Question

QUESTION 8 Carbohydrates (select the BEST CORRECT statement)

Beta 1-4 linkages are found in both chitin and cellulose.

Glycogen has more alpha 1-6 linkages than does amylose.

Dextrose is an insoluble carbohydrate that cannot be broken down by enzymes encoded in the mammalian genome.

All of the above are correct.

Only (a) and (b) are correst

Answer 1

Carbohydrates are macromolecules that constitute the basic food and important for a healthy diet. Cereals, fruits, vegetables, and dairy products are some common sources of carbohydrates. Carbohydrates are the main source of instant energy (glucose, a monosaccharide). They also have structural roles (polysaccharides such as cellulose and chitin), energy storage (glycogen), the backbone of genetic material (pentose sugar). Chemically carbohydrates are divided into four groups: Monosaccharide (simple sugar); disaccharide (two monosaccharides are linked by a covalent bond called glycosidic linkage); oligosaccharide (a polymer of few saccharides); polysaccharide (a long chain of monosaccharides).

Only (a) and (b) are correct is the right answer. Chitin and cellulose are polysaccharides and both have structural roles. Cellulose is present in the cell wall of plants and chitin is a component of the fungal cell wall and part of the exoskeleton of many arthropods. Cellulose is a long-chain polymer of glucose that is linked to each other by beta 1-4 glycosidic linkage. Chitin is a polymer of N-acetyl glucosamine (glucose derivate) that are linked together by beta 1-4 glycosidic linkage. Glycogen and amylose both are polymer of glucose units and have alpha 1-4 glycosidic linkage. The difference is that glycogen is a branched polysaccharide whereas amylose is a linear long-chain polysaccharide. The branches are linked through alpha 1-6 glycosidic linkage, therefore, glycogen has more alpha 1-6 glycosidic linkage than amylose because alpha 1-6 glycosidic linkage is absent in amylose.

Therefore, statements, Beta 1-4 linkages are found in both chitin and cellulose. Glycogen has more alpha 1-6 linkages than does amylose is correct.

Dextrose is a simple sugar that is chemically similar to glucose. It is made from corn and soluble in water. It is used as a sweetener for many baking products. It is also used in intravenous (IV) solutions and given during dehydration and low sugar level. Therefore, dextrose is an insoluble carbohydrate that can not be broken down by the enzyme encoded in the mammalian genome is not the right answer.