Investigating the Rate of Respiration in Yeast: Triple/double science Biology coursework for GCSE - page 4
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: 4 of 6 pages: 1 2 3 4 5 6Sit Back, Relax, and Get Paid for What You Think!
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First, I will work out the rate of reaction at each glucose concentration (from the average).
0% : 0.3
300 = 0.001 cm³/sec
2% : 0.7
300 = 0.002 cm³/sec
4% : 2.0
300 = 0.007 cm³/sec
6% : 4.1
300 = 0.014 cm³/sec
8% : 3.2
300 = 0.011 cm³/sec
10% : 2.9
300 = 0.01 cm³/sec
Approximately, 4% glucose concentration results in a rate of reaction that is half of a 6% concentration rate. The glucose concentration rate of 2% is twice that of 0%, but 8%’s rate is less than 6%’s.
Graph
The graph has a positive correlation increase up until 6% glucose concentration because as more glucose is available for the yeast to respire. But after this, the concentration of water is higher in the yeast cells than in the burette, so via osmosis water will move from the cells to the external water in the experiment. The cell will then plasmolyse and be able to respire less.
I can conclude that the more glucose there is, the more gas the yeast will produce because it is respiring more (up until 6% glucose concentration). After this, water moves out of the yeast cells via osmosis because there is a higher concentration of water outside of the cells. Because the cell is plasmolysed, it can respire less.
My prediction was partially correct. I predicted that the more glucose there is, the more the yeast will respire. In the actual experiment, this is correct from 0% to 6% glucose concentration. Then I predicted the graph will even out to a plateau when the yeast has all the glucose it needs to respire anerobically at its optimum rate – those results will be the same. Collision theory says that the more energy available, the more times molecules collide with one another, so the more reactions will occur. Therefore, using the “lock and key” theory, at 6% glucose concentration in my results, the yeast had enough glucose available to respire as much as possible in five minutes. However, I didn’t take osmosis into account when I was making my prediction. The cells did not continue to respire the same amount because osmosis meant that they became plasmolysed as they lost water. The concentration of glucose in the water in the experiment was so high, that there was
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