to observe and count stomata in leaf peals of different species of plants to investigate how stomata numbers are influenced by leaf type

Transcription

1 Project 2: Plant Stomata Lab Name: Potential Credits: /25 Project Goals: to observe and count stomata in leaf peals of different species of plants to investigate how stomata numbers are influenced by leaf type Note: Please note that this project has be adapted from the Biology Junction website at Background: Stomata are pores, typically found on the underside of the leaves, which allow gases to enter and exit the leaves. Stomata can be opened or closed by the surrounding guard cells. The stomata will open when guard cells swell with water and move apart or close when guard cells lose water and move together. Purpose: The purpose of this lab is to become familiar with how to prepare and view specimens with a smart phone microscope and to view and compare stomata structure and numbers from the leaves of several species of plants. Materials: smartphone smartphone microscope (you may build your own microscope following the instructions given in Unit 7 Project 1: Make a Microscope or you may purchase a smartphone microscope generally for under $30.00). leaves from 3 different species of plants (leaves must be at least 1 cm by 1 cm) clear nail polish transparent/clear tape (scotch tape) Page 1 of 7

2 Procedure: 1. Collect all of the required material. 2. Pick one healthy leaf from each of the three plant species. 3. Paint a 1 cm x 1 cm square patch of clear nail polish on the underside of each leaf. 4. Allow the nail polish to dry completely! 5. Tape a piece of the transparent tape over the dried nail polish. 6. Gently pull on a corner of the tape to peel the nail polish patch off of the leaf. You should end up with a leave impression (stomata and all) embedded in the nail polish and attached to the tape. 7. Tape your leaf impression to either a glass microscope slide or a 2.5 cm x 7.5 cm piece of clear plastic to make a "slide". You may use a clear sheet protector or plastic from packaging or some other suitable source as long as it is clear. 8. Label your "slide" with the name of the plant species, both its common name and its scientific name (you may need to look up the plant's scientific name). 9. Examine the leaf impression with the microscope using as high of a magnification as possible. 10. Search for areas of the leaf impression that have many stomata yet no fingerprints, dirt, major leaf veins of damaged leaf. 11. Take photographs of the stomata from at least three different regions of the leaf impression for each of the plant species. Ensure that the photographs are taken at comparable magnifications. 12. Present the photographs in the observation section below (either by printing and cutting and pasting or preferably by directly importing the photographs into this document). Please be sure to fill in the name of the plant in the blank spot left in the figure legend. 13. Count the number of stomata from at least 3 different photographs (of comparable magnification) for each plant species. Record the numbers in the data table given below. 14. Complete the discussion portion of this project. Page 2 of 7

3 Observations: a. Region 1 of Leaf Impression b. Region 2 of Leaf Impression c. Region 3 of Leaf Impression Figure 1. Leaf Impression of a Leaf. A leaf impression was created by painting clear nail polish on the underside of a leaf, allowing the nail polish to dry and then placing tape over the dry polish. The tape and nail polish were then gently pulled away from the leaf to create a leaf impression. The leaf impression was then viewed and photographed at maximum magnification using a smartphone microscope. (3 marks) a. Region 1 of Leaf Impression b. Region 2 of Leaf Impression c. Region 3 of Leaf Impression Figure 2. Leaf Impression of a Leaf. A leaf impression was created by painting clear nail polish on the underside of a leaf, allowing the nail polish to dry and then placing tape over the dry polish. The tape and nail polish were then gently pulled away from the leaf to create a leaf impression. The leaf impression was then viewed and photographed at maximum magnification using a smartphone microscope. (3 marks) Page 3 of 7

4 a. Region 1 of Leaf Impression b. Region 2 of Leaf Impression c. Region 3 of Leaf Impression Figure 3. Leaf Impression of a Leaf. A leaf impression was created by painting clear nail polish on the underside of a leaf, allowing the nail polish to dry and then placing tape over the dry polish. The tape and nail polish were then gently pulled away from the leaf to create a leaf impression. The leaf impression was then viewed and photographed at maximum magnification using a smartphone microscope. (3 marks) Table 1. Comparing Stomata Numbers from the Underside of Three Different Species of Plants. A leaf impression was created by painting clear nail polish on the underside of a leaf, allowing the nail polish to dry and then placing tape over the dry polish. The tape and nail polish were then gently pulled away from the leaf to create a leaf impression. The leaf impression was then viewed and photographed at maximum magnification using a smartphone microscope (refer to Figures 1-3 above). The number of stomata per photograph were then counted and recorded. (3 marks) Plant Species Number of Stomata Common Name Scientific Name Region 1 Region 2 Region 3 Average Page 4 of 7

5 Questions: Please answer all questions in full sentences using proper spelling and grammar. 1. Did you use a homemade smartphone microscope or a commercial smartphone microscope? (1 mark) 2. What is the maximum magnification of the smartphone microscope that you used? (1 mark) 3. Please explain the set-up that you used to take the photographs of your leaf impression including noting lighting conditions, approximate magnification and the approximate percentage of camera zoom (if any) that was used to take the photographs. (3 marks) Page 5 of 7

6 4. How do the number of stomata compare in the three different species of plants? (3 marks) 5. What is a possible explanation of the various numbers of stomata that were observed between the three different species of plants? You may have to do some background research to answer this question well. (3 marks) Page 6 of 7

7 6. Please identify at least two ways that you would improve upon this lab and explain how and why you would make these improvements. (2 marks) Page 7 of 7