This biology question covers important biological concepts and processes. The step-by-step explanation below helps you understand the underlying mechanisms and reasoning.
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Welcome back — missed you this week. Here are the answers to your questions: 1a) When starch is digested by amylase, the primary product is maltose. Further digestion can produce glucose. This product (maltose or glucose) is not detected by iodine. Iodine (I₂/KI) is used to detect the presence of starch itself, turning blue-black in its presence. 1b) Amylase is an enzyme. Its role in this experiment is to catalyze the hydrolysis (breakdown) of starch into smaller sugar molecules, primarily maltose. 1c) Assuming a standard experimental setup for starch hydrolysis: • Test tube B (Starch + Water) is a control. Its role is to show that starch is present and does not spontaneously break down without the enzyme. It serves as a positive control for the presence of starch. • Test tube C (Amylase + Water) is a control. Its role is to show that the amylase solution itself does not contain starch or other substances that react with iodine, and that amylase alone does not react with iodine. It serves as a negative control for starch presence. 1d) Based on the assumption that Test tube A contains starch and amylase, Test tube A is expected to show evidence of starch hydrolysis. 2) Here are the results for adding 3 drops of iodine (I₂/KI) to each test tube: | Test tube number | Colour before adding I₂/KI | Colour after adding I₂/KI | Was starch hydrolysed? Why or why not? | | :--------------- | :------------------------ | :------------------------ | :------------------------------------- | | Test tube A | Cloudy white/translucent | Yellow/brown | Yes, because amylase broke down the starch into maltose, so iodine no longer detects starch. | | Test tube B | Cloudy white/translucent | Blue-black/purple | No, because there was no amylase to break down the starch. | | Test tube C | Clear/colorless | Yellow/brown | Not applicable, as there was no starch initially to be hydrolysed. | 3) Yes, these results support the hypothesis in 1d). Explanation: Test tube A, which contained starch and amylase, showed a yellow/brown color after adding iodine, indicating the absence of starch. This means the starch was hydrolysed. In contrast, Test tube B (starch only) remained blue-black, confirming that starch was present and did not break down without the enzyme. Test tube C (amylase only) also showed no starch, as expected. Send me the next one 📸