Model Matter and Energy Cycling Practice Test

Matter cycles only between the snail and decomposers; photosynthesis and respiration are not connected because plants only do photosynthesis and animals only do respiration.

Only photosynthesis matters: CO2 + H2O + sunlight → glucose + O2, and the plant does not respire, so the cycle is complete without respiration.

Matter cycles: photosynthesis uses CO2 + H2O to make glucose + O2; respiration uses glucose + O2 to make CO2 + H2O, returning those molecules to photosynthesis. Energy flows one-way: Sun → photosynthesis (stored in glucose) → respiration (ATP for work) → heat leaving the terrarium.

Energy cycles in a loop: Sun → photosynthesis → respiration → Sun, while matter flows one-way: CO2 + H2O → glucose + O2 and then leaves the terrarium.