In plant products, which chemical substance forms the main structural base of most vegetable fibres such as cotton, flax and jute?

Introduction / Context:
Vegetable fibres obtained from plants are widely used in textiles, paper production, ropes, and many other products. These fibres are derived from different plant parts such as seed hairs, stem bast fibres, or leaf fibres, but they share a common chemical foundation. This question asks you to identify the major chemical component that forms the structural base of most vegetable fibres.

Given Data / Assumptions:

• Examples of vegetable fibres include cotton, flax, jute, hemp, and ramie.
• Options list cellulose, proteins, fats, oils, and starch.
• We focus on the main structural polymer rather than minor components.
• We assume plant cell wall chemistry as described in basic botany and food science.

Concept / Approach:
Plant cell walls are primarily composed of cellulose, a polysaccharide formed from long chains of glucose units. In many fibre crops, the useful strands are bundles of cellulose rich cells with high tensile strength. Cotton is nearly pure cellulose. Jute and flax also have high cellulose content with some hemicelluloses and lignin. Proteins, fats, oils, and starch are present in plants but serve as enzymes, energy storage, or membrane components rather than the structural base of fibres. Therefore, cellulose is the main chemical base of vegetable fibres.

Step-by-Step Solution:
Step 1: Recall that plant cell walls are made largely of cellulose microfibrils embedded in a matrix of hemicelluloses and pectins. Step 2: Understand that vegetable fibres are derived from these cell wall rich tissues, especially long sclerenchyma or bast fibres. Step 3: Recognise that cotton lint is one of the purest natural sources of cellulose known. Step 4: Flax and jute fibres also consist mostly of cellulose, giving them strength and flexibility. Step 5: Proteins play roles in metabolism and structure but do not form the bulk of these fibres. Step 6: Fats and oils are storage lipids found in seeds and fruits, not the strong strands used as fibres. Step 7: Starch is a storage polysaccharide in seeds and tubers and is not the main structural polymer of fibres.

Verification / Alternative check:
Chemical analysis of cotton and other plant fibres consistently reports cellulose content above eighty percent, with the remainder made up of small amounts of waxes, pectins, and other substances. Industrial processes such as mercerisation and bleaching in the textile industry are designed to treat cellulose. Paper production also relies on breaking down cellulose fibres from wood or other plants. In contrast, oils and proteins are extracted from seeds or leaves for nutritional and industrial uses, not for making strong fibrous materials.

Why Other Options Are Wrong:
Proteins are present in plant cells but in much smaller amounts compared to cellulose in fibrous tissues. Fats and oils are concentrated in seeds and certain fruits as energy rich reserves and are not the main component of fibres. Starch is a carbohydrate used for energy storage in seeds, roots, and tubers and is easily digested, unlike cellulose, which is resistant and forms strong structural elements. None of these match the role of cellulose as the base of vegetable fibres.

Common Pitfalls:
Students may confuse cellulose with starch because both are polysaccharides made from glucose. The difference is in their linkage types and biological roles: starch is a storage molecule, while cellulose is a structural polymer. Remembering that cotton is almost pure cellulose and is a classic textile fibre helps to anchor the idea that cellulose is the key component in vegetable fibres.

Final Answer:
The main structural base of most vegetable fibres is Cellulose.