Study Notes
Gas exchange in plants involves the movement of oxygen and carbon dioxide, with the net effect depending on light intensity and time of day. The structure of leaves and the role of stomata are crucial for efficient gas exchange.
- Photosynthesis — the process by which plants use sunlight to synthesize foods with the help of chlorophyll. Example: During the day, photosynthesis results in a net release of oxygen.
- Respiration — the process of breaking down glucose to release energy. Example: Plants respire all the time, releasing carbon dioxide.
- Stomata — tiny pores on the leaf surface that control gas exchange. Example: Stomata open in light when guard cells are turgid.
- Spongy Mesophyll — a layer in the leaf with loosely packed cells for gas exchange. Example: Allows gases to diffuse through the leaf.
- Diffusion — the movement of particles from an area of high concentration to an area of low concentration. Example: Oxygen diffuses into the leaf when stomata are open.
Exam Tips
Key Definitions to Remember
- Photosynthesis
- Respiration
- Stomata
- Diffusion
Common Confusions
- Photosynthesis only occurs during the day, while respiration occurs all the time.
- Stomata are not always open; they close in the dark.
Typical Exam Questions
- What happens to gas exchange in plants at night? Photosynthesis stops, leading to a net release of carbon dioxide.
- How do stomata function in gas exchange? Stomata open and close to regulate gas exchange based on light and water availability.
- Why is the spongy mesophyll important? It provides space for gases to diffuse within the leaf.
What Examiners Usually Test
- The role of stomata in gas exchange
- Differences in gas exchange during day and night
- Adaptations of leaves for efficient gas exchange