photosynthesis uses carbon dioxide / reduces carbon dioxide concentration of the atmosphere;
autotrophs/plants/cyanobacteria convert/fix carbon dioxide into carbon/organic compounds;
cell respiration produces/releases carbon dioxide;
glucose/carbon/organic compounds oxidised/broken down to produce/release carbon dioxide;
carbon dioxide released from aerobic (cell) respiration AND anaerobic respiration in yeast/plants (but not animals);
carbon dioxide released from saprotrophs/detritivores/decomposers from dead organic matter / during decay/decomposition/respiration;
(partially) decomposed organic matter can lead to the formation of peat / fossilized organic matter (coal/oil/natural gas)
carbon dioxide released when carbon/organic compounds burn / during combustion (of biomass/fossil fuels) / forest fires;
carbon dioxide dissolves in aquatic ecosystems / can form carbonic acid/hydrogen carbonate ions;
reef-building corals/molluscs use calcium carbonate to make/build shells/exoskeletons or other body parts;
hard parts/shells/exoskeletons / precipitation of calcium carbonate to form limestone/tufa;