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In this investigation my aim is to find out how the concentration of enzyme (amylase) will affect the rate of reaction.

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Scientific Knowledge An enzyme is a biological catalyst and affects every reaction in the body. Without enzymes in the body metabolism would be at a rate too slow to sustain life. Enzymes are used in the body for both anabolic and catabolic reactions for example the enzyme amylase breaks down starch into maltose for absorption into the blood. This investigation will consider the factors (in particular enzyme concentration) that affect the break down of substrate by amylase. The Lock and Key theory states that every enzyme can break down a certain type of substrate. This is because the active site(s) will only fit that particular substrate or group of substrates. This is like a key fitting a lock and the reaction that occurs being like the key turning in the lock. Enzymes work by lowering the activation energy for the reaction; this may be due to the way they hold the substrate molecule(s). In collision theory it states that for a reaction to occur the particles must collide and with sufficient activation energy, an enzyme therefore increase the rate of reaction by facilitating reaction initiation. ...read more.


'Average' was calculated as a mean of values form tests 1-7 for each amylase concentration. 'Rate' was based on the average using the formula Starch Digested / Time Taken To Digest= Rate mg/sec Conclusion In the results we can definitely see that as the concentration of Amylase is increased the rate also increases. This is because as the concentration of Amylase increases the number of active sites for reaction to occur will also increase meaning that more collisions could occur every second therefore allowing the starch to be digested faster. We can also see through the graph that the speed is not exactly doubled as the concentration is doubled this may be because of wasted collisions between the enzyme and the substrate. In a wasted collision the substrate does not join to the enzyme as it does not hi the active site fully this means that the collision does not result in a reaction therefore no starch is digested into maltose. I can see that my prediction was partly correct as I had stated that as the concentration was increased the rate would also increase. But the results did not double as the concentration was doubled as I had stated but this may be down to other factors that we had not accounted for. ...read more.


This equation shows the reaction 2H202 O2+H2O this shows us that the Hydrogen peroxide is broken down into water and oxygen and this oxygen could be used to measure the rate of the reaction. The experiment could be carried out using this method. Method 1. Set up equipment as in diagram. 2. 3. Set timer for 3minutes and place a measured amount of liver in the beaker and start time. 4. After the time has finished remove the delivery tube from the tub leaving just the measuring cylinder and then measure the amount of oxygen produced. Record this in a table. 5. Repeat this for concentration 0.25%, 0.50%, 0.75, 1.00%, 1.25%. 6. Record these results repeat practical under same conditions 3X. 7. Work out averages and rate of reaction and draw graph. This method would produce accurate results as nothing is subjective to a person's opinion and also as the experiment is repeated 3 times under the same conditions the results would be quite accurate. An alteration that could be made is that instead of liver, catalyse could be by itself which would give a more accurate results because the weight could be altered due to density or even water content. ...read more.

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