Almost every organism has the same basic needs -water , air , food and a place to live . All organism are made of cells- single or many. These organisms carryout specific function at cellular level to keep the organism living .
One of the main function of the living being is the respiration and digestion of food to release energy .
To demonstrate these two process , a practical experiment was conducted in grade 8 class .
The title of the lab was 'is it alive'
Initially a sample of live yeast was given to students .
When sugar and water was added to live yeast , bubbles formed . Also the colour of the water changed to milky white. the temperature of the container changed too.
This changes made students understand that yeast is living organism.
Next 2 unknown samples were given to students . One of the sample was dead yeast and another was live yeast . Based on their previous observation , students had to identify the samples .
An extension of this lab was conducted too. Sugar is metabolized by yeast during anaerobic respiration which results in the production alcohol and carbon dioxide. These 2 end products are useful in bakery for making breads.
Students made bread dough using flour , yeast and sugar. The rise in the dough was observed.
All these experiments made students realize that living organism undergo the process of respiration and energy is released during the metabolism of sugar .
Since energy is one of the requirement of living beings , it is produced during respiration digestion of food.