Flow of Energy Through Living Systems

Food ChainsFood Webs

Energy Pyramids

•Begins with the SUNBegins with the SUN

•PhotosynthesisPhotosynthesis

6CO2 + 6H2O + sunlight & chlorophyll C6H12O6 + 6O2

Photosynthesis• Is a chemical reaction where green plants useIs a chemical reaction where green plants use

water water andand carbon dioxide carbon dioxide to store theto store the sun’s sun’s energy energy in the form ofin the form of glucose. glucose.

• ENERGY is stored in glucoseENERGY is stored in glucose

• Glucose is Glucose is stored as stored as starch starch in in plantsplants

Organisms that can make glucose during photosynthesis are called

PRODUCERS.

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Producers Producers use most of the use most of the

energy they makeenergy they make for themselves.for themselves.

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Producers

use cellular respiration

to supply the energy they need to live.

CELLULAR RESPIRATION is the chemical reaction

that releases the energy in glucose.

6O2 + C6H12O6 -->  6H2O + 6CO2 + energy

The energy that is not used by producers can be passed on to

organisms that cannot make their own energy.

Organisms that cannot make their own energy are called

CONSUMERS.

Consumers that eat Producers to get energy:

• Are first order or primary consumers

• Are herbivores (plant-eaters)

Most of the energy

the primary consumer gets from the producer is used by the consumer.

Some of the energy

moves into the atmosphere

as heat.

Some of the energy

is not lost to the atmosphere or used by the consumer.

This energy is available for another consumer.

(about 10%)

A consumer that eats another consumer for energy:

• Is called a secondary or second order consumer

• May be a carnivore

or an omnivore

• May be a predator

• May be a scavenger

Most of the energy the

secondary consumer gets from the primary consumer is

used by the secondary consumer.

Secondaryconsumer

Some of the energy

is lost as heat, but some energy

is stored and can be passed on to another consumer

(about 10%).

A consumer that eats a consumer that already ate a consumer:

• Is called a third order or tertiary consumer

• May be a carnivore or an omnivore

• May be a predator

• May be a scavenger

Consumers that eat xx producers & other consumers

• Are called omnivores

• Omnivores eat plants and animals

Consumers that hunt & kill other consumers

are called predators.

The animals that are hunted & killed are called prey.

Consumers that eat other consumers

that have already died are called scavengers.

Consumers that chemically breakdown organic matter like animal

remains are called decomposers.

The transfer of energy from sun

to producer to primary consumer

to secondary consumer to tertiary consumer

can be shown in a FOOD CHAIN.

FOOD CHAINS

A food chain shows the path of energy from one organism to the next

– energy flows from producers to

consumers

– arrows point to who is eating

(plant is eaten by herbivore)

– Can vary in lengthCan vary in length

– Usually decomposers are left out

Another food chain

Another way of showing the transfer of energy in an

ecosystem is theENERGY PYRAMID.

10% Rule

ONLY 10% of the energy from an organism on one level can be passed on to an organism on the next level.

Energy Pyramids

show • That the amount of available energy decreases up the food chain

• It takes a large number of producers to support a small number of primary consumers

• It takes a large number of primary consumers to support a small number of secondary consumers

ENERGY

LOSS

Producers

1st Order Consumers

(Herbivores)

2nd Order Consumers

(Carnivore or Omnivore)

3rd Order Consumers

(Carnivore or Omnivore)

ENERGY

LOSS

Food WebsFood Webs

• Feeding Feeding relationshipsrelationships are much more are much more complicated than a single, one-way complicated than a single, one-way chainchain

• Many animals eat more than one kind of Many animals eat more than one kind of foodfood

• Food webs show these relationshipsFood webs show these relationships

Food Webs:

• Are interconnected food chains

• They show the feeding relationships in an ecosystem

FOOD WEBS• Typically, food webs go like this:

PRODUCER

CONSUMER(HERBIVORE)

CONSUMER(CARNIVORE)

CONSUMER(OMNIVORE)

DECOMPOSER

remember: decomposers receive energy from all other organisms in an ecosystem

FOOD CHAINS AND WEBS• Practice! Draw a food

chain that includes the following organisms:– grasshopper– mouse– grass– owl

• Now label the organisms as producers, consumers (which type?), or decomposers PRODUCER

CONSUMER(HERBIVORE)

CONSUMER(CARNIVORE)

CONSUMER(CARNIVORE)

FOOD CHAINS, WEBS & ENERGY PYRAMIDS

• Food chains/webs can

be written as a pyramid:

– Producers form the base of the pyramid

– Consumers form the upper layers

Review Review Identify the following as producers or Identify the following as producers or consumers.consumers.

