Agar IB Lab DCP Practice 2015 DP
3DIFUSSION IN AGAR CUBES – LAB REPORT
Research Question: What is the effect of surface area on volume ratio on the rate of diffusion of pigment from the agar cube measured by percentage volume of diffusion over time?
Background Research:
Diffusion is the passive movement of molecules or particles along a concentration gradient, or from high to low concentration regions. Essential towards living organism’s functions, as it describes how the nerve cells are able to communicate with each other, through electrical signals in other cells. Diffusion can also be used to describe the cells exchange of toxic gasses for life sustaining gases. Some factors that can affect diffusion are temperature, and concentration difference. As the rate of diffusion will increase along with the temperature; as well as due to a concentration difference, the higher the difference in concentration- the faster the two solutions will diffuse.
As both the solution and the agar are colourless I will use agar that had before been mixed with phenolphthalein. Phenolphthalein is a solution used as an indicator often used in titration focused labs. This is because it helps identify acidic and basic solutions, as phenolphthalein will either turn pink in basic solutions or colourless in acidic solutions. This will help us observe diffusion, in our lab because the agar cubes- which have been made with phenolphthalein, and is evenly distributed through the entire agar cube. When the agar cube comes in contact with Sodium Hydroxide (NaOH) it will turn pink, and will continue to do so as diffusion occurs, and the Sodium Hydroxide solutions begins to be absorbed into the agar cubes, allowing us to later identify the distance the Sodium Hydroxide solution travelled over time.
We want to examine whether ad how the rate of diffusion over time is dependent on the cubes surface area to volume ratio (SA:V). Smaller cubes have bigger SA:V than big cubes. We know that e.g. cells seek to have the biggest surface
Research Question: What is the effect of surface area on volume ratio on the rate of diffusion of pigment from the agar cube measured by percentage volume of diffusion over time?
Background Research:
Diffusion is the passive movement of molecules or particles along a concentration gradient, or from high to low concentration regions. Essential towards living organism’s functions, as it describes how the nerve cells are able to communicate with each other, through electrical signals in other cells. Diffusion can also be used to describe the cells exchange of toxic gasses for life sustaining gases. Some factors that can affect diffusion are temperature, and concentration difference. As the rate of diffusion will increase along with the temperature; as well as due to a concentration difference, the higher the difference in concentration- the faster the two solutions will diffuse.
As both the solution and the agar are colourless I will use agar that had before been mixed with phenolphthalein. Phenolphthalein is a solution used as an indicator often used in titration focused labs. This is because it helps identify acidic and basic solutions, as phenolphthalein will either turn pink in basic solutions or colourless in acidic solutions. This will help us observe diffusion, in our lab because the agar cubes- which have been made with phenolphthalein, and is evenly distributed through the entire agar cube. When the agar cube comes in contact with Sodium Hydroxide (NaOH) it will turn pink, and will continue to do so as diffusion occurs, and the Sodium Hydroxide solutions begins to be absorbed into the agar cubes, allowing us to later identify the distance the Sodium Hydroxide solution travelled over time.
We want to examine whether ad how the rate of diffusion over time is dependent on the cubes surface area to volume ratio (SA:V). Smaller cubes have bigger SA:V than big cubes. We know that e.g. cells seek to have the biggest surface
Bibliography: 1. Katarzyna Zaremba, „IB DIPLOMA PROGRAMME BIOLOGY SL AND HL STUDENT HANDBOOK” 2. „Writing a good biology lab report”, http://signatureibbiology.wikispaces.com/file/view/The+Perfect+Biology+Lab+Report.doc, , Web, 11.09.2014 3. „How to write a good biology lab report”, http://www.ibsurvival.com/topic/13178-how-to-write-a-good-biology-lab-report/, 21.02.2014, Web, 11.09.2014 4. „Diffusion”, http://en.wikipedia.org/wiki/Diffusion , 07.09.2014, Web, 12.09.2014 5. „Sodium hydroxide”, http://en.wikipedia.org/wiki/Sodium_hydroxide, 21.08.2014, Web, 13.09.2014 6. „What does stansard deviation show us about our data”, http://science.halleyhosting.com/sci/soph/inquiry/standdev2.htm, Web, 16.09.2014