2. Living Organism
• Help investigate food
• Yeast - single-celled organisms
– Dormant
• What do you think the yeast will need to
break out of resting, dormant state and
become active?
– Water
– Food
– Warmth
3. Activating Yeast
• Warm water - provide warmth & water
• Food - cookies
• Measuring tools, containers, zip-lock
bags
• Plan for finding out what yeast need to
break dormancy - How will you find out
what conditions are needed to activate
the yeast?
4. Activating Yeast
• If warmth, water, and food activate
yeast, how will you know if yeast needs
all three variables to become active, or
if only food, or only water, or only
warmth will activate the yeast?
5. Question?
• Control with no water, only food and
yeast.
• Does yeast need water and food to
become active or does it just need
water to become active?
6. Procedure
• Two zip bags, label one “cookie”
• Add two level 5-ml spoons yeast to
each bag
• Add 50-ml hot water to bag. Wet all of
yeast.
• Add two animal cookies to “cookie”
bag, soak, then crush
• Seal bags shut, pushing air out.
• Place sealed bags in hot water bath.
7. Procedure
• Keep hot water between 40 - 50
degrees Celcius
• Yeast lab sheet procedure
• Place in hot water bath for 10 minutes
8. • Analyze Cookie Ingredients - Answer
questions on bottom of worksheet
• Ingredients ordered from most to least.
• After 10 minutes, remove bags and lay
flat - what do you see?
– Bubbles and gas are evidence yeast is
alive and active
– Yeast getting energy from food
• Cookie provides food for yeast
• Plain water does not
9. • What are two most abundant
ingredients on cookie labels?
– Flour
– Sugar
• Something in cookie is food for yeast.
• Think of a way to find out what is in the
cookie that is food for yeast.
• Is one of the ingredients the food that
activated the yeast?
10. • What are two most abundant
ingredients on cookie labels?
– Flour
– Sugar
• Something in cookie is food for yeast.
• Think of a way to find out what is in the
cookie that is food for yeast.
• Is one of the ingredients the food that
activated the yeast?
