1. Focus Question: What does yeast need to break its dormancy?
Investigation 2
Part 1A
Focus Question:
What does yeast need
to break its dormancy?
developed by Caryn Dingman July 2015

2. Investigation 2 Part 1A Yeast is a living organism.
* yeast is not an animal or a plant
* yeast is a fungus and has only one cell
* yeast can’t make its own food
* until you give yeast food, it’s like yeast is asleep or dormant
What do you think yeast might need
to become active?
developed by Caryn Dingman July 2015

3. Investigation 2 Part 1A Each group will get:
* warm water can provide water & warmth
* cookies food source
* zip-loc bags can define space
* 50 mL syringe to measure & distribute water
* thermometers
* 1 L containers can become a place to keep yeast warm
* sharpie marker for labeling
developed by Caryn Dingman July 2015

4. what is needed to activate yeast?
Investigation 2 Part 1A
How can we investigate
what is needed to activate yeast?
If warmth, water, and food activate the yeast, how will we know if yeast needs all 3 to become active?
developed by Caryn Dingman July 2015

5. Investigation 2 Part 1 1.) Each group will get 2 1L zip-loc bags
label one bag “food” or “cookie”
no label on other baggie
2.) add 2 level 5mL spoons of dry yeast into each bag
3.) fill syringe with 50mL warm water & add to bags- make sure all yeast is wet
4.) put 2 animal crackers in “food” bag- get them wet and crush them a little pressing on the bag gently
5.) seal bags pressing out air as you go
6.) put bags in 1L container warm water bath
developed by Caryn Dingman July 2015

6. Investigation 2 Part 1
While your baggies spend about 10 minutes in their “bath”, look at the 3 cookie labels.
Read the cookie ingredients on each label.
Discuss and answer the questions.
Each student should write a response in
his/her Science Notebook.
developed by Caryn Dingman July 2015

7. What changes do we see? Investigation 2 Part 1A
Remove the baggies from their bath.
What changes do we see?
The bubbles and gas in the baggie with the cookies show that the yeast is using energy.
Yeast with plain water is not active; it’s not using energy.
The cookie is the source of energy for the yeast.
developed by Caryn Dingman July 2015

8. flour sugar Investigation 2 Part 1A
Look at the Activating Yeast Sheet in your Science Notebook.
What are the 2 most abundant cookie ingredients?
flour
sugar
The cookie is the source of energy for the yeast.
But, is it the flour or the sugar
that activates the yeast?
We’ll explore this in Part 1B of our Investigation!
developed by Caryn Dingman July 2015

9. 1.) Fill 2 water bottles with ¼ cup very warm water.
Investigation 2 Part 1B
1.) Fill 2 water bottles with ¼ cup very warm water.
Label 1 bottle “S” and the other bottle “F” with the sharpie marker.
2.) Add ½ teaspoon sugar to the “S” bottle and ½ teaspoon flour to the “F” bottle.
3.) Add 1 packet of dry yeast to each bottle and gently swirl the contents to mix them a bit
4.) Place a balloon over the top of each bottle and observe what happens.
developed by Caryn Dingman July 2015

10. 2.) Describe what happened to both bottles.
Investigation 2 Part 1B
1.) In your Science Notebooks make a drawing of each bottle. Label your drawings to make them clear.
2.) Describe what happened to both bottles.
developed by Caryn Dingman July 2015

11. What does yeast need to break its dormancy?
Investigation 2
Let’s answer the
Focus Question:
What does yeast need to break its dormancy?
Sugar is what yeast needs to “wake it up” or break its dormancy.
Carbon dioxide gas is released when yeast is eating.
Yeast “eats” by absorbing sugar through its membrane.
The balloon inflating over the bottle with the sugar shows carbon dioxide release.
developed by Caryn Dingman July 2015