Answer:
See blow
Step-by-step explanation:
a and b) Metformine inhibits the enzime glycerol-3-phosphate dehydrogenase. This enzime catalyzes the conversion of glycerol phosphate to dihidrocetone phosphate. This decreases the concentration of NAD on the cytosol, and the realation NADH/NAD increases in this comparment, and decreases on the mitochondria, which restricts the conversion of lactate to pyruvate, preventing the use of the substracts to the gluconeogenesis.