This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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This experiment, "Digestion of Starch by Amylase," investigates the breakdown of starch by the enzyme salivary amylase. The setup uses three test tubes (A, B, C) to observe the enzyme's activity and provide controls. Here's an analysis of each test tube and the expected results if a starch test (using Iodine/KI solution) is performed after incubation: Test tube A: Positive Control for Starch Contents: 2 ml of 1% starch solution + 3 ml of water. (No salivary amylase) Purpose: This tube serves as a control to show the initial presence of starch. Since no amylase is present, the starch should not be digested. Expected Starch Test Result: After incubation, adding Iodine/KI solution will result in a blue-black* color, indicating the presence of starch. Test tube B: Negative Control for Starch Contents: 2 ml of water + 3 ml of salivary amylase. (No starch solution) Purpose: This tube ensures that the salivary amylase solution itself does not contain starch or give a false positive result with the iodine test. Expected Starch Test Result: After incubation, adding Iodine/KI solution will result in a yellowish-brown* color (the color of the iodine solution), indicating the absence of starch. Test tube C: Experimental Tube Contents: 2 ml of 1% starch solution + 3 ml of salivary amylase. (No additional water) Purpose: This tube is where the digestion of starch by salivary amylase is expected to occur. Amylase breaks down starch into smaller sugar molecules (like maltose). Expected Starch Test Result: After incubation at 37°C for 10 minutes, the salivary amylase should have digested most, if not all, of the starch. Therefore, adding Iodine/KI solution will result in a yellowish-brown* color, indicating the absence or significant reduction of starch. If digestion is incomplete, a reddish-brown or lighter blue color might be observed.