Investigation Of Osmosis Using Potato Core Biology Essay

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Osmosis is the action of water moving through a semi-permeable membrane, dividing solutions of different concentrations. The water starts in a region of high concentration and then continues to a lower concentrated regain, until the two concentrations are equal. A cell membrane is a semi-permeable membrane, while osmosis is a necessary to transport fluids within the organism, for example, while water moves from within soil to roots in trees. When a cell comes into contact with a lower concentrated solution of water than its own, the water then exits the cell membrane by osmosis. Water is lost, from both the cytoplasm and the vacuole in the tonoplast. The live contents inside the cell will contract and extract from the cell wall, becoming flaccid, this is otherwise known as plasmolysis. When you put a plant cell into water it will start to grow again, this is caused by osmosis again. Although the cell will never break whilst this happens because the cell wall consists of cellulose, an extremely strong polysaccharide. At some point, the cell will become turgid, this means the cell will stop growing. This is essential for plants because it makes the stems healthy and stand up straight.

Materials

Big Potato

Cork Borer

Solutions of water and NaCl ( Deionised water, 6%, 3%, 1% and 0.5%)

Blotting Paper

Electronic Balance

Ruler

Scalpels

Test Tubes or beakers

Test Tube Racks

Lids

Plastic foil

Thermometer

Procedure

l) Five test tubes or beakers are labeled, each one with the different concentration of NaCl

solutions: (0,0%, 6%, 3%, 1% and 0.5%)

2) The tubes/beakers are filled with the different concentration up to three quarters of the tube/beaker.

3) With a cork borer five potato cylinders (4cm in length and each with the same diameter) were cut and placed over five different 'blotting papers that were labeled with the 5 different concentration solutions randomly.

4) The potato cylinders are dried (for a short period of time) and each of them are then weighed on an electronic balance and the lengths of each is measured.

5) Then each cylinder is placed in the test tube with the solution according to the concentration described on the blotting paper.

5) All the initial data are recorded on a previously prepared table.

6) The samples are left for a day in the test tube racks or beakers. Cover the test tubes with plastic foil or the beakers with a lid.

.

7) The next day the potato cylinders are taken from the test tubes (beakers) and placed on blotting

paper labeled with its respective NaCl concentration.

.

8) The cylinders are weighed and their lengths are measured.

Then the final data was recorded on the table.

9) The room temperature should be measured both days for the experiment.

Data Collection

Solute Concentrate

(%)

0

Hypotonic

0.1

Hypotonic

1

Isotonic

3

Hypertonic

6

Hypertonic

Lengths Before

(cm)

5.9, 5.6, 5.0, 6.0, 5.4

5, 5.5, 5.1, 5.8, 4.8

5.8, 5.1, 5.5, 6.1, 6.0

6.0, 5.7, 5.5, 5.6, 5.5

4.7, 5.4, 6, 4.8, 5.0

Average Length Before

(cm)

5.6

5.2

5.7

5.7

5.1

Length After

(cm)

6.1, 6.1, 5.8, 5.5, 5.4

5.7, 5.8, 5.5, 5.0, 6.0

5.1, 5.8, 6.1, 5.6, 6.1

5.1, 5.7, 5.8, 5, 5.0

5.5, 5.0, 4.2, 4.5, 4.2

Average Length After

(cm)

5.8

5.6

5.7

5.3

4.7cm

Mass Before

(g)

1.8, 1.8, 1.7, 1.9, 1.8

1.8, 1.8, 1.8, 1.7, 1.8

2.0, 2.0, 2.0, 2.0, 2.0

1.8, 1.8, 1.8, 1.8, 1.8

1.9, 1.9, 1.9, 1.9, 1.9

Average Mass Before

(g)

1.8

1.8

2.0

1.8

1.9

Mass After

(g)

1.8, 1.9, 2.1, 2.0, 1.6

1.9, 1.9, 1.9, 1.6, 2.0

1.8, 1.9, 2.0, 1.9, 2.0

1.5, 1.5, 1.6, 1.5, 1.5

1.5, 1.5, 1.1, 1.2, 1.2

Average Mass After

(g)

1.9

1.8

1.9

1.5

1.3

Data Processing

Solute Concentrate

(%)

Initial Average Mass

(g) +/- 0.1

Final Average Mass

(g) +/- 0.1

Average Difference in Mass from Initial to Final

(g) +/- 0.2

Average Difference in Mass from Initial to Final

(%)

0

1.8

1.9

+0.1

5.56

0.1

1.8

1.8

+/-0.0

0

1.0

2.0

1.9

-0.1

5

3.0

1.8

1.5

-0.3

16.7

6.0

1.9

1.3

-0.6

31.6

Conclusion

To conclude, I can declare that concentration of different solutions will affect how it will move through a semi-permeable membrane. The higher the concentration of solution, the more the potato will lose its weight, width and length. I know this because I can refer to the results of my hypertonic solutions. Before I placed the potato pieces in either solution they were longer and weighed more,

Kinetic energy causes water molecules to continuously move from place to place in either a gas or a liquid form. If there is a larger concentration of water molecules in a solution, then there is a larger total of kinetic energy, and the water potential will be higher. This means that if the level of glucose is increased in a solution the water concentration will decrease, which also means the water potential in the solution will lessen, which causes its ability to move between concentrations lower. So, the larger the concentration of glucose that there is, the harder it is for the water to pass through the potato, which then causes the water within the potato to become part of the solution, which then shrinks the length, weight, and width.

As osmosis happens when a selectively permeable membrane separates two solutions, in the biological system of osmosis there is an exchange of water between the cytoplasm and the surrounding medium, with the plasma membrane being the semi- permeable membrane.

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