Assertion A is true because ATP is indeed used at two steps in glycolysis. These steps are the conversion of glucose to glucose-6-phosphate, and the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. In both of these steps, a phosphate group is added to the substrate, and ATP is used to provide the phosphate group.
Reason R is also true and provides the correct explanation for Assertion A. The first ATP is used in the conversion of glucose to glucose-6-phosphate, and the second ATP is used in the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. Therefore, Reason R correctly explains why ATP is used at two steps in glycolysis.
Therefore, The correct answer is (D): Both A and R are true and R is the correct explanation of A.
It is the process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. If the process takes place in cytoplasm of a cell and it does not require oxygen. It occurs in both aerobic and anaerobic organisms.