Unit: Cells
Topic:
Movement through the Cell Membrane
Do Now- Using a Venn Diagram compare diffusion and osmosis.
Answer examples: osmosis is a type of diffusion but requires semi-permeable membrane and water; both are passive transport no energy required
Aim- What makes osmosis occur?
Answer: Solute levels in water; water moves from low solute to high solute area.
Standards
S4 Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and
recognize the historical development of ideas in science.
Performance Indicator : 1.2g Each cell is covered by a membrane that performs a number of important functions for the cell. These include:
separation from its outside environment, controlling which molecules enter and leave the cell, and recognition of chemical signals. The processes of
diffusion and active transport are important in the movement of materials
in and out of cells.
1.2h Many organic and inorganic substances dissolved in cells allow necessary chemical reactions to take place in order to maintain life. Large
organic food molecules such as proteins and starches must initially be broken down (digested to amino acids and simple sugars respectively), in
order to enter cells. Once nutrients enter a cell, the cell will use them as building blocks in the synthesis of compounds necessary for life.
Performance Objectives
1. Students will be able to describe what happens during osmosis.
2. Students will be able to analyze data from a grape activity.
3. Students will be able to compare and contrast how different solutions affect the cell.
4. Students will be able to distinguish between diffusion and osmosis.
Vocabulary:
Concentration- Concentration= the amount of substance in a particular area; Mass of solute in a given volume of solution= M/V
Hypertonic- the concentration of solute outside the cell is greater than inside
Hypotonic- the concentration of solute outside the cell is lower than inside the cell
Isotonic- the concentration is the same on both sides (inside and outside the cell)
Material List
Grapes, cups, water, grape juice, corn syrup, napkins.
Safety and Disposal
Teacher will collect grapes. Students will throw out any used napkins.
Anticipatory Opening
Cartoon Image of Osmosis Jones.
Activity:
Students will be given a table data of the results from a previous activity involving grapes in 3 different solutions. One set of data was collected by
them, and the other three by me at different times. They will analyze the data to determine the effects of the solutions on the grapes: hypertonic,
hypotonic, and isotonic. They will also make observations of the grapes to see the effects. They will make rough graphs of the data and answer
some questions.
Development of Lesson: Follows
LESSON ACTIVITY SEQUENCE:
Estimated
time:
5 min
Teacher Activity(s): What will teacher do?
Write Do Now, Aim and HW on the board.
Venn Diagram: diffusion/osmosis comparison
Set up material.
Go over Do Now. Ask for volunteers (or pick on 2
students) to answer question.
1 min
Anticipatory event. Image on board.
5 min
Introduce lesson, show video and images, ask students
questions. List important vocabulary words on the
board:.Only provide definition of concentration at this
point.
(Review) Concentration- Concentration= the amount
of substance in a particular area; Mass of solute in a
given volume of solution= M/V
Hypertonic- the concentration of solute outside the cell
is greater than inside
Hypotonic- the concentration of solute outside the cell
is lower than inside the cell
Isotonic- the concentration is the same on both sides
(inside and outside the cell)
Student Activity(s): What will students do?
Start Do Now.
Independent thinking of question and completing Venn
Diagram.
Answer questions, 2 students go to the board and illustrate
and fill in diagram.
Students get motivated.
Students answer questions and take notes on vocabulary.
Students get into groups and work on activity and questions.
Prepare to answer questions and put graph on board.
Students answer questions.
9 min
Prepares students for activity. Gives instructions. Puts
students in groups. Asks students questions, puts data
on board. Passes out worksheet and procedure.
Review with students their observations and ask
students for definitions of hypertonic, hypotonic and
isotonic. Have them provide definitions and put up your
definitions on the board.
3 min
Read the Aim. Guide students to use vocabulary.
Student reads Aim. Answers Aim.
4 min
Extension of lesson; ask students relevant questions.
Students answer questions.
1 min
Homework announcement.
Students read HW.
Summative assessment
Ask questions.
Students answer.
