This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
Oxaloacetate synthesized from which amino acid - 
Select and explain. 
A. Aspartate, B. Glycine, C. Serine, D. Valine
A: Aspartate
Answer: A: Aspartate 
Explanation: Ans. is 'a' i.e., Aspartate* Oxaloacetate, an intermediate in citric acid cycle is formed from Aspartate and Asparagine# Aspartate undergoes transamination in the presence of Aspartate Transaminase (AST) or Serum Glutamate Oxaloacetate Transaminase (SGOT)# Aspartate + a Ketoglutarate------------Oxaloacetate + Glutamate AST/ SGOT # Asparagine in the presence of Asparaginase, gets converted to Asparate. Aspartate is then converted to OxaloacetateAsparagine------------Aspartate + NH3 ASPARAGINASE