Instructions: Complete this assignment using the resources on your Canvas site. Please type your answer to each question or insert a picture or graph when that is what is needed. Do NOTre-number the questions or change the layout. Once your work is done you should save in either a Word document or PDF and upload it to the Lab Assignment link on Canvas. Your work on this homework assignment should be your own. If you need assistance, please come to your instructor’s student support time or visit the science tutoring center.
Name: Date:
Stomatal Density of Rhododendron Adaxial versus Adaxial Leaf Epidermal Tissue
In this assignment you will use the scientific method to explore the anatomical differences between the adaxial and abaxial epidermis of rhododendron leaves. The anatomy of these leaves are typical of many broad leaf Angiosperm perennial (live for many years) plants.
Observation(from lab 1): On a leaf organ, the adaxial epidermis covers tightly packed palisade mesophyll tissue, whereas the abaxial epidermis covers loosely packed spongy mesophyll tissue and a network of air space.
Question: Does the density of stomata differ between the adaxial epidermis and abaxial epidermis of a leaf organ?
- (a) Please make a directional hypothesis that is a tentative answer to this question. A directional hypothesis specifies what is longer/shorter, bigger/smaller, faster/slower, etc.
Hypothesis:
(b) In this hypothesis, what is the independent variable and is it continuous or categorical?
- Please make a prediction for the results of an experiment observing leaf impressions of rhododendron leaves. Template: If [hypothesis you wrote], then [predicted results of the experiment]. Hint: to write a pedictoin you need to know how the experiment will be done so you can predict results. Read the rest of this worksheet so you know the experiment, then return to this question and write your prediction.
Prediction:
The next step is to run an experiment. For this experiment, surface impressions of rhododendron leaves have been made for you using clear nail polish and mounted to microscope slides. Four leaves were sampled from plants around the Natural Sciences building. For each leaf an impression was made of the adaxial (top) and abaxial (bottom) leaf surface. We used a compound microscope to observe the surface impressions, and we captured pictures of the field of view (FOV) of the microscope at 400x magnification (40x objective x 10x ocular). The pictures are located inthe “Lab Assignment 1” page on your Canvas site.Please view each picture, count the stomata in each, calculate density, and complete the table below.
(a) Complete this table
| Leaf Surface | Leaf Number | Number of stomatal complexes (count) | Stomatal Density (count/mm2) |
| Adaxial | Leaf 1 | ||
| Adaxial | Leaf 2 | ||
| Adaxial | Leaf 3 | ||
| Adaxial | Leaf 4 | ||
| Abaxial | Leaf 1 | ||
| Abaxial | Leaf 2 | ||
| Abaxial | Leaf 3 | ||
| Abaxial | Leaf 4 |
(b) Calculate central tendance of the data. Specifically, what is the mean stomatal density for the adaxial and abaxial epidermal tissueof rhododendron?
Adaxial mean stomatal density_____________stomata/mm2
Adaxial mean stomatal density_____________ stomata/mm2
- Create a scientific figure in Excel showing the results of this experiment. Scientific formatting is expected. Please use your material from lab 1 as a template and resource. After making your graph in Excel paste it below and write a figure caption.Hint: you only need to copy the first and forth columns of the table into Excel.
- State the concussions of this study using correct scientific terminology.
- What do the results of thisexperiment, tell us about leaf form and function?
- Anatomy both constrains and allows physiological function. Name twofunctions of epidermal tissue in the shoot system.
- If you found anatomical differences between the adaxial and abaxial epidermis in the experiment, please explain the implications of this finding for differences infunctional specialization. What do you predict is the main function of the adaxial epidermis? What do you predict is the main function of the abaxial epidermis?