Is Yeast Alive Demonstration-Demo

*Is yeast alive?(can be used as demo or lab)
Objective: Observe the product of a metabolic pathway
Observe metabolism(one of the characteristics of
Distinguish between living and non-living objects
Materials:500ml beaker
100ml beaker
Lrg. test tube
Sm. test tube
(needs to fit inside lrg. tube)
Hot plate
Procedure:1. Prepare a fresh lukewarm yeast solution
2. Add some sugar to the solution and stir
3. Set up a warm-water bath
4. Put one beaker inside the other
5. Keep temperature of bath at about 380C
6. Fill the large and small test tubes to the top with
yeast solution.
7. Turn the sm. tube upside down and place it inside
the lrg. test tube.( try not to trap air bubbles)
8. Put the “double test tube” setup in the sm. beaker
9. Let setup sit for about 10 to 15 min. while
students observe
10. Tell students the solution also contains sugar
11. Ask the students to tell you what they are
observing . You can ask students to give reasons
for what they are observing.
Bubbles form in the bottom of the small test tube because the
yeast cells are using the sugar in a metabolic pathway called cellular
respiration . As a result, carbon dioxide gas is produced.
*Demonstration taken from Modern Biology, Chapter 1 pg. 12