Plants get oxygen at night primarily through diffusion via structures like stomata and lenticels, which allows them to perform cellular respiration.
The Process Explained
During the day, plants perform photosynthesis, utilizing sunlight to convert carbon dioxide and water into glucose (sugar) and oxygen. They produce more oxygen than they consume, releasing the excess into the atmosphere. At night, however, photosynthesis ceases because there is no sunlight to drive the process. Consequently, plants rely solely on cellular respiration for energy, just like animals. Cellular respiration requires oxygen to break down glucose and release energy, producing carbon dioxide as a byproduct.
Key Mechanisms for Oxygen Intake at Night:
- Stomata: These are small pores on the surface of leaves and stems that facilitate gas exchange. While stomata tend to close at night to conserve water, they don't completely shut down. This slight opening allows oxygen to diffuse into the leaf and carbon dioxide to diffuse out.
- Lenticels: These are small, raised pores on the stems and roots of woody plants. They remain open and permit gas exchange between the plant's internal tissues and the atmosphere.
- Diffusion through the Plant Surface: A small amount of oxygen can also diffuse directly through the plant's surface, although this is a less significant pathway than stomata and lenticels.
Comparing Day and Night Oxygen Exchange:
| Process | Day | Night |
|---|---|---|
| Photosynthesis | Occurs, producing oxygen. Oxygen production exceeds oxygen consumption. | Does not occur. |
| Respiration | Occurs, consuming oxygen and releasing carbon dioxide. | Occurs, consuming oxygen and releasing carbon dioxide. |
| Net Gas Exchange | Net release of oxygen and uptake of carbon dioxide. | Net uptake of oxygen and release of carbon dioxide. |
| Stomata | Generally open to facilitate gas exchange for both photosynthesis and respiration. | Tend to close to conserve water but still allow for some gas exchange for respiration. |
Conclusion
In summary, plants obtain oxygen at night through diffusion, primarily via stomata and lenticels, to fuel cellular respiration. This process is essential for plants to generate energy in the absence of photosynthesis.
