Acceptor of `CO_2` in `C_4 and C_3` plants respectively

Options

A. PEP case and RUBISCO
B. OAA and PGA
C. PEP and RUDP
D. PGAL and malic acid

Answer

To answer the question about the acceptor of carbon dioxide in C4 and C3 plants, we can break down the process step by step:

### Step 1: Understand the types of plants
C4 and C3 plants are two different types of plants that utilize different pathways for photosynthesis.

### Step 2: Identify the CO2 acceptor in C4 plants
In C4 plants, the first acceptor of carbon dioxide (CO2) is phosphoenolpyruvate (PEP). This reaction occurs in the mesophyll cells of the plant.

### Step 3: Describe the reaction in C4 plants
PEP combines with CO2 in the presence of the enzyme phosphoenolpyruvate carboxylase (PEP carboxylase) to form oxaloacetic acid (OAA), which is a four-carbon compound.

### Step 4: Identify the CO2 acceptor in C3 plants
In C3 plants, the first acceptor of CO2 is ribulose 1,5-bisphosphate (RuBP). This reaction occurs in the stroma of the chloroplasts.

### Step 5: Describe the reaction in C3 plants
RuBP combines with CO2 to form a six-carbon intermediate compound, which is unstable and quickly splits into two molecules of 3-phosphoglycerate (PGA), a three-carbon compound.

### Step 6: Summarize the findings
To summarize, the acceptors of CO2 in C4 and C3 plants are:
- C4 plants: Phosphoenolpyruvate (PEP)
- C3 plants: Ribulose 1,5-bisphosphate (RuBP)

### Final Answer
The correct answer is: PEP for C4 plants and RuBP for C3 plants.

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