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"Enzymes are biological catalysts, which increase the rate of chemical reactions within living cells. They effectively lower the activation energy required for the chemical reaction to start, without undergoing any physical change"

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Analysing evidence and drawing conclusions Background information: Enzymes are biological catalysts, which increase the rate of chemical reactions within living cells. They effectively lower the activation energy required for the chemical reaction to start, without undergoing any physical change. They are not used up by the reactants, and therefore do not appear within the products. Enzymes are globular proteins, either in a tertiary or quaternary protein form. The shape is three dimensional, with one area, designed specifically for a particular substrate called the active site. The active site consists of a sequence of amino acids which will chemically bind with a substrate, altering the chemical bonds of the structure and therefore making it easier for a particular reaction to take place. The substrate binds to the active site of the enzyme to form an enzyme substrate complex. This lowers the activation energy, allowing the reaction to take place at a lower temperature. When the products are formed, they leave the active site, leaving the enzyme unchanged. The enzyme can now bond with another molecule of the same substrate and cause another reaction to take place. The enzyme used in this investigation is peroxidase, otherwise known as catalase. It is an enzyme which is found in many living cells, including mammalian liver, and in plants such as potatoes and celery. ...read more.


= 0.67 The statistical tests on the two sets of data show that although they were collected as a result of two individual experiments, they have similarities between them in terms of mean and median. The mean and median are two methods of an average, and it being similar for the two sets of data proves that the data has good consistency. The spread of the data was measured by the standard deviation, and as can be seen from the values, the distributions of the sets of values are different. However, this does not make such a difference in the reliability of the data, as it is the trends and patterns that the data shows that is of importance to me. Overall, the statistical tests have provided me with results showing that they are consistent, and therefore are a good basis for my conclusion. Statistical significance test Statistical significance tests are used to show whether the difference between the means of two sets of data are truly significant. I have decided to use the Mann-Whitney U test, as this is the best significance test to use for independent measures design experiments, which does not take the distribution of the data into consideration. ...read more.


A low number of particles, in a high number of water particles means only a small number of particles will combine with the catalase to be broken down at any one time. In comparison, a high concentration, like the 20 volume concentration contains many more hydrogen peroxide particles available for the catalase to combine with. This results in more particles combined with the active sites of the catalase, causing a larger number of particles being broken down at any one time. Therefore, a higher number of oxygen and water particles are produced at a given time, which results in a larger volume of oxygen given off by the reaction with a higher concentration of the hydrogen peroxide. In conclusion, the increase in oxygen with the concentration supported the idea of an increase in rate of reaction of the breakdown of hydrogen peroxide stated within my hypothesis. This showed that the increase of the amount of hydrogen peroxide substrate caused the enzyme catalase to act upon it at a faster rate increasing the amount of the oxygen product produced. Fundamentally, this supports the biological theory that increasing an amount of substrate will increase the enzyme activity upon it, providing that the amount of enzyme active sites available for that substrate is more than the substrate particles involved. ?? ?? ?? ?? Shakila Chowdhury Analysis Biology Paul Smith 5 ...read more.

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