The Effect of Food Availability on the Cellular Respiration of Yeast


  • Christina Rayos


In this experiment, I observed which conditions were optimal for cellular respiration of
yeast (Saccharomyces cerevisiae). Because CO2 is released during respiration of yeast, this
provides a way of measuring how much cellular respiration has taken place (Rymer, 2019). As
CO2 is produced, the gas can be trapped and measured. I manipulated the amount of food (in this
case, the amount of sucrose) to see how this affected the rate of cellular respiration by yeast. I
measured the volume of CO2 collected at 4 different treatment levels: 0g of sucrose (control), 5 g
of sucrose, 15 g of sucrose, and 30 g of sucrose. Since yeast must get their food from their
surrounding environment in order to grow and reproduce, I hypothesized that if we use 15 g of
sucrose, then this treatment level with the yeast will produce the most CO2 and will therefore
have the fastest rate of cellular respiration (mL CO2/minute). If we were to add 0 g of sucrose or
30 g of sucrose (i.e. too little or too much sucrose), then these environments will show to be the
least optimal conditions for yeast activity and produce the least CO2 with the slowest rate of
cellular respiration (mL CO2/minute). After completing the data collection phase of my
experiment, the cellular respirations rates were calculated for each treatment. A one-way ANOVA
test was used to evaluate the statistical difference between these results. It was found that the
results were statistically significant with a reported p-value of 1.0629e-65 which is less than the
threshold of 0.05 (p < 0.05). Therefore, there was sufficient evidence to reject the null hypothesis
and we can conclude that of the three treatment levels, adding 5 g of sucrose (treatment group B)
was the most optimal conditions for cellular respiration of yeast. For future studies, we can
evaluate the effects of manipulating other environmental factors on the growth of yeast, such as
temperature, pH levels, and type of sugar (i.e. glucose, fructose, galactose).