Question

For the synthesis of one pentose sugar, the difference of $ATP$ molecules for $C_3$ and $C_4$ plants is-

• A. $2ATP$
• B. $10ATP$
• C. $5ATP$
• D. $15ATP$

Answer 1

Answer: (C)

$5ATP$

• The energy consumption in $C_4$ plants is greater than in $C_3$ plants.
• $C_4$ cycle includes phosphoenolpyruvate carboxylase (PEP) regeneration from $C_4$ acid and this step requires 2ATP per carbon dioxide fixed; whereas, the $C_3$ cycle needs 3 ATP per carbon dioxide fixed.
• For a pentose sugar, the difference of ATP molecule is 5 ATP.

So, the correct answer is option C.