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Which of the following statements about the metabolism of amino acids is correct?

a) Essential amino acids can be formed from other amino acids supplied in the diet.

b) Excess dietary amino acids cannot be converted to other metabolites.

c) Excess dietary amino acids that cannot be oxidised are stored as muscle proteins.

d) Essential amino acids cannot be formed from other amino acids but must be supplied in the diet.

Which of the following statements about the role of glutamate dehydrogenase is correct?

a) Glutamate dehydrogenase has an FAD prosthetic group.

b) Glutamate dehydrogenase has a pyridoxal phosphate cofactor.

c) Glutamate dehydrogenase transaminates glutamate producing α-ketoglutarate.

d) Glutamate dehydrogenase oxidatively deaminates glutamate producing α-ketoglutarate.

Which of the following statements about transamination reactions is correct?

a) Transamination reactions involve ATP hydrolysis.

b) Transamination reactions are irreversible.

c) Transamination reactions require NAD⁺ or NADP⁺.

d) Transamination reactions require pyridoxal-5'-phophate.

Which of the following statements about the urea cycle is correct?

a) Argininosuccinate is lysed to urea and ornithine in the urea cycle.

b) Carbamoyl phosphate supplies both of the nitrogen atoms of urea in the urea cycle.

c) The formation of urea from the urea cycle yields energy.

d) Arginine is hydrolysed to urea and ornithine in the urea cycle.

Which of the following statements about aminolevulinate synthase (ALA synthase) is correct?

a) ALA synthase synthesis decreases in individuals treated with drugs such as barbiturates.

b) ALA synthase catalyses the rate-limiting reaction in haem degradation.

c) ALA synthase catalyses the rate-limiting reaction in haem synthesis.

d) ALA synthase is decreased in patients with acute intermittent porphyria.

Oxford University Press, Online Resource Centre, Chapter 19.