The Effect of Food Availability on the Cellular Respiration of Yeast

Abstract

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).