Food Chains and Food Food Chains and Food WebsWebs

Structure and FunctionStructure and Function

Diagrams used to show how energy moves through an ecosystem.

Food ChainFood Chain

A food chain is a diagram that shows A food chain is a diagram that shows one particular example of energy one particular example of energy flow through an ecosystem. flow through an ecosystem.

Includes one organism per trophic Includes one organism per trophic level.level.

Trophic level Trophic level - place in the food - place in the food chain based on separation from the chain based on separation from the sunsun

Food WebFood Web Shows how energy flows through the Shows how energy flows through the

community.community.

Show more than one organism per Show more than one organism per trophic leveltrophic level

Laws of ThermodynamicsLaws of Thermodynamics

11stst Law of Thermodynamics- Energy Law of Thermodynamics- Energy can never be created or destroyed in a can never be created or destroyed in a chemical reaction. It can only be chemical reaction. It can only be transferred from one form to another.transferred from one form to another.

22ndnd Law of Thermodynamics- Any time Law of Thermodynamics- Any time energy is transformed that process is energy is transformed that process is not 100% efficient. Some energy is not 100% efficient. Some energy is converted to an unusable form.converted to an unusable form.

Implications for the Laws of Implications for the Laws of ThermodynamicsThermodynamics

11stst Law of Thermodynamics- Law of Thermodynamics- • Plants are able to convert light energy Plants are able to convert light energy

to chemical energy in glucose and other to chemical energy in glucose and other organic compoundsorganic compounds

• Organisms that eat plant can covert Organisms that eat plant can covert chemical energy stored in plant to forms chemical energy stored in plant to forms they can used to do work.they can used to do work.

22ndnd Law of Thermodynamics Law of Thermodynamics

• Not all solar energy an autotroph Not all solar energy an autotroph converts is usable to heterotrophs. converts is usable to heterotrophs. Some of that energy is used by the Some of that energy is used by the autotroph.autotroph.

• Some energy from the heterotroph is Some energy from the heterotroph is also required to digest and store energy also required to digest and store energy they consumed.they consumed.

• Therefore, there must be more energy Therefore, there must be more energy stored in the 1st trophic level than the stored in the 1st trophic level than the 22ndnd, and more energy in the 2nd trophic , and more energy in the 2nd trophic level than the 3level than the 3rdrd..

Rule of 10%Rule of 10%

In general 10% of the energy and In general 10% of the energy and biomass stored in one trophic level biomass stored in one trophic level can be passed on to the next trophic can be passed on to the next trophic level.level.

This can diagramed using energy and This can diagramed using energy and biomass pyramids. biomass pyramids.

Energy Energy PyramidPyramid

Biomass PyramidsBiomass Pyramids

A questionA question

Given This Why are Carnivores Good Given This Why are Carnivores Good Predictors of Ecosystem Health?Predictors of Ecosystem Health?

If there is any trouble in a food chain If there is any trouble in a food chain it will effect the top trophic levelit will effect the top trophic level

Biodiversity & StabilityBiodiversity & Stability What’s What’s biodiversitybiodiversity??

The number of different kinds of species The number of different kinds of species living in an area.living in an area.

How does ecosystem biodiversity affect How does ecosystem biodiversity affect ecosystem stability? ecosystem stability?

the more biodiverse the ecosystem the the more biodiverse the ecosystem the more options. The more options, the more more options. The more options, the more stablestable

Introduced Species and Changing Introduced Species and Changing Food WebsFood Webs

Sometimes nonnative species are Sometimes nonnative species are introduced by humans into an introduced by humans into an ecosystem. When this happens, they ecosystem. When this happens, they may disrupt the cycle of energy flow. may disrupt the cycle of energy flow. How? How?

Adding a new member to a food web Adding a new member to a food web will reduce resources from otherswill reduce resources from others

Rabbits in AustrailiaRabbits in Austrailia

Rabbits in AustraliaRabbits in Australia

Rabbits are not native to Australia.Rabbits are not native to Australia.

24 rabbits were introduced in 1859.24 rabbits were introduced in 1859.

They reproduced, well like rabbits, They reproduced, well like rabbits, and the population rose quickly to and the population rose quickly to over 2 billion by 1952.over 2 billion by 1952.

Introduced SpeciesIntroduced Species

Why do you think the population increased Why do you think the population increased so quickly and so much?so quickly and so much?

What do you think happened to the native What do you think happened to the native plant population?plant population?

What do you think happened to the What do you think happened to the populations of animals that the competed populations of animals that the competed for resources with the rabbits?for resources with the rabbits?