on this cheat sheet
Everything on the GCSE Biology Leaf Structure & Plant Tissues poster is written out below, section by section. Use it to search the sheet, copy parts into your own notes, or check a fact quickly.
Cross section of a leaf
The leaf is an organ built for photosynthesis and gas exchange.
Waxy cuticle
- Covers the epidermis.
- Reduces water loss by evaporation.
Upper epidermis
- Transparent so light passes straight through to the palisade layer below.
Palisade mesophyll
- Packed with chloroplasts.
- Site of most photosynthesis, near the top of the leaf to catch the most light.
Spongy mesophyll
- Loose cells with big air spaces.
- Increases the rate of diffusion of gases in and out of cells.
Lower epidermis
- Contains the stomata that let CO₂ diffuse directly into the leaf.
Stomata
- Small pores, mostly on the lower epidermis.
- Let CO₂ in for photosynthesis; let O₂ and water vapour out.
Guard cells
- Two kidney-shaped cells bordering each stoma.
- Open the stoma in the light (turgid).
- Close them in the dark or in dry conditions (flaccid).
Vascular tissue
Xylem - transports water and mineral ions up from the roots; helps support the plant.
Phloem - transports dissolved sugars (food made by photosynthesis) around the plant.
Meristem tissue
- Found at the growing tips of shoots and roots.
- Can differentiate into any plant cell type.
Key idea
Every tissue's structure suits its function. The leaf is an organ built for efficient photosynthesis and gas exchange.