Question:

Sucrose in water is dextrorotatoiy, $[\alpha]_D$ =+ 66.4$^{\circ}$ when boiled with dil. HCl, the solution becomes leavo rotatory, $[\alpha]_D$ = - 39.9$^{\circ}$. In this process the sucrose breaks into

Updated On: Aug 3, 2024

L-glucose + D-fructose
L-glucose + L-fructose
D-glucose + D-fructose
D-glucose + L-fructose

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The Correct Option is C

Solution and Explanation

The aqueous solution of sucrose is dextrorotatory having $[\alpha]_D$ = + 66.4$^{\circ}$. On hydrolysis with dilute acids or enzyme invertase, cane sugar (sucrose) gives equimolar mixture of D-(+)-glucose and D-(-)-fructose .
So, sucrose is dextrorotatory but after hydrolysis gives dextrorotatory glucose and laevorotatory se. D-(-)-fructose has a greater specific i than D-(+)-glucose. Therefore, the resultant solution is laevorotatory in nature with specific rotation of -39.9$^{\circ}$.

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Concepts Used:

Biomolecules

Biomolecules are the most essential organic molecules, which are involved in the maintenance and metabolic processes of living organisms. These non-living molecules are the actual foot-soldiers of the battle of sustenance of life.

There are four major classes of Biomolecules – Carbohydrates, Proteins, Nucleic acids and Lipids.

Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones or compounds which produce them on hydrolysis.
Proteins are another class of indispensable biomolecules, which make up around 50per cent of the cellular dry weight. Proteins are polymers of amino acids arranged in the form of polypeptide chains. The structure of proteins is classified as primary, secondary, tertiary and quaternary in some cases.
Nucleic acids refer to the genetic material found in the cell that carries all the hereditary information from parents to progeny. There are two types of nucleic acids namely, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The main function of nucleic acid is the transfer of genetic information and synthesis of proteins by processes known as translation and transcription.
Lipids are organic substances that are insoluble in water, soluble in organic solvents, are related to fatty acids and are utilized by the living cell.