1. The Structure of a Leaf The Structure of a Leaf Stoma ta wa xy Stomata pore Guard cellAir spaces

2. Stomata Closed Open

3. Thick inner cellulose cell wall of guard cell. Thinner outer cell wall of guard cell.

4. Stomata epidermal cell nucleus thick inner wall of guard cell guard cell thick inner wall of guard cell epidermal cell nucleus chloroplast stomatal aperture chloroplast

5. Stomata epidermal cell nucleus thick inner wall of guard cell guard cell thick inner wall of guard cell epidermal cell nucleus chloroplast stomatal aperture chloroplast

6. Stomatal opening is triggered by higher light intensities and low concentrations of CO 2 This allows CO 2 to enter for photosynthesis, but water will also leave by transpiration

7. An increase in potassium ion and glucose concentrations in the guard cells causes water to move in by osmosis from the surrounding cells. The guard cells swell and because the thick inner cell wall can’t expand, the two guard cells bend away from each other, which opens the stomata pore. However, some plants close their stomata at midday to conserve water!

8. Thick inner cellulose cell wall of guard cell. Thinner outer cell wall of guard cell.