1. Place a drop of water at the center of the clean slide and place a thin layer of skin peeled off from the inner surface of onion bulb, Allum cepa L. With a dissecting needle, put a cover slip on the specimen by tilting it along one side of the slide so that one edge touches the water. Gently lower the cover slip by withdrawing the needle slowly to prevent air bubbles.
2. Examine one cell under the HPO.
2.1 Is the cell wall uniform in thickness?
Yes
2.2 Can you observe the narrow canals or depressions along the walls? If yes, identify these structures.
Plasmodesmata
2.3 Can you distinguish the protoplast clearly?
No
2.4 Can you see the cytoplasmic strands? No
3. Using filter paper as absorbent, remove the water from the slide by gently pressing one side of the coverslip. Immediately apply a drop of iodo-potassium iodide solution on the opposite side of the coverslip. The solution will slowly replace the water. After a minute or two,wipe off the excess solution
3.1 Do you observe the cytoplasmic strands now?
Yes
3.2 In what part of the cell is the nucleus found?
Cytoplasm
3.3 Do you see more than one nucleolus?
Yes
3.4 What structure(s) is/are between the cytoplasmic strands?
Organelles
4. Take a leaf from the actively growing shoot of a water plant, hydrilla, Hydrilla verticillata (Roxb.) Royle which has been previously exposed to bright light. Make a water mount by placing the upper surface of the leaf next to slide. By moving the LPO up and down, you can see two layers of cells. Under the HPO observe the streaming protoplast (cyclosis) and note the direction of its movement.
4.1 What structure in the cell contains the green pigment?
Chloroplast
4.2 What is the shape and arrangement of the structure?
In stacks (grana)
4.3 Do they move along with the streaming protoplast?
Yes
6. On a slide, make separate mounts of the skin and pulp of a ripe fruit of tomato, Lycopersicon lycopersicun (L.) Karsten and red pepper, Capsicum frutescens L.
6.1 What structure in the cell contains the pigments?
Chromoplast
7. Make water mounts of both upper and lower surfaces of the leaf of boat of Moses, Rhoeo discolor (Hert.) Hence. One surface contains a vacuole pigment and the other a plastid.
7.1 What types of pigment are found on each surface?
Anthocyanin – vacuole
Chlorophyll – chloroplast
7.2 How do these pigments differ from those of the tomato pulp and hydrilla leaf?
Differ in location and color.
8. Prepare free-hand sections of any 5 of the following specimens representing the different types of crystals: petioles of Begonia sp.; castor oil plant, Ricinus communis L.; the laminae of santan, Ixora sp.; bowstring hemp, Sanseviera zeylanica Roxb.; the midribs of fringed waterplant, Raphidophora merili Engl.; dumbcane, Diefferenbachia sp.; guava, Psidum guajava L.; pigweed, Amaranthus viridus l.; purslane, Portulaca oleracea L.; sweet potato, Opomoea batatas Lam. and stem of Pilea cadieri.
8.1 Identify and sketch the types of crystals observed.
9. Examine prepared slides of a cross-section of any stem or root and fresh surface sections of the lower epidermis of the leaf of the boat of Moses under the LPO and HPO. Locate cells that ar bounded by a single cell wall called the primary cell wall. Locate the middle lamella (the intracellular layer) between the primary walls of adjacent cells.
9.1 What must be the function of the middle lamella?
Cement adjacent walls together
10. Examine fresh sections of green and ripe tomato fruits.
10.1 Compare the appearance of the cells
Cells in the unripe tomato fruit are closer together
10.2 What happens to the middle lamella when fruits ripen
Loss of cell wall components particularly pectin, which makes up the middle lamella
11. Scrape cells from a shell of a coconut, Cocos nucifera L. and stain with 18% alcoholic phloroglucinol-sulfuric acid solution. Examine under the compound microscope. Lignin will turn red with this solution. These cells have both the primary and secondary walls.
11.1 Draw a cell and label parts
a basic sketch of cell from coconut husk (sclereid cells)
Notes:
Some questions are dependent on the specimen and therefore differs for each student. Questions 2.2,. 2.4, 3.1, 3.3 may be answered yes/no dependent on what you observed.
For the types of crystals:
CaC2O4:
prismatic
raphides
druses
styloids
CaCO3:
cystolith
wormlike cystolith
Your instructor will draw a basic sketch of what these crystals look like and that’s pretty much it.
Notes and Guides for the Frustrated 