Read Food Chains: Arrows Show Food and Energy
Read every food-chain arrow as ‘is eaten by’ or ‘energy passes to’. Start with the producer and work forward one trophic level at a time.
Living-system questions are solved by matching a structure or organism to its function, process and stated condition.
Follow energy one eater at a time
Arrow = energy moves to the eater
Start at the producer. When one population changes, first trace the organisms that directly depend on it for food.
Build the chain
Plants are producers; decomposers recycle nutrients after organisms die.
Predict a disturbance
If insecticide greatly reduces insects, insect-eating birds may decline; predators of those birds can then decline. Follow the direct food shortage before predicting later effects.
Check the consumer label
A herbivore eats plants and is a primary consumer. A carnivore eats animals. An organism’s position, not its size, decides its trophic level.
OlympIQ exam lens
- ✓Start every chain with the producer.
- ✓Follow arrows in the direction of energy transfer.
- ✓Predict the direct population change before indirect changes.
Decomposers do not begin the food chain, but they are essential because they return nutrients to the system.
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