How Ecosystems Work

How Ecosystems Work Big Ideas

• Energy is transferred from the sun to producers

• Producers then transfer the energy to consumers

• Inefficient energy transfer has an effect on community structure

Life Depends ENERGY, LOTS OF ENERGY…from the Sun

• Average Star

• 93 million miles away

• Nuclear Fusion

• No Sun, No Life

Life Depends on the SunALL organisms need a constant supply of energy or they die

Why do plants grow upwards?

CO2 + H2O + Sunlight O2 + C6H12O6

What is photosynthesis?

The process of converting

carbon dioxide, water and

sunlight into oxygen and

glucose.(In plants, algae,

some bacteria)Occurs in

chloroplasts

From Producer to Consumer

• Producer: an organism that makes it own food

• Plants

• Autotrophs, self-feeders

• Use sunlight• Base of all food

chains

What role do Autotrophs (Producers) Play?

• Gather the energy from the sun and turn it into food via photosynthesis. Lichens are an example.

Phytoplankton get no credit

From Producer to Consumer

• Consumer: gets it energy by eating producers or other consumers

• Heterotrophs• Indirectly solar

powered

What role do Heterotrophs

(Consumers) play?

Heterotrophs eat other organisms to obtain their energy.

Stored energy in food is extracted with or

without oxygen.

Types of Consumers

• Herbivore: eats only producers (vegetarian)• Cows, sheep, deer, grasshopper, mice, rabbits

Herbivore

Types of Consumers

• Carnivore: eats other consumers

• Lion, hawks, snakes, alligator, toothed whales

Carnivore

Types of Consumers

• Omnivore: eats both producers and consumers

• Bears, pigs, raccoons and most humans

Omnivore

Types of Consumers

• Decomposer: breaks down dead decaying organisms

• Critical to ecosystem health

• Returns nutrients• Fungus, bacteria

Detritivores and decomposers: recycle nutrients within the ecosystem by breaking down nonliving organic matter

Decomposer

How do Organisms Use Energy

Most organisms spend large amounts of time/energy in search of food and a mate.

How do organisms get the energy from the food (glucose)? Two

ways.Aerobic Respiration – use oxygen to

extract energy from glucose

Anaerobic Respiration – oxygen is NOT used to extract energy from glucose

Cellular Respiration (Aerobic Respiration) allows organisms to use the energy store in glucose.

C6H12O6 O2 CO2 H2O ATP+ + +

Aerobic Respiration aka “Cellular Respiration”

Formula

Photosynthesis & Cellular Respiration

In photosynthetic organisms, the processes of

photosynthesis and cellular respiration

work together.The products of one can be used for the

other.

Energy TransferEach time one organism eats another, energy is transferred

Ecosystems are all about energy flowing from one organism to another

Energy Transfer

• Who are the producers?

• Consumers?• Herbivores?• Carnivores?• Omnivores?• Decomposers?• Where does the

energy start?

How does energy flow through an ecosystem?

• A food chain is a series of steps in which organisms transfer energy by eating or being eaten (arrows?)

• All food chains have a producer on bottom, which supplies each level above with food

• Energy flows in one direction through a Food Chain.

• Each step in a food chain is called a trophic level.

Energy Transfer

• Food Chain: sequence in which energy is transferred from one organism to another

• Starts with producers• Energy flows in one

direction

Food WebA food web shows the various food chains within an

ecosystem.

Can you describe one food chain within

this food web?

What is missing from this food web?

Energy Flow• Food Web:

shows many feeding relationships that are possible in a ecosystem

• More complex and realistic

Energy Flow

• Trophic Level: each step which energy is transferred

How is energy monitored in a food chain?

Energy Pyramid track available energy in a food chain. Only 10% of the available energy is passed from one trophic level to the next.

Energy Pyramid

10,000 units of energy

1,000 units of energy

100 units of energy

10 units of energy

1 unit of energy

Energy Flow

• At each trophic level about 90% of energy is lost

• Cellular respiration• Lost to heat body

and carry out living

Energy Flow

• Why are there fewer organisms at the top? (Why fewer bears than the fruit they feed on)

• Why aren’t there more than 4-5 trophic levels in a energy pyramid?

Review

• Energy is transferred from the sun to producers through the process of photosynthesis

• Consumers use the glucose made by producers for energy

• Food webs show more complex & realistic feeding relationships in a ecosystem

• Energy pyramids track available energy in a food chain. Only 10% of the available energy is passed from one trophic level to the next.