2. Life Depends on the Sun Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules. Photosynthesis Plants, algae, some bacteria capture solar energy. Solar energy powers a series of reactions that require carbon dioxide and water. Sugar molecules (carbohydrates) are produced. Carbohydrates provide the energy that organisms need to carry out daily activities. As organisms consume food and use energy, the energy travels from one organism to another.
4. Life Depends on the Sun Producers (Autotrophs) – Organisms that make their own food. Plants, algae, some bacteria Consumers (Heterotrophs) – Organisms that get energy by eating other organisms. Humans, coyotes, cats, cows,
5. Deep-Ocean Ecosystems Total darkness Bacteria use Hydrogen Sulfide (H2S) to make their own food. H2S comes from the hot water that escapes the cracks in the ocean floor. The bacteria are then eaten by consumers.
6. What Eats What Organisms can be classified by what they eat. Types of Consumers: Herbivores Carnivores Omnivores Decomposers
8. Sun Oxygen (O2) Producer Carbon dioxide (CO2) Secondary consumer (fox) Primary consumer (rabbit) Precipitation Producers Falling leaves and twigs Soil decomposers Soluble mineral nutrients Water Fig. 3-10, p. 57
9. Scavengers Decomposers Termite and carpenter ant work Carpenter ant galleries Bark beetle engraving Long-horned beetle holes Dry rot fungus Wood reduced to powder Mushroom Powder broken down by decomposers into plant nutrients in soil Time progression
10. Cellular Respiration Organisms break down food to yield energy. Cellular Respiration Occurs inside cells of organisms Cells absorb oxygen and use it to release energy from food Cellular Respiration is the reverse of photosynthesis Sugar and oxygen combine to yield carbon dioxide, water, and energy.
12. Energy Transfer Each time one organism eats another organism, a transfer of energy occurs. Food chains, food webs, and trophic levels tell us how energy is transferred and how much energy is transferred. Studying the paths of energy between organisms can tell us which organisms in an ecosystem depend on other organisms to survive.
13. Food Chains, Food Webs, Trophic Levels Food Chain – A sequence in which energy is transferred from one organism to the next as each organism eats another organism. Food Web – Includes many organisms and multiple food chains linked together. Trophic Levels – Each step through which energy is transferred in a food chain or web.
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15. First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Tertiary consumers (top carnivores) Secondary consumers (carnivores) Producers (plants) Primary consumers (herbivores) Heat Heat Heat Solar energy Heat Heat Heat Heat Detritivores (decomposers and detritus feeders) Heat
16. Humans Blue whale Sperm whale Crabeater seal Elephant seal Killer whale Leopard seal Adelie penguins Emperor penguin Squid Petrel Fish Carnivorous plankton Krill Herbivorous plankton Phytoplankton
17. Energy Loss in an Ecosystem Each time energy is transferred from one organism to another, some of the energy is lost as heat and less energy is available to organisms at the next trophic level. About 90% of the energy at each trophic level is used for life functions. The remaining 10% of the energy becomes part of the organism’s body and is stored in its molecules. The stored 10% is all that is available to the next trophic level when one organism consumes another organism.
19. Energy Loss in an Ecosystem The Loss of Energy… Means there are fewer organisms at each level. Limits the number of trophic levels in an ecosystem
20. Summary Questions Describe how energy is transferred from one organism to another. Give examples. Describe the role that producers play in an ecosystem. What would happen if the producers became extinct? Define and give examples of herbivore, carnivore, and omnivore. Compare energy transfer in a food chain to energy transfer in a food web. Could more people be supported by 20 acres of land if they only ate plants instead of both plants and animals. Explain your answer.
