Which of the following is a test to distinguish between monosaccharides and disaccharides?
**Core Concept**
The question is testing the student's knowledge of the classification and biochemical properties of carbohydrates. Monosaccharides and disaccharides are two categories of sugars, with monosaccharides being single sugar molecules (e.g., glucose, fructose) and disaccharides being composed of two sugar molecules (e.g., sucrose, lactose).
**Why the Correct Answer is Right**
The correct answer involves the use of Benedict's reagent, a chemical solution used to test for the presence of reducing sugars. **Benedict's reagent** contains copper(II) ions, which are reduced to copper(I) ions by the **aldehyde** group present in reducing sugars. This reduction results in a color change from blue to green, yellow, or brick-red, depending on the concentration of the sugar. Monosaccharides like glucose and fructose are reducing sugars, whereas disaccharides like sucrose are not, as they do not have a free aldehyde group.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the classification of monosaccharides and disaccharides.
* **Option B:** This option is incorrect because the Fehling's solution test is also used to distinguish reducing sugars from non-reducing sugars, but it is not the most commonly used test for this purpose.
* **Option D:** This option is incorrect because the Iodine test is used to detect the presence of starch, not monosaccharides or disaccharides.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Benedict's reagent is not only used to test for reducing sugars but also to detect the presence of glucose in urine, which is a common diagnostic test for diabetes mellitus.
**Correct Answer: C. Benedict's reagent**