Practice question

Decomposers, chiefly fungi and bacteria, secrete enzymes that cleave complex dead organic polymers into soluble molecules. They absorb these products for growth and oxidize part for energy, releasing inorganic forms such as CO₂, ammonium, and phosphate. This differs from physical shredding by detritivores, although the two processes reinforce each other. Producers build organic compounds from inorganic resources, whereas consumers mainly transfer existing organic matter; decomposers complete mineral recycling and make nutrients available for renewed primary production. Real communities are networks rather than isolated chains, so omnivory, detrital links, and changes in interaction strength modify the simplified trophic sequence. Energy budgets must distinguish stocks from rates: standing biomass can remain high or low even when production and transfer through that compartment are rapid. Matter can cycle repeatedly through producers, consumers, and decomposers, whereas usable energy requires continuous external input because respiration degrades it to heat. The amount reaching a consumer level depends jointly on resource production, the fraction consumed, assimilation efficiency, and conversion of assimilates into new biomass.