POPULATIONS & ENVIRONMENTSFood Chains, Food Webs, Energy

Pyramids

The Food Chain

A visual representation of how energy is transferred in a system

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Producer Consumers

Produce their own energy (autotrophs)

Depend on other organisms for their energy (heterotrophs)

Understanding the food chain

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We call each level of the food chain a “trophic” level – meaning energy level. Each trophic level shows how energy is being transferred from one animal to another. Each level is designated with specific terminology.

Understanding the food chain

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Primary producer

Make their own food from the energy they gain from the sun.

Understanding the food chain

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Primary Consumer

Get their energy directly from producers. This level of the food chain is occupied by either herbivores or omnivores – those organisms that eat plant tissue as part or all of their diet.

Understanding the food chain

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Secondary Consumer

Get their energy directly from other organisms. This level of the food chain is occupied by either carnivores or omnivores – those organisms that eat animal tissue as part or all of their diet.

Understanding the food chain

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Tertiary Consumer

Get their energy directly from other organisms. This level of the food chain is occupied by either carnivores or omnivores – those organisms that eat animal tissue as part or all of their diet.

Understanding the food chain

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Beyond tertiary consumers

There is a possibility of another level (quaternary consumers). This is a very rare occurrence. The last trophic level is often referred to as the top-level consumer – this is the consumer that doesn’t have many organisms that want to eat it (like humans).

Understanding the food chain

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Is the top-level consumer safe?

Just because there isn’t an organism that eats them, there is an aspect of a food chain that takes the energy of the top level consumer and places it back into the food chain system.

Understanding the food chain

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Fungi

Decomposer

These organisms feed from the dead tissue. They break it down into simple nutrients that are returned to the soil that is used by the plants.

A. B. C. D.

A B C D

What level is considered the primary consumer?

What does level D represent?

A. Primary ProducerB. Secondary ConsumerC. Tertiary ConsumerD. Quaternary Consumer

A B C D

Limitations of the Food Chain

The food chain implies that our consumers only eat ONE thing, but that is not the case

Just like you, animals of all types like a variety of food…

Therefore we rely on a food web to show us the entire energy transfer that is happening within an ecosystem.

A Food Web

When energy goes from one trophic level to another, does

all of the energy go to the next level?

A. YesB. No

Food Pyramids

In truth, only 10% of the overall energy is transferred from one trophic level to another.

How does this affect the number of trophic levels an ecosystem can support?

When you start with a limited supply, each level only gets 10% of that previous level 100% 10% 1% 0.1%

Food Pyramids0.1%

1%

10%

100%

Primary Producer

Primary Consumer

Secondary Consumer

Tertiary Consumer

Food Pyramids

0.1%1

%10%

100%

• The pyramid shows a picture of less energy at each level

• The pyramid also represents the amount of organisms that can be present at each level

More Energy, large population

Less Energy, small population

Where does the energy go?

Only 10% of the previous level’s energy passes on, so where does the rest go?

Law of Conservation of Energy states: Matter (Energy) is neither created nor destroyed.

Therefore, what is not passed on must be used by the organism The energy is used for basic function

Breathing Running Reproduction Digesting Released as heat

The Review

Which is more realistic of a communities interactions?

A. A food webB. A food chain

A producer is best described as

A. Being made up of many overlapping food chains

B. An organism that converts heat or light energy from the sun into other energy

C. A model that shows how energy is lost as it is transferred up the food chain

D. An organism that gets its energy by eating plants or animals

E. A model that shows one set of feeding relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

A consumer is best described as

A. Being made up of many overlapping food chains

B. An organism that converts heat or light energy from the sun into other energy

C. A model that shows how energy is lost as it is transferred up the food chain

D. An organism that gets its energy by eating plants or animals

E. A model that shows one set of feeding relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

A decomposer is best described as

A. Being made up of many overlapping food chains

B. An organism that converts heat or light energy from the sun into other energy

C. A model that shows how energy is lost as it is transferred up the food chain

D. An organism that gets its energy by eating plants or animals

E. A model that shows one set of feeding relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

A food chain is best described as

A. Being made up of many overlapping food chains

B. An organism that converts heat or light energy from the sun into other energy

C. A model that shows how energy is lost as it is transferred up the food chain

D. An organism that gets its energy by eating plants or animals

E. A model that shows one set of feeding relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

A food web is best described asA. Being made up of many overlapping food

chainsB. An organism that converts heat or light

energy from the sun into other energyC. A model that shows how energy is lost as it

is transferred up the food chainD. An organism that gets its energy by eating

plants or animalsE. A model that shows one set of feeding

relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

An energy pyramid is best described as

A. Being made up of many overlapping food chains

B. An organism that converts heat or light energy from the sun into other energy

C. A model that shows how energy is lost as it is transferred up the food chain

D. An organism that gets its energy by eating plants or animals

E. A model that shows one set of feeding relationships between a producer and several consumers

F. An organism that breaks down dead plants and animals into simpler compounds

The source of energy for almost all life on Earth is

A. fungiB. animalsC. waterD. sunlight