(FR-Unit1) 03.1 Ecosystem

Autotrophs are organisms that can capture energy from nonliving sources and convert it into forms living cells can use.

Primary producers are the first producers of energy-rich compounds that can be used later by other organisms.

Photosynthesis is the process by which plants and algae harness solar energy to convert carbon dioxide and water into energy-rich carbohydrates such as sugars and starches.

Photosynthesis produces oxygen that is released into the atmosphere and removes carbon dioxide. Without photosynthesis, there would be no oxygen to breathe.

Plants are the main primary producers on land.

Plants and algae share the role of primary producers in freshwater ecosystems.

Algae are the primary producers in sunlit parts of the ocean.

Chemosynthesis is a process in which chemical energy powers the production of carbohydrates. It is used by certain bacteria to obtain energy from inorganic compounds such as hydrogen sulfide.

Chemosynthetic bacteria can be found around volcanic vents in the deep sea, deep within Earth's crust, in underground streams and caves, and in the mud of tidal flats.

Chemosynthesis has been found to be more common and to occur in more environments than previously expected. It serves as an alternate form of primary production and supports diverse ecosystems.

Heterotrophs are organisms that cannot harness energy directly from the environment as primary producers do. They must acquire energy from other organisms, usually by eating them.

Consumers are organisms that rely on other organisms for energy and nutrients. They acquire energy and nutrients by consuming other organisms.

Animals that eat leaves cultivate microorganisms inside their guts that can digest cellulose for them. These microorganisms break down cellulose into digestible components.

Grazing animals extract relatively little energy from each mouthful of leaves, so they need to consume a large quantity of leaves to meet their energy needs.

The digestive system needed to extract energy and nutrients from leaves is very heavy, which limits the number of bird species that can efficiently digest leaves.