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Investigating the Effect of Temperature on Rate of Respiration.

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* Biology A2 Coursework Name: Luke Meredith Form:13 CJN PLANNING Title: Investigating the Effect of Temperature on Rate of Respiration Aim: I am to investigate and take readings of oxygen consumption, on an organism at several temperatures including replicate readings to give a mean value. At each temperature I will leave the invertebrates for about 10 minutes for the rate of respiration to reach equilibrium. Diagram Experiment 1 Experiment 2 Partial 2b . Complete 4c. Apparatus List: Test tubes x2 Invertebrates (maggots) Respirometer Data Harvesting software on computer and probe Gauze platform clamp stands 1cm syringe Glass beads Sodium hydroxide . Preliminary Work Conducted The first diagram shows two test tubes linked to respirometer. One test tube contains invertebrates (in this situation, maggots) with sodium hydroxide underneath separated by a gauze platform. The other contains glass beads and also sodium hydroxide as shown on the diagram. The glass beads act as inert material to the volume of the invertebrates. Using this method I could measure the rate of respiration at different temperatures, of these invertebrates, by changing the temperature of test tube one and then take readings from the respirometer, from the U-tube containing manometer fluid. What should happen is the invertebrates will respire and the carbon dioxide produced will be absorbed by the sodium hydroxide, so then the oxygen consumed will be showed on the manometer fluid scale. ...read more.


The presence of the second test tube (control tube) helps to compensate for changes in atmospheric pressure. I have also decided that I will use 20 fresh maggots for each experiment. This does bring up the problem of weather to use the same maggots on the repeats and throughout the temperatures. However I feel that maggots are similar enough organisms for the change in maggots not to affect the experiment much at all. So I will use a fresh back of maggots for each repeat and temperature. Also if I do use the respirometer I need to make sure I have something to counteract th4e production of carbon dioxide. So I would use sodium hydroxide, which would absorb all of the carbon dioxide and would allow the respirometer to measure the consumption of oxygen. Finally I have decided that the temperatures 40oC, 45oC, 50oC 60oC and room temperature (22oC). At each of these temperatures I would repeat three times to ensure that no anomaly results happen. However using the data-harvesting equipment should mean that my results will be correct first time round, unless we have set the experiment up wrong. . Method As you can see on the previous page I have two different diagrams. ...read more.


During the cycle two molecules of carbons dioxide are given off, a pair of hydrogen atoms is removed and a molecule of ATP is formed. the hydrogen atoms are taken up by NAD, but one pair that is attached straight to flavine adenine dinucleotide. The pairs of hydrogen's taken from taken from the respiratory intermediates during the oxidation of glucose are accepted by a hydrogen acceptor (NAD). The hydrogen atoms in NAD2are finally oxidised to water by oxygen. This is known as the Electron Transfer System. At three points in the chain, energy is released and is used in the synthesis of ATP from ADP and a phosphate in the presence of an ATP-synthesis enzyme. As you can see from all of these three steps enzymes are a major factor in respiration. So as the temperature increases then we know that enzymes begin to denature and do not work as efficiently. So therefore the rate will slowly begin to decrease. If you look at our preliminary work then you can see I have already investigated into the effect of temperature. Safety conditions. Finally we have to take into account some safety issues. Now because I am using the data-harvesting program, there are much fewer safety precautions. The main hazard we need to consider is when using maggots. I need to ensure that I wash my hands so no food poisoning may occur after the experiment. ...read more.

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