Carolina Investigations® for Use with AP® Biology: Osmosis and Diffusion

Explore how cell volume and surface area, molecule size, and concentration affect osmosis and diffusion. Students conduct 3 different activities during the Guided Investigation. In the first, students explore the relationship between cell size and diffusion as they measure how quickly a base (NaOH) diffuses into agar cubes of different sizes. In the second, students conduct an experiment to determine how molecule size affects the diffusion of a solute across a membrane. In the third, students conduct an experiment to determine how solute concentration affects osmosis in model cells. Additionally, students extrapolate the data to determine the concentration of unknown solutions and use collected data to calculate relative differences in water potential. Finally, in the Inquiry Investigation, students design an experiment to further investigate osmosis and diffusion. Kit includes enough materials for 8 groups.

Unit Connection
Unit 2: Cell Structure and Function, topics 2.3: Cell Size and 2.8: Tonicity and Osmoregulation

Standards Connection
ENE-1 The highly complex organization of living systems requires constant input of energy and the exchange of macromolecules.

ENE-2 Cells have membranes that allow them to establish and maintain internal environments that are different from their external environments.

Time Requirements
30 minutes of preparation before each of the following: the Pre-Lab, each Guided Investigation, and the Inquiry Investigation. The Pre-Lab takes approximately 60 minutes. The Guided Investigations takes approximately 30 minutes. The time required for the Inquiry Investigation will vary based on students' plans.

Digital Resources
Includes 1-year access to digital resources that support instruction. Digital resources may include a teacher manual and student guide, pre-lab activities and setup videos, simulations, and post-lab analysis and assessments.

Prerequisite Knowledge and Skills
Students should be familiar with cell structure and the concepts of molecules, molecular movement, concentration, homeostasis, and selectively permeable membranes. They should also be familiar with the concepts of the random nature of diffusion, dynamic equilibrium, and kinetic energy. Students should understand the terms "solute" and "solvent. "

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