Practice question

The keyed sequence, desert greater than tundra greater than tropical forest greater than temperate forest, is not scientifically consistent with established comparisons of net primary productivity per unit leaf area. Water limitation suppresses desert carbon gain, while warm, wet tropical forests generally sustain high daily photosynthesis. It also conflicts with rows 65 and 80 of this workbook, which place deserts below temperate and tropical systems. The key should therefore be treated as erroneous rather than rationalised. Energy is lost as metabolic heat at every trophic transfer, while elements such as nitrogen and phosphorus are recycled through organisms and the physical environment. Mechanistic interpretation connects individual physiology and species interactions to population change, community composition, and ecosystem-level fluxes. Reliable inference requires the complete experimental design, definitions, units, and statistical evidence; missing labels cannot be reconstructed from an answer key alone. Net primary production equals gross primary production minus plant respiration and represents biomass or energy made available for growth and consumers.