This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
The end product of purine metabolism in non-primate mammals is 
Select and explain. 
A. Uric acid, B. Ammonia, C. Urea, D. Allantoin
D: Allantoin
Answer: D: Allantoin 
Explanation: In non-primate mammals, the end product of purine metabolism is allantoin due to the presence of enzyme uricase. Uricase converts uric acid to allantoin. Humans lack the enzyme uricase. Therefore, the end product of purine catabolism in humans is uric acid