When a reducing sugar is heated with Benedict's solution, the colour changes from blue to
Correct answer: A. green, then yellow, then brick red
- A. green, then yellow, then brick red
- B. purple within a few seconds
- C. blue black
- D. completely colourless
Explanation
The free aldehyde or ketone group of a reducing sugar reduces copper ions in Benedict's solution, precipitating red copper oxide, with green and yellow as intermediate shades. Iodine gives the blue black colour with starch, which is a common source of confusion between the two tests.
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About Classification of Biological Molecules
Biological molecules are classified as carbohydrates, lipids, proteins and nucleic acids, with water, minerals and vitamins also supporting cellular processes. The key distinctions involve their monomers, chemical bonds, structures and functions, including glucose and starch, fatty acids and triglycerides, amino acids and polypeptides, and nucleotides in DNA and RNA.
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