Question

Type your answers in the boxes provided. Use numerals, not words. The ecological pyramid below shows the organisms found in each trophic level of a simplified ecosystem. The amount of energy at each trophic level in an ecosystem decreases as it moves through the ecosystem. Typically, only about 10 percent of the energy at one trophic level is transferred to the next level. The remaining energy is lost through metabolic processes as heat. Suppose that, in the ecosystem modeled above, 150,000 kcal (kilocalories) of energy are contained within green plants. Assuming that the amount of energy transferred from one trophic level to the next is exactly 10 percent, determine the following amounts of energy in the ecosystem.

kcal of energy will be transferred from green plants to rabbits.
kcal of energy will be transferred from rabbits to weasels.
kcal of energy will be transferred from weasels to eagles.

Answer 1

In an ecosystem with green plants containing 150,000 kcal, 15,000 kcal of energy will be transferred to rabbits, 1,500 kcal from rabbits to weasels, and 150 kcal from weasels to eagles, illustrating the decrease of energy at higher trophic levels.

Step-by-step explanation:

Assuming that the ecosystem modeled has 150,000 kilocalories (kcal) of energy contained within green plants, and taking into account that typically only about 10 percent of the energy at one trophic level is transferred to the next level, we can determine the energy transfer at each level:

• Green plants to rabbits: 10% of 150,000 kcal is 15,000 kcal.
• Rabbits to weasels: 10% of 15,000 kcal is 1,500 kcal.
• Weasels to eagles: 10% of 1,500 kcal is 150 kcal.

This demonstrates that the energy available decreases significantly at each higher trophic level due to the ecological efficiency of energy transfer.