Biological Yeast Sugar-Fermentation Gas Manometer

60 mins Ages 10-14 Indoor

A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.

Materials Needed

  • • Active dry baking yeast packets (3 packets)
  • • Small clear plastic drink bottles (500 mL) (3 units)
  • • Latex party balloons (9-inch) (3 units)
  • • Granulated table sugar (2 tablespoons)
  • • Zero-calorie artificial sweetener packet (2 tablespoons)
  • • Flexible sewing tape measure (1 unit)

Pro Tips

  • → Fill Bottle 1 with warm water, yeast, and pure table sugar; Bottle 2 with warm water, yeast, and zero-calorie sweetener; Bottle 3 with yeast and water only as a control.
  • → Stretch the balloons over the bottle mouths; escaping carbon dioxide gas inflates the balloons over time.
  • → Measure balloon circumference with a sewing tape measure every 15 minutes to plot fermentation rates.

Safety First

Use warm water (approx. 40°C), not boiling water, which would denature and kill the live yeast enzymes.

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Step-by-Step Instructions

1

Step 1

Fill three identical 500 mL water bottles with 1 cup of warm water (approx. 40°C).

2

Step 2

Add 1 packet of yeast to each; add 2 tablespoons of sugar to Bottle 1, 2 tablespoons of sweetener to Bottle 2, and leave Bottle 3 plain.

3

Step 3

Stretch an uninflated latex balloon tightly over the neck of each bottle and seal with tape.

4

Step 4

Measure and log the circumference of each balloon every 15 minutes for 35 minutes to graph metabolic carbon dioxide production.

What they are learning

Anaerobic cellular respiration and fermentation Metabolic carbon dioxide generation rates Substrate specificity (sucrose vs. artificial non-caloric sweetener)