Catalyzes the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate using ADP as the phosphate donor. ADP + beta-D-fructose 6-phosphate = AMP + beta-D-fructose 1,6-bisphosphate + H(+) Binds 1 Mg(2+) ion per subunit. Carbohydrate degradation; glycolysis. Belongs to the carbohydrate kinase PfkC family.