Question

During fixation of one molecule of $CO_{2}$ by $C_{3}$plants, number of $ATP$ and $NADPH_{2}$ required are

• A. $ 3 ATP$ and $2 NADPH_{2}$
• B. $ 5 ATP$ and $2 NADPH_{2}$
• C. $ 12 ATP$ and $12 NADPH_{2}$
• D. $ 2 ATP$ and $3 NADPH_{2}$

Answer 1

Answer: (A)

For every $CO _{2}$ molecule entering the Calvin cycle, 3 molecules of ATP and 2 molecules of NADPH are required. To make one molecule of glucose, 6 turns of the cycles are required $(6 \times 3 A T P = 1 8 A T P$ and $6 \times 2 N A D P H = 1 2 N A D P H )$
$\begin{array}{ll}\text { In } & \text { Out } \\ \text { 6 CO }_{2} & \text { 1 glucose } \\ \text { 18ATP } & \text { 18ADP }\end{array}$
12NADPH 12NADP, So, the correct answer is ' 3ATP and 2NADPH2'