Question

Which of the following is not polysaccharide?

• A. Ribose
• B. Starch
• C. Gum
• D. Glycogen

Hint:

Remember: ribose and glucose are monosaccharides, while starch, cellulose, and glycogen are polysaccharides.

Answer 1

The Correct Option is A

Step 1: Understand what a polysaccharide is.
Polysaccharides are complex carbohydrates made up of a large number of monosaccharide units joined together by glycosidic bonds. They are generally used for energy storage or structural purposes in living organisms.
Step 2: Identify the nature of ribose.
Ribose is a monosaccharide, not a polysaccharide. It is a five-carbon sugar, so it is classified as a pentose sugar. Ribose is an important component of RNA, ATP, and several biomolecules. Since it is a single sugar unit, it cannot be called a polysaccharide.
Step 3: Check the remaining options.

• (B) Starch: It is a polysaccharide made of many glucose units.
• (C) Gum: Gums are natural polysaccharides obtained from plants.
• (D) Glycogen: It is a storage polysaccharide found in animals and is made up of glucose units.

Thus, all these are polysaccharides except ribose.
Step 4: Conclusion.
Therefore, the substance which is not a polysaccharide is ribose.
Final Answer:Ribose.