Part 1A Focus Question What does yeast need to break its dormancy d eveloped by Caryn Dingman July 2015 1 Investigation 2 Part 1A d eveloped by Caryn Dingman July 2015 2 What do you think yeast might need ID: 475461
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Slide1
Investigation 2
Part 1A
Focus Question:
What does yeast need to break its dormancy?
developed by Caryn Dingman July 2015
1Slide2
Investigation 2 Part 1A
d
eveloped by Caryn Dingman July 2015
2
What do you think yeast might need to become active?
Yeast is a living organism.
*
y
east is a fungus and
has only one
cell
*
y
east can’t
make its own food
* until you give yeast food, it’s like yeast is asleep or dormant
*
y
east is not an animal or a plantSlide3
Investigation 2 Part 1A
d
eveloped by Caryn Dingman July 2015
3
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 labelingSlide4
Investigation 2 Part 1A
If warmth, water, and food activate the yeast, how will we know if yeast needs all 3 to become active?
d
eveloped by Caryn Dingman July 2015
4
How can we investigate
what is needed to activate yeast?Slide5
Investigation 2 Part 1
1.) Each group will get 2 1L zip-
loc
bags label one bag “food” or “cookie”
no label on other baggied
eveloped by Caryn Dingman July 2015
5
4.) put 2 animal crackers in “food” bag- get them wet and crush them a little pressing on the bag gently
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
5.) seal bags pressing out air as you go
6.) put bags in 1L
container warm
water bathSlide6
Investigation 2 Part 1
While your baggies spend about 10 minutes in their “bath”, look at the 3 cookie labels.
d
eveloped by Caryn Dingman July 2015
6
Read the cookie ingredients on each label.
Discuss
and answer the
questions.
Each
student should write a response in
his/her
Science Notebook. Slide7
Investigation 2 Part 1A
Remove the baggies from their bath.
d
eveloped by Caryn Dingman July 2015
7
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. Slide8
Investigation 2 Part 1A
d
eveloped by Caryn Dingman July 2015
8
What are the 2 most abundant cookie ingredients?
flour
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!
Look at the Activating Yeast Sheet in your Science Notebook.
sugarSlide9
Investigation 2 Part 1B
d
eveloped by Caryn Dingman July 2015
9
2.) Add ½ teaspoon sugar to the “S” bottle
and ½ teaspoon flour to the
“F”
bottle.
1.) Fill 2 water bottles with ¼ cup very warm water
.
Label 1 bottle “S” and the other bottle “F” with the sharpie marker.
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. Slide10
Investigation 2 Part 1B
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eveloped by Caryn Dingman July 2015
10
2.) Describe what happened to both bottles.
1.) In your Science Notebooks make a drawing of each bottle. Label your drawings to make them clear. Slide11
Investigation
2
Let’s answer the
Focus Question:What does yeast need to
break its dormancy?
d
eveloped by Caryn Dingman July 2015
11
The balloon inflating over the bottle with the sugar shows carbon dioxide release.
Carbon dioxide gas is released when yeast is eating.
Sugar is what yeast needs to “wake it up” or break its dormancy.
Yeast “eats” by absorbing sugar through its membrane.