Detailed Instructions: You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.
Problem:The Urea (or the Krebs-Hensliet) cycle outlines the mechanism by which ammonia is finally produced in the final reaction (involving Arginine, if I am right)

Ammonia excretion can also be regarded as excretion of Nitrogen from different intermediates in the body. All of these N containing intermediates converge into the TCA cycle from where they become amino acids through enzymes known as deaminases or transminases. These amino acids converge to a common amino acid (alanine in humans, if i recollect well) which then travels to Kidney and initiates the UREA cycle to finally result in the production of Ammonia
Solution:
the main substrate for the secretion of ammonia in the kidney?