Final answer:
- Amylase functions optimally at specific pH levels, with salivary amylase operating best around pH 7.0.
- Tube 3 (amylase, starch, pH 7.0 buffer) is likely the most effective for starch digestion.
- Tube 7's acidic pH and Tube 8's basic pH are not conducive for amylase activity.
Step-by-step explanation:
The question pertains to the effect of pH levels on the enzyme amylase, which is responsible for the digestion of starch into maltose and subsequent conversion into glucose. Enzymes have optimal pH levels at which they function most effectively.
- Salivary amylase, produced in the mouth, has an optimal pH around 6.9 to 7.1, according to the information provided, making it efficient in breaking down starch into maltose in the oral cavity. As the food is not in the mouth for an extended period, digestion is not complete here.
- In the stomach, despite the continued action of salivary amylase, the acidic environment (pH 2.0) due to hydrochloric acid production and the action of another enzyme, pepsin, inhibit the activity of amylase.
- Further digestion occurs in the intestine, where pancreatic amylase takes over. This enzyme, optimal at a pH of around 7.1, breaks down both cooked and uncooked starch. However, it cannot act on the α-1→ 6 glycosidic linkages found at the branching points of starch and glycogen, which are later digested by isomaltase.
In the context of the given question:
- Tube 3 with a pH 7.0 buffer represents conditions closest to the optimal pH for amylase activity, suggesting likely effective starch digestion.
- Tube 7, with a pH 2.0 buffer, is too acidic for amylase to work efficiently.
- Tube 8, with a pH 9.0 buffer, is too basic, as the optimum pH for most enzymes, including amylase, is closer to the physiological pH of 7.4.