Author: Louphelia B. Mathis - Thurgood Marshall Middle School-

Camp Springs, MD
Western Maryland College - Westminster, MD
Summer - June - 1999



OVERVIEW: Many teachers take for granted that students are knowledgeable of basic information. From my experience, do not make any assumptions. Therefore, students should be able to:
  • identify the term cell
  • list and diagram the many different kinds of cells found in the body( blood cells, bone cells, skin cells, nerve cells, fat cells, etc.,)
  • explain the basic difference between an animal cell and a plant cell
  • draw and label (the structures) a plant cell and an animal cell

PURPOSE: The students should be able to describe (with details) the four methods of moving materials across a cell membrane at the end of this week.


OBJECTIVES: Students will be able to:

  • identify the term osmosis
  • predict the movement of water as it enters and leaves the cell, based on the cell's environment

WARM -UP ACTIVITY: Write in complete sentences.

1. Explain , what is a cell ?

2. Identify and describe the basic structures in a plant and animal cell.


The cell membrane is the outer covering of the cell, This covering maybe called a plasma cell membrane, This plasma membrane allows water to move in and out of the cell. When water passes through a membrane very easily, it is said that the membrane is permeable. However, if there is any difficulty for the water to pass into or out of the membrane, then it is said to be semi-permeable or impermeable. When two solutions (water-a solvent and ink a solute in water) are separated by a permeable membrane there the water will move (diffuse) across the membrane into the cell from a lower concentrated region(water) to a higher solute concentration (ink). This process is called osmosis or passive diffusion.



1. permeable membrane

5. osmotic pressure

2. osmosis

6. hyperosmotic

3. semi-permeable membrane

7. hypoosmotic

4. impermeable membrane

8. isosmotic

RESOURCES/MATERIALS: Video Flex Microscope w/ microscope, Elodea plant cells, salt solution,

microscope slides, slide covers, beakers, test tubes, permeable membrane, and distilled water (also see diagrams in this lesson)

SUGGESTION FOR TEACHER TO ENGAGE STUDENTS: You went to the movies this weekend. While watching the movies , you ate a bucket of salty popcorn, a large bag of potato chips, and a bag of salty peanuts. You then, became very, very thirty, Why? Discuss with your seatmate your condition. (Give students a time limit of not more than two minutes)

Students will explore and express their finding (answers will vary)

Teacher will explain with the use of the Video Flex Microscope, microscope slides of Elodea plant cells,

where the plant cell is visible, that what the class is about to observe is what happened to you at the movies. With the aid of a student who explains the structure of the plant cell. Then the student adds a couple of drops of a concentrated salt solution. From the observation of the class, the student explains what has happened and why.


For elaboration, the teacher will group the class in groups of five students. Each student knows his responsibility in the group. The following work sheet is passed out to students:


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