試題詳解

36. Which of the following statements about urea cycle is correct?
 1. The urea cycle is linked to the citric acid cycle by arginine.
 2. Aspartic acid is the main amino acid precursor for the carbon chain in arginine.
 3. Citrulline is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction.
 4. Ornithine is synthesized in the mitochondrial matrix and transported to the cytosol for subsequent reaction.
(A) All of above are incorrect.
(B) 1 and 3 are correct.
(C) 2 and 4 are correct.
(D) 1 and 2 are correct.
(E) 3 and 4 are correct.