Experiment
time!
17
Materials:
• Fresh yeast (about 15 grammes)
• 200 ml warm water
• 2 spoonfuls of sugar
• 3 plastic 1–litre water bottles
• 3 balloons
Unicellular organisms
Aim:
Find out how yeast carries out the process of nutrition.
Hypothesis:
Answer this question in your notebook before you do
the experiment
.
What do you think yeast needs to carry out nutrition?
Method:
1.
Label the plastic bottles:
A –
water, sugar and yeast,
B –
water and yeast,
C –
sugar and yeast.
2.
Add the following materials to each bottle:
•
Bottle A: 100 ml warm water, 1 spoonful of sugar
and 5 grammes of yeast
•
Bottle B: 100 ml warm water and 5 g of yeast
•
Bottle C: 1 spoonf
u
l of sugar and 5 g of yeast
3.
Put a balloon over the neck of each bottle. Then leave
the bottles in a warm place for 20 minutes.
Results:
1.
A er 20 minutes, describe the three balloons. Which
balloon has in ated the most? Which balloon has in ated the least?
The balloon on bottle A inflated the most/least.
2.
Yeast produces carbon dioxide as it carries out nutrition.
Which combination produced carbon dioxide? How do you know?
The combination of … produced carbon dioxide. I know this because…
3.
What does yeast need to carry out nutrition?
Yeast needs … to carry out nutrition.
a
b
c
