All organisms need energy to function. They get energy by converting nutrients. Photosynthesis, respiration and fermentation are all examples of nutrients being converted to energy.


Plants take in Carbon Dioxide (CO2) , Water (H20) and photons from sunlight. These are converted to carbohydrates, which plants cells convert to energy, and oxygen, which is given off.


Cellular Respiration is the process by which cells convert carbohydrates, like glucose (C6H1206) to energy. The body then uses the energy to carry out its functions.


Fermentation is carbohydrates being converted to gases or alcohol. Foods that are fermented may taste sour or contain alcohol.  Kimchi (pictured) is a fermented food.

Energy Pyramid

Energy in an ecosystem flows through a pyramid. Energy producers (like plants) are consumed by primary consumers (herbivores). Primary consumers are consumed by secondary consumers (carnivores). Secondary consumers are consumed by Tertiary consumers (carnivores who eat other carnivores). The primary consumers rely on there being enough producers to feed them. The secondary consumers rely on there being enough primary consumers to eat. Any disruption in the ecosystem can disrupt all levels of the pyramid.

Energy Flow in the Pyramid

Energy flows through the pyramid. Organisms take in energy through sunlight and producers and low-level consumers. An organism loses energy by giving off heat or by being consumed by higher-level consumers.

Food Web

The food web describes matter flowing through the ecosystem. Predators rely on prey to survive, and changes in population can affect other populations. Species that rely on each other are said to have symbiosis.

Carrying Capacity

The Carrying Capacity is the maximum number of a species that can survive in an ecosystem. The carrying capacity depends on habitat, water, food and other necessities available. Some woodpeckers are an example of a species with a low carrying capacity for its size. Because they are territorial and require hollowed trees to nest in, few of them can live in the same area of forest.

Disruption of Ecosystems

Disruption of ecosystems can hurt populations of species. Some examples of disruption include: invasive species, which are species that are introduced to an area and kill or crowd out the native species; flooding, which destroys habitat; desertification, which is the absence of water in an ecosystem; and any other disaster that kills species populations or leaves them without habitat.


Disruption of ecosystems can lead to extinction. Extinction of a species is when no surviving members exist. Once a species is extinct, it can never be reproduced.









Kimchi Photo:  User nhlord/Wikimedia; Woodpecker Photo:  Aida Villaronga