For the synthesis of two molecules of PGAL, how many ATP and NADPH + H+molecules are required in Calvin cycle ?

To determine the number of ATP and NADPH + H$^+$ molecules required for the synthesis of two molecules of PGAL (phosphoglyceraldehyde) in the Calvin cycle, we can follow these steps:

1. ### Break Down the Problem

The Calvin cycle has three main phases: carbon fixation, reduction, and regeneration of RuBP.

• It takes 3 molecules of CO$_2$ to produce 1 molecule of PGAL.
• Therefore, to produce 2 molecules of PGAL, we would need to process 6 molecules of CO$_2$.

2. ### Relevant Concepts

In the Calvin cycle:

• For every 3 molecules of CO_2\, it requires:
  • 6 molecules of ATP
  • 6 molecules of NADPH + H$^+$

Thus, the reaction for 6 CO$_2$ would be:

• ATP required = 6 ATP
• NADPH + H(^+ required = 6 NADPH + H(^+)

3. ### Analysis and Detail

Since each turn of the cycle incorporates one CO$_2$ molecule and generates one molecule of PGAL:

• After 6 cycles (to account for 2 PGAL), the need scales up as follows:
  • Total ATP = 6 (for 2 PGAL)
  • Total NADPH + H(^+ = 6 (for 2 PGAL)

4. ### Verify and Summarize

After confirming the requirements for producing 2 molecules of PGAL from CO$_2$ through the Calvin cycle, it is clear that the calculations are consistent based on the biochemistry of photosynthesis.

Final Answer

For the synthesis of two molecules of PGAL, 6 ATP and 6 NADPH + H$^+$ molecules are required in the Calvin cycle.