Final answer:
Tubes that indicate the deionized water was free from starch or maltose contaminants are Tube 3 (amylase, starch, pH 7.0 buffer) and Tube 6 (maltose, pH 7.0 buffer), as their outcomes show expected results without unintended reactions.
Step-by-step explanation:
To determine which tubes indicate that the deionized water did not contain contaminating starch or maltose, we need to understand the components of each tube and their expected reactions. Amylase is an enzyme that breaks down starch into maltose. If deionized water contains neither starch nor maltose, no reaction will occur in tubes where these components are absent, and the water is used as a negative control.
The correct answer is tubes 3 (amylase, starch, pH 7.0 buffer) and 6 (maltose, pH 7.0 buffer). Tube 3 should show a reaction if amylase is active since it contains starch and a neutral buffer, which is the optimal condition for amylase activity. Tube 6, containing maltose, would show no change since maltose is the end product of amylase activity on starch and no enzyme is present to further break it down. The absence of change in these tubes indicates that the deionized water used in other tubes was free of starch or maltose contaminants, as no unintended reactions occur.