Pacing/Teacher's Notes Investigation #11: Transpiration Click on - PDF document

Slide 1 / 34 Slide 2 / 34 New Jersey Center for Teaching and Learning AP BIOLOGY Progressive Science Initiative This material is made freely available at www.njctl.org and is intended for the non-commercial use of Investigation #11 students and teachers. These materials may not be used for any commercial purpose without the written Transpiration permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Summer 2014 www.njctl.org Click to go to website: www.njctl.org Slide 3 / 34 Slide 4 / 34 Pacing/Teacher's Notes Investigation #11: Transpiration Click on the topic to go to that section · Pacing/Teacher's Notes · Pre-Lab · Guided Investigation · Independent Inquiry - Potometer Method · Independent Inquiry - Whole Plant Method Return to Table of Contents Slide 5 / 34 Slide 6 / 34 Pacing Teacher's Notes General Reference Lab procedure adapted from College Board AP Biology Day (time) Activity to Unit Plan Notes Description Investigative Labs: An Inquiry Approach Teacher's Manual Day 1 (HW) Pre-Lab EP Day 10 Pre-lab questions Homework Click here for CB Investigation If necessary - complete as Day 2 (20) Step 1 EP Day 11 AP Biology Surface Area homework Teacher Manual Calculate If using whole plant method - do step Day 3 (40) Step 2 stomata per EP Day 12 1 today, watering the plants area Test factor's If using whole plant method - set up Independent affect on today (about 40 minutes), and Day 4 (80) EP Day 13 Invesigation transpiration reserve 10 minutes each period for 4 rate or 5 days to weigh plants Independent Analysis and Day 5 (40) EP Day 14 Investigation Share Day 6 (20) Assessment Lab Quiz EP Day 15

Slide 7 / 34 Slide 8 / 34 Pre-Lab Question/Objectives What factors, including environmental variables, affect the rate of transpiration in plants? In this lab we will: · Investigate the relationship among leaf surface area, number of stomata, and the rate of transpiration. · Design and conduct an experiment to explore other factors, including different environmental variables, on the rate of transpiration. · Investigate the relationship between the structure of vascular tissues (xylem and phloem) and their functions in transporting water and nutrients in plants. Return to Table of Contents Slide 9 / 34 Slide 10 / 34 Pre-Lab Questions Pre-Lab Questions Read the background information and answer the following 3. Describe the difference between the xylem and the phloem. questions in your lab notebook. (modified from pgs S137-S138 in lab manual) 4. If you wanted to transplant a tree, would you choose to move the tree in the winter, when it doesn't possess any leaves but it's 1. If a plant cell has a lower water potential than its surrounding cold outside, or during the summer, when the tree has leaves and environment, make a prediction about the movement of water it's warm and sunny? Explain your answer. across the cell membrane. In other words, will the cell gain water or lose water? Explain your answer in the form of a diagram with annotations. 2. In winter, salt is sometimes spread over icy roads. In the spring, after the ice has melted, grass often dies near these roads. What causes this to happen? Explain your answer in the form of a diagram with annotations. Slide 11 / 34 Slide 12 / 34 Safety Guided Investigation If you investigate transpiration rates using a potometer, you should be carful when assembling your equipment and when using a razor blade or scalpel to cut the stem of a plant, cutting to a 45 o angle. When appropriate, you should wear goggles for conducting investigations. Nail polish used in this investigation is toxic by ingestion and inhalation, and you should avoid eye contact. All materials should be disposed of properly as per your teacher's instruction. Return to Table of Contents

Slide 13 / 34 Slide 14 / 34 Materials Guided Practice Step 1 In your lab groups, investigate methods of calculating · Living representative plant species such as Impatiens, Coleus, surface area. (You will need to calculate surface area when you oleander, Phaseolus vulgaris, pea plants, tomato, peppers and/or conduct your experiments). Think about and formulate answers ferns to the following questions as you work through this activity: · Calculator · How can you calculate the total leaf surface area expressed · Graph paper in cm 2 ? In mm 2 ? · Microscope · How can you estimate the total leaf surface area of the entire · Slides plant without measuring every leaf? · Clear cellophane tape · What predictions and/or hypotheses can you make about the · Clear nail polish number of stomata per mm 2 and the rate of transpiration? · Scissor · Is the leaf surface area directly related to the rate of · Lab notebook transpiration? · What predictions can you make about the rate of transpiration in plants with smaller or fewer leaves? · Because most leaves have two sides, do you think you have to double your calculation to obtain the surface area of one leaf? Why or why not? Slide 15 / 34 Slide 16 / 34 Guided Practice Guided Practice Step 1 cont'd Step 1 cont'd · Based on the data in the following table, is there a · Water is transpired trough stomata, but carbon dioxide also relationship between the habitat (in terms of moisture) to must pass through stomata into the leaf for photosynthesis to which the plants are adapted and the density of stomata in occur. There is evidence that the level of carbon dioxide in their leaves? What evidence from the data supports your the atmosphere has not always been the same over the answer? history of life on Earth. Explain how the presence of a higher Average # of Stomata per mm 2 PLANT or lower concentration of atmospheric carbon dioxide would IN UPPER EPIDERMIS IN LOWER EPIDERMIS impact the evolution of stomata density in plants. Anacharis 0 0 Coleus 0 141 Black Walnut 0 160 Kidney Bean 40 176 Nasturtium 0 130 Sunflower 85 156 Oats 25 23 Corn 70 88 Tomato 12 130 Water Lily 460 0 Slide 17 / 34 Slide 18 / 34 Guided Practice Guided Practice Step 2 Make a wet mount of a nail polish stomata peel to view Step 2 cont'd leaf epidermis using the following technique: · Tape the peeled impression to a clean microscope slide. Use · Obtain a leaf (the leaf may remain on the plant or be removed) scissors to trim away any excess tape. Label the slide as · Paint a solid patch of clear nail polish on the leaf surface being appropriate for the specimen being examined and label the side studied. Make a patch of at least one square centimeter. of leaf from which the peel was taken. · Allow the nail polish to dry completely. · Examine the leaf impression under a light microscope to at least · Press a piece of clean, clear cellophane tape to the dried nail 400x (or higher magnification). Draw and label what you polish patch. Using clear (not opaque) tape is essential here. observe. Try to locate an area with numerous stomata. You might also try pulling the peel away from the leaf without · Count all the stomata in one microscope field. Record the using any tape and then preparing a wet mount of the peel with number. a drop of water and a cover slip. · Repeat counts for at least three other distinct microscope fields · Gently peel the nail polish patch from the leaf by pulling a corner and record the number of stomata. of the tape and peeling the nail polish off the leaf. This is the · Estimate the area of the microscope field by placing a leaf impression that you will examine. (Make only one leaf transparent plastic ruler along its diameter, measuring the fields impression on each side of the leaf, especially if the leaf is being diameter, and then calculating area. left on the plant) · Trade slides with two other lab teams so you examine three different slides under the microscope using the same procedure described above.