Name:

Date:

Experiment: Identify the compound used to poison Yanni the Yeast

There are three unidentified compounds – Compound A, Compound B and Compound C. You will perform a dose response curve with your compound, and compare it to the dose response curves generated by other groups. Rank the compounds in terms of toxicity, from most toxic to least toxic.

In the presence of warm water and sugar, yeast will begin to produce carbon dioxide. In this experiment, the carbon dioxide will begin to fill the bag. When we add different compounds to the yeast, the amount of carbon dioxide may be altered. The less carbon dioxide is produced, the more ‘toxic’ a compound is. In this experiment, there are three compounds that you will rank in terms of toxicity, from most toxic to least toxic. By making a dose response curve, you can compare the curve to that of known chemicals, in order to identify the unknown compound.

Each group will test one compound. The groups will then compare their results to that of the other groups, to rank the compounds, and then identify them. These dose response curves will then be compared to the dose response curve of the chemical that was used to poison Yanni the Yeast.

Instructions

1)Take 1 bag, and write “Control”

  1. Add 1 ½ teaspoons of yeast to the bag
  2. Add 1 ½ teaspoons of sugar to the bag

2)Take three more baggies, and label them with your compound

  1. Write “High” on one baggie, “Medium” on one bag, and “Low” on the third bag.
  2. Add 1 ½ teaspoons of yeast to each bag
  3. Add 1 ½ teaspoons of sugar to each bag

3)Take the baggie labeled “High” and add 1 teaspoon of your compound

4)Take the baggie labeled “Medium” and add ½ teaspoon of your compound

5)Take the baggie labeled “Low” and add ¼ teaspoon of your compound

6)Add 2 tablespoons of warm water to ALL your baggies, and seal the baggies quickly, making sure to remove all the air.

7)Place the baggie near a heat source, and lay a strip of paper on top of each bag.

8)Wait for 15-20 minutes, as the yeast produces carbon dioxide, inflating the bag.

9)Measure the height of the baggie, and write down the height in centimeters.

Control
(Height of bag in cm) / Concentration / Substance ______
(Height of bag in cm)
High
Medium
Low

10)Graph your results, and then compare your dose response to that of other groups

11)Rank the three compounds from most toxic to least toxic, and identify them.

Compound A: ______

Compound B: ______

Compound C: ______