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The Effects of Glucose Concentration on Yeast Respiration

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Myesha Radney

on 30 October 2013

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Transcript of The Effects of Glucose Concentration on Yeast Respiration

The Effects of Glucose Concentration on Yeast Respiration
In this experiment, we are trying to study how the concentration of glucose affects the rate of fermentation.

Our variable is the varying amounts of glucose.
Our control group is the sample that has 5% (1.0g glucose).

The greater the concentration of glucose, the faster the rate of respiration will be.
Step 1:
Weigh four different amounts of glucose.
0.12g, 0.24g, 0.36g, and 1.0g and place each amount into a flask.
Step 2:
Add 10ml of H20 to the flask and gently swirl until the glucose is dissolved.
Step 3:
Using a 10ml pipet, transfer 10ml of the yeast mixture into the 50 ml flask.
Step 4:
Occasionally swirl the yeast suspension for 5 minutes, and leave to settle.
step 5:
Take 3ml exactly of the yeast in the 50 ml flask into the syringe and then draw 1ml of air.
step 6:
Complete the respirometer and hold it with one hand, and the other hand covering the syringe.

(insert pic of respirometer here)
Thank You
for Watching
What does it all mean?
Interpreting the Results
Evaluation of Hypothesis
Implications of Results
Based on our results, it is evident that our data did not support our hypothesis. As we mentioned earlier, we initially predicted that respiration rates would be directly proportional to concentration, or in other words, that respiration rates would increase as concentrations increase. However, it is evident that our outcomes were much different than expected.
Maximal Value
Our results actually illustrated immense variation with the slopes, or respiration rates, for various concentrations. The respiration rates seem to fluctuate amongst our different sample concentrations. Based on this, we can infer that even though there might be a relationship between respiration rate and sugar concentration, it is difficult to assess it without taking into account other factors such as temperature. For example, if the temperature of my respirometer was lower than the temperature of my group mate's. then my yeast respiration rate could have been slower.

We can also infer that some other factors could have affected our results. Some of these include:
step 7:
Wait until water bubble reaches 0ml.
step 8:
When water bubble reaches 0ml, start to record measurements for 1 minute intervals.
(read the top of water bubble not the bottom)
Concentration Calculation:
5% = (n/20ml)*100

n = (5*20)/100

n = 1.0g
Linear Equations:

trial 1: y=0.039x+0.081

trial 2: y=0.0466x-2E-14

Concentration Calculation:
0.6% = (n/20ml)*100

n = (0.6*20)/100

n = 0.12g

Linear Equations:

trial 1: y=0.01x+0.03
slope= 0.01

trial 2: y=0.01x+0.08
slope= o.o1
Concentration Calculation
1.8% = (n/20ml)*100

n = (1.8*20)/100

n = 0.36g

Linear Equations:

trial 1: y=0.085x-0.1911
slope= 0.085

trial 2: y=0.023x-0.043
slope= 0.023
Concentration Calculation:
1.2% = (n/20ml)*100

n = (1.2*20)/100

n = 0.24g

Linear Equations:

trial 1: y=0.053x-0.005
slope= o.o53

trial 2: y=0.0389x-0.1932

Yeast are single celled eukaryotic cells that are in the kingdom fungi. Some types of yeast can be found
naturally on plants or in the soil. Scientists love to work with yeast because it can be grown quickly and its DNA can be easily manipulated.
Fermentation is a process that allows cells to gain energy from different types of carbohydrates while being anaerobic (without oxygen) to form carbon dioxide. Fermentation can be used to produce food and drinks.
Biofuel is very important in science because it is renewable and burns cleaner unlike fossil fuels. Biofuel
is a great source of energy that can be used. Biofuels start of as grains of corn and wheat and through a
process are made into biofuels.
Glucose is a carbohydrate and the most important simple sugar in human metabolism. It is also a
monosaccharide because it’s one of the smallest forms of carbohydrates. Different amounts of glucose can affect the rate of fermentation. Energy is obtained from glucose using this reaction.

C6H12O6 + 6O2 --> 6CO2 + 6H2O
Myesha Radney
Dunya Bazzi
Faris Ahmed

Other Factors
- Temperature

- Type of respirometer holder

- Size of water bubble

- Disparity between glucose
Due to the ambiguity of our results, we were not able to identify a maximal or optimal value.
Alternative Hypothesis
In efforts to retest our experiment and obtain data that supports our hypothesis, we could perform an alternative experiment or standardize certain variables.

We could still use different concentrations of sugar, but we could standardize the temperature of the respirometer and the respirometer holder. We could then hypothesize:
If the temperature is held constant, yeast respiration rates for various samples will increase as the concentration of sugar added increases.
Implications for Biofuel Production
Although our results were ambiguous. if we were in fact able tweak our experiment and find support for our hypothesis then we could infer that since yeast are hungry for carbohydrates, like glucose, then by increasing the respiration rates of yeast by controlling for certain variables like concentration, then we might be one step closer to replacing fossil fuels with biofuels.

In other words, if increased concentrations of glucose means faster yeast respiration rates then we might be able to conduct fermentation, production of ethanol, more rapidly and efficiently by providing and growing more grain and plants to obtain more glucose for yeast to metabolize.
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