- Sunlight provides energy for most life on Earth through the process of photosynthesis, where plants, algae, and some bacteria use carbon dioxide, water, and sunlight to produce sugar and oxygen. - Producers are organisms that convert sunlight into chemical energy through photosynthesis. Consumers eat other organisms for energy and include herbivores, carnivores, and omnivores. Decomposers and detritivores break down dead organic matter. - Cellular respiration is the process where cells use sugar and oxygen to produce energy, carbon dioxide, and water. Energy transfers between organisms as they eat each other in food chains and food webs.

1. Energy Flow in Ecosystems Environmental Science

2. Life Depends on the Sun Energy enters an ecosystem when a plant uses sunlight to make sugar (carbohydrates) This process is called photosynthesis CO 2 + H 2 O + energy  C 6 H 12 O 6 + O 2 Plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce sugar and oxygen.

3. Producers Sunlight is the ultimate source of energy for most life on earth Organisms that convert sunlight into chemical energy are called producers Also called autotrophs OR chemotrophs Chemotrophs the exception to the rule – they are found at the bottom of the ocean where no sunlight reaches Bacteria use hydrogen sulfide to create energy Other organisms feed off the bacteria

4. Consumers Organisms that consume other organisms for energy are consumers ( heterotrophs) Types of heterotrophs Herbivores – eat only producers Carnivores – eat only other consumers Omnivores – eat producers and consumers

5. More consumers… Detrivores – also called scavengers Eat animal remains and other dead matter Decomposers - break down organic matter Include bacteria and some fungus

6. Cellular Respriation The process in which cells use sugar to create energy is called cellular respiration C 6 H 12 O 6 + O 2  CO 2 + H 2 O + energy Cells use glucose (sugar) and oxygen to produce carbon dioxide, water, and energy. Cellular respiration occurs inside the cells of most organisms

7. Energy Transfer Each time one organism eats another, energy is transferred Food chains Show one-way flow of energy in an ecosystem Each step on the food chain is called a trophic level

8. Feeding Relationships Food webs Includes more organisms and multiple food chains linked together

9. Trophic Levels Visualization of the loss of energy from one trophic level to the next Often shown as an pyramid Shows relative energy movement in an ecosystem Only 10% of the energy moves to the next level

10. Biomagnification Pollution can lead to biomagnification – the concentration of toxic substances in organisms as you move up trophic levels Ex. DDT and birds of prey; mercury in tuna and sharks