Question

Which one of the following natural polymers are found in both insects and fungi?
A. Pectin
B. Chitin
C. Cellulose
D. Suberin

Answer 1

Hint: Several natural polymers like cellulose, pectin, and chitin are seen in certain plants and animals. Plants contain cellulosic cell walls while bacteria have a cell wall made up of polysaccharides.

Step by step answer: The cell walls of fungi are made up of chitin and polysaccharides. Chitin is a complex polysaccharide that is also seen in the exoskeleton of arthropods. Arthropoda is the largest phylum of the animal kingdom and it includes insects. The body of insects are covered by a hard exoskeleton made up of chitin. It helps to protect their body from adverse conditions. Pectin is a polysaccharide that is present in the plant cell wall. It is used for the preparation of jellies. It is present along with cellulose in the plant cell wall which also is a polysaccharide. A paper made from plant pulp and it is also cellulosic. Cotton fibre also contains cellulose. It is a homopolymer and its individual units are made up of glucose. Humans don't have the ability to digest cellulose, but animals have developed mechanisms for their digestion. Starch also is made up of glucose but it differs from cellulose in their bonding between individual glucose units. In starch, glucose molecules are linked by alpha linkage while in cellulose it is beta linkage. Suberin is a water impermeable waxy material. They are seen in the roots of dicotyledonous plants. It helps plant parts to resist water and also gives protection from germs.
Hence option B is correct.

Note: In molluscs, exoskeleton is made up of calcium carbonate. It is called a calcareous exoskeleton. It protects the animal from predators. The exoskeleton is secreted by a thin layer of tissue called the mantle.