IB Biology 4.2 Energy flow
Terms in this set (7)
Feeding position of an organism in a food chain
Outline how energy enters and flows between trophic levels in an ecosystem.
- Sunlight is the source of energy for most ecosystems.
- Photosynthetic organisms absorb light energy.
- Photosynthesis converts light energy into chemical energy in organic carbon compounds.
- Consumers obtain their organic carbon compounds by feeding on the previous trophic level.
How is energy released from organic carbon compounds within organisms?
- All organisms release energy from organic carbon compounds by cell respiration (to make ATP).
- ATP is used for essential cell processes.
- Energy is lost as heat.
- The heat energy lost cannot be re-used by organisms.
How is energy lost between trophic levels?
- Energy transfer is approximately 10% from one level to the next.
- Some material is not consumed.
- Of the organic carbon compounds eaten, only a small fraction becomes assimilated; most of the food is used as an energy source.
- Of the energy that is assimilated, not all is passed onto the next trophic level.
- The material not eaten by the consumer in the next trophic level will be available for detritivores and saprotrophs.
Outline how biomass is lost at each trophic level.
Biomass is lost when waste products of metabolism are excreted (carbon dioxide and water are waste products of cell respiration, urea is lost in the urine).
What is the consequence of energy loss at each trophic level?
Energy loss limits the length of food chains and the biomass of higher trophic levels.
Distinguish between the way nutrients and energy move in an ecosystem.
- Energy flows through an ecosystem.
- Nutrients are recycled.