Trophic Levels in an Ecosystem

• What does a food chain show?

  Feeding relationships and biomass transfer
• What are trophic levels?

  The stages in a food chain
• How are trophic levels represented?

  By numbers starting from 1
• What is trophic level 1?

  Plants and algae, called producers
• What is trophic level 2?

  Herbivores, called primary consumers
• What is trophic level 3?

  Carnivores that eat herbivores
• What is trophic level 4?

  Carnivores that eat other carnivores
• What is an apex predator?

  A carnivore with no predators
• How do decomposers break down dead matter?

  By releasing enzymes to catalyze breakdown
• What is biomass?

  The dry mass of living organisms
• Why is dry mass used for biomass?

  Wet mass varies with water content
• How do you calculate the efficiency of biomass transfer?

  efficiency = (energy transferred / total energy available) × 100
• What percentage of incident energy do producers transfer?

  1%
• What percentage of biomass is transferred to the next trophic level?

  Approximately 10%
• Why are biomass transfers not 100% efficient?

  Energy is lost through various processes
• How does the efficiency of biomass transfers affect trophic levels?

  Fewer efficient transfers lead to fewer trophic levels
• What is a biomass pyramid?

  A pyramid showing total dry mass at levels
• What is a pyramid of numbers?

  A pyramid showing the number of organisms
• Why can a pyramid of numbers not be pyramid shaped?

  It doesn't account for size and mass
• Why does egestion cause energy loss in biomass transfers?

  Egestion is the removal of faeces. Egestion removes undigested food as faeces, meaning that energy stored in this material is not passed on to the next trophic level.
• Why does excretion cause energy loss in biomass transfers?

  Excretion removes waste products like urine, which contain lost energy in the form of excess nitrogen and other substances that cannot be used by the next consumer.
• Why does respiration cause energy loss in biomass transfers?

  Respiration uses energy for movement and essential body processes, releasing some as heat, carbon dioxide, and water, which cannot be transferred to the next organism.
• Why do inedible parts cause energy loss in biomass transfers?

  Some energy is locked in bones, shells, and other inedible structures that are not consumed, preventing it from being passed through the food chain.