What amount of energy would be at the producer level if it is 50 KJ at third trophic level?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 5000 KJ
By the 10 per cent law, energy rises ten times at each step down. Third level 50 kJ → second level 500 kJ → producers 5000 kJ.
Option (4) 5000 KJ — Correct. By the 10 per cent law, only about 10% of the energy (here in kJ, kilojoules) passes to the next trophic level. Going back two levels from the third level: 50 × 10 = 500 kJ at the second, and 500 × 10 = 5000 kJ at the producers.
NCERT Extract:
Energy Flow – “… The number of trophic levels in the grazing food chain is restricted as the transfer of energy follows 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from the lower trophic level.”