1. The Effect of Sugar Substitutes Compared to Sugar on the Growth of Yeast By: Darcy Horn 10 th Grade Honors Biology

2. Why I Chose This?  Home Use  Not Very Time Consuming  Materials Easily Accessible  New Information

3. Hypothesis and Problem Hypothesis: If sugar substitutes are solutions added to the yeast, then the yeast will have less growth. Problem: To see how sugar is compared to sugar substitutes in the growth of yeast.

4. Vocabulary Concepts Water displacement- used to measure the volume of a solid object, occurring when an object is immersed in a fluid, pushing it out of the way Proofing- a way to test whether yeast is good Yeast Fermentation- the process where yeast is used to change sugar into lactic acid Lactic Acid- a colorless or yellowish, syrupy, water- soluble liquid, produced during muscle contraction as a product of anaerobic glucose metabolism, abundant in sour milk, prepared usually by fermentation of cornstarch, molasses, potatoes, etc.

5. Background to Yeast Yeast are unicellular, aerobic or anaerobic organisms Yeast, like animals, give off CO2 as a byproduct of respiration reproduce through budding in which an adult yeast cell grows an offspring from its body For reproducing yeast cells need energy. Yeast utilizes the glucose in its environment to make energy Sugar acts as a catalyst to yeast growth

6. Experiment Independent Variables Pure granulated sugar (control) Aspartame-Equal Sucralose- Splenda Acesulfame Potassium- Nutra-Sweet ADDED TO Active yeast Water

7. Experiment (continued) Let balloon sit for one hour Water displacement method Record data

8. Design Diagram IV:Sugar Substitutes Levels: Granulated Sugar (control) SucraloseAspartameAcesulfame Potassium Trials:10 DV: The Growth of Yeast (mL of CO 2 produced) Constants: Amount of each sugar/sugar substitute (12.6g), amount of water added to each test (30mL), temperature of water (43°C-46°C), amount of yeast in each test (1/4 ounce each), amount of time given to each trial (1 hour), environment of experiment

9. Photo Documentation

10. Results with Averages Granulated Sugar (control) SucraloseAspartameAcesulfame Potassium 60 mL112 mL87 mL84 mL 110 mL108 mL93 mL88 mL 80 mL110 mL90 mL80 mL 100 mL115 mL91 mL82 mL 80 mL95 mL79 mL82 mL 90 mL114 mL85 mL90 mL 110 mL 92 mL89 mL 110 mL107 mL66 mL84 mL 100 mL116 mL84 mL80 mL 93.5 mL109 mL85.5 mL84 mL Sugar Substitutes (IVs) Growth of yeast (mL)

11. Averages Sucralose- 109 mL Granulated Sugar (control)- 93.5 mL Aspartame- 85.5 mL Acesulfame Potassium- 84 mL

12. The Effect of Sugar Substitutes Compared to Sugar on the Growth of Yeast

13. Statistical Analysis- ANOVA (mean)- 93.5, 109, 85.5, 84 S x (standard deviation)- 16.338, 6.307, 8.045, 3.741 Total sample size- 40 (overall average)- 93 SSTR= 3935 SSE=3468.83 SST= 7403.83 MSTR= 1311.667 MSE= 93.752 F data =13.99 Critical Value- 2.79 P=.05

14. ANOVA Table Source of Variation Sum of Squares Degrees of Freedom Mean Square F test Statistic Sugar (treatment) 393531311.66713.99 Error3468.833793.752 Total7403.83 13.99 > 2.79 (critical value) REJECT H o- -All sums are equal H a - Not all sums are equal

15. Conclusion- Why? Most dextrose (sugar) in Splenda – All substitutes contained some dextrose Reason they caused yeast to grow at all Substitutes have no calories- cell organisms can’t break them down (Can’t feed yeast)

16. Sources of Error Tying balloons- water spillage – Effect on yeast growth Improvement: have someone else help tie balloons Water displacement – Each balloon not sunk to same level – Inaccurate results Improvement: Be more careful with displacement of balloon Time in between water measurement and water inserted in balloon – Caused temperature to change Effect on yeast growth Improvement: Enter water into balloon immediately after measuring

17. Real-World Application and Further Research Bread Making – Do not use Sucralose; undependable – Use sugar for better results – Sucralose only worked because contained sugar Further research on yeast – Test temperature of water on yeast growth – Test concentration of sugar on yeast growth

18. Acknowledgements My parents Karen and Fred Horn My biology Teacher Mrs. Pietrangelo The librarians at WHS library