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
At isoelectric pH proteina) Have Net charge '0'b) Are positively chargedc) Are negatively chargedd) Don't migrate 
Select and explain. 
A. ad, B. c, C. ac, D. ab
A: ad
Answer: A: ad 
Explanation: its isoelectric pH, amino acid bears no net charge and does not move (migrate) in an electric field.