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Help with a biology experiment? I have no idea what to do?
So I'm homeschooled and I did this experiment with yeast and soda and water and balloons. It didn't work, and today is the deadline. I can't do it again because it takes 2 days... here is the assignment. Does anyone know what was supposed to happen?
The basic idea of this experiment is to measure the amount of carbon dioxide (CO2) released during the growth of yeast. The growth of the yeast stops when one of the nutrients required by the yeast is gone, or when the liquid gets too acidic (low pH) and kills the yeast. To conduct this experiment, follow the directions below.
Keep careful records as while collecting data. This is very important when analyzing, concluding, and submitting work.
Problem: What is the effect of sugar on the growth of yeast?
Procedure
Label each bottle to keep track of what each one contains--2 bottles of water, these are your control group, 2 bottles of soda, the experimental group, so that you can tell bottles containing the same solution (replicates) apart. Color is not a reliable means of identification--the caramel color used in cola is a carbohydrate and the yeast can eat it.
Put a level teaspoon of dried yeast in all bottles.
Seal the bottles tightly and shake all bottles the same amount of time to dissolve the yeast.
Remove the lids and stretch a balloon over the mouth of each bottle.
Record the diameters of the balloons,
Create a table in which to record your measurements.
Measure the diameter of the balloons approximately every 12
1 Answer
- Anonymous4 years ago
I have never done this experiment. Having read the instructions it also seems to me a good argument against homeschooling.
In the bottles containing the carbonated beverage (soda, cola, whatever) the yeast should have used the sugar in the drink for respiration. A by-product of respiration is carbon dioxide. As the carbon dioxide escaped from the bottles it probably was supposed to inflate the balloon. The bottles with water in possibly had no nutrients so the yeast may have respired for a short time prior to dying of starvation. Thus the balloon on that bottle may have either not inflated at all or much less.
Without even bothering to spend time thinking about this I see two fundamental problems. In a lab the bottles with water in would have been distilled water. The water you used at home, well you have no way of knowing what was in it so it is not a good control.
The carbonated beverage is carbonated (or made fizzy) by the gas carbon dioxide. So, how can you know if the yeast produced any carbon dioxide or if it wasn't already there?
Poorly designed and poor science. I am sorry it failed for you but that is the price you pay when you are not taught by (a) those who know their subject and (b) how to teach it properly.