Which of the following photosynthetic characteristics are present in `C_(3)` plants but not in `C_(4)` plants-
I. `CO_(2)` compensation point of 0-10 ppm-
II. Relatively higher rate of photorespiratory `CO_(2)` evolution-
III. Presence of well developed bundle sheath-
IV. Initial involvement of RUBP carboxylase in `CO_(2)` assimilation -
Select the correct answer using the codes given below

Options

A. I, II, III
B. I, II, IV
C. I, III
D. II, IV

Answer

To determine which photosynthetic characteristics are present in C3 plants but not in C4 plants, we will analyze each of the given statements one by one.

### Step-by-Step Solution:

1. **Statement I: CO2 compensation point of 0-10 ppm**
- **Analysis**: The CO2 compensation point refers to the level of CO2 at which the rate of photosynthesis equals the rate of respiration. C3 plants typically have a low CO2 compensation point, often around 0-10 ppm, because they are more efficient at utilizing CO2 under normal conditions. In contrast, C4 plants have a higher compensation point due to their adaptation to high light and temperature conditions.
- **Conclusion**: This characteristic is present in C3 plants but not in C4 plants.

2. **Statement II: Relatively higher rate of photorespiratory CO2 evolution**
- **Analysis**: C3 plants are known for a higher rate of photorespiration because their enzyme Rubisco can bind to both CO2 and O2. When it binds to O2, it leads to photorespiration, which releases CO2. C4 plants have a mechanism that minimizes photorespiration by separating the initial fixation of CO2 and the Calvin cycle, thus they have a lower rate of photorespiratory CO2 evolution.
- **Conclusion**: This characteristic is present in C3 plants but not in C4 plants.

3. **Statement III: Presence of well-developed bundle sheath**
- **Analysis**: C4 plants possess well-developed bundle sheath cells that are crucial for their photosynthetic pathway. These cells help in the concentration of CO2 around Rubisco, thereby reducing photorespiration. C3 plants do not have this specialized structure.
- **Conclusion**: This characteristic is not present in C3 plants.

4. **Statement IV: Initial involvement of RUBP carboxylase in CO2 assimilation**
- **Analysis**: In C3 plants, the initial fixation of CO2 is carried out by the enzyme Rubisco, which catalyzes the reaction with ribulose bisphosphate (RuBP). This is a defining characteristic of C3 photosynthesis. In C4 plants, the initial fixation of CO2 is performed by PEP carboxylase, not Rubisco.
- **Conclusion**: This characteristic is present in C3 plants but not in C4 plants.

### Final Answer:
Based on the analysis:
- Characteristics present in C3 plants but not in C4 plants are:
- I. CO2 compensation point of 0-10 ppm
- II. Relatively higher rate of photorespiratory CO2 evolution
- IV. Initial involvement of RUBP carboxylase in CO2 assimilation

Thus, the correct answer is:
**Statements II and IV are correct.**