Question: 92: When one \mathrm{CO}_{2} molecule is fixed as one molecule of triose phosphate, which of the following photochemically made, high energy chemical intermediates are used in the reduction phase?
(1) 1 ATP +1 NADPH
(2) 1 ATP +2 NADPH
(3) 2 ATP +1 NADPH
(4) 2 ATP +2 NADPH
Answer: Option (1)
Explanation:
The reduction phase of the Calvin cycle uses energy-rich compounds produced during the light reactions of photosynthesis.
In this phase, each molecule of \mathrm{CO}_{2} fixed is first converted into
3-phosphoglycerate, which is then reduced to triose phosphate.
For the reduction of one molecule of 3-phosphoglycerate to triose phosphate, one molecule of ATP provides energy and one molecule of NADPH provides reducing power.
Thus, when one \mathrm{CO}_{2} molecule is fixed as one molecule of triose phosphate, the reduction phase consumes one ATP and one NADPH.
Therefore, the correct answer is 1 ATP + 1 NADPH