Practical 6: Identifying structures in a stem

Question 1

Identifying structures in a stem

Answer 1

1. Calibrate the eyepiece graticule by placing both on the stage and lining up the
   divisions of the stage micrometer (which have a known length) with the divisions of
   the eyepiece graticule (for which the length is unknown) to calculate the length of one
   division of the graticule.
2. Cut transverse sections of the plant stem (on the white tile using a razor, wet to
   reduce friction) as thinly as possible. Select the thinnest sections.
3. Place one section on a microscope slide. Draw a line in wax crayon from top to
   bottom of the slide either side of the specimen to prevent the dye from spreading. Add
   a few drops of concentrated phloroglucinol and lower the cover slip down carefully
   onto the slide. Make sure there are no air bubbles in the slide which may distort the
   image.
4. Place under a microscope and set the objective lens on the lowest magnification, then
   use the coarse adjustment knob to move the lens down to just above the slide.
5. Use the fine adjustment knob to carefully re-adjust the focus until the image is clear
   (can use a higher magnification if needed).
6. Observe and draw the stem.
7. Measure the size of the stem diameter and vascular bundle using the calibrated
   eyepiece graticule.

risks- broken glass, razor

variables- N/A

plot data by drawing a biological sketch