Lignin: Definition and Properties

Lignin is a complex organic polymer that provides structural support to the cell walls of plants. It is one of the main components of wood and is responsible for the rigidity and strength of plant cells. Lignin is a crucial substance in the process of water transport within plants, as well as providing defense against pathogens and pests.

Chemical Composition

Lignin is composed of phenolic compounds and is highly resistant to degradation. It is made up of three main monolignols: coniferyl alcohol, sinapyl alcohol, and p-coumaryl alcohol, which are linked together to form a complex network of polymers.

Role in Plants

One of the key functions of lignin in plants is to provide structural support, allowing plants to grow upright and resist the forces of gravity and wind. It also plays a crucial role in the transport of water and nutrients within the plant, as well as providing defense against pathogens and herbivores.

Study Guide

1. What is lignin and what is its role in plants?
2. Describe the chemical composition of lignin.
3. Explain the importance of lignin in the structural integrity of plant cells.
4. Discuss the role of lignin in water transport within plants.
5. How does lignin contribute to the defense mechanisms of plants?