Question

What are carbohydrates?
A. Aldehydic and ketonic derivatives
B. Polyhydroxy compounds
C. Optically active substrates and hydrates of carbon
D. All of the above.

Answer 1

Hint: The carbohydrates are our chief source of energy. The food we eat contains various carbohydrates that are oxidized by metabolic reactions and energy is produced in the form of ATP.

Complete step by step answer:Carbohydrates are the essential components of our diet. We get carbohydrates from foods like cereals, pulses, vegetables, etc. They are also present in milk products. Chemically, carbohydrates are polyhydroxy aldehydes or ketones. The meaning of the term saccharide is ‘sugar-containing‘. Based on the number of sugars in a molecule, they are classified into three. They are monosaccharides, oligosaccharides, and polysaccharides. Monosaccharides are the simplest form of carbohydrates having only one sugar unit in it. Oligosaccharides contain few sugar units and polysaccharides have more number of sugar units than the other two. As oligosaccharides have many monosaccharide units linked together, they can be separated into several single sugar units by hydrolysis. Depending on the primary functional group present in these compounds, they can be divided into two. They are aldoses and ketoses. Aldoses are the sugars that contain aldehyde functional groups and ketoses contain ketones. Carbohydrates have the ability to rotate the plane-polarized light either to the left or right. So, they are optically active molecules. When the light is rotated to the right, they are called dextro and those who rotate to the left, levo. Glucose is a dextrorotatory carbohydrate.
Hence option D is correct.

Note:Depending on the individual units of a polysaccharide, they are of two types. They are homopolymers and heteropolymers. Homopolymers are made up of the same individual units linked together and heteropolymers have different individual units.