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The Effect On Respiration of Yeast At Different Temperatures.

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Introduction

Davie Webb Biology Coursework1 11RMC Glucose + oxygen = carbon dioxide + water In this investigation I'm going to investigate the effect on respiration of yeast at different temperatures. For a fair test- * Only change the temperature of the water in the experiment. * Use same amount of yeast each time. * Use the same size tubing. * Keep the Amount of time between taking results the same. * Use same amount of yeast. I am going to find out the speed at which yeast respires at a range of temperatures and at what temperature it respires best. As shown in the diagram, I am going to fill a test tube up near the top with yeast. I filled it almost near the top because there will be less air to compress and my results will be more reliable because there will be twice as many bubbles produced than a half full tube. ...read more.

Middle

I think that at room temperature, there will be little or no respiration because the enzymes just aren't active at such a low temperature. FERMENTATION is the breakdown of sugars by bacteria and yeast using a method of respiration without oxygen (anaerobic respiration). It involves a culture of yeast and a solution of sugar, producing ethanol and carbon dioxide with the aid of the enzymes. This process can be slowed down by DENATURATION of the enzymes at a certain temperature. All the ENZYMES are protein chains of amino acids. Along the chain there are active sites where interaction between the enzyme and the substrate happens. These sites are sensitive to heat, like the hydrogen bonds that hold the 3D molecule together. When heat is applied to the enzyme, energy is given into the molecule. The active sites deform and the hydrogen bonds break, denaturing this enzyme. ...read more.

Conclusion

My results show that it increases up until the enzymes reach there optimum temperature, then rate of carbon dioxide bubbles produced goes down. From the successful experiment- I can conclude that temperature is a factor that does affect the rate of respiration in enzymes. Evaluation I think my experiment went as successfully as it possibly could. I think I did the experiment enough times to draw out a clear average then draw out a line of best fit. On the graph, the amount of carbon dioxide produced went up as the temperature went up. It rose straight away and after 40 degrees, it started to fall due to the denatured enzymes unable to produce carbon dioxide as efficiently as the previous temperatures. In this case, an inverted 'u'. If I were to do the experiment again I would take more readings to get even clearer results. I would also take more regular temperatures, like every 30, 30.25, 30.5 etc. just to get a clearer idea of the optimum temperature of the enzymes. ...read more.

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