Why was it difficult to observe lipase activity in the tube containing a pH 2.0 buffer?

• A. The buffer keeps pH constant at 2.0, masking decrease.
• B. The lipase is denatured by acid.
• C. The oil was not present.
• D. The experiment temperature inconsistent.

Answer: (A)

The main idea is that a buffer at pH 2.0 resists changes in pH. Lipase action on triglycerides releases fatty acids, which would lower the pH of the solution. But in a tube with a strong pH 2.0 buffer, those protons are neutralized by the buffer, so the pH stays essentially constant. Because the common way to observe lipase activity in this setup is by a change in pH, the reaction appears not to occur even though it is. The other options aren’t the primary reason here—acidic conditions can affect enzymes, but the key factor masking activity is the buffer’s buffering action.