Question

In a food chain, energy is transferred from one trophic level to another. What happens to the energy as it moves up the food chain?

• A. It increases
• B. It decreases
• C. It remains constant
• D. It fluctuates randomly

Hint:

• Energy flow in food chains is unidirectional and inefficient.
• Only about 10% of energy is typically transferred from one trophic level to the next (the "10% rule").
• The majority of energy (approx. 90\%) is lost as heat during respiration or is present in unconsumed/undigested parts.
• This leads to a progressive decrease in available energy at higher trophic levels.

Answer 1

The Correct Option is B

To solve the problem, we need to understand how energy is transferred through the trophic levels of a food chain and what happens to it as it moves from one level to the next.

1. Understanding the Concepts:

- Food Chain: A food chain is a sequence of organisms where each is eaten by the next one in the chain. Energy flows from one trophic level to the next, beginning with producers (usually plants) that capture solar energy through photosynthesis, which is then passed to herbivores (primary consumers), carnivores (secondary and tertiary consumers), and finally decomposers.

- Energy Transfer: At each trophic level, energy is transferred to the next level. However, the transfer is not 100% efficient. According to the second law of thermodynamics, some energy is always lost as heat during metabolic processes, such as respiration. This loss of energy means that the amount of energy available decreases as you move up the food chain.

2. Given Values:

The options provided refer to the change in energy as it moves up the food chain. We need to identify which one correctly explains the energy transformation.

3. Explanation:

The correct answer is that the energy decreases as it moves up the food chain. Each trophic level only passes a fraction of its energy to the next level, with most of the energy being lost as heat due to metabolic processes. Typically, only about 10% of the energy is transferred to the next level, while the rest is lost.

Final Answer:

As energy moves up the food chain, it decreases.