Ecosystem Energy Flow

Unit 11: Energy Flow through Ecosystems

• Ecosystems need a continuous energy supply for life processes.
• The continuous supply replaces energy lost as heat.
• Most ecosystems depend on sunlight for energy.
• Energy in carbon compounds enters biological communities.
• Autotrophs include plants, algae, and cyanobacteria.
• Light converts to chemical energy via photosynthesis in carbon compounds.
• Autotrophs and heterotrophs are two methods of nutrition for species.
• Autotrophs produce their own food.
• Heterotrophs consume other organisms for nutrition.
• Plants and algae are mostly autotrophic.
• Parasitic plants have nutritional discrepancies.
• Parasitic plants get nutrients from a host, despite being photosynthetic.
• Consumers are heterotrophs, feeding on living organisms through ingestion.
• Consumers exhibit various feeding behaviors.
• Examples of consumers are herbivores, carnivores, and omnivores.
• Detritivores are heterotrophs, extracting organic nutrients from detritus through internal digestion.
• Detritus includes dead organic matter and feces.
• Examples of detritivores are earthworms and woodlice.
• Saprotrophs, also heterotrophs, obtain organic nutrients from dead matter via external digestion.
• Examples of saprotrophs include fungi and bacteria.
• Species can be classified as autotrophs, consumers, detritivores, or saprotrophs based on nutrition mode.
• Chemical energy flows through food chains through feeding.
• A food chain illustrates energy transfer.
• Arrows in food chains/webs show energy direction.
• Food chains consist of producers, primary, secondary, and tertiary consumers.
• Respiration releases energy from carbon compounds, converted to heat.
• Three reasons organisms need energy are cell activities, growth, and reproduction.
• ATP (adenosine triphosphate) stores and transports energy within cells.
• ATP forms through cellular respiration.
• Respiration releases heat as a byproduct.
• Living organisms cannot convert heat into other energy forms.
• Heat dissipates from ecosystems.
• Heat generated by organisms is eventually lost.
• Energy loss between trophic levels limits food chain length and biomass in higher levels.
• Biomass is the total mass of living organisms in a given area or volume.
• A trophic level is an organism's position in a food chain or web.
• Energy in each trophic level uses units like kilojoules per square meter per year (kJ m⁻² yr⁻¹).
• Energy decreases at higher trophic levels due to respiration, non-consumption, and excretion.
• 10% is the average energy transferred between trophic levels.
• Energy flow theory explains the limited length of food chains.
• Limited organisms exist in a food chain because of energy flow.
• Pyramids of energy quantitatively represent energy flow.
• Pyramids of energy are shaped like pyramids.
• Units for pyramids of energy include kJ m⁻² yr⁻¹.
• The law of conservation of energy states energy is neither created nor destroyed, only converted.
• Energy conversion is the change in energy from one form to another.