Section 5-1: Energy Flow in an ecosystem

Objectives: Describe how energy is transferred from the sun to producers and then to consumers. Describe one way in which consumers depend on producers. Identify two types of consumers. Explain how energy transfer in a food web is more complex than energy transfer in a food chain. Explain why an energy pyramid is a representation of trophic levels.

Life Depends on the Sun Energy from the sun enters an ecosystem when plants use light energy to make sugar molecules. This happens through a process called photosynthesis.

Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen. (know formula) 6 CO H 2 O → C 6 H 12 O O 2 Carbon dioxide + Water + Light energy → Glucose + Oxygen

From Producers to Consumers A producer is an organism that can make organic molecules from inorganic molecules. Producers are also called autotrophs, or self- feeders.

From Producers to Consumers A consumer is an organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources. Consumers are also called heterotrophs, or other- feeders.

The Cycling of Nutrients… *Decomposition connects all trophic levels*

What eats what? Organisms can be classified by what they eat. Types of Consumers: Herbivores Carnivores Omnivores Decomposers

Cellular Respiration: Burning the Fuel The process of breaking down carbohydrates to yield energy is called cellular respiration. Cellular respiration occurs inside the cells of most organisms. the opposite of photosynthesis (know formula) C 6 H 12 O 6 +O 2 ---> CO 2 + H 2 O + ATP sugar + oxygen ----> carbon dioxide + water + energy

Energy Transfer Each time an organism eats another organism, an energy transfer occurs. This transfer of energy can be traced by studying food chains, food webs, and trophic levels. Most of the remaining energy is used by the organism to maintain daily functions such as producing new cells, regulating body temperature, moving etc. 10% is passed to the next level

Energy Transfer Energy is studied as it travels through food chains, webs and trophic levels Food chains = energy flow from 1 organism to the next Food webs = many feeding relationships Each step in the transfer of energy through a food chain or food web is called a trophic level Energy pyramids illustrate trophic levels in ecosystems

Trophic Levels Each step in the transfer of energy through a food chain or food web is known as a trophic level. A trophic level is one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers.