Catalyzes the irreversible reaction from fructose-1,6-bisphosphate to fructose-6-phosphate and inorganic phosphate, to regenerate the primary CO(2) acceptor molecule, ribulose-1,5-bisphosphate (Probable). Involved in the regulation of photosynthetic electron flow and sucrose synthesis (PubMed:15448173, PubMed:20081115). Its activity is critical for normal plant development and important for the regulation of a wide range of metabolic processes (PubMed:25743161). beta-D-fructose 1,6-bisphosphate + H2O = beta-D-fructose 6-phosphate + phosphate Binds 3 Mg(2+) ions per subunit. Carbohydrate biosynthesis; Calvin cycle. Homotetramer. Light activation through pH changes, Mg(2+) levels and also by light-modulated reduction of essential disulfide groups via the ferredoxin-thioredoxin f system. Reduced growth rate, dwarf phenotype and delayed flowering. In plants there are two FBPase isozymes: one in the cytosol and the other in the chloroplast. Belongs to the FBPase class 1 family.