• FungiFungi• CowsCows• HumansHumans• Mushrooms Mushrooms • GrassGrass• TreesTrees• MouseMouse

ReviewReviewYoung rabbits that eat grass are sometimes eaten by raccoons, which also eat seeds and berries. Bacteria help to decompose the excretions of the raccoon. Which statement about these nutritional relationships is accurate?

1.1. Bacteria are scavengers.Bacteria are scavengers.

2.2. Rabbits are secondary consumers.Rabbits are secondary consumers.

3.3. Raccoons eat only producers.Raccoons eat only producers.

4.4. Raccoons are both primary and secondary consumers.Raccoons are both primary and secondary consumers.

ReviewReviewBase your answer on the chart and your Base your answer on the chart and your knowledge of biology. Which is an example of knowledge of biology. Which is an example of the nutritional pattern of a primary consumer?the nutritional pattern of a primary consumer?

1.1.prickly pear cactuses – desert ratsprickly pear cactuses – desert rats2.2.grasshoppers – lizardsgrasshoppers – lizards3.3.scorpions – bacteriascorpions – bacteria4.4.lizards – roadrunnerlizards – roadrunner

Review Review Which statement best describes an Which statement best describes an energy pyramid?energy pyramid?

1.1. There is more energy at the consumer level than There is more energy at the consumer level than at the producer level.at the producer level.

2.2. There is more energy at the producer level that at There is more energy at the producer level that at the consumer level.the consumer level.

3.3. There is more energy at the secondary-consumer There is more energy at the secondary-consumer level than at the primary-consumer level.level than at the primary-consumer level.

4.4. There is more energy at the decomposer level There is more energy at the decomposer level than at the consumer level.than at the consumer level.

ReviewReview

The diagrams represent four members of a food The diagrams represent four members of a food chain. Which sequence best represents the chain. Which sequence best represents the transfer of energy between these organisms?transfer of energy between these organisms?

1.1. toads – predaceous insects – herbivorous toads – predaceous insects – herbivorous insects – plantsinsects – plants

2.2. predaceous insects – herbivorous insects – predaceous insects – herbivorous insects – plants – toadsplants – toads

3.3. plants – herbivorous insects – predaceous plants – herbivorous insects – predaceous insects – toadsinsects – toads

4.4. plants – herbivorous insects – toads – plants – herbivorous insects – toads – predaceous insectspredaceous insects

Review Review If birds eat insects that feed on corn, which If birds eat insects that feed on corn, which pyramid level in the diagram would birds pyramid level in the diagram would birds occupy?occupy?

1.1. AA

2.2. BB

3.3. CC

4.4. DD

Review Review

Compared to the energy contained in the Compared to the energy contained in the plants eaten by cows, the amount of energy plants eaten by cows, the amount of energy available to the organisms that eat the cows is available to the organisms that eat the cows is less, since cowsless, since cows

1.1. reproduce rapidly and pass on most of the energy to reproduce rapidly and pass on most of the energy to their offspringtheir offspring

2.2. convert solar energy to foodconvert solar energy to food

3.3. store all their energy in milkstore all their energy in milk

4.4. use energy for their own metabolismuse energy for their own metabolism

Review Review In an ecosystem, the more living In an ecosystem, the more living requirements that two different species requirements that two different species have in common, the more intense will be have in common, the more intense will be their…their…

1.1.ecological successionecological succession

2.2.competitioncompetition

3.3.energy requirementsenergy requirements

4.4.adaptationadaptation