You have three samples of different enzymes, but somehow, their labels got lost. Your job is to figure out which enzyme is in each tube. Read about the three enzymes that are in the tubes. Then, move on to the next page to carry out your investigation and get those labels back on the right tubes! Salivary amylase is an enzyme component of saliva. The pH of saliva is between 6.5 and 7.5. The temperature in the mouth is close to internal body temperature, about 37°C.

Pepsin is an enzyme released by cells of the stomach. The stomach contents have a pH of 1.5–3.5, and normal internal body temperature.

Thermophilic bacteria thrive in hot springs, with temperatures at or near the boiling point of water (100°C). The pH of the hot springs these bacteria were taken from varies between 6 and 8.