Starch forms a helical structure that traps certain molecules and gives a blue colour. Which of the following tests is used to confirm the presence of starch?
Correct answer: A. Iodine test
- A. Iodine test
- B. Benedict's test
- C. Biuret test
- D. Sudan III test
Explanation
Among the listed tests, only the iodine test detects starch by producing a blue-black colour. This occurs because iodine molecules fit into the helical structure of amylose, forming a coloured complex. The other tests-Benedict's for sugars, Biuret for proteins, and Sudan III for lipids-are specific to different types of biomolecules and do not detect starch.
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The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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