Investigating the Rate of Respiration in Yeast: Triple/double science Biology coursework for GCSE - page 1
Keywords: Investigating the Rate of Respiration in Yeast: Triple/double science Biology coursework for GCSE, anerobic respiration, A, Higher Level
By Glamurus on 02/11/2006 17:54:57
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 6 pages: 1 2 3 4 5 6
Investigating the Rate of Respiration in Yeast
Introduction
I am going to try and measure the rate of respiration in yeast and find out what factors affect the rate of respiration. I am going to change the concentration of the glucose solution and I’m going to measure the volume of gas produced during respiration in cm³.
Yeast contains enzymes. Enzymes speed up a chemical reaction – they’re biological catalysts. Yeast can respire both aerobically and anaerobic; the anaerobic respiration of yeast is known as fermentation. The equation for this type of respiration in yeast is:
Glucose Carbon Dioxide + Ethanol
The presence of ethanol means that yeast is used in the process of fermenting wine. Yeast tends to respire anaerobically.
Preliminary Experiment Details and Plan
The four variables that are factors in this experiment are:
o Temperature of the solution used in the experiment.
o pH of the solution used in the experiment.
o Substrate concentration (in this case, glucose).
o Enzyme concentration (in this case, yeast).
Apart from substrate concentration, which I will be changing in this experiment, it is important to keep the other variables the same to ensure the results are reliable and to get a fair test – results must change because of a difference in the input variable, not because of a different variable. I can monitor the temperature and check it stays the same by using a thermometer. I can keep the pH the same by always using water from the same source. To keep the concentration of yeast the same each time the experiment is repeated I will accurately mix the same concentration each time. I will change the concentration of glucose every repeat of the experiment, and I will measure the output of gas each time.
List of apparatus:
o Stopwatch
o Burette
o Dish
o Water
o Thermometer
o Delivery Tube
o Bung
o Conical Flask
o Boiling Tube
o Yeast
o Glucose
o Measuring Cylinder
This is how I’m planning to set out the equipment:
Preliminary Experiment
I did two repeats of a preliminary experiment for a 10% glucose concentration solution. This was to make sure the experiment planned was fair, and to sort out any problems found before carrying out the actual experiment. Every variable apart from the glucose concentration will need to be kept the same, so this initial experiment is needed to check that the values of these
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