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 Sun ALL organisms need a constant supply of energy or they die Why do plants grow upwards?

What is photosynthesis? CO2 + H2O + Sunlight  O2 + C6H12O6 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.

Aerobic Respiration aka “Cellular Respiration” Formula C6H12O6 + O2 CO2 + H2O + ATP

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 Transfer Each 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 Web A 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 1 unit of energy 10 units of energy 100 units 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.