The total number of ATP and NADPH required to fix six molecules of `CO_2` in `C_3` plants are

Options

A. ATP-12, NADPH-12
B. ATP-5, NADPH-3
C. ATP-18, NADPH-12
D. ATP-12, NADPH-18

Answer

To solve the problem of determining the total number of ATP and NADPH required to fix six molecules of CO2 in C3 plants, we can follow these steps:

### Step 1: Understand the requirements for fixing one molecule of CO2
In the C3 pathway (Calvin cycle), the fixation of one molecule of CO2 requires:
- 3 ATP
- 2 NADPH

### Step 2: Calculate the requirements for six molecules of CO2
Since we need to fix six molecules of CO2, we will multiply the requirements for one molecule by six:
- For ATP:
\[ 3 \text{ ATP} \times 6 = 18 \text{ ATP} \]
- For NADPH:
\[ 2 \text{ NADPH} \times 6 = 12 \text{ NADPH} \]

### Step 3: Summarize the total requirements
After performing the calculations, we find that to fix six molecules of CO2, the total requirements are:
- Total ATP = 18
- Total NADPH = 12

### Final Answer
Thus, the total number of ATP and NADPH required to fix six molecules of CO2 in C3 plants are:
- 18 ATP and 12 NADPH.