In the context of natural selection and evolution, which statement best describes the '10 percent rule' as it applies to energy transfer in trophic levels, such as those involving apes in a food web?

• A. Only about 10% of the energy from one trophic level is transferred to the next higher level.
• B. 10% of ape populations survive natural selection pressures each year.
• C. Apes lose 10% of their body mass every time they change habitats.
• D. Apes retain 10% of their genetic mutations in each generation.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of trophic levels in a food web. Trophic levels represent the hierarchical positions of organisms in a food chain, starting with producers (plants) at the base, followed by primary consumers (herbivores), secondary consumers (carnivores), and so on.
2. Step 2: Learn about the '10 percent rule' in ecology. This rule states that only about 10% of the energy available at one trophic level is transferred to the next higher level. The remaining 90% is lost as heat, used in metabolic processes, or remains in unconsumed biomass.
3. Step 3: Analyze the options provided in the problem. The correct statement should align with the ecological principle of energy transfer between trophic levels, not unrelated concepts like body mass loss, genetic mutations, or population survival rates.
4. Step 4: Relate the '10 percent rule' to apes in a food web. Apes, as consumers, would receive only about 10% of the energy from the trophic level below them (e.g., plants or herbivores they consume). This is consistent with the energy transfer principle.
5. Step 5: Conclude that the correct answer is: 'Only about 10% of the energy from one trophic level is transferred to the next higher level,' as this accurately describes the '10 percent rule' in the context of natural selection and evolution.