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

African Violet• Looking at some specialised cells using microscopes

African violet : Saintpaulia

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

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

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

Trichomes (hairs)

• Made of several cells

• Form a physical barrier

• May produce chemicals

• May help conserve water

Air bubbleTrichomes

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

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

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

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

Petal cells• Dome shaped cells

• Maybe to allow pollinators to get a better grip on the petals*

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

t

p

m

s

u

l

Successful learning todaySkills-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?

Follow on workBuilding 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