This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzyme basics and serine proteases, Subject name: Biochemistry
True regarding isozymes is: 
Select and explain. 
A. Forms of the same enzymes that catalyze different reaction, B. Forms of the same enzymes that catalyze same reaction, C. Forms of the different enzymes that catalyze different reaction, D. Forms of the different enzymes that catalyze same reaction
B: Forms of the same enzymes that catalyze same reaction
Answer: B: Forms of the same enzymes that catalyze same reaction 
Explanation: Isozymes/Isoenzymes are different forms of same enzyme,catalyzing same reaction in same species, Example:- There are five isozymes of Lactate Dehydrogenase (LDH-1 to LDH-5), All conve Pyruvate to Lactate. Same for Isoenzymes Reaction Species Different for Isoenzymes Structure (subunits) Km, Vmax Electrophoretic mobility Genes (but closely relate) Heat stability Susceptibility to inhibitor If species different, then it is known as Alloenzyme Isoenzymes may be present in same/different tissues