This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Physiology, Subject name: Physiology
Facilitated diffusion is characterized by all except: 
Select and explain. 
A. Vmax, B. Competitive inhibition, C. Requires energy, D. Specificity
C: Requires energy
Answer: C: Requires energy 
Explanation: Facilitated diffusion is a carrier-mediated transpo. ATP is not consumed in this transpo. A conformational change in the carrier molecule causes the substance to be transpoed to the other side of the membrane. Some models hypothesised for the carrier proteins ~ flip-flop model, ferryboat model. Saturability, Specificity and inhibition are the characteristics of the Facilitated diffusion