Biology Lab 8

Complete and attach to the correct drop box

Experiment 1: Fermentation by yeast

Table 1: Gas production

Tube|Initial gas height (mm)|Final gas height (mm)|Net Change|

1|7 mm|8.5 mm|1.5mm|

2|7mm |9mm|2mm|

3|5mm|5mm|0mm|

4|4mm|4mm|0mm|

5|5mm|6mm|1mm|

Experiment 1: Questions

1. Hypothesize why some substances were not metabolized, while others were. Research the chemical formula of Equal™ and Splenda™ and explain how it would affect respiration.

• Theobromine an enzyme, cannot be processed in the body, but it is ingested quite often because it is an enzyme found in chocolate. Since the body is unable to process it, it comes out in the urine. So splenda was extracted from sugar and the respiration results came out different.

2. If you have evidence of respiration, identify the gas that was produced. Suggest two methods for positively identifying this gas.

• The gas would be carbon dioxide, and the two methods are to look at eh bottom of the tube, and use the millimeter measurements.

3. How do the results of this experiment relate to the role yeast plays in baking?

• It shows how yeast acts in different sized materials. When bread is baking the yeast makes the dough rise separating it and when it is fully baked it comes out airy and light. Yeast is what makes bread so light and airy.

4. What would you expect to see if the yeasts’ metabolism was slowed down? How could this be done?

• The bread would not rise as quickly, or wouldn’t rise at all and giving the bread it’s light and airy texture. It could be done if the yeast is cold. When mixing yeast you have to mix it with warm water to get it to activate right, but if you put it in the fridge or mix it with cold water the yeast will not activate right.

5. Indicate sources of error and suggest improvement.

• There was not a good source of heat. It was a cold wintery day that made my house colder than normal, and I needed more heat inside to help with warming part or the...