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Osmosis is a simple, but highly effective process that is happening all the time inside us and around us. It is vital process which would make it exceedingly difficult for living things to thrive without. The basic concept involves the movement of solvent molecules in a solution and a membrane (soft barrier). Osmosis is the process of balancing the number of solvent molecules across this membrane. Given enough time, the number of molecules will balance on each side of this membrane. The movement of the molecules from a high concentration to the lower concentration is called osmosis. This is how plants and human body cells take in water. When we sit in a bathtub and our fingers get wrinkled, you guessed it, osmosis is the culprit. The skin in our fingers absorbs the water and gets expanded and bloated, leading to wrinkles.

This worksheet collection looks at this process in detail and we explore the applications of reverse osmosis. Students will explore all types of natural movement of particles. We will take a deep dive into solution science and the nature of dissolved particles and solvents. We will also look at how this process relates and functions in animal and plant cells.

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What is It?

Since a solute cannot pass through the membrane, the equalization has to occur by movement of the solvent. In biological systems, the solvent is always water.

Question Set: What is It?

In animals, osmosis plays a role in distributing nutrients to the cells and moving waste products out of them. In plants, it plays a role in how the plants absorbs water from the soil, and how that water makes its way higher up into the plant and out to the leaves.

Cell Membranes

A cell membrane (also plasma membrane or cytoplasmic membrane) is the thin, supple layer that encloses the cells of living organisms.

QUESTIONS: Cell Membranes

Its job is to keep what is inside of the cell separate from the outside of the cell.

Reverse Osmosis

In a biological system like a plant or an animal, osmosis is the movement of water through a cell membrane from an area of higher concentration of water to an area where the concentration of water is lower.

Question Set: Reverse Osmosis

Reverse osmosis has many common applications. It is a common step in the purification of drinking water, as well as in converting seawater to drinking water by removing the salt and other undesirable particles.

Passive Transport

In passive transport, the molecules move freely. This happens in processes like diffusion and osmosis, where molecules move spontaneously from areas of higher concentration to areas of lower concentration.

Question Set: Passive Transport

In diffusion, molecules move spontaneously from a higher to a lower concentration. Diffusion usually occurs in gas molecules or between molecules of liquid and gas.

Examples of Osmosis

When a plant absorbs water from the soil, particles of nutrients come along for the ride, and they enter the plant through the roots as well.

Question Set: Examples

The function of the kidneys is to filter waste products from the blood and move them out of the body in the form of urine. After the kidneys separate waste particles from blood molecules, they have to absorb more water so that there is enough water in the blood.

Osmosis vs. Diffusion

Diffusion is what happens when you spray air freshener. The particles immediate begin to move away from one another until they fill the whole room.

Questions: Osmosis vs. Diffusion

The two processes are similar in that both result in two solutions having equal concentrations.

Tonicity

When there are differing concentrations of solute on either side of a membrane, it causes osmotic pressure on the side of the membrane where the concentration is highest.

Tonicity Question Series

A hypotonic solution has less solute and more water. A hypotonic solution has lower osmotic pressure than another solution.

Why It Happens

When molecules move away from each other (from an area of higher concentration to an area of lower concentration), they aren’t doing it because they are aware of their surroundings.

Question Set: Why It Happens

The same thing happens with osmosis. Think of the water molecules as being in two rooms with a doorway between them that the molecules can move through.

The Discovery

Dutrochet noticed the similarity of the physical and chemical processes that take place in plants and animals.

The Discovery

Dutrochet was one of the first people to recognize that each individual cell plays a role in how a biological system (organism) functions.

Animal vs. Plant Cells

When the concentration of solute is lower outside of the cell than it is inside of the cell, the tonicity is said to be hypotonic. A hypotonic solution has lower osmotic pressure than another solution.

Animal vs. Plant Cells Questions

n an isotonic situation in the human body, the fluid inside of a cell is in equilibrium with the fluid on the outside.