Model WORKSHEET

POSSIBLE RESPONSES

Building The Model

You just did a virtual experiment with a red blood cell, salt, and water. Now let's build a model that will let us predict its behavior.

 

A. Describe the experiment you observed.
I changed the amount of salt and water in the solution containing red blood cells. They either expanded or contracted as a result.

 

B. If you wanted to do this experiment in the lab, what would you need? In other words, what are the important parts of the model/experiment. Isolate one cell and then list all the things that relate to it (ONLY whatever else you see in the microscope). These will be components of your model.

1. water,

2. salt mixed in the water outside the cell

3. glass slide in which this mixture is placed

4. a red blood cell

5.

6.

C. Can you think of any factors that might at work that you can't see? if so, list them too. e.g. temperature, pressure

 

C. Describe what can change in this model and what cannot change.[ e.g. different dissolved materials, quality of materials, membrane permeable or not, size of pores, temperature, pressure.]

 

D. What are the relationships among the parts? Use the questions below to help you reason about this.

The more you add water in the outside container, the more the erythrocyte's membrane expands. My guess is that this happens because... I don't know.

The more you add salt, the more the erythrocyte's membrane contracts. My guess is that this happens because... I don't know.

What might be the consequences if a cell loses water? What if it gains water? It could die in either case.

 

[E. Apply the computer model to the experiment.

What would the barrier stand for? The cell membrane.

What would the solution on either side stand for? The inner and outer solutions of a cell.

What would you add to the model? Holes in the membrane?]

 

F. Draw a picture of your model.