What is the 10% rule of energy transfer in food webs?

What is the 10% rule of energy transfer in food webs?

• A. Approximately 10% of energy is transferred to the next trophic level; rest is lost as heat, metabolism, and maintenance.
• B. About 50% of energy is transferred; rest is stored.
• C. About 90% is transferred; only 10% is lost.
• D. Energy transfer is unlimited; no losses.

Answer: (A)

Energy transfer between trophic levels is inefficient; organisms use much of the energy they obtain for metabolism, movement, growth, and maintenance, and energy is lost as heat and in waste. The practical takeaway is that only a fraction of the energy at one level becomes usable energy for the next level. The commonly cited rule of thumb is that about one-tenth of the energy at a given level is passed on to the next level, with the rest lost as heat during respiration and other metabolic processes or left unavailable in undigested material. This is why energy pyramids drop off at each step and why higher trophic levels support fewer organisms. Other statements overstate or misstate the efficiency (suggesting 50% or 90% transfer, or unlimited transfer); in reality, energy transfer is limited and largely dissipated as heat and waste.

Energy transfer between trophic levels is inefficient; organisms use much of the energy they obtain for metabolism, movement, growth, and maintenance, and energy is lost as heat and in waste. The practical takeaway is that only a fraction of the energy at one level becomes usable energy for the next level. The commonly cited rule of thumb is that about one-tenth of the energy at a given level is passed on to the next level, with the rest lost as heat during respiration and other metabolic processes or left unavailable in undigested material. This is why energy pyramids drop off at each step and why higher trophic levels support fewer organisms. Other statements overstate or misstate the efficiency (suggesting 50% or 90% transfer, or unlimited transfer); in reality, energy transfer is limited and largely dissipated as heat and waste.