question_answer

Pentoses and hexoses are common :

A)                  monosaccharides

B)                  disaccharides

C)                  polysaccharides

D)                  oligosaccharides

Correct Answer: A

Solution :

                 Carbohydrates are compound of carbon, hydrogen and oxygen where hydrogen and oxygen occur in the ratio of 2 : 1 and general formula is \[{{C}_{n}}{{H}_{2n}}{{O}_{n}},\]They are of? (i) Monosaccharides are monomer sugars which cannot be hydrolysed further into smaller units e.g., trioses, tetroses, pentoses (ribulose), hexoses (fructose). Pentose sugars like ribose, deoxyribose are monosaccharides which has 5 carbons. Hexose sugar like glucose, fructose are monosaccharides which has 6 carbons. (ii)Disaccharides are carbohydrates made up of two monomeric units, e.g., Sucrose = 1 glucose + 1 fructose Lactose = 1 glucose + 1 galactose (iii) Oligosaccharides are made up of 3-9 monomeric units e.g., raffmose. (iv) Polysaccharides are carbohydrates made up of more than 9 monomeric units e.g., starch, glycogen.