Question

Test that can distinguish between monosaccharides and disaccharides is
A) Benedict’s test
B) Barfoed’s test
C) Tollen’s test
D) Nylander’s test

Answer 1

Hint: Monosaccharide or simple sugars are any of the basic compounds that serve as the building blocks of carbohydrates. Disaccharides are sugars (carbohydrate molecules) that are formed when two simple sugars i.e. monosaccharides unite. A monosaccharide is the simplest form of carbohydrate.

Complete answer: The ‘Barfoed's test’ is utilized to separate lessening monosaccharide from a disaccharide sugar. The response is directed in a marginally acidic medium. A combination of ethanoic (acidic) corrosive and copper acetic acid derivation, is added to the test arrangement and bubbled. It also distinguishes between monosaccharides and disaccharides.
i. Benedict Test: Benedict's test is a synthetic test that can be utilized to check for the presence of diminishing sugars in a given analyte. Hence, straightforward sugars containing a free ketone or aldehyde utilitarian gathering can be related to this test. The test depends on Benedict's reagent (otherwise called Benedict's answer), which is a combination of sodium citrate, sodium carbonate, and the pentahydrate of copper(II) sulfate. When presented to decreasing sugars, the responses gone through by Benedict's reagent bring about the arrangement of a block red accelerate, which shows a positive Benedict's test.
ii. Tollen's Test: Tollen's reagent is a substance reagent used to decide the presence of aldehyde and sweet-smelling aldehyde utilitarian gatherings alongside some alpha-hydroxy ketone which can tautomerize into an aldehyde. The reagent comprises an answer of silver nitrate, alkali and some sodium.
iii. Nylander’s Test: Nylander’s test is a compound test utilized for distinguishing the presence of diminishing sugars. Glucose or fructose decreases bismuth oxynitrate to bismuth under antacid conditions.

Additional information: Starches are polyhydroxy aldehydes and ketones. Starches may have an aldehyde gathering (aldoses) or ketose gathering. Barfoed’s test recognizes monosaccharides from disaccharides. This test, copper acetic acid derivation in weakening corrosive is decreased in 30 seconds by monosaccharides through disaccharides that take a few minutes.
Thus, the correct answer is option B.

Note: Carbohydrates, particularly polysaccharides, are one of the four significant biomolecules. The others are proteins, amino acids, and nucleic acids. A starch alludes to any of the gatherings of natural mixes comprising carbon, hydrogen, and oxygen. Carbohydrates are the most bountiful among the significant classes of biomolecules. They are significant supplements, giving energy that will fuel different metabolic cycles.