Transpiration lab

I had the students do the stomata count lab a week or so ago. The data collection really needs only about one hour.  The tulips had finished blooming so I could take a few leaves.  Tulip leaves sheer easily to get the whitish epidermis.  These leaves are vertical so no real upper or lower side, but rather inside or outside surfaces.  I am sure the students got confused about which surface was which but as there are nearly the same number of stomata on each side, it did not really matter.  They compared the tulip stomata counts with dandelion leaves.  These grow profusely in Germany from April to October so are nice to use.  This gave the students a monocot and a dicot leaf to make comparisons.  Dandelions were painted with clear nail polish over 1cm x 1 cm area, allowed to dry and then peeled off.  Wet mounts of the nail polish and the tulip epidermis were viewed with a microscope at the 100x or 400x power.  The number of stomata in five different fields of view were  counted.  Students measured the surface areas of the entire leaves to be able to estimate the total number of stomata on the leaves.

With their counts, students could then do a t-test to determine if there was a significant difference between the two surfaces and between the two leaves.

If the t test has already been taught to the students, this is a good DCP lab as students all have their own data for DCP 1 ( stomatal counts), lots of data processing for DCP 2 that is not difficult ( stomatal densities, surface areas, total stomata numbers).   DCP 3 can be based on how well the students present their calculations and perhaps simple bar charts showing the differences between the leaves and surfaces.