When a reducing sugar is heated with Benedict's solution, the colour changes from blue to
- 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.
Related questions
Which class of organic molecule forms the greatest proportion of the dry mass of a typical cell?
The four elements that together make up about 99 per cent of the mass of living matter are
The monomer unit from which a nucleic acid is built is
The process by which small molecules join together to build a macromolecule, with water released at each link, is called
Which element is always present in proteins but never in simple carbohydrates or triglycerides?