Say goodbye to those pesky potometers and try this method for measuring the rate of transpiration in plants. In this living plant lab, students will measure the rate of transpiration under various conditions to determine the effects of heat, wind, and humidity.
I use this lab when teaching my introductory unit on plants. The PowerPoint and Notes that I use to teach this unit can be viewed here: Introduction to Plants PowerPoint with Notes for Teacher and Student.
Introduction: Open stomata are a major source of water loss from the leaf. The loss of water from the leaf is called transpiration. It is estimated that about 90% of the water that enters through the roots of a plant, will be lost to the atmosphere through transpiration. A balance must be maintained between the gain of carbon dioxide and the loss of water by regulating the opening and closing of stomates on the leaf surface. Many environmental conditions influence the opening and closing of stomates and also affect the rate of transpiration. In this lab, the student will determine the effect of several different environmental conditions on the rate of transpiration.
1. To measure the amount of water lost from the leaves of a plant over a given amount of time.
2. To calculate the surface area of leaves on a plant.
3. To calculate the rate of transpiration from the leaf under different environmental conditions.
Materials: Small potted plant, Plastic sandwich bag, Gallon Ziploc bag, Fan, Balance, Desk lamps, Small beaker or cup
PLEASE NOTE: This product is included in my bundled complete unit plan which can be viewed here: The Plant Kingdom: Introduction and Classification. Complete Unit Bundle of Products.
This lab comes with a 6-page student packet of worksheets, and is suitable for biology and life science classes in grades 8-12.
The lab is divided into two parts. Students of all ability levels can complete part 1. It is easy to set up, always gets great results, and the analysis questions are appropriate.
Part 2 requires mathematical calculations. Part 2 is an optional add-on to the lab. If you choose not to complete Part 2, the first part of the lab stands alone very well.
Also included is a 6-page teacher guide to the lab. Complete teacher prep information is included, as well as sample data, solutions to calculations, and answers to all questions.
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