The aim of this experiment was to investigate the effect of different amounts of a substrate on the respiration rate of yeast and to compare this to the effect of different amounts of glucose on the rate of yeast respiration. The substrate which I chose to further investigate was fructose. Fructose is a fruit sugar which is one of the three, along with glucose and galactose, dietary monosaccharides that are directly absorbed into the bloodstream during digestion.
2% yeast solution
pH meter & data logger
Sensitive digital scale (g)
Fructose (1.0g, 1.5g, 2.0g, 2.5g)
Glucose (1.0g, 1.5g, 2.0g, 2.5g)
Measuring cylinder (cm3)
Independent: Concentration of glucose (1.0g, 1.5g, 2.0g, 2.5g) , concentration of fructose (1.0g, 1.5g, 2.0g, 2.5g) Dependent: Amount of carbon dioxide produced, i.e. rate of yeast respiration Controlled: 2% yeast solution (20cm3), initial temperature of yeast solution (35-40˙C), amount of time that the reaction is measured (180 seconds)
20cm3 of yeast solution was measured using a measuring cylinder and then poured into a conical flask. •
1.0g of glucose was weighed on a digital balance.
Hot wáter was poured into a large beaker, and the conical flask containing the yeast was placed inside with a thermometre inside. •
The conical flask was kept inside
The conical flask was held like this until the 2% yeast solution reached an initial temperature between 35-40˙C (specific temperature was noted down) When this temperature was reached, the thermometer was taken out of the conical flask and the conical flask out of the hot wate
Please join StudyMode to read the full document