Effect of substrate concentration on catalase activity (Biology IA)
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Introduction
Title Effect of substrate concentration on catalase activity Aim To prove that at different concentrations of hydrogen peroxide, the rate of catalase activity in chicken liver differs. Hypothesis When chicken liver is exposed to hydrogen peroxide, the higher the concentration of the solution, the faster the activity of catalase because the decomposition rate of hydrogen peroxide increases when its concentration is higher (in the presence of chicken liver). Variables Independent Variables * Concentration of hydrogen peroxide Dependent Variables * Time taken for coloured liquid to rise by 5cm against different concentrations of hydrogen peroxide Controlled Variables * Amount of chicken liver used - cubes cut with a scalpel to approximately 1cm x 1cm x 1cm * Amount of hydrogen peroxide used - 5cm3 measured with a syringe before addition to the chicken liver * Temperature of liver (not controlled) * Age of liver (not controlled) * Source of liver (not controlled) Materials and Apparatus Materials: Apparatus: * 6x Chicken Liver Pieces - 1cm x 1cm x 1cm * 5% Hydrogen Peroxide Solution (5cm3) * 4% Hydrogen Peroxide Solution (5cm3) * 3% Hydrogen Peroxide Solution (5cm3) * 2% Hydrogen Peroxide Solution (5cm3) ...read more.
Middle
Results Pooled data of the time taken for the coloured liquid to rise by 5cm against concentrations of 5%, 4%, 3%, 2%, 1%, and 0.5% hydrogen peroxide: Concentration of Hydrogen Peroxide Solution (%) Time taken for the coloured liquid to rise by 5cm (seconds) ?0.01seconds Reading 1 Reading 2 Reading 3 Reading 4 Reading 5 0.5 29.37 21.10 33.63 30.10 29.81 1.0 12.95 19.02 26.73 25.60 15.31 2.0 9.23 10.34 12.63 10.50 6.12 3.0 5.72 4.81 5.36 4.30 5.24 4.0 2.42 2.34 2.07 3.19 3.84 5.0 0.82 0.92 0.96 1.14 1.53 The average time taken for the coloured liquid to rise by 5cm against concentrations of 5%, 4%, 3%, 2%, 1%, and 0.5% hydrogen peroxide, and the standard deviation: Concentration of Hydrogen Peroxide Solution (%) Average time taken for the coloured liquid to rise by 5cm (seconds) ?0.01seconds Standard Deviation 0.5 28.80 4.63 1.0 19.92 6.11 2.0 9.76 2.38 3.0 5.09 0.55 4.0 2.77 0.73 5.0 1.07 0.28 Calculation's Involved Average time taken for the coloured liquid to rise by 5cm (seconds) ...read more.
Conclusion
higher the concentration of the solution, the faster the activity of catalase because the decomposition rate of hydrogen peroxide increases when its concentration is higher (in the presence of chicken liver). Evaluation The individual chicken liver pieces were not very accurately cut and measured due to their slippery nature. A further way of ensuring equal size of liver pieces could be to weigh them - making sure that the pieces are equal both in size and weight, allowing more accurate reactions and accurate data. When the rubber bung was inserted back into the tube after the hydrogen peroxide had been added, due to the added pressure, the coloured liquid may have been forced up by pressure of insertion, and not just by the reaction between the hydrogen peroxide and chicken liver. In order to avoid severe distortion of results, the rubber bung should be inserted slowly and insertion time should be measured and be equal for each investigation. Also, by collecting data when the coloured liquid had risen to 8cm and 10cm, the results and conclusions would be more extensive and reliable with more data to back them. ?? ?? ?? ?? ...read more.
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Here's what a teacher thought of this essay
3 star(s)
The introduction did not use / introduce any of the scientific theory that is needed to be understood in order to carry out this investigation.
Catalase breaks down hydrogen peroxide in to oxygen and water This was the gas that was being collected (not mentioned). This is found in the liver cells and is useful because hydrogen peroxide is a poisonous substance.
In this investigation choosing hydrogen peroxide as the independent variable was a mistake as all that can be concluded here is that with more substrate there is more product.
However, the data that was collected was good and displayed in a logical and clear table.
A way this investigation could be improved is by making the independent variable the size / mass of chicken liver (as this contains catalase).
Marked by teacher Jon Borrell 22/05/2013