5 min
Differentiated Instruction
A few students participate more than others so there would be questions throughout the lesson to fill their need. There are also some students that are
fairly quiet and will be randomly chosen to answer a question. Other students that do not generally participate will possibly be chosen through a
system of drawing sticks with their names on it to answer questions. Students that like to come to the board will have a couple chances for this.
Students that are more artistic have an opportunity to draw the graph.
Recall, analysis, evaluating, and creating are skills they will be using at different points in the lesson. Collaboration and individual work is applied.
The types of learners targeted here include, visual, logical/mathematical, artistic, linguistic, interpersonal and intrapersonal. Students will take notes,
students will participate in interactive activities on the board.
Notes for Revision:
Homework
Illustrate hypotonic, hypertonic, and isotonic effects on cells (plant or animal). Label and use coloring utensils. Describe what happens for each in a
few sentences. OR: Do a Venn Diagram for Hypertonic, Hypotonic and Isotonic
Summative Assessment
-Students will be asked several questions related to the lesson:
What happened to the paramecium in the video when salt was added to its environment?
- It lost water, shriveled and died.
What is an example of a hypertonic solution or situation?
- More solutes than solvent; more sugar or salt in the water outside the membrane.
How do red blood cells look when salt is added to their external environment?
-Shriveled up
Why did they look like that? What is that process called?
-They look like that because the solution they were in was hypotonic, and the cells lost water.
How is osmosis different from diffusion?
-Osmosis is different from diffusion because it involves a semi-permeable membrane that requires water; moves down a solute
concentration gradient (from low solute to high solute).
When might you not want osmosis to occur? Explain.
-When you want the cell to maintain its shape and water; when you want fruits to stay juicy and firm; when you want plants to not
wilt; when you don’t want pesticides to diffuse in with the water.
What is the importance of the concentration of a solution?
-It will determine if the cell maintains the proper amount of water inside; it can determine if the cell (or organism, or fruit), shrivels,
dies, wilts.
Name:
Group originally in A, B, or C (circle)
Date:
Osmosis Grapes?
Worksheet to be completed by every student for collection.
Procedure:
1. In your group of 4-5 people you will each be responsible for a task (analyze data, compare data, obtain the grapes for
observations, and graph the data).
2. In your group you will discuss and analyze the results in the groups you were in last week (A,B, and C) from the data
table included.
3. In your group you will also discuss and analyze the results from the other Groups and compare and contrast them to
your Groups’ results.
4. Prepare a (rough) graph to illustrate the results of your group. Be prepared to present the results on the board and to
speak about them.
Questions:
1. What was the initial mass(g) and the final mass(g) of the grapes for each solution (water, grape juice, corn syrup)?
2. Is there evidence of osmosis in the grapes? Explain briefly.
3. Based on your observations of the grapes in the solutions, which solutions were
a) hypertonic =
b) hypotonic =
c) isotonic =
and how do you know? Explain. Was this what you expected? Explain.
4. Use a (rough) bar graph to illustrate the data/results of your groups’ data [for each solution (water W, grape juice G,
corn syrup CS) compare: initial mass (I.) and final mass (F.)].
I.
F.
W
I. F.
G
I. F.
CS
5. How does the data of the other groups compare to yours? (similar, different, be specific).
6. Discuss and state what could be done differently in the future to alter the results or experiment in any way (one
possible example).
Grape weight (g) after being in 50 ml of:
Group A water grape juice corn syrup
period 1
4.79
5.33
4.74
period 2
4.87
5.35
4.85
period 7
4.95
5.36
4.7
day 6
5.35
5.37
4.46
Grape weight (g) after being in 100 ml of:
Group B water grape juice corn syrup
period 1
4.05
5.13
5.86
period 2
4.07
5.15
5.81
period 7
4.15
5.16
5.78
day 6
4.45
5.27
5.36
Grape weight (g) after being in 150 ml of:
Group C water grape juice corn syrup
period 1
4.54
4.58
4.71
period 2
5.47
5.5
5.53
period 7
4.74
4.74
4.65
day 6
5.06
5.72
4.32