What will I be learning today?

2. What will I be learning today? • Knowledge • Plants have many different types of specialised cell • Plant cells have similar features • Investigation skills • Using / focusing a microscope • Making up your own slides • Interpreting what you see

3. African Violet • Looking at some specialised cells using microscopes African violet : Saintpaulia

4. Preparing a sample to investigate • Take a small sample from underneath a leaf • Mount on a microscope slide in a drop of water • Care with scalpels and glass

5. Stomata: what you can expect to see • The pink pigment is in some of the cells • It is not in the guard cells (or subsidiary cells) so they look white Stoma (pore) Subsidiary Cell Guard cell

6. Close up on guard cells • Find a clear stoma • Identify the guard cells • Use x10 or x40 objective lens • Chloroplasts should be clearly visible chloroplasts

7. Trichomes (hairs) • Made of several cells • Form a physical barrier • May produce chemicals • May help conserve water Air bubble Trichomes

8. Close up on trichomes • Find a big cell that’s part of a trichome • Focus it on the highest magnification that you can • Watch closely – you may see the cell contents moving

9. Other specialised cells • Take thin slices along leaf veins • Or along leaf petioles • You may see spirals of lignin that strengthen xylem cells chloroplasts Spiral lignin in xylem vessels

10. Pollen • Set up a microscope slide with a drop of water on it • Remove a yellow anther from a flower • Crush a section of the anther into the water using the blunt end of a dissecting needle or tweezers • Cover with a cover slip Pollen grains

11. Petal Cells • Prepare a slide with a drop of water • Tear a petal to expose a ragged thin edge • Place slices of the thin edge into the water on the slide • Place a cover slip over the petal tissue Torn thin edge

12. Petal cells • Dome shaped cells • Maybe to allow pollinators to get a better grip on the petals*

13. Leaf Structure • Take thin cross sections through a leaf • Put these into a drop of water on a microscope slide • Look for thin areas under the microscope to investigate the different tissues t p u m l t s

14. Successful learning today Skills • Did you learn any new skills today? • What skills were they? • If not – why do you think that was? Knowledge - What are hairs called on plants? • Can you name more specialised cells in plants? • Which cells that you have seen have chloroplasts? • What else have you learned?

15. Follow on work Building on the structures that students have seen, follow-on lessons could be developed to investigate: • The function of guard cells • experiments with long balloons and sellotape to show curving of the balloon during inflation when one side has been taped • The role of chloroplasts in photosynthesis • why doesn’t onion epidermis have chloroplasts? • why are they green? (pondweed stops photosynthesising in green light) • The role of xylem • why do xylem vessels need strengthening with lignin? • The structure of leaves / leaf tissues • The function of trichomes • as a research / extension project