The 10% Rule for Biomass Transfer in Food Chains

Steps:

• Identify the trophic levels: Primary consumers eat producers; secondary consumers eat primary consumers.
• Recall that most biomass is lost as heat, respiration, or undigested material at each level.
• Apply the 10% rule: Only about 10% of biomass from one level transfers to the next.
• Confirm the transfer efficiency between primary and secondary consumers follows this rule.

Why B is correct:

• The 10% rule (Lindeman's trophic transfer efficiency) states that approximately 10% of biomass is passed from one consumer level to the next due to energy losses.

Why the others are wrong:

• A: 1% underestimates transfer; it's the approximate efficiency from tertiary to quaternary consumers after multiple losses.
• C: 20% overestimates; actual transfer is lower due to metabolic inefficiencies.
• D: 50% is unrealistic; far too much biomass would be retained, violating observed energy pyramids.

Final answer: B