Da VIP Academy / GED / Science / Life Science
Ecosystems & Energy Flow
Trace energy through food webs and predict how changes affect populations.
How it works
Energy flows one way
Producers capture sunlight, consumers eat producers, and decomposers recycle nutrients. Only about 10% of energy passes to the next level, which is why top predators are few.
Change one part, change the web
Remove a predator and prey populations often spike, then crash when food runs out. Add a limiting factor — water, nutrients, space — and growth slows.
Worked examples
A disease kills most hawks in an area. Predict the effect on mice.
- Fewer predators.
- Mouse population rises at first.
- Then food and space limit further growth.
Words to know
- Producer
- An organism that makes its own food, usually by photosynthesis.
- Limiting factor
- A resource that caps population growth.
Test-day tips
- • Arrows in a food web point in the direction energy moves — toward the eater.