If the solar energy available to a particular ecosystem is 1,000,000 J. What will be the energy available at 2^nd trophic level in the food chain?

1 kJ

The correct answer is Option (3) → 1 kJ

In a food chain, energy transfer between trophic levels follows the 10% rule. Only about 10% of the energy from one trophic level is passed on to the next trophic level, while the remaining 90% is lost as heat, metabolic processes, etc. Only about 1% of the solar energy that producers receive is converted into biomass available for consumers—this is known as net primary productivity (NPP).

When primary consumers consume producers, they receive only 10% of the energy stored in the producers' biomass. This pattern continues through each trophic level, with only 10% of the energy at one level being transferred to the next.

In this scenario:

Total solar energy available = 1,000,000 J.

Energy converted by producers (1% of solar energy) = \(\frac{1}{100}\)×1,000,000=10,000J.

Energy at each successive level follows the 10% law:

• Primary consumers: \(\frac{10}{100}\)×10,000=1,000 J
• Secondary consumers: \(\frac{10}{100}\)×1,000=100 J
• Tertiary consumers: \(\frac{10}{100}\)×100=10J

Thus, the energy decreases with each level, confirming the correct distribution.

 Note : 1kJ = 1000J