Biology · Grades 4–8
Food chains, food webs and energy
Use arrows consistently and distinguish cycling matter from flowing energy.
Learn the idea
Arrows
In this guide, arrows point from a food source toward the consumer receiving energy.
Producer
A primary producer builds organic material using an energy source such as light.
Web
A food web contains several connected feeding relationships.
Energy
Energy transfers through the system with dissipation; matter can cycle through reservoirs.
Worked examples
Using the stated convention, grass → rabbit means what?
The arrow points toward the energy recipient.
The rabbit obtains energy by eating grass.
Which is a primary producer in this simple land food chain?
Grass produces organic matter using photosynthesis.
Grass.
Check your understanding
Why is a food web often more realistic than one chain?
- Organisms can have multiple feeding relationships.
- Every predator eats exactly one species.
- Only one organism exists in nature.
A stated model transfers 20% of 500 energy units to the next level. How many units are transferred?
Why is it misleading to say energy cycles in exactly the same way as carbon atoms?
Answers and marking notes
Answers and marking notes
- Organisms can have multiple feeding relationships.
A web allows connected pathways.
- 100
0.20 × 500 = 100; the efficiency is supplied, not assumed universal.
- Energy is transferred and dissipated, while atoms can be reused across chemical forms.
Distinguish energy flow from matter cycling.
Further reading and review references
- openstax.org · reference 1
- www.genome.gov · reference 2
- www.genome.gov · reference 3
- www.genome.gov · reference 4
- www.genome.gov · reference 5
- www.genome.gov · reference 6
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.