Experiment+1.+Pasteur's+Experiment

PASTEUR’S EXPERIMENT Due Date: __ Hypothesis __ : Microbes do not arise by spontaneous generation. __ Aim __ : To investigate Pasteur’s hypothesis about spontaneous generation. __ Materials __ : sugar, salt, stock cube, 300ml water, 500ml measuring cylinder, 500ml beaker, Bunsen burner, 3 round bottomed flasks, 3 one holed rubber corks and 3 glass tubes (1 x straight, 1 x single bend, 1 x double bend) __ Method __ : 1. Pour 300ml of water into a beaker. Add 2 spoons of sugar, a pinch of salt and 1 stock cube and stir. Heat the broth until the solids have dissolved. The solution will be pale brown but transparent. 2. Pour 100ml of the broth into each of three flasks and boil the broth to kill the microbes in the broth. 3. Seal each flask with a cork fitted with different shaped glass tubing. Before putting the cork in the flask, heat the bottom of the cork in the Bunsen burner flame for about two seconds, to kill any microbes that could fall into the broth. This is called flaming. 4. Put your name on each flask and put them in a warm place. After 24 hours, observe the colour of the broth. If it is cloudy there are bacteria present, if it is clear there are no bacteria present. __ Results __ : __ Discussion __ : 1. What methods were used to kill the microbes in the broth and on the cork? 2. In which flask(s) did the broth stay clear? Why? 3. In which flask(s) did the broth turn cloudy? Why? __ Conclusion __ : Did your experiment support the hypothesis? Why? What problems did you have completing this experiment?
 * Flask ||  Colour of the broth  ||
 * Flask with straight glass tube ||   ||
 * Flask with single bend glass tube ||   ||
 * Flask with double bend glass tube ||   ||