Practice question

The keyed cave response is only conditionally valid and conflicts with accepted ecology if interpreted generally. Most cave food webs depend on photosynthetically derived material carried in by water, wind, roots, or animals such as bats, so they are indirectly solar-dependent. Some caves host chemoautotrophic bacteria that oxidize sulfide, methane, ammonium, or ferrous iron and fix carbon without sunlight; those specific communities can support solar-independent food webs. The item therefore confuses absence of local light with independence from solar energy and should be flagged as a key mismatch. 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.