7.4 Trophic levels in an ecosystem (Triple) Flashcards
What does a food chain show? (Triple)
It describes the feeding relationships between organisms and the resultant stages of biomass transfers
What are trophic levels? (Triple)
The stages in a food chain
How are trophic levels represented? (Triple)
Trophic levels are represented by numbers, starting from 1. After 1, trophic levels are numbered according to how far along the organism is in the food chain.
What is trophic level 1? (Triple)
Plants and algae which make their own food (through photosynthesis) - called producers.
What is trophic level 2? (Triple)
Herbivores which eat producers - called primary consumers.
What is trophic level 3? (Triple)
Carnivores that eat herbivores - called secondary consumers
What is trophic level 4? (Triple)
Carnivores that eat carnivores - called tertiary consumers
What is an apex predator?
A carnivore with no predators
How do decomposers break down dead matter?
Decomposers release enzymes which catalyse the breakdown of dead material into small molecules. Soluble small food molecules then diffuse into the organisms.
What is biomass?
The dry mass of all of the living organisms in an area
What is dry mass used for biomass?
Because the wet mass varies as the volume of water in the organism varies
How do you calculate the efficiency of biomass transfer?
Efficiency = (energy transferred / total energy available) x 100
What percentage of the incident energy from light for photosynthesis do producers transfer?
1%
What percentage of the biomass from one trophic level is transferred to the level above it in feeding?
Approximately 10%
Why are biomass transfers not 100% efficient?
Energy lost through:
● Egestion (removal of faeces)
● Excretion (removal of waste products e.g. urine containing urea and water)
● Respiration (loss of carbon dioxide and water) in which large amounts of glucose are used
● The production of inedible bones and shells
