Food webs and energy transfer
Follow the direction of energy transfer and predict a possible ecosystem effect.
Before you begin
- Plants and animals
- Reading arrows in a diagram
Read a feeding relationship
In a food chain, an arrow points from the organism eaten to the organism that eats it, showing energy transfer. Producers such as green plants store energy through photosynthesis. Consumers obtain energy by feeding. Decomposers break down dead material and waste, returning nutrients to the environment. A food web links several chains and better represents multiple food sources.
Make a cautious prediction
Less energy is available to organisms at higher feeding levels because organisms transfer energy to their surroundings and not all material is eaten or assimilated. If one population changes, several others may respond. A food web supports plausible predictions, but real population sizes also depend on disease, habitat, weather and alternative food sources.
Worked example
In grass → rabbit → fox, predict one possible effect of a large fall in rabbit numbers.
Show the worked solution
- Rabbits transfer energy from grass to foxes when eaten.
- Fewer rabbits may reduce the food available to foxes.
- The effect may be smaller if foxes can use other food sources.
Fox numbers may fall; the food chain alone does not guarantee the outcome.
Try it yourself
What does the arrow in grass → rabbit represent?
Common mistakes
- Do not describe energy as being recycled exactly like matter.
What can you explain now?
Explain one difference between the movement of energy and nutrients in an ecosystem.
Compare with the explanation
Energy flows through and is dispersed; nutrients can be recycled.
Energy is transferred between organisms and ultimately to the surroundings. Decomposition returns mineral nutrients that producers can use again.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Original StudyForA content. AI-assisted checks completed; subject-teacher review is still pending. These lessons are not endorsed by an exam board.
NGSS science topic progressions ↗