Skip to main content

How Ecosystems Work

Energy Flow in Ecosystems

     Sun energy enters the ecosystem by photosynthesis.  Photosysnthesis uses light energy from the sun, CO2, and H2O to make sugar molecules.  Sugar is a carbohydrate, which is an energy-rich molecle which organisms use to carry out daily activities.

6 CO+ 6H2O + solar energy -→ C6H12O6 + 6 O2


A producer is an oeganism that makes its own food.producer are also called consumers, orgnisms that get their energy by eating other organisms.consumers are also called heterotrphs, the energy fro m the sun.

Some consumers get their food by breaking down organisms and are called decomposers. Bacteria and fungi are examples of decomposers.



Energy Source


Producer plants

Makes its own food through

Grasses, ferns, cactuses, flowering


Gets energy by eating producers or other consumers

Mice, starfish, elephants, turtles, humans, and ants


Cellular respiration is the proces of breaking down food to yield energy during cellular respiration.  Cells absorb oxygen and use it to release energy from food.

C6H12O+ 6O2----->6 CO+ 6 H2O + energy

Food chain – is a sequence in which energy is transferd from one organism to the next as each organism eats another organism.

Food web – shows many feeding relationships that are possible in an ecoystem. 

Trophic level – each step in the transfer of energy through a food chain or food web in an ecosystem.

The decreased amount of energy at each trophic level affects the organization of an ecosystem.

The carbon cycle is a process witch carbon is cycled between the atmosphere, land, water, and organisms. a process in which nitrogen is cycled between the atmosphere, bacteria, and other organisms is known as the nitrogen cycle. 

Algal Booms – excess nitorogen and phosphorus in an aquatic ecosystem or nearby waterway that causes an excess growth of algae.

Ecological Succession – is a gradual process of change and replacement of the types of species in a community

Primary Succession – is a type of succession that occurs on a suface where no ecosystem existed before.

Secondary Succession – occurs on a surface where an ecosystem has previously existed.

Such plants are called pioneer species the first organisms to colonize any newly available area and begin the process of ecological seccession.

A climax community is a final and stable community.