Explain how an iodine test determines what it tests for and how it works. Also, explain one potential reason for having a positive result in your negative control.
Understand the Problem
The question is asking for an explanation of how an iodine test determines the presence of starch and how it works. Additionally, it requests a potential reason for a positive result in a negative control, which is important in experimental design.
Answer
The iodine test turns blue-black if starch is present. A positive result in the negative control might indicate contamination.
The iodine test detects the presence of starch by turning blue-black when starch is present. A positive result in the negative control could be due to contamination, which means starch unintentionally got into the sample.
Answer for screen readers
The iodine test detects the presence of starch by turning blue-black when starch is present. A positive result in the negative control could be due to contamination, which means starch unintentionally got into the sample.
More Information
The iodine-starch reaction occurs because iodine molecules slip into the structure of the amylose in starch, causing the color change. Contamination in lab environments is a common source of error in controls.
Tips
Ensure lab equipment is cleaned thoroughly to avoid cross-contamination.
Sources
- Iodine test - Definition and Examples - Biology Online Dictionary - biologyonline.com
- Why Does Iodine Turn Starch Blue? - ChemistryViews - chemistryviews.org
- Iodine Test: Principle, Procedure, Result, Uses - Microbe Notes - microbenotes.com
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