Class X Biology - Chapter: Our Environment - Topic: Energy Flow in Ecosystems Numerical Problems

Problem 1: Ten Percent Law of Energy Transfer

If producers in an ecosystem have 10,000 Joules (J) of energy, how much energy will be available to the secondary consumers?

Solution:

The Ten Percent Law states that only about 10% of the energy is transferred from one trophic level to the next. The remaining 90% is lost as heat or used for metabolic activities.

• Energy at Producer level: 10,000 J
• Energy at Primary Consumer level: 10% of 10,000 J = 0.10 * 10,000 J = 1,000 J
• Energy at Secondary Consumer level: 10% of 1,000 J = 0.10 * 1,000 J = 100 J

Therefore, 100 Joules of energy will be available to the secondary consumers.

Problem 2: Calculating Energy Loss

In a food chain, if the primary consumers obtain 500 J of energy from the producers, how much energy was lost during the transfer from producers to primary consumers?

Solution:

According to the Ten Percent Law, the primary consumers received 10% of the energy from the producers.

Let 'X' be the energy at the producer level. 0.10 * X = 500 J X = 500 J / 0.10 = 5,000 J

Energy lost = Energy at Producer level - Energy at Primary Consumer level Energy lost = 5,000 J - 500 J = 4,500 J

Therefore, 4,500 Joules of energy was lost during the transfer from producers to primary consumers.