Everything Life Sciences Grade 10

1. Use the forceps or needle to lift a small piece of soft pear tissue onto your microscope
   slide.


2. Add a drop of iodine solution.


3. Mash the tissue slightly to separate the cells.


4. Cover with a cover slip and observe under low power. You should focus on the groups
   of dark ”stones” that appear amongst the rounded parenchyma cells of the pear. Try to
   find one or two stone cells or sclereids that are separate from the rest.


5. Enlarge a good specimen (or focus on the edge of a group where one cells sticks out)
   and adjust the lighting.


6. Look carefully while you focus up and down to see the long, narrow PITS running
   through the extremely thick walls of these cells.


7. These ”stone cells” are called sclereids. They are a modified form of sclerenchyma
   found in pears, guavas and the shells of nuts for extra support.


8. Also observe the large round cells around the sclereids.

Questions:

1. Do you see cytoplasm inside the stone cells? Are they living or dead cells?


2. What tissue type do the large round cells around the sclereids belong to?

Activity: To investigate sclerenchyma fibres

Aim:

To see sclerenchyma fibres in tissue paper

Materials:

• cheap toilet paper (single ply)


• iodine solution or water


• microscopes and slides

Instructions:

1. Tear a tiny piece of toilet paper off the sample and mount it in water or iodine solution.


2. Place on a cover slip and examine under the microscope on low power.


3. Focus on the torn edge of the paper and observe the long sclerenchyma fibres.


4. Observe on high power.

Questions:

1. Describe the shape of these cells.


2. Are they living or dead cells?


3. Suggest their function.

126 5.3. Plant tissues