Remember that field labs must be done in order....on time if possible.

Biology Lab: Field Lab #6

Goal: To observe several angiosperms closely

Materials

• Magnifying glass
• Specimen cases for small specimens
• Bush bean plant (You should buy seeds and germinate bush beans (Phaseolus vulgaris), mung beans, or other rapidly-growning bean plant. Make your observations when the plant is close to 2-weeks old.
• Ethanol 50% solution (if you buy pure ethanol, mix 1:1 with distilled water)
• Staining kit (toluidine blue O and glycerine)

Procedure:

1. Preparation: Review the procedures in IGHBC Lab X-2, Investigating Seed Plants, for observations of germination, root, stem, and leaf structures. If possible, follow the instructions provided; otherwise, use the instructions in #5 and #6 below to complete close observations of plant structures, including microscopic observations.
2. In situ observation (habitat observation)
   1. Return to your field area in the early morning; try to do this on a day when it has not rained for 24 hours.
   2. Chose four plants to observe; be sure at least one is a dicot and one a monocot.
   3. Note plant conditions: are the plants leafing? Flowering? Are the plants wet or dry?
   4. Repeat your observations at mid-day (it does not have to be the same day).
3. Collection:
   1. If possible, collect several plant specimens for closer observation (be sure to get permission first). You will need a leaf, a flower, a piece of stem (with tip!) and a root with tip, if possible. A good choice for at least one speciment is a weed; most people don't mind if you want the whole dandelion.
4. Sample Observation:
   1. Clean and dry the plant. Set aside the flowers for later observation.
   2. Prepare thin slices from the very end of the root tips and stem tips for the microscope following the instructions in the Slide Preparation lab.
   3. If you have time, prepare slices from at least one root and one stem specimen, as far from the tip as possible. Compare the structures to the end-of-tip specimens from the same plant. Are the cells the same size and shape?
   4. Compare the root and tip structures, paying special attention to any differences between the monocot and dicot plants.
5. Bush Bean Observation:
   1. Using your microtome (see above), make 8-10 thin slices of bush bean stem.
   2. Place the slices in your 50% ethanol solution for at least 5 minutes. Make sure the slices are free of parafin.
   3. Stain the slices, immersing them in a tuluidine blue O stain solution for 5-10 minutes.
   4. Mount the sections in 50% glycerine on a glass microscope slide, adding a coverslip carefully to expel all bubbles.
   5. Draw your observations. Identify and label
      • parenchyma cells
      • sclerenchyma cells
      • collenchyma cells
      • xylem
      • phloem
      • epidermis
6. Flower "dissection":
   1. Make a drawing of the flower, and identify the major sections, including the stem, petals, sepals, stamen, filament, anther, pistil, stigma, style, and ovary (if visible).
   2. Remove the sepals and petals and examine them under low magnification with a magnifying glass. Describe the surface texture of each (for example, is it smooth? veined? hairy?).
   3. Remove the stamens and examine them with the magnifying glass. Draw a picture of the stamen and identify the filament and anther.
   4. Shake off some pollen from the anther and examine the pollen with a magnifying glass; describe its shape and surface texture. Examine the pollen under the microscope. Make a drawing of your observations.
   5. Remove all parts of the flower until the pistil remains alone on the stem. Cut it in half lengthwise and examine it with the magnifying glass. Draw a picture of the structure of the pistil and the ovary.
   6. If you have time, use your microtome to cut cross-section specimens of the anther and ovary; examine these under the microscope. Draw your observations and label the types of cells you find.
7. Hypothesis: Review your report from Field Lab #1. Copy your table of information and include updated information and measurements. Assess the hypothesis your created in Field lab #1: do any changes in the plants and animals you observe now support your hypothesis?

Report

Your report should include the explanation of how you obtained your samples, and a chart of their characteristics, with enough detail to identify each one again (if possible, use your chart from Field Lab #1 for the same specimens, and make any useful comparisons in size, color, foliage, etc.). Make a chart of your microscope observations as well, comparing different characteristics from each specimen. What general conclusions can you draw about the structures of roots and stems for all plants? For dicots? For monocots?

© 2005 - 2024 This course is offered through Scholars Online, a non-profit organization supporting classical Christian education through online courses. Permission to copy course content (lessons and labs) for personal study is granted to students currently or formerly enrolled in the course through Scholars Online. Reproduction for any other purpose, without the express written consent of the author, is prohibited.