Effects of Activators and Ethanol on Fermentation Rates

Effects of Activators and Ethanol on Fermentation Rates

In this lab we examined how the rate of fermentation is influenced by the type

of substrate, and activators and inhibitors. We used four fermentation tubes in

which we separately combined yeast with MgSO4, pyruvate, ethanol, and glucose.

At five minute intervals we recorded the volume of gas produced in each

fermentation tube. Our results are displayed in the graph. Our results

supported the prediction that pyruvate is an activator of fermentation. But our

results did not support the prediction that MgSO4 is an activator of

fermentation. This could be due to experimental errors, such as the fermentation

tube not being clean, or the glucose being added at a different time. Our

results indicated that as fermentation proceeded and ethanol concentration rose,

the rate of fermentation slowed down. From five to ten minutes there was a sharp

increase in fermentation, then as the ethanol concentration rose, it started to

level off.

Effects of Temperature on Fermentation Rates

In this part of the lab we examined the relationship between respiration rate

and temperature. We combined yeast separately in four fermentation tubes with

four glucose solutions that had been equilibrated to four different

temperatures. We then recorded that volume of carbon dioxide produced in each

fermentation tube at five minute intervals. Our results are displayed in the

graph. We measured the rate of metabolism by measuring the amount of carbon

dioxide produced in milliliters per minute. Our results showed that the rate of

metabolism increased with increased temperature. The correlation between

metabolism and temperature is positive. As temperature increased, the metabolic

rate increased. The difference in rate between the 10 degrees celcius and the 20

degrees celcius tubes was not equal to the difference in rate between the 30

degrees celcius and the 40 degrees celcius tubes. Instead the relationship

seemed to be exponential. Temperature could slow down or stop enzymes which

affect metabolic rate. Generally, reactions are slower in a lower temperature.

Oxygen Consumption by Respiring Beans

In this lab we observed aerobic respiration by quantifying oxygen consumption by

germinated beans. We placed germinated beans, frozen beans, and plastic beads in

three different test tubes. We then place a cotton ball topped with KOH on top

of the beans. We coved the tubes with aluminum foil and placed them in clamps

on a stand. We then added a drop of dye at the end of the graduated pipet of

each tube and monitored its movement at