Which statement about photosynthesis is incorrect ?

Options

A. In `C_4` plants , the mesophyll cells have PEPcase but don't have RuBisCo
B. `F_0` portion of ATP synthase enzyme protrudes on the outer surface of the thylakoid membrane on the side that faces the stroma.
C. Stromal lamellae don't have PSII and NADP reductase enzyme.
D. When carbon dioxide and oxygen is available in equal quantity , RuBisCo has a much greater affinity for carbon dioxide

Answer

To determine which statement about photosynthesis is incorrect, we will analyze the statements provided in the context of the process of photosynthesis, particularly focusing on the roles of various enzymes and structures involved.

### Step-by-Step Solution:

1. **Understanding the Role of PEP Carboxylase and Rubisco**:
- In C4 plants, the mesophyll cells contain PEP carboxylase (PEPcase) which is responsible for fixing CO2 into a 4-carbon compound. Notably, these cells do not contain Rubisco, which is primarily found in the bundle sheath cells. This statement is correct.

2. **Location of F0 and F1 Particles in ATP Synthase**:
- The ATP synthase enzyme consists of two main parts: F0 and F1. The F0 portion is embedded within the thylakoid membrane, while the F1 portion protrudes into the stroma. The statement claiming that the F0 particle is on the stroma side is incorrect, as it is actually located within the thylakoid membrane.

3. **Presence of Photosystem II and NADP Reductase in Stroma Lamellae**:
- Stroma lamellae are the regions connecting thylakoids and do not contain Photosystem II (PSII) or NADP reductase. This statement is correct.

4. **Affinity of Rubisco for CO2 and O2**:
- Rubisco (Ribulose bisphosphate carboxylase/oxygenase) has a higher affinity for CO2 compared to O2, especially when CO2 and O2 are present in equal quantities. This statement is also correct.

### Conclusion:
The incorrect statement about photosynthesis is the one that claims the F0 particle of ATP synthase is on the stroma side. Therefore, the answer is that the second option is wrong.