Which of the following explains why animals totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation?
A)They lack the enzyme aminotransferase. B)They lack the enzymes to reduce N₂ and NO₃- to NH₄⁺. C)They lack carbamoyl-phosphate synthetase I. D)They lack glutamate dehydrogenase.
Which of the following describes the role of N-acetylglutamate in the incorporation of ammonium into metabolic intermediates?
A)coenzyme for glutamine synthetase (GS) B)competitive inhibitor for glutamine synthetase (GS) C)allosteric activator for carbamoyl-phosphate synthetase I (CPS-I) D)substrate for the amination of the g-glutamyl-phosphate