Gas exchange inside the leaf
A leaf must exchange gases because carbon dioxide is used during photosynthesis and oxygen is needed for respiration.
Much of the internal exchange area is formed where spongy mesophyll cells border the leaf's air spaces. This exposes a large amount of cell surface to the air contained inside the leaf.
| Feature | Contribution to gas exchange |
|---|---|
| Spongy mesophyll surfaces bordering air spaces | Provides a large internal area over which gases can cross between air and cells. |
| Numerous internal air spaces | Provide routes through the leaf so gases can reach many mesophyll cell surfaces. |
| Thin, flat shape | Keeps the pathway for diffusion through the leaf short. |