Day 1

What is homeostasis?  How do cells maintain equilibrium?

Objective:

 Explain how cells maintain homeostasis through membrane permeability.

Conduct an experiment that illustrates how cells maintain equilibrium by diffusion

Texas and National Standards 

1A, 2A,B,C,D, 3A,C,E,4B

Materials: (per group of 4)

PowerPoint presentation, “Transport of Materials”, hand out

Diffusion lab hand-out

1 Dialysis tubing (2.5 cm X 30 cm)

1 Beaker or plastic drinking cup

15 ml 15% glucose/1% starch solution

~200 ml distilled water

1 IKI dropper bottle (Lugol’s)

2 pieces Clinistix or testape (for detection of glucose)

1 marking pencil and labeling tape

string for tying dialysis bags

 Activities:

1. Discuss how materials move to establish prior student knowledge.  PowerPoint discussion, “Transport of Materials”.  Teacher demonstrates diffusion in solids, liquids, and gases
2. Student will formulate a hypothesis and conduct a diffusion experiment. Lab activity:  Diffusion
3. Draw a conclusion based on experimental data.  Lab write-up in journal.