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.
BACKGROUND INFORMATION:
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.
VOCABULARY WORDS:
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1. permeable membrane
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5. osmotic pressure
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2. osmosis
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6. hyperosmotic
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3. semi-permeable membrane
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7. hypoosmotic
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4. impermeable membrane
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8. isosmotic
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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: