How many molecules of ATP and how many molecules of NADPH are spent to fix three molecules of `CO_2` in Calvin cycle?

Explanation

To determine how many molecules of ATP and NADPH are spent to fix three molecules of CO2 in the Calvin cycle, we can break down the process into steps:

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**:
The Calvin cycle consists of three main stages: carbon fixation, reduction, and regeneration. During this cycle, carbon dioxide (CO2) is fixed into organic molecules.

2. **Carbon Fixation**:
...