Description
Students conduct investigations and analyze the carrying capacity and biotic potential of a model plant species, Lemna minor, known commonly as duckweed. Students formulate a hypothesis, set up an experiment where they grow duckweed in different conditions, collect data, and analyze population growth. Then they discuss and apply the knowledge gained from their experiments to a real-world scenario. The activity is conducted over a 4-week period. Kit includes materials for 5 groups of students. Note: Kit includes perishables when shipped.
Unit Connection
This laboratory investigation correlates to Unit 3: Populations, topics 3.4: Carrying Capacity and 3.5: Population Growth and Resource Availability in the AP® Environmental Science Course and Exam Description.
Standards Connection
This kit addresses the following AP® Environmental Science concepts:
Big Idea 2: Interactions Between Earth Systems (ERT). The Earth is one interconnected system. Natural systems change over time and space. Biogeochemical systems vary in ability to recover from disturbances.
- ERT-3 Populations change over time in reaction to a variety of factors.
- ERT-3.B Identify differences between K– and r-selected species.
- ERT-3.B.3 Biotic potential refers to the maximum reproductive rate of a population in ideal conditions.
- ERT-3.D Describe carrying capacity.
- ERT-3.D.1 When a population exceeds its carrying capacity (carrying capacity can be denoted as K), overshoot occurs. There are environmental impacts of population overshoot, including resource depletion.
- ERT-3.F Explain how resource availability affects population growth.
- ERT-3.F.1 Population growth is limited by environmental factors, especially by the available resources and space.
- ERT-3.F.3 When the resources needed by a population for growth are abundant, population growth usually accelerates.
- ERT-3.F.5 When the resource base of a population shrinks, the increased potential for unequal distribution of resources will ultimately result in increased mortality, decreased fecundity, or both, resulting in population growth declining to, or below, carrying capacity.
Time Requirements
Teacher Preparation (before class):
- Prelab: 30 minutes
- Investigation: 60 minutes
Class Time:
- Prelab: 45 minutes
- Investigation: Day 1, 45 minutes; Observations, 10 minutes; Final Day, 45 minutes
- Free-Response Questions: 60 minutes
The times provided are estimates. The time required may vary based on your student population.
Digital Resources
Includes 1-year access to digital resources that support instruction. Digital resources may include teacher manual and student guide, prelab activities and setup videos, simulations, and postlab analysis and assessments.
Prior Knowledge and Skills
Students should be familiar with the following skills or concepts:
- The basics of experimental design (controls, independent variables, dependent variables)
- Algebraic reasoning and natural log
- Data collection
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