For glucose estimation in blood, the mode of transport from a PHC to lab:

Ans. A. Sodium fluorideIn glycolysis, (i.e. the pathway in which, glucose is utilized to form energy), 'Enolase' is an enzyme which converts 2- phosphoglycerate to a high energy compound phosphoenolpyruvate.a. This enzyme requires Mg++&Mn++ & is inhibited by fluoride.b. For blood glucose estimation, fluoride is added to the blood to prevent glycolysis by cells, so that the blood glucose is correctly estimated.