2. Use of the light microscope, including simple stage and eyepiece micrometers and drawing cells from a specialised tissue.

Question 1

Method:

Answer 1

1. Calibrate the eyepiece graticule.
2. Collect a piece of stem and add a few drops of water to the centre of the white tile and wet the razor (reduce friction). Cut several sections, as thin as possible, and use a brush to transfer the sections into water in a watch glass.
3. Select the two thinnest sections and place them on separate slides.
   Stem one: mount in na water drop, lowering the coverslip to the section using the mounted needle and ensuring there are no air bubbles.
4. Stem two: remove excess water by carefully touching with absorbent paper. Add two drops of TOLUIDINE blue O stain and leave for 2-4 minutes. Add the coverslip as before and gently remove excess stain with a paper towel.
5. Turn objective lens to low power. Examine unsustained slide first and then the stained slide.
6. For the stained slide, remain on low power and draw and annotate a simple outline plan of the plant stem. Show the arrangement of tissues within the stem but do not include any cell details. Compare what can be seen for the stained and unstained slides.
7. Using the eyepiece graticule, measure a vascular bundle and or stem diameter. Add a scale bar to the diagram. Add title and include total magnification.
8. Turn objective disc to medium-power lease. Finally to high power and focus using fine focusing knob. Choose 10 cells at the junction of two tissue types. Draw them and label the detail of these cells as accurately as possible. Measure the length and breadth of two cells.

Question 2

Risks:

Answer 2

Toluidine blue O stain is harmful if swallowed (but otherwise classed as hazardous)

• Avoid skin contact
• Wear gloves and eye protection.
• Clean any spills immediately and dispose of excess stain in the receptacle provided.

Sharp razor

• Be cautious when using and carrying.
• Do not leave blades lying on desk.

Question 3

Information about Toluidine blue O stain.

Answer 3

Toluidine blue O is a METACHROMATIC stain: it reacts with different chemical components of cells to produce a variety of colours- which can provide information on the nature of the cell.
Lignin and tannins: blue—> green
Pectins: pinkish purple
Nucleic acids: purplish/greenish blue

Question 4

‘Magnification’ calculation.

Answer 4

Magnification= Size of Image/ Size of actual object.

Question 5

Instructions for when drawing:

Answer 5

• Use sharp HB pencil
• Draw only what is visible.
• Start with outline.
• Do not use shading or colour.
• Draw label lines in pencil with a ruler.
• lines should not have arrowheads and should just touch the labelled item.