Microorganisms friend or foe

1. SAS / Winmore
Student name: Vikranth Ponnala
Class and section: VIII M
MICROORGANISMS - FRIEND AND FOE
ACTIVITY

2. SAS / Winmore
➢ Do the activity according to the given procedure.
➢ Write your observation and inference in the
respective slides.
➢ Answer the questions that follow.
➢ Paste the picture of your activities in the respective
slides.
INSTRUCTIONS

3. SAS / Winmore
Aim: To prove that yeast feeds on the sugar(nutrients) and releases
carbon dioxide and alcohol. Uses of Microorganisms.
Apparatus: Disposable cup, flour, sugar, warm water, small bottle,
balloon, yeast, candle or lime water.
Procedure:
Activity 1-
● Take ¼ kg of flour.
● Add some sugar and mix it with warm water.
● Add a small amount of yeast powder and knead it to make
dough.

4. SAS / Winmore
Activity 2-
● Take a bottle filled with ½ of warm water.
● Add ⅔ spoons of sugar and let it dissolve.
● Add ½ spoon of yeast powder to the sugar solution.
● Now place a balloon on the mouth of the bottle.
ACTIVITY 2
Flour + sugar
+ yeast +
warm water
ACTIVITY 1

5. SAS / Winmore
Observation -
Activity 1- Yeast respires anaerobically. In this process it releases
Carbon dioxide which gets trapped within the dough.
This causes air bubbles or air spaces. This raises the dough and
makes it fluffy.
Activity 2- Yeast feeds and acts on sugars and releases ethanol,
commonly known as ethyl alcohol.

6. SAS / Winmore
Answer the following:
Why are the following required in the activity:
S. No. Material Why are they required?
1 Sugar Sugar is a source of carbohydrates.
Hence yeast require sugars for them
to convert this energy into carbon
dioxide.
2 Yeast Yeast is required. Without yeast the
sugars can’t be partially broken down
to release alcohol and nor can it
release carbon dioxide.

7. SAS / Winmore
S.No. Material Why are they required?
3 Warm water We need warm water so
that the yeast can be
active. If the water is
too cold the the yeast
becomes inactive. If the
water is too hot it may
kill the yeast and hence
there will be no
fermentation.

8. SAS / Winmore
PICTURE OF THE ACTIVITY

9. SAS / Winmore