Question

In addition to the 12 molecules of $NADP{H}_2$ the energy required for the synthesis of one mole of hexose by $C_3$ and $C_4$ pathway is

• A. 18 molecules of ATP
• B. 30 molecules of ATP
• C. 18 and 30 molecules of ATP respectively
• D. 30 and 18 molecules of ATP respectively

Answer 1

Answer: (C)

18 and 30 molecules of ATP respectively

In $C_3$ plants 3 molecules of ATP and 2 molecules of $NADP{H}_2$ are required per carbon atom fixed into sugars making the total requirement to produce one molecule of hexose sugar as 18 molecules of ATP and 12 molecules of $NADP{H}_2$. In $C_4$ plants 5 molecules of ATP and 2 molecules of $NADP{H}_2$ are required per carbon atom fixed into sugars making the total requirement to produce one molecule of hexose sugar as 30 molecules of ATP and 12 molecules of $NADP{H}_2$.