Biology Essay
Diffusion of Cell Size
2012
Kayla Szabo
Loxton High School
2/20/2012
Rate of Diffusion
Practical report
Introduction:
Diffusion is the movement of a substance from an area of high concentration to an area of low concentration. Cells need to utilise diffusion to exchange materials from outside of the cell to the inside of the cell for them to survive. Diffusion is a passive process, which means it doesn’t involve the need of energy.
For a cell to survive it relies greatly on its size or volume. The larger the cell, the less efficient the cell will be, as there will be relatively more surface area to exchange substances. A cells ability to exchange substances relies greatly on the fact that the surface area is sufficient for the volume of the cell. Hence the smaller the cell, the more surface area it has in comparison to its volume which means it’s more efficient in supplying the cell with the right amount of nutrients.
The theory of surface area to volume ratio and its effect on the rate of diffusion is the basis of the experiment to be conducted. Cell size will be modelled using agar cubes soaked in the indicator phenolphthalein. The cubes will be cut into various sizes of 1cm to 3cm, then will be immersed into the acid, therefor the rate of diffusion can be measured by the decolouration that take place as the acid diffuses into the agar cube.
Aim: To investigate how varying the surface area to volume ratio affects the rate of diffusion between three agar cubes.
Hypothesis: The greater the surface area to volume ratio of the phenolphthalein agar cubes, the greater the percentage of decolouration that takes place.
Independent variable: size of agar cubes
Dependent variable: volume (or %) of decolouration of agar cubes
Factors held constant: * Shape of agar cubes * Type of concentration of acid (0.1M sulfuric acid) * Amount of acid (150mL) * Time in which cubes are immersed (10minutes) * Temperature of the solution
Materials:
2012
Kayla Szabo
Loxton High School
2/20/2012
Rate of Diffusion
Practical report
Introduction:
Diffusion is the movement of a substance from an area of high concentration to an area of low concentration. Cells need to utilise diffusion to exchange materials from outside of the cell to the inside of the cell for them to survive. Diffusion is a passive process, which means it doesn’t involve the need of energy.
For a cell to survive it relies greatly on its size or volume. The larger the cell, the less efficient the cell will be, as there will be relatively more surface area to exchange substances. A cells ability to exchange substances relies greatly on the fact that the surface area is sufficient for the volume of the cell. Hence the smaller the cell, the more surface area it has in comparison to its volume which means it’s more efficient in supplying the cell with the right amount of nutrients.
The theory of surface area to volume ratio and its effect on the rate of diffusion is the basis of the experiment to be conducted. Cell size will be modelled using agar cubes soaked in the indicator phenolphthalein. The cubes will be cut into various sizes of 1cm to 3cm, then will be immersed into the acid, therefor the rate of diffusion can be measured by the decolouration that take place as the acid diffuses into the agar cube.
Aim: To investigate how varying the surface area to volume ratio affects the rate of diffusion between three agar cubes.
Hypothesis: The greater the surface area to volume ratio of the phenolphthalein agar cubes, the greater the percentage of decolouration that takes place.
Independent variable: size of agar cubes
Dependent variable: volume (or %) of decolouration of agar cubes
Factors held constant: * Shape of agar cubes * Type of concentration of acid (0.1M sulfuric acid) * Amount of acid (150mL) * Time in which cubes are immersed (10minutes) * Temperature of the solution
Materials: