Dialysis tubing in a solution to demonstrate osmosis
Dialysis tubing in a solution to demonstrate osmosis

Diffusion and Osmosis

All cells are bound by some type of permeable or semipermeable membrane that governs the ions, small molecules, and large molecules that enter and leave the cell. Diffusion is the general process of movement down a gradient that results in equal concentrations of solutes on both sides of the membrane. When water is the molecule entering or leaving the cell the process is osmosis.

This guide breaks down the important information students need to know, provides links to products and free digital resources, and includes suggestions for hands-on-labs that reinforce student learning. We gathered a variety of products and resources to better help you teach this concept. They include:

  • Models and manipulatives to simplify teaching diffusion and osmosis
  • Diffusion and osmosis activities, experiments, and kits
  • Free resources for you and your students

The major areas covered in this topic:

Cell Membrane

The cell membrane regulates the passage of substances into and out of the cell based on concentration gradients. The movement of molecules across a membrane can be easily visualized and studied quantitatively with student kits and activities.

684272 Osmosis and the Cell Membrane

Give your students a simple way to perform osmosis and diffusion experiments with this kit. Students use Carolina® Osmosis Chambers (item #684270) and nanofiltration membranes that allow water molecules to pass through but not larger molecules, such as sugars. Glucose and sucrose solutions are injected into each chamber using a pipette. Students observe changes in volume on each side of the chamber and make both qualitative and quantitative observations.

Beginning—Easy to perform; requires little or no prior knowledge.

695803 Kidney Filtration Simulation Kit

Students build a simple model of the renal artery, renal vein, glomerulus, and nephron to simulate kidney filtration and learn about the process of excretion. Using beads of different sizes and colors to represent essential blood components, they model the filtration process that occurs in the kidney as blood flows in via the renal artery. Students also learn about the process of complete and selective reabsorption and explore why urinalysis is such a powerful tool in diagnosing disease.

Beginning—Easy to perform; requires little or no prior knowledge.

251022 Inquiries in Science®: Examining Cellular Transport Kit

Students explore the processes of osmosis and diffusion using a semipermeable model of the cell membrane. They examine how concentration, molecular size, surface area, and volume relationships affect these processes. Students further their learning by determining the concentration of unknown salt solution.

Beginning—Easy to perform; requires little or no prior knowledge.

684064 Cell Size and Diffusion Kit

Living organisms depend on water. Approximately 60% of the human body is water. Plants are 90–95% water. The movement of water between the parts of an organism and within its cells is very important in maintaining homeostasis. In this series of investigations, students use an osmosis chamber to investigate how water moves across the cell membrane and how that movement helps cells maintain homeostasis.

Beginning—Easy to perform; requires little or no prior knowledge.

Diffusion and Osmosis

Diffusion is the movement of particles from an area of higher concentration to lower concentration to equalize concentration while osmosis is the movement of solvent particles across a semipermeable membrane from a dilute solution into a concentrated solution. As the solvent moves, the concentrated solution is diluted and the concentration on both sides of the membrane is equalized.

684206 Carolina BioKits®: Diffusion-Osmosis

Students use dialysis tubing and solutions to study the movement of materials across a semipermeable membrane by diffusion and osmosis.

Beginning—Easy to perform; requires little or no prior knowledge.

747650 Carolina Investigations® for Use with AP® Biology: Osmosis and Diffusion Kit

During a Guided Investigation, students explore how cell volume and surface area, molecule size, and concentration affect osmosis and diffusion. They use the data collected to determine the concentration of an unknown solution and calculate water potential of model cells. In an Inquiry Investigation, students design their own experiment to further investigate osmosis and diffusion.

Beginning—Easy to perform; requires little or no prior knowledge.

Dialysis Tubing

High quality dialysis tubing is key for every successful diffusion and osmosis lab. Carolina has multiple options that will meet your experimental needs.

684202 Dialysis Tubing
684200 Carolina® Dialysis Tubing Clamps
684270 Carolina® Osmosis Chamber Set
684030 Membrane Disc

Models and Manipulatives

211132 Phospholipid & Membrane Transport Kit©
684100 Osmosis Demonstration Unit
490961A Visualizing Cell Processes: Cell Movement and Transport DVD
A model of an animal cell with 3D representations of organelles
563957 3B® Animal Cell Model
An animal cell model with printed images of organelles
952314 Cross-Sectional Animal Cell Model
211312 Origami Organelles™ 3-D Model Kit: Cell Membranes

Other Dialysis and Osmosis Products

We offer a number of products that will help facilitate your biology lessons.

399260 VR Dogfish Dissection
684258 Osmosis Poster
684105 Glass Osmometer Tube
684250 Diffusion Demonstration Kit
490795 Cell Membranes: The Boundaries of Life DVD
684112 Deluxe Osmometer

Additional Physiology Support

We have free resources to help you teach this concept, including:

  • Free Activities and Resources
  • Helpful Buying Guides

Osmosis and Diffusion Activities

Use these free resources to supplement your instruction about osmosis and diffusion.

Osmosis Videos

Looking for videos to enhance your osmosis and diffusion instruction? Try one of these.

Buying Guides

Choosing the appropriate equipment for your labs can be a challenging task. Our buying guides are designed to make your decisions easy. Review Carolina recommended microscopes or this handy guide.

For More Guidance

These are our top picks. If you don’t see what you’re looking for, we’ll be happy to help you find the right activities and kits to simplify your planning and implementation. If you have questions, please contact us at product@carolina.com.

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