Which of the following is false statement?

Options

A. PEP acts as first acceptor of `CO_(2)` in both CAM plants and `C_(4)` plants.
B. The plants undergoing crassulacean acid metabolism do not undergo `C_(3)` cycle
C. In CAM plants there is separation of intitial carboxylation and Calvin cycle in time instead of space in `C_(4)` plants
D. All of the above

Answer

To determine which statement is false regarding photosynthesis and the different metabolic pathways in plants, let's analyze each statement step by step:

### Step 1: Analyze the First Statement
**Statement:** PEP acts as the first acceptor of carbon dioxide in both CAM plants and C4 plants.

**Analysis:**
- In both CAM (Crassulacean Acid Metabolism) and C4 plants, phosphoenolpyruvate (PEP) is indeed the first molecule to accept carbon dioxide.
- This reaction is catalyzed by the enzyme PEP carboxylase, resulting in the formation of oxaloacetic acid (OAA), a four-carbon compound.

**Conclusion:** This statement is true.

### Step 2: Analyze the Second Statement
**Statement:** Plants that undergo Crassulacean Acid Metabolism do not undergo the C3 cycle.

**Analysis:**
- The C3 cycle, also known as the Calvin cycle, is a universal process that occurs in all plants, including those that utilize CAM and C4 pathways.
- CAM plants fix carbon dioxide at night and store it as malate, which is then used in the Calvin cycle during the day. Therefore, they do undergo the C3 cycle.

**Conclusion:** This statement is false.

### Step 3: Analyze the Third Statement
**Statement:** In CAM plants, there is separation of initial carboxylation and the Calvin cycle in time instead of space, as in C4 plants.

**Analysis:**
- In CAM plants, carbon dioxide is fixed at night (initial carboxylation) and the Calvin cycle occurs during the day. This is a temporal separation.
- In contrast, C4 plants separate these processes spatially, with initial carbon fixation occurring in mesophyll cells and the Calvin cycle occurring in bundle sheath cells.

**Conclusion:** This statement is true.

### Step 4: Analyze the Fourth Statement
**Statement:** All of the above.

**Analysis:**
- Since we have established that the first and third statements are true, and the second statement is false, the statement "All of the above" cannot be true.

### Final Conclusion
The false statement among the options provided is the **second statement**: "Plants that undergo Crassulacean Acid Metabolism do not undergo the C3 cycle."

### Summary of the Answer
The correct answer to the question is the **second statement**.

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