IGCSE Biology glossary
Spongy mesophyll
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A layer of loosely arranged, irregularly shaped cells in the lower part of a leaf with large air spaces between them. These air spaces allow gases (carbon dioxide and oxygen) to diffuse easily between the stomata and the photosynthesising cells.
What to include in an exam answer
The air spaces are the key adaptation of spongy mesophyll. They provide a large internal surface area for gas exchange and create a short diffusion pathway between stomata and mesophyll cells.
Example in context
Explain the function of air spaces in the spongy mesophyll (2 marks): Air spaces allow carbon dioxide to diffuse from the stomata to photosynthesising cells and oxygen to diffuse out, increasing the rate of gas exchange.
Related syllabus topic
Plant nutrition