During day time , CAM plants procure carbon dioxide for photosynthesis from

Options

A. Pyruvic Acid
B. Oxaloacetic Acid
C. Oxalic Acid
D. Malic Acid

Answer

**Step-by-Step Solution:**

1. **Understanding CAM Plants:**
- CAM stands for Crassulacean Acid Metabolism. This is a photosynthetic adaptation found in certain plants that thrive in arid conditions.
- CAM plants have a unique way of fixing carbon dioxide to minimize water loss.

2. **Stomatal Behavior:**
- In CAM plants, stomata (the pores on leaves) open at night to take in carbon dioxide, which helps to reduce water loss during the hot daytime.
- During the day, the stomata remain closed to conserve water.

3. **Carbon Dioxide Fixation at Night:**
- At night, when the stomata are open, carbon dioxide enters the mesophyll cells.
- The enzyme PEP carboxylase facilitates the fixation of carbon dioxide into a four-carbon compound, oxaloacetic acid.

4. **Formation of Malic Acid:**
- Oxaloacetic acid is then converted into malic acid, which is stored in vacuoles during the night.

5. **Daytime Process:**
- During the day, the stored malic acid is transported to the chloroplasts.
- In the chloroplasts, malic acid is converted back into carbon dioxide.

6. **Conclusion:**
- Therefore, during daytime, CAM plants procure carbon dioxide for photosynthesis primarily from malic acid.

**Final Answer:**
- During daytime, CAM plants procure carbon dioxide for photosynthesis from **malic acid**.

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