Introduction, Using the Light Microscope, Plant Body the Cell and Parenchyma

Lab. No.1 Introduction, using the light microscope, plant body the cell and parenchyma. Slides Prepared slides 1- Ficus elastica leaf c.s 2- Coleus stem c.s. 3- Syringa leaf c.s 4- Nymphea leaf c.s 5- Pinus leaf c.s 6- Smilax root c.s 7- Aristolochia stem c .s Fresh specimen 1- Allium bulbs 2- Red pepper or tomato 3- Soaked Phaseolus (bean) seeds 4- Musa (banana) 5- Ginger 1 Lab. No.1 Introduction, using the light microscope, plant body the cell and parenchyma. LABORATORY INSTRUCTIONS Each period laboratory exercises and directions will be distributed. The laboratory is a period of semi-independent study designed to enhance and supplement the lecture material. MATERIALS You will need a 4H -6H pencil, gum eraser, ruler and drawing paper. Any plain white paper (non-lined) will do. Also a notebook is required. PREPARATION OF DRAWINGS Each student will be asked to prepare a notebook of required drawings. This book will be helpful in studying this lab. slides Drawings do not require a talent for illustrating. They should only be a means to enable the student to grasp and show basic facts and ideas simply and clearly. -Label the drawings fully. -Use a ruler to make straight pointed lines that end in the object designated. - write your labels .Make the pointer lines parallel, when possible, and place the labels on only the right hand side of the drawing. Never cross pointer lines and try to make them end on the same vertical lines. - Use only one side of the paper. - Do not make the drawings too small. Most should occupy at least half a page. The drawings should always be of sufficient size to nicely illustrate the details required. -Do not draw too much, only what is required. Drawings to be required will be three general types, (1) Sketch- represents the material as it appears to the unaided eye or under the dissecting scope. Draw only what is seen. 2 (2) Drawing- represent exactly that which appears under the microscope by firm, clear lines. Never shade or use color. (3) Diagram- reconstruct in outline as the material should appear in the ideal condition. Artistic ability is not a necessity, but the accuracy of details and proportion is of importance BASIC LABORATORY TECHNIQUES (1) Use of materials in the laboratory - fresh and preserved material should be used as necessary Used slides and cover slips should be washed, dried and placed in a slide box for reuse. Prepared slides should be neatly placed back in their appropriate boxes. Use only one slide at a time and return it to its proper box before obtaining the next slide. (2) Preparing temporary or wet mounts- place a small drop of water on a clean slide. Place the specimen in the drop of water. Cover the specimen with a cover slip by first touching the slide with one edge of the cover slip and then lowering the other edge with a needle. Water should fill the space between the elide and cover slip; if it spreads over any part of the slide, this excess should be blotted carefully. (3) Cutting freehand sections- Sections are most easily cut by holding the plant material on the moist slide with the forefinger. Cut downward under a dissecting microscope and allow the section to float off the razor blade into a drop of water on the slide. This takes practice, so be patient with yourself and ask for assistance if necessary. (4) Each person will be assigned a microscope which s/he will be responsible for during the semester. Any problems with scopes should be reported to the instructor. At the end of each period. 3 THE PLANT CELL Cell Structure and Contents 1. STRUCTURAL RELATIONSHIPS: a. Allium: (onion) epidermis & scales - fresh material - carefully peel off a portion of the epidermis and make a wet mount. Draw a group of adjacent cells, show clearly the spacial and structural relationships of cell walls, cytoplasm, nucleus, vacuoles (if visible), etc. Label appropriately. Note the occurrence of prismatic crystals in some cells. You can prepare a wet mount slide for the scales (brown) to observe the prismatic crystals better. 2. PLASTIDS: b. Capsicum (red pepper) or c. Lycopersicon (tomato) - fresh fruit - spread a small portion of fresh fruit (pulp) or make a thin slice of pigmented tissue and place on a slide. Squash gently under coverslip. Draw a population (about five) of chromoplasts. Is there any difference in morphology or size of these plastids? What color are they? Why? c. Daucus (carrot) taproot - fresh material - prepare a thin section of a carrot. Observe and draw a population of chromoplasts. Any variations within the population? d. Avocado fruit - fresh material - prepare a hand section of the soft tissue of avocado fruit. Observe and draw the abundant elaioplasts (oil droplets) in these cells. Stain for a few minutes with Sudan IV and observe again. e. Phaseolus (bean) seed (cotyledon) - fresh material - place a thin section of material on half of a slide and several drops of cell sap on the other. Draw a population of starch grains (amyloplasts). Label the concentric rings and hilum (if visible). Stain with iodine (I3K) [Lugol's solution]and observe the positive stain. f. Musa (bananas) fruit - fresh material - prepare a hand section of the soft tissue of banana fruit Compare these starch grains with those of Phaseolus and draw a group of them. g. Solanum (potato) tuber - fresh material - prepare a thin section that includes the epidermis.Express several 4 drops of cell sap on a separate portion of the slide. Draw starch grains. 3-ERGASTIC SUBSTANCES: CRYSTALS: a. Ficus leaf - fresh leaves - make a thin section (transection) of the fig leaf. Observe the large crystals of calcium carbonate (cystoliths) in enlarged specialized cells (lithocysts). you can examine the prepared slide for Ficus leaf C.S. Notice: multiple epidermis in this leaf, with special epidermal cell called lithocysts containing cystolith crystals of calcium carbonate as one of crystals that may be found in plant cells. b. Zingiber (ginger) rhizome - fresh material. Place a thin section of tissue on one side of a slide and express cell sap on the other side. Note the golden droplets of ginger oil. Unlike some storage lipids, ginger oil is not formed in elaioplasts, but it is synthesized directly in the cytoplasm Parenchyma Parenchyma - parenchyma is the main cell type in ground tissue (cortex, pith (stems &roots) and , leaf mesophyll the endosperm of seeds, flesh of fruits and in association with vascular tissue.) -Parenchyma cells are defined as living cells with thin (usually) primary walls. - Parenchyma cells are usually isodiametric with intercellular space between them. - Function of parenchyma vary depending on their location in the plant body (photosynthesis, respiration, secretion, storage and as transfer cells. using fresh material and prepared slides 5 1-Coleus stem C.S. Prepared slide Notice: - Parenchyma in cortex and pith (shape of cells, cell wall, intercellular spaces between cells) 2-Syringa leaf C.S. Prepared slide Notice : - parenchyma in mesophyll (chlorenchyma), palaside mesophyll of elongated parenchyma and spongy mesophyll. Why it is called spongy? Why chlorenchyma? 3-Nymphea leaf C.S. Prepared slide Notice the spongy mesophyll in this leaf which is made of stellate parenchyma (aerenchyma). 4- Pinus leaf C.S. Prepared section Notice plicate( ‫)مروحي‬mesophyll of folded parenchyma cells. 5- Smilax root C.S. Prepared slide Notice parenchyma in pith with secondary lignified cell wall (sclerefied parenchyma) 6-Aristolochia stem C.S. Prepared slide Notice: druses crystals of calcium oxalate found in parenchyma cells. 6