|Plant Physiology (Biology 327) - Dr. Stephen G. Saupe; College of St. Benedict/ St. John's University; Biology Department; Collegeville, MN 56321; (320) 363 - 2782; (320) 363 - 3202, fax; email@example.com|
The structure of the stomatal apparatus varies from species to species. In general, guard cells are either bean-shaped (eudicot type) or barbell-shaped (grass type). Guard cells may or may not be accompanied by subsidiary cells.
What is the structure of the stomatal apparatus of plants such as wandering Jew (Tradescantia), Broad bean (Vicia faba), RCBr (Brassica rapa) and maize (Zea mays)?
Hypotheses: Since RCBr and Broad bean are eudicots they will
have bean-shaped guard cells. Maize,
a monocot, will have barbell-shaped guard cells.
a Broad bean leaf and make an epidermal peel
from the lower (abaxial) surface.
the strip in a drop of water on a microscope slide and cover with a cover
glass. Examine at 400x. Do not
use the oil immersion lens.
Sketch the stomatal apparatus. Be sure to record the
magnification of the object and calculate the plate
magnification (= drawing size / actual size; same units).
Be sure to give your diagram a caption and label stomata, guard cells, subsidiary cells and epidermal cells.
Obtain a leaf of a plant from the greenhouse and prepare an epidermal peel. Use the digital camera to prepare an image from this species. Record the actual size of the guard cell or stomata.
Data: Sketch of the stomatal apparatus of broad bean and digital image of a species of your choice. Label these Fig's 1 & 2).
organelles do you observe in the epidermal cells? Guard cells?
similarities do you observe between the stomatal apertures of the species?
they appear as you expected? Explain.
good (free of mesophyll) are your epidermal strips?
organelles do you observe in the guard cells?
other epidermal cells?
species was easiest to peel? Offer
Do any of the species you observed have distinct subsidiary cells? Which ones? What do they look like?
What percent of the epidermal cells are guard cells?
On average, how many epidermal cells are between a stoma and its nearest neighbor?
01/07/2009 � Copyright by SG