Chapter 23, Problem 57A

Interpretation Introduction

Interpretation:

The functions of starch and cellulose should be contrast and compared in plants. The reason should be explained for the importance of structures to their functions.

Concept introduction:

A biological molecule which consists of carbon, hydrogen and oxygen is known as saccharide or carbohydrate. The general formula of saccharide is ${{\text{(CH}}_{\text{2}}\text{O)}}_{\text{n}}$.

Saccharides (sugar) are classified as: monosaccharides, disaccharides and polysaccharides.

Monosaccharides are defined as a simpler carbohydrate which contains one sugar molecule and can’t ne hydrolysed into smaller carbohydrate.

Disaccharides are defined as a saccharide which contains two sugar molecules that is when two monosaccharides are linked by glycosidic bonds. It is a double ring structure.

Polysaccharides are defined as a saccharide which contains many units of sugar molecules that is more than two monosaccharides are linked by glycosidic bonds.

Explanation of Solution

Starch consists of many units of monosaccharide as it is a polymeric carbohydrate which consists of glucose units linked with glycosidic bonds.

Cellulose consists of many units of monosaccharide or sugar as it is a polymeric carbohydrate which consists of various sugar units linked with glycosidic bonds.

Both cellulose and starch is found in plants.

The main substance which is present in the walls of plant cells is known as cellulose which helps plant to remain stiff and upright whereas the starch is obtained by the green plants and which is used to store energy.

The structures of both cellulose and starch are similar as both contains similar ring structures consist of carbon atoms, hydrogen atoms and oxygen atoms.

Now, the linear structure of cellulose results in the strong and rigid structure as linear structure allows the chain (molecule) to stick with each other whereas the starch consist of glucose units which makes them insoluble in water results in the storage reservoir for energy.

Hence, structures are important for their functions.