Photosynthesis in Higher Plants

For assimilation of one CO2 molecule, the energy required in form of ATP and NADPH2 are

1. 2 ATP and 2 NADPH2
2. 5 ATP and 3 NADPH2
3. 3 ATP and 2 NADPH2
4. 18 ATP and 12 NADPH2

Answer

(3) 3 ATP and 2 NADPH2

Solution

As per NCERT, fixation of one CO2 molecule in the Calvin cycle requires 3 molecules of ATP and 2 molecules of NADPH.

Reduction of 3-PGA uses 2 ATP and 2 NADPH, and regeneration of RuBP uses 1 ATP.

⇒ Total for one CO2 = 3 ATP + 2 NADPH2

(For one glucose, 6 turns: 18 ATP + 12 NADPH2.)

Answer: (3)