Cell Regulation: Entry and Exits

Lesson Plan

State Standards:

Massachusetts Science and Technology/Engineering Curriculum Framework

Biology standard 2, Cell Biology, strand 2.1,
“Relate cell parts/organelles (plasma membrane, nuclear envelope, nucleus, nucleolus, cytoplasm, mitochondrion, endoplasmic reticulum, Golgi apparatus, lysosome, ribosome, vacuole, cell wall, chloroplast, cytoskeleton, centriole, cilium, flagellum, pseudopod) to their functions. Explain the role of cell membranes as a highly selective barrier (diffusion, osmosis, facilitated diffusion, active transport).”

Scientific Inquiry Skills Standards SIS1, SIS2
SIS1. Make observations, raise questions, and formulate hypotheses.
SIS2. Design and conduct scientific investigations.

Essential Question:

Lesson Question:


Cellular processes are chemical in nature. Cells use chemical resources and produce chemical products and wastes. Many of the necessary resources for metabolic processes must enter from outside the cell. Likewise wastes must exit the cell and some products are exported from the cell. These materials must pass through the cell’s outer boundary, the cell membrane. The cell membrane dictates what materials enter and exit the cell. Some materials enter through passive transport, moving based on their own kinetic energy without added energy from the cell; others too large to pass through the membrane, enter or exit with assistance from the cell. When water diffuses (moves from an area of high concentration to an area of lower concentration) across the cell membrane, or other semi-permeable membranes, it is called osmosis.


You will be manipulating different types of solutions today. You will be making predictions about what you think will occur. You will be working cooperatively in groups to ask questions, develop procedures, discuss outcomes and to try to explain what you see. You will be looking at solution interactions to better understand how different solutions behave in and around cells. Specifically you will:
• predict and observe diffusion patterns
• develop and record a procedure investigating your group’s question
• take three pictures of your investigation using a digital camera or phone
• discuss the results within your group
• answer and post/discuss the analysis questions on a wiki
• take a short online quiz
• complete osmosis practice problems, applying the principle of osmosis

Lesson Experiences:

  1. Engage: Food Coloring Diffusion: Students will predict what happens to food coloring dropped in a glass of water; students observe what happens after they place drops of food coloring into glasses of water. Depending on the group, there may be waters of different temperatures.
  2. Elicit: Question Students: Students record and discuss with the class, answers to the following questions: “What happened?”, “Why did the red dye move?”, “How will it look at the end of the period?” (This could be emailed or tweeted to teacher for projection in class assuming phone usage is allowed.)
  3. Explore: Cell Model Diffusion: Students make a cell model using dialysis tubing. Students will ask the question, develop procedures, make predictions and record data. Students will have access to glucose, starch solution, Logol’s starch-indicating solution, and glucose test strips. They will be informed that Lugol’s changes color when starch is present. Students will be reminded that water, glucose and starch are different sized molecules. Students will answer analysis questions, “Which substance(s) entered the bag? Which left the bag? How do you know this? What evidence supports this? Why didn’t all of the molecule types move? Students answer questions on class wiki and take Zoho challenge osmosis quiz on their own.
  4. Explain: Diffusion, Osmosis & Passive Transport notes : Students work through slide-share presentation, taking notes Active Passive Transport slideshow (This can be done in class or outside of class).
  5. View more presentations from MissBol416

    Alternately, teacher may deliver delivers notes using PowerPoint or Prezi.
  6. Elaborate: Osmosis Problems : Students complete osmosis problems. (Can be in class or at home.)
  7. Extend: Reverse Osmosis Video: Students will watch a video about reverse osmosis filtration systems for desalinating seawater.


Having taken notes on the power point presentation and investigated solution interactions, you can explain how molecules might enter a cell. You can predict which ones enter (or exit) easily and which won’t! You engaged in social discourse regarding your data and ideas about diffusion & osmosis on the wiki. Use this knowledge to complete the Zoho quiz and osmosis problems.


-Zoho quiz (scored by application)
-Osmosis problems (students check their answers with class key)
-Wiki response = general rubric

General Scoring Rubric/ Scoring Language

4 - Exemplary
3 - Proficient
2 - Satisfactory
1 Limited


Exceeds expectations



Meets all Expectations



Meets some expectations



Meets few expectations


-Cooperation = group work rubric

Group Work Rubric
Working with Others
Rarely listened to, shared with, or supported the efforts of others. Often is not a good team player.
Often listened to, shared with, and supported the efforts of others, but sometimes was not a good team member.
Usually listened to, shared with, and supported the efforts of others. Did not cause "waves" in the group.
Almost always listened to, shared with, and supported the efforts of others. Tried to keep people working well together.
Focus on the task
Rarely focused on the task and what needs had to be done. Let others do the work.
Focused the task and what had to be done some of the time. Other group members must sometimes nag, prod, and remind to keep on-task.
Focused on the task and what needed to be done most of the time. Other group members can count on this person.
Consistently stayed focused on the task and what needed to be done. Very self-directed.


Image Credit: Cell Membrane