A plant biochemist received a spicemen from a fellow scientist who noticed that the plant's stomata are closed during the day. The biochemist observed that radioactive carbon supplied in the form of carbon dioxide fed to the plant at night, was first found in organic acids that accumulated in the vacuole.During the day, the label moved to sugars being manufactured in the chloroplast. What was the conclusion of the biochemist?

Options

A. It is a CAM plant
B. It is a C4 plant
C. It is a C3 plant
D. It is a plant showing pentose phosphate pathway

Answer

### Step-by-Step Solution:

1. **Understanding the Observations**: The biochemist received a specimen of a plant with closed stomata during the day. This indicates that the plant is likely adapted to conserve water, which is a characteristic of certain types of plants.

2. **Analyzing the Carbon Dioxide Supply**: The biochemist observed that radioactive carbon dioxide supplied at night was first found in organic acids accumulating in the vacuole. This suggests that the plant is capable of fixing carbon dioxide at night, which is not typical for most plants.

3. **Identifying the Daytime Process**: During the day, the radioactive label moved to sugars being manufactured in the chloroplast. This indicates that the plant is utilizing the fixed carbon from the organic acids to produce sugars during the day.

4. **Considering Plant Types**:
- **C3 Plants**: These plants do not have special adaptations for water conservation and typically fix carbon dioxide during the day when stomata are open.
- **C4 Plants**: These plants fix carbon dioxide during the day but have a different mechanism that allows them to minimize photorespiration.
- **CAM Plants**: Crassulacean Acid Metabolism (CAM) plants fix carbon dioxide at night when their stomata are open, storing it as organic acids, which are then converted to sugars during the day when the stomata are closed.
- **Pentose Phosphate Pathway**: This is an alternative metabolic pathway that is not directly related to the observations made in the question.

5. **Conclusion**: Given that the plant's stomata are closed during the day and that it fixes carbon dioxide at night into organic acids, which are then converted to sugars during the day, the biochemist concluded that the plant is a **CAM plant**.

### Final Answer:
The biochemist concluded that the plant is a **CAM plant**.

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