(Choices A and D) Phosphorylated glycogen phosphorylase (active form) is allosterically inhibited by ATP and glucose-6-phosphate in both liver and muscle cells. Increased intracellular ATP levels help to decrease the rate of glycogenolysis upon cessation of active muscle contraction.
(Choice C) Although increased cAMP stimulates muscle glycogen breakdown via the action of epinephrine on beta-1 adrenergic receptors, it is not responsible for synchronization of active muscle contraction and glycogen breakdown.
(Choice E) Lactate is produced in tissues during anaerobic gtycolysis, such as in muscles during strenuous exercise as a result of relatively hypoxic conditions. The lactate produced by the muscles can be converted to glucose in the liver via gluconeogenesis.

(Choice A) Acid α-glucosidase (or acid maltase) deficiency causes glycogen storage disease type II (Pompe disease). Affected infants have cardiomyopathy, muscle weakness, and hypotonia.
(Choice B) Aldolase B deficiency is a life-threatening disorder caused by the inability to metabolize fructose-1-phosp hate (a toxic intermediate that accumulates in cells and depletes intracellular phosphate). Patients become acutely symptomatic after ingesting fructose-containing foods and eventually develop liver failure. Treatment includes elimination of dietary fructose.
(Choice D) Galactosemia is an autosomal recessive disorder caused by galactose-1-phosphate uridyl transferase deficiency. It is characterized by neonatal jaundice, vomiting, cataract formation, hepatomegaly, and failure to thrive. Treatment includes elimination of all milk products from the diet and feeding with soy-based infant formula.
(Choice E) Lactase is a mucosa! enzyme responsible for the digestion of lactose. Acquired lactase deficiency is the most common cause of selective carbohydrate malabsorption. Patients with lactase deficiency experience gastrointestinal symptoms (eg, bloating, diarrhea) following the ingestion of dairy products.

(Choice D) Regulation of glycolysis and gluconeogenesis occurs mainly through the inverse regulation of phosphofructokinase-1 and fructose 1,6-bisphosphatase by fructose 2,6-bisphosphate. High levels of fructose 2,6-bisphosphate activate phosphofructokinase-1 and accelerate glycolysis; low levels disinhibit fructose 1,6-bisphosphatase and promote gluconeogenesis.
(Choice E) Lactate is an important source of carbon atoms for glucose synthesis during gluconeogenesis. During anaerobic glycolysis in skeletal muscle, pyruvate is reduced to lactate by lactate dehydrogenase. Lactate formed in the contracting muscles is released into the bloodstream and transported to the liver, where it is converted back into glucose.
(Choice F) Oxaloacetate is the product of pyruvate carboxylase during gluconeogenesis. As such, increased levels of oxaloacetate would decrease the activity of the enzyme.