Why is there a limit to the number of trophic levels that a food chain can reach?

• A. Because producers cannot survive without consumers.
• B. Because energy is lost as heat at each trophic level, limiting the amount available to higher levels.
• C. Because all organisms at higher trophic levels are herbivores.
• D. Because higher trophic levels reproduce more quickly than lower levels.

Answer: (B)

Verified step by step guidance

1. Understand the concept of trophic levels: Trophic levels represent the hierarchical positions in a food chain, starting with producers (plants and algae) at the base, followed by primary consumers (herbivores), secondary consumers (carnivores), and so on.
2. Recognize the principle of energy transfer: Energy flows through trophic levels, but only a fraction of the energy is transferred from one level to the next. This is due to the second law of thermodynamics, where energy is lost as heat during metabolic processes.
3. Learn about the 10% rule: Typically, only about 10% of the energy at one trophic level is passed on to the next level. The remaining 90% is lost as heat, waste, or used for the organism's life processes.
4. Understand the implications of energy loss: As energy diminishes with each transfer, there is less energy available to support organisms at higher trophic levels. This limits the number of trophic levels a food chain can sustain.
5. Conclude why there is a limit: The energy loss at each trophic level creates a bottleneck, making it energetically unfeasible to support many levels. This explains why food chains typically have 4-5 trophic levels at most.