Covalent modification is one way the activity of specific enzymes can be regulated. Which enzyme is NOT regulated in this way（）
A. phosphofructokinase-2
B. pyruvate dehydrogenase
C. phosphorylase kinase
D. All of these enzymes are regulated by covalent modification
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Which statement about mammalian glycogen synthase is NOT correct（）
A. It is especially predominant in liver and muscle
B. The donor molecule is a sugar nucleotide
C. The phosphorylated form of this enzyme is active
D. This enzyme adds the initial glucose unit to a tyrosine residue in glycogenin
Which statement is TRUE of glycogen synthase（）
Activation of the enzyme involves a phosphorylation
B. It catalyzes addition of glucose residues to the nonreducing end of a glycogen chain by formation of （α1 -4） bonds
C. It uses glucose-6-phosphate as donor of glucose units
D. The enzyme has measurable activity only in liver
Which enzymatic activity would be decreased by thiamine deficiency（）
A. α-ketoglutarate dehydrogenase complex
B. isocitrate dehydrogenase
C. malate dehydrogenase
D. fumarase
Which compound（s） is/are a high-energy intermediate（s） in glycolysis（）
A. fructose 1,6-bisphosphate
B. NADH
C. 1,3-bisphosphoglycerate and phosphoenol pyruvate
D. fructose 1,6-bisphosphate, 1,3-bisphosphoglycerate, and phosphoenol pyruvate
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