Microbes

 It was good to meet kids after a 10 days break.  We greeted each other and discussed the experiments that we had done before. Kids recollected that we had made crystal hangings , candy crystals and snacks for Christmas celebration. 

The students shared that they were learning about plant reproduction in school. Since, we had done activities around how flower's help in reproduction in some plants, root  vegetables, how they reproduce, we focused on how microbes reproduce. 

What are microbes?

Microbes are microscopic organisms that are too small to be seen through naked eye. There are various forms of microbes with different characteristics , different life forms. Familiar ones are

1. bacteria - example E.coli, lactobacillus 

2. Viruses  - cold, flu virus

3.Fungi - Mushroom, yeast 

4. Protists - amoeba

We talked about 

1. How bread is made?. 

2. What is the main ingredient for making bread?.

 Kids  replied that  it was yeast and how it helps to raise the dough and which makes it easier for it to be soft. We spoke about how milk turns into yogurt by a teaspoon of yogurt, how wine is fermented grape juice etc. One student shared how the muffin came out hard when mom forgot to add baking soda.

What is yeast?

Yeast is a single celled organism and is found everywhere  in the world. The Scientific name for active dry yeast is Saccharomyces Cerevisiae, otherwise known as “sugar-eating fungus.” This is a strong variety of yeast and it is responsible for fermentation. Fermentation is the step when the yeast makes carbon dioxide in the bread making process.

Yeast likes to multiply their numbers  in a warm environment by eating their sugar. So, the conditions for growing yeast are sugar and warm temperature. To test it out how it affects yeast growth we did the following activities.

 

Materials

1. Cups - 4

2.Sugar - 4 tsp

3.warm Water - 1/4 cup 

4.hot water - 1/4 cup

5.cold water - 1/4 cup

6. tap water -1/4 cup

7. yeast - 1 packet

Procedure

1. Take  4 cups and pour tap water, warm water, hot water and cold water in each one of them. Mark it as tap, warm, hot and cold water accordingly.

2. Put 1 tsp of sugar in each one of the cups. Mix it with a spoon.

3.Put 1/2 tsp yeast in each cup. 

4. Set it aside for  20 minutes to observe.

Observation

You will notice that the yeast in warm water would have multiplied whereas in hot and cold water it does not . This shows that in cold conditions yeast does not even activate and in hot water we had killed the yeast and hence it does not grow at all. It needs warm temperature to multiply. 

Yeast growth with Different  amounts of Sugar 

1. Small bottles - 4.

2. warm water - 1cup 

3. sugar - 5 tsp

4. Balloons - 4

5. Funnel -1

6. yeast - 1 packet

Procedure

1. Pour 1/4 cup warm water in all the 4 bottles . 

2. Using the funnel put 1/2 tsp sugar in 1st bottle ,1 tsp sugar in the second bottle,2 tsps in  3 rd bottle , 3 tsps in 4th bottle

3. Put 1 tsp of yeast in all the bottles.

4. Attach the same size balloons in all the bottle heads. 

5. Set aside the bottle in a corner and observe it after 1-2 hrs. 

6.Ask the students to share their hypothesis about what they expect to happen and verify it later.

Observation

We noticed that all the balloons had carbon dioxide released in them and hence the balloons had stood up. But the 3rd and 4th bottle had more carbon dioxide which made the balloon blow up bigger in size.

The reaction that happens in this experiment can be written down as,

Glucose ⟶ Ethanol + Carbon dioxide

which can be written as…

C6H12O6(aq)  ⟶ 2C2H5OH(aq) + 2CO2(g). 

Here due to yeast added to sugar in warm water,  the sugar (glucose) breaks down to ethanol and carbon dioxide.