Download Diffusion Lab Make

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TOC#____
Diffusion Lab Make-up
Introduction: Diffusion is the process in which substances move from areas of high concentration to areas of
low concentration. This is particularly important in regulating a cells equilibrium. Diffusion allows substances
such as nutrients, water, oxygen, and cellular wastes are transported between living cells and their environment.
This activity will help you explore the relationship between diffusion and cell size by experimenting with model
“cells.”
In this experiment, you will use agar cubes to which the indicator bromthymol blue has been added.
Bromthymol blue is an acid/base indicator that turns yellow in the presence of an acid such as vinegar. Thus
the surface of the agar cubes will turn yellow immediately when put into a vinegar solution. The agar cubes are
semi-permeable like a cell membrane and the vinegar will diffuse through the cube and gradually turn the inside
of the cube yellow.
The guiding question for this lab is: What determines the efficiency of diffusion throughout the model “cells”?
Does size matter? Will the smaller cells or the larger cells be yellower in the middle?
Focus Questions: By the end of this lab, you should be able to answer the following questions.
● What is diffusion?
● How does cell size relate to diffusion?
Pre-Lab Questions: In order to be completing this lab, first, answer the following questions.
1. Define Diffusion
2. Define osmosis
3. Define hypotonic, hypertonic, isotonic
4. Define Passive transport
5. Define Active transport
6. What is the cell membrane made of?
Watch the video: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
After the video scroll down and take the quiz. Submit your answers. When you have the
results of your quiz, write down your score here: ________
Name: _____________________________________ Per: ____
Watch the video:
TOC#____
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
After the video scroll down and take the quiz. Submit your answers. When you have the results
of your quiz, write down your score here:___________
Visit: http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS03/LS03.html
Directions: Complete the graph and answer the following questions while completing the virtual lab.
Data Table: Concentration of Solution vs. Type of Cell
Red Blood Cell:
Net water
movement
in/out
Red Blood
Cell:
Appearance
of Cell
Elodea:
Net water
movement
in/out
Elodea:
Appearance
of Cell
Paramecium:
Net water
movement
in/out
Paramecium:
Appearance
of Cell
Hypotonic
Solution
Isotonic
Solution
Hypertonic
Solution
Analysis Questions:
1. Did water move into or out of the cell when in a hypotonic solution? What about in a hypertonic solution?
2. Could elodea or paramecium from a freshwater lake be expected to survive if put into the ocean? Explain.
3. Explain why a salad becomes soggy and wilted when left with dressing on it? Explain why, in terms of
osmosis.