Unit: Interactions among Organisms
Section: Trophic Relationships
Key Words: trophic levels, energy, food chain, food web, consumer, producer, predator, prey, decomposer
Essential Questions:
- What is a trophic level?
- How do different populations from the same trophic level interact
- How do populations from different trophic levels interact?
Trophic Levels
- Energy exchanged or transferred in a food web
- Loss of energy in transfer from organism to organism is lost as heat energy to the environment
- Depends upon:
o The population of the organisms
o Availability of energy to the organisms
- measures the energy available in the environment
o higher the trophic level, the less energy available
 consumers
 decomposers
o lower the trophic level, the more energy available
 producers
o inverse relationship
- competition
o limits the size of populations involved
o organisms on the same trophic level can compete for food
o predator/prey relationships
 higher level (predator) hunts a lower level (prey)
o different levels, may have symbiotic relationships
 bees (primary consumers) and flowering plants (producers)
 bees obtain food from plants
 plants use bees as pollinators
 mutualism – both benefit from the relationship