Biology · Biomolecules · NEET
Inulin is a polymer of fructose. NCERT states this in one clear line: "Inulin is a polymer of fructose." This is important for NEET because most other polysaccharides you learn (cellulose, starch, glycogen) are polymers of glucose, so inulin is the odd one out. If a question says inulin is a polymer of glucose, it is WRONG.
Chitin is a complex polysaccharide built from modified sugar units (amino-sugars such as N-acetylglucosamine). It is NOT a simple glucose polymer like cellulose. NCERT says complex polysaccharides may have amino-sugars and chemically modified sugars as building blocks, and gives chitin (arthropod exoskeleton) as the example.
Both are structural polysaccharides, but cellulose is the plant cell wall material and is a polymer of plain glucose, while chitin makes arthropod exoskeletons and fungal cell walls and is a polymer of a modified sugar (an amino-sugar). So NEET trick: plant wall = cellulose; fungal wall + insect shell = chitin.
NCERT says these complex polysaccharides are mostly homopolymers, meaning the same repeating unit is used. Chitin repeats the same modified sugar unit, so it is treated as a homopolymer for NEET, even though its building block is a chemically modified sugar.
Complex polysaccharides are polysaccharides whose building blocks are not just simple sugars but amino-sugars and chemically modified sugars, for example glucosamine and N-acetyl galactosamine. Chitin is the classic NCERT example. They are mostly homopolymers.
No. Inulin is a polysaccharide (a polymer of fructose) and has glycosidic bonds. Insulin is a protein (a polypeptide hormone) and has peptide bonds. NEET 2020 tested exactly this: inulin has the glycosidic bond, insulin has the peptide bond.
Inulin is a polymer of:
Exoskeleton of arthropods is composed of:
Identify the substances having glycosidic bond and peptide bond, respectively in their structure:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Chitin. Fungal cell walls are made of chitin and other polysaccharides, not cellulose. This is a repeated NEET fact (asked in Biological Classification too).
No. Chitin is a polysaccharide (a carbohydrate), even though its building block is an amino-sugar. The "amino" part confuses students, but chitin has glycosidic bonds, not peptide bonds, so it is not a protein.
Chitin is made of a modified amino-sugar unit (N-acetylglucosamine). NCERT lists amino-sugars and chemically modified sugars, such as glucosamine and N-acetyl galactosamine, as building blocks of complex polysaccharides like chitin.
NCERT says they are mostly homopolymers, meaning one type of repeating unit. So chitin is treated as a homopolymer of its modified sugar unit.
Because it is the one polysaccharide made of fructose, while cellulose, starch and glycogen are made of glucose. NEET loves to trap students who assume every polysaccharide is a glucose polymer.
