First and Last Name
Date
Try This: Yeast vs. Sand p. 3
Question
What makes yeast different from
sand?
Observations:
1a) Get 5 ml of sand, and 5 ml of yeast. Compare the
texture, colour, and size of the grains:
Feature
Sand
Yeast
Texture
Rough
Smooth
Colour(s)
Mostly white Beige
Size
Larger
Smaller
Shape
Irregular
crystals
Ovals/rods
2b) Predict what will happen when you
add sand and yeast to sugared water:
• 2b) When I add sand to sugared water, it
will…..
• When I add yeast to sugared water, it
will…
3. Add 20 ml of sugared water to two
graduated cylinders.
• Add the sand to one, and the yeast to the
other. Wait a few minutes, then record what
happens in each.
• 3c) The sand….sank to the bottom.
No changes were visible.
• The yeast….sank at first, then
floated. The water became cloudy,
and bubbles rose to the top.
3d) Why was it important to use an
equal amount of sand and yeast, and
sugared water in each grad. Cylinder?
• 3d) It was important to use the same
amount of sand and yeast, and the
same amount of sugared water in
each graduated cylinder because
then it’s a fair test. If you had too
little of one material, you might not
get a reaction, giving an incorrect
conclusion.
3e) Speculate about what happened in
the yeast container. (Try to explain why
the yeast produced bubbles.)
• 3e) The yeast produced bubbles because…
• They are a waste product of the yeast
using the sugar and water.
• Yeast “eats” the sugar and water, to make
energy. Carbon Dioxide is the waste
product, forming bubbles.
3f) How does this activity illustrate one
way to distinguish living things from
non-living?
• 3f) One way to tell that something
is living is if it reacts with a food
source and produces a waste
product.
Clean up!
•
•
After you are done, pour the sugar water and
yeast down the sink and rinse out the graduated
cylinder. Use the test tube brush if necessary
Drain most of the water out of the graduated
cylinder with sand and shake the sand into the
garbage can. Do NOT pour the sand down the
sink. Rinse the graduated cylinder. Use the
test tube brush if necessary.
Finished early?
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1. What gas is in the bubbles?
2. What do we use yeast for in
A) bread-making?
B) wine production?
3. Why can’t you get drunk from eating
bread?
Watch yeast budding, (reproducing)
• http://www.youtube.com/watch?v=BTHYa
f-EuYs