Data

(This picture was taken after 45 minutes)

•  Per test-tube we had 20 ml of water and one gram of yeast
• Depending on the color of the balloon, we distributed sugar accordingly: making the pink balloons 75% sugar, the blue balloons 50% sugar, the yellow balloons 25% sugar.
• For the red balloon we just made the mixture 20 ml of water and one gram of yeast

 After we added all of our ingredients together and before we recorded their circumferences at the 30 minute mark, they looked like "lava lamps" with the yeast moving up and down and they started bubbling and fizzing
     * The red balloon mixture didn't fizz (lack of sugar)
Some balloons would just "pop up"

30 Minutes (circumferences)

• Yellow:  (one up) 8.5 cm
• Blue: (two up) 7.5 cm, 9 cm (AVG: 8.25)
• Pink: (three up) 9 cm, 8.5 cm, 8.4 cm: most bubbles (AVG: 8.63)
• Red: not up

40 Minutes (observations)

• Pink: All balloons came up faster. We lost a balloon at 42 minutes but we put it back on and it re-inflated within 7 minutes, but not as big as the other balloons. 
• Blue: All balloons came up after the pink balloons, and one blew off at us. 
• Yellow: Not as inflated as the pink and blue balloons. 
• Red: Not inflated

60 Minutes (circumferences)

• Pink: 11.5 cm, 13 cm, 12 cm, 7 cm* (this is the one that had come off and re-inflated) (AVG: 10.875)
• Blue: 12 cm, 13 cm, 10.5 cm (just popped off after we measured it...), 8 cm* (this is the one that blew off at us at the 40 minute mark, re-inflated after we put it back on, obviously) (AVG: 10.875)
• Yellow: 11.5 cm, 10.5 cm, 9 cm, 9.5 cm (AVG: 10.125)
• Red: Not inflated

24 Hours (circumferences/ observations)

• Pink: One blew off (not the same one that came off before), 12 cm, 14 cm, 12.5 cm (AVG: 12.83) 
• Blue: All balloons were deflated (to an extent), one blew off. When the three "deflated" balloons were squeezed, there was still some tension inside them. 
• Yellow: Two balloons were deflated, two were still "up", but their circumference couldn't be measured. When the two "deflated" balloons were squeezed there was still some tension inside them, similar to the blue balloons.
• Red: Never inflated

There was definitely an "optimal range" with the yeast and the sugar, and that was around 30- 60 minutes, when most of the balloons were up and the most inflated and had the largest circumference. This "optimal range" was definitely over by 24 hours because all of the balloons had become deflated.(Our group couldn't tell when this range ended concretely because we don't nest in the bio lab).

Also, the higher concentration of sugar there was, the more reaction (fermentation) took place with the yeast and the more carbon dioxide was produced and collected in the balloons.
     - The red balloon didn't inflate at all, it had no sugar.

Due to human and scientific error, our group lost balloons here and there, but only in the concentrations of 50% and 75%, and when we put the balloons back on, they re-inflated-- meaning that there was still fermentation going on and that they could still collect that carbon dioxide.

Implications

Our initial hypothesis for this experiment was that if we had a higher concentration of sugar compared to yeast then there would be a more respiration in the cell. What is very close to what we predicted. The balloons that we used to measure the cell respiration were the biggest on the highest concentration of sugar (75%). The difference in central tendency is because of the amount of sugar in the concentrations. What we can take from this is that yeast respires more when there is more to break down. This is because it does not stop breaking down cells until it is all gone.

Method

(This photo was taken after 30 minutes)

Our Materials included yeast, sugar, water, balloons, string, and our generalizable materials.
                                      What we did:

• we set up four test tubes with 75% sugar-water mixture to one gram of yeast (pink), 

• four test-tubes with 50% sugar-water mixture to one gram of yeast (blue), 

• four test-tubes with 25% sugar-water mixture to one gram of yeast (yellow), 

• one test-tube with one gram of yeast and just 20 ml of water (red).  

• we put color-coded balloons on top of the test-tubes to measure the output of carbon dioxide, recorded the amount of bubbles going on in each reaction (because more bubbles means more reaction) and recorded the circumferences of the balloons at 30 minutes, 60 minutes, and 24 hours (the bigger the circumference, the more fermentation)

Purpose

The purpose of this experiment was to measure the cell respiration of yeast when mixed with various concentrations of sugar.
The mixture without any sugar and the red balloon was our control.
The sugar concentrations were our independent variables and the yeast respiration ended up being the dependent variable-- the respiration of the yeast was dependent on the concentration of the sugar in the mixture.
Our group predicted that when we raised the concentration of sugar, more CO2 would be released into the balloon, evidence that there is more respiration.
Our hypothesis: If there is a higher concentration of sugar in the mixture, then the yeast respiration will increase and more carbon dioxide will be produced.