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Population Growth and Carrying Capacity TEACHER’S MANUAL AND STUDENT GUIDE
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Population Growth and Carrying Capacity TEACHER’S MANUAL AND STUDENT GUIDE
Table of Contents
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Population Growth and Carrying Capacity
Carolina EcoKitsTM:
TEACHER’S MANUAL Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Content Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Time Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Perishable Materials Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Answers to Questions in the Student Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Extension Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Related Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Sample Data Table 1. Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Sample Graph: Duckweed Population Growth in a Closed System . . . . . . . . . . . . . . . . . . .10 Sample Data Table 2. Population Growth Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 STUDENT GUIDE* Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-1 Pre-laboratory Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-3 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-4 Student Worksheet and Data Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-5 Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-7 Graph Template . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S-9
*Photocopy the Student Guide as needed for use in your classroom. Carolina EcoKits™ activities are designed to help students grasp the relationships between and among populations, their ecosystems, and global ecology. The background information, investigative activities, and follow-up questions all stress relevance. The sciences are integrated, and students use a number of methods to analyze data. Through these investigative experiences, students have the opportunity to better understand their own interactions with the environment.
Cover image ©2011 Jupiterimages Corporation ©2011 Carolina Biological Supply Company/Printed in USA.
Teacher’s Manual
Carolina EcoKitsTM:
NOTES
Population Growth and Carrying Capacity Overview In this investigative activity, students work in pairs to study the population dynamics of duckweed (Lemna minor), a floating freshwater plant. First, students predict how a duckweed population in a closed system will change. Students place duckweed in a plastic container and conduct counts of the population for 3 to 4 weeks. Students graph the population data, calculate the growth rate, and determine the carrying capacity of the system. This activity is designed to accommodate a class of up to 30 students working in pairs.
Objectives Students will • observe the population dynamics of duckweed in a closed system. • describe the differences between exponential growth and logistic growth. • measure the growth rate of the duckweed population. • graph the population growth of duckweed. • determine the carrying capacity of the closed system.
Content Standards This kit is appropriate for high school students and addresses the following National Science Education Standards:
Grades 9–12 Unifying Concepts and Processes • Systems, order, and organization • Change, constancy, and measurement • Evolution and equilibrium
Science as Inquiry • Abilities necessary to do scientific inquiry • Understandings about scientific inquiry
Life Science • Interdependence of organisms
Science in Personal and Social Perspectives • Population growth
© Carolina Biological Supply Company/Printed in USA.
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Teacher’s Manual
NOTES
Carolina EcoKitsTM: Population Growth and Carrying Capacity
Time Requirements Preparation . . . . . . . . . . . . . . . . . . . . .20 minutes Setting up the closed system . . . . . . . .10 minutes Population counts . . . . . . . . . . . . . . . .5 minutes, 3 days a week for 3–4 weeks Data Analysis . . . . . . . . . . . . . . . . . . . .30 minutes
Materials The materials in this kit are designed for a class of 30 students working in pairs. Included in the kit: Order Form for the following perishable item (if not shipped with the order): duckweed (Lemna minor) 15 plastic containers and lids 15 hand lenses 15 jumbo pipets Teacher’s Manual and reproducible Student Guide Needed, but not supplied: permanent markers light source spatula graduated cylinders push pins or thumbtacks
Perishable Materials Handling Order Form for Perishable Items If you requested that your perishable items ship separately, this kit contains an Order Form for prepaid delivery of perishable items. Place your request at least 2 weeks before your selected delivery date. Consult the form for instructions on the submission process.
Care of Duckweed (Lemna minor) As soon as you receive the duckweed, transfer the plants temporarily to a large container of springwater. Place a 30-W white fluorescent light 15 cm above the plants, and leave the light on continuously. The plants grow well at 25°C. Begin the experiment as soon as possible after you receive the plants. The most important factor that determines duckweed growth is light. During the lab activities, if the fronds reproduce slowly or not at all, increase the amount of light they receive. Use only fluorescent lights, because heat from incandescent bulbs can damage the fronds.
Using the Correct Water Springwater or dechlorinated tap water is ideal for this experiment. Springwater is available from Carolina Biological Supply Company (see Related Products). Unlike tap water, springwater contains no harmful chemicals that might kill the
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© Carolina Biological Supply Company/Printed in USA.
Carolina EcoKitsTM: Population Growth and Carrying Capacity
plants, and it contains trace minerals that cannot be found in distilled water. If you use store-bought springwater, make certain that it is completely free of chemical additives. If you use tap water, you must condition it first. Many municipalities add chlorine or chloramines to kill bacteria in drinking water. Unfortunately, these disinfectants may harm the plants. To remove the chemicals, use a tap water conditioner, available from Carolina Biological Supply (see Related Products) or from a local pet store. If you are certain that your water is treated only with chlorine (not chloramines), you can leave some water in an open container for 24 hours, allowing the chlorine gas to escape. You can then safely use the water for these activities.
Teacher’s Manual
NOTES
Disposal After the exercises have been completed, dispose of all the duckweed plants. Do not remove them from the classroom or lab, and do not release them into the environment. Place all of the plants in plastic bags and freeze them for 3 days. Then, discard the materials in the regular trash.
Safety Ensure that students understand and adhere to safe laboratory practices when performing any activity in the classroom or lab. Demonstrate the protocol for correctly using the instruments and materials necessary to complete the activities, and emphasize the importance of proper usage. Model proper laboratory practices for your students and require them to adhere to all laboratory safety rules.
Preparation 1. If your perishable items ship separately, place your request for delivery at least 2 weeks before your selected delivery date. Consult the form for instructions on the submission process. 2. Familiarize yourself with the content of the Teacher’s Manual and Student Guide. 3. Locate the materials that are needed but not supplied for the activity. 4. Immediately upon arrival of the duckweed, follow the care and handling procedures given in the Perishable Materials Handling section of this manual. 5. Unpack the kit materials. Set up 15 laboratory workstations and equip them with the following materials: one plastic container and lid, one graduated cylinder, one hand lens, and one permanent marker. 6. Use a thumbtack or push pin to punch several holes in each plastic lid. This will allow for gas exchange. 7. Set up an area where students can access springwater. Note: To save class time, fill the plastic container at each station with 400 mL of water. 8. Set up a growing station with fluorescent light or natural light. 9. Photocopy the Student Guide for each student. 10. During the population counts, make sure groups can access springwater and jumbo pipets to refill their closed systems.
© Carolina Biological Supply Company/Printed in USA.
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