Bring 'active dry yeast' from the market. Mix a spoonful of yeast, two spoonful sugar with a sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. What changes do you observe after 10 minutes? Mix limewater with the gas accumulated in the balloon. Collect that lime water in a beaker and observe it. What do you notice?

Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two poonfuls sugar with «sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. Find out how to use the solution prepared in the above experiment, to make bread. Follow the recipe and make the bread. Find out and note down the reasons why the dough rises and makes the bread spongy.

Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two poonfuls sugar with «sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. Take a drop of the solution from the bottle on a glass slide, put a cover -slip over it and observe it under the compound microscope. Store the solution in the bottle carefully.

Take two rubber balloons. Fill one with water and blow air into the other. Now prick both balloons with a pin. What do you observe ?

Answer the following questions: Take a large shining metal spoon. Bring the deeper(i.e., concave) surface closer to your face. Can you see your image? Now take the spoon away from your face. What change do you observe in the image? Now repeat the activity by turning the convex surface of the spoon to the front. What changes do you notice in the image?

Activity 2 : Bring the active dry yeast powder from market . Take 50ml lukewarm water in a conical flask. Add 5gm of active dry yeast powder and 10 gm table sugar to that water andmix the mixture well. Keep the flask in warm place and after an hour take a drop of that mixture on a clean glass slide. Put a cover-glass on that drop and observe it under the compound microscope.