Question

Structurally, cellulose is a linear polymer of:
A.$\beta$ -D-glucose unit
B.Sucrose molecules
C.$\alpha$ -d glucose units
D.Glucose and fructose unit

Answer 1

We know that glucose is an organic compound which has many polymers. These polymers exist to form various chemical compounds. It is a monosaccharide. Cellulose is a polymer of glucose but it is polysaccharide. It is formed with long linear chains of $\beta$ -D-glucose unit.

Complete answer:
We can draw the structure of $\beta - D - {\text{glucose}}$ is

This structure forms a long chain by replacing one hydrogen atom from the alcohol group and bonding with the adjacent oxygen atom of the other group. Thus, to form a new compound so called cellulose.

So here, we have the answer that cellulose is obtained by a long chain of $\beta - D - {\text{glucose}}$.
Now, let us know what the other structures form.
The $\alpha - D - {\text{glucose}}$ when combined to form long chains, they form starch (amylose).
The structure can be visualized as –

Sucrose is also called sugar and commonly used as sugar. It is a complex compound like cellulose and starch. It is formed by monosaccharides – glucose and fructose.
The structure can be represented as

Hence, the correct answer to the given question is A. $\beta - D - {\text{glucose}}$ units.

Note:
-We have to remember that glucose, fructose, and sucrose are called carbohydrates. There are many other carbohydrates as well like – galactose, maltose, lactose, etc. They are formed by long chain bonding of monosaccharide compounds to form disaccharide and polysaccharide compounds.
-Carbohydrates are distinguished in two different forms. One is simple, which consists of monosaccharides – glucose, fructose and galactose and disaccharides – maltose, sucrose and lactose. The other form is complex structures like – starch, glycogen and fiber.