the levels of nourishment in a food chain.

Energy flows up the food chain from the lowest trophic level to the highest.

Producer-Herbivore-Carnivore

Primary consumer, Secondary Consumer, Tertiary Consumer

What are food webs?What are food webs?

Food web-is a model that shows the complex network of feeding relationships and the flow of energy within an ecosystem.

At each link some energy is stored by an organism and some is lost.

The stability of an ecosystem depends on the producers.

What are food webs?What are food webs?

What happens to the energy What happens to the energy in a food web?in a food web?

Energy pyramid-A diagram that compares energy used by producers, primary consumers, other trophic levels.(kilocalories)

Shows how energy is distributed among trophic levels

Start with large base (producers) and each level gets smaller because energy is lost (10%) as heat

Energy PyramidEnergy Pyramid

Energy PyramidEnergy Pyramid

What happens to the energy What happens to the energy in the pyramid?in the pyramid?

SunlightProducersHerbivores CarnivoresProducers-use energy to make foodHerbivores-use energy to grow and for

cellular respiration. Most of the energy is lost as heat.

Carnivores-Most of the energy is lost as heat

Each level in food chain contains less energy

Summary Questions:Summary Questions:

What is the difference between food webs and food chains?

Why does the stability of ecosystems depend on producers?

What is the role of decomposers in ecosystems?

What are trophic levels?What happens to energy at each trophic

level?