In this practical investigation I am investigating the effects of osmosis in a potato. I will place potato chips in different concentrations of salt solution and water.

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Osmosis

Science Practical Investigation

Fatimah Jilani

11. A1

Osmosis

Aim:

In this practical investigation I am investigating the effects of osmosis in a potato. I will place potato chips in different concentrations of salt solution and water.

Introduction:

I am investigating the effects of osmosis in a potato chip. Below are other factors that could be investigated:

  • Temperature of water.
  • Size of chip.
  • Light.
  • Mass of potato.
  • Concentration of water.

As part of this Science Practical Investigation I am investigating the effects of Osmosis on potato chips.

Water is the most important thing determining the growth as well as the survival of plants. Therefore water and other substances need to enter and leave the cell through the cell membrane.

Particles enter and leave cells through these processes:

  • Diffusion
  • Osmosis

Particles in liquids and gases have kinetic energy. This allows them to move around at different speeds in different directions. In an area of high concentration, some of these particles collide with each other and lose their energy therefore slowing down. Other particles will escape from the concentrated area to places where there are fewer particles or no particles, a less concentrated area. Very few particles leave an area of low concentration to go to an area where the concentration is higher.

This creates a diffusion gradient. So the result is that particles diffuse from an area of high concentration to an area of low concentration caused by the kinetic energy of the molecules. These particles will continue to move from an area of high concentration to an area of low concentration as long as there is a concentration gradient or until the particles are evenly spread out through the available space. The larger the difference in concentration, the larger the gradient and therefore the greater the movement of particles. This process is called Diffusion.

On the next page is an example of Diffusion. Crystals of Potassium Manganate VIII were placed in a beaker of water and we observed how the crystals diffused in the water after 15 minutes and after an hour.      

                            After 15 minutes:                              After 1 hour:

                                  

     Potassium Manganese VIII                                  Water

Another example of diffusion would be the constant removal of oxygen in the blood from the alveolar air spaces in the lungs only if there is more oxygen in the alveolar air spaces than in the blood supply.

The circulation takes the oxygen-rich blood away and replaces it with blood low in oxygen.

Osmosis is basically a specific type of Diffusion, which only involves water molecules and can also be known as water diffusion. Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration across a selectively permeable membrane.

All cells have membranes. In plant cells, the cell membrane is located just inside the cell wall. In animal cells, the cell membrane forms the outer covering of the cell. A selectively permeable cell membrane allows needed materials such as oxygen and water to enter the cell and waste products such as carbon dioxide to exit while keeping in such important molecules as proteins and DNA.

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The rate at which osmosis takes place is affected by the concentration of water in the two solutions on each side of the cell membrane.

If the selectively permeable membrane separates two solutions, water moves through it in both directions at the same time. Although more water leaves the high water concentration and passes into the low water concentration solution than enters it. The water seems to move across the membrane in one direction, but is moving in both directions with more water moving one way than the other. When the concentration of water on ...

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