In the following food chain, only 2J of energy was available to the peacocks. How much energy would have been present in Grass ? Justify your answer.
GRASS → GRASS HOPPER → FROG → SNAKE → PEACOCK
Generated by claude-sonnet-4-6 · 2026-06-15 06:45 · grounding rag
Model Answer
Using the 10% Law of Energy Flow, only 10% of energy passes from one trophic level to the next.
The food chain has 5 trophic levels:
Grass → Grasshopper → Frog → Snake → Peacock
Since Peacock (5th level) has 2 J, working backwards:
- Snake: 2 × 10 = 20 J
- Frog: 20 × 10 = 200 J
- Grasshopper: 200 × 10 = 2000 J
- Grass: 2000 × 10 = 20,000 J
Energy present in Grass = 20,000 J
Justification: According to the 10% law, each trophic level transfers only 10% of its energy to the next. So energy at each lower level is 10 times the level above it.
Explanation
- The key concept is the 10% Law: only 10% of energy at one trophic level is available to the next.
- To find energy at a lower level, multiply by 10 for each step going backwards.
- There are 4 steps between Grass and Peacock, so multiply 2 J by 10⁴ = 20,000 J.
- Always state the law and show stepwise calculation for full marks.