Guard cells are living and contain chloroplasts.

Answer

**Step-by-Step Solution:**

1. **Understanding Guard Cells**: Guard cells are specialized cells located on the surface of leaves, surrounding the stomata. Their primary function is to regulate the opening and closing of these stomatal pores.

2. **Living Nature of Guard Cells**: The statement claims that guard cells are living. This is true; guard cells are indeed living cells that play an active role in the plant's physiological processes.

3. **Presence of Chloroplasts**: The statement also mentions that guard cells contain chloroplasts. This is also true. Chloroplasts are the organelles responsible for photosynthesis, allowing guard cells to produce food (glucose) for the plant.

4. **Role in Photosynthesis**: The chloroplasts in guard cells contain chlorophyll, the pigment necessary for photosynthesis. This process enables guard cells to synthesize glucose, which is essential for their function and for the plant's energy needs.

5. **Impact on Stomatal Function**: The production of glucose increases the osmotic potential within the guard cells. This osmotic change leads to the uptake of water from surrounding cells, causing the guard cells to become turgid (swollen). As a result, the stomata open, allowing for gas exchange and transpiration.

6. **Conclusion**: Therefore, the statement "Guard cells are living and contain chloroplasts" is true, as both aspects are essential for their function in regulating stomatal openings.

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