Osmosis

Osmosis

Osmosis is the process by which water molecules move from a solution of low solute concentration to a solution of high solute concentration through a semipermeable membrane.

Experiment: Investigating Water Absorption Through Osmosis in Plants

Objective:

To show that osmosis occurs in the cells of living organisms.

Materials:

• Cassava, potato, or pumpkin
• Pot
• Stove
• Fire/Heat
• Salt
• Two glass bowls (or beakers or two glass plates)
• Water
• Teaspoon

Procedure:

1. Peel the potatoes and cut them to make a bowl-shaped hole. If you don't have potatoes, you can use pumpkin or cassava following the same procedure.
2. Boil one potato with a hole for five minutes and leave the other potato raw.
3. Put two teaspoons of salt in the hole of each potato you made.
4. Pour water into two different beakers such that the potatoes do not submerge.
5. Place the potatoes with salt in the water contained in the two different beakers.
6. Make a mark with a pencil on each beaker to show the initial water level.
7. Wait for 2 hours or more.

Results and Questions:

(a) What happened after waiting for 2 hours or more? (Observe the changes in the water level in each beaker). (b) Why was one potato boiled in the second step?

Explanation:

In this experiment, there was a salt solution inside the potatoes. The water inside the beakers had no salt (or had a very small amount of salt). The water in the beakers penetrated into the cells of the raw potato and moved towards the areas with a high concentration of salt solution. The cells of living organisms are surrounded by membranes that allow only certain types of molecules to pass through. This process of water traveling from a dilute solution (with a small amount of salt) to a concentrated solution (with a large amount of salt) is called osmosis.

The boiled potato did not allow water to pass through because its cells were dead. Dead cells do not have the ability to control the passage of water through their membranes.

Importance of osmosis

Osmosis is important especially in the bodies of living things. The importance of osmosis includes the following:

1. It balances water in the body cells of a living thing.
2. Plant roots absorb water from the soil by osmosis.
3. Osmosis helps cells and organs of a living thing to have their specific shapes.
4. It helps in food preservation. For example, salt is applied on meat in order to reduce water and kill germs.
5. It distributes nutrients and oxygen gas throughout the body and removes carbon dioxide from the body.
6. It makes plants firm and minimizes shrinking.