4. Trophic Levels

• Level 1 Trophic levels

  PRODUCERS : Plants and algae make their own food by photosnythesis
• LEVEL 2 TROPHIC LEVELS

  PRIMARY CONSUMERS : Herbivores eats plants/algae
• LEVEL 3 TROPHIC LEVELS

  • Secondary consumers : carnivores that eat herbivores
• LEVEL 4 TROPHIC LEVELS

  • Tertiary consumers : Carnivores that eat other carnivores
• Apex predators


  • Carnivores with no predators
• TROPHIC LEVELS : role of decomposers


  • Break down dead plant and animal matter by secreting enzymes into the environment.
  • Small soluble food molecules then diffuse into the microorganism.
• Order of TROPHIC LEVELS

  1. Producer
  2. Primary consumer
  3. Secondary consumer
  4. Tertiary consumer
  5. Apex predator
• Define biomass

  • Mass / living tissue of living organisms
• What does each bar in a pyramid of biomass show?

  • The biomass of all organisms in that trophic level
• What percentage of biomass from a trophic level is passed to the one below it?

  • Only 10%
• Losses are biomass are due to what 3 reasons?

  1. Not all ingested material is absorbed - some are egested as faeces.
  2. Some absorbed material is lost as waste e.g carbon dioxide and water in respiration. Water and urea in urine.
  3. Large amounts of glucose is used in respiration
• Efficiency of biomass 


  Gain of biomass / total biomass intake x 100
• How much of the energy that plants and algae take in from light transferred to the next trophic level?

  • 1%
• Explain how the loss of biomass at each trophic level affects the number of organisms at each level.

  • At each trophic level, less of the original biomass is passed on.
  • This means a smaller amount of biomass can be supported at each level.
  • Number of organisms usually decreases at each level.