What gives wood its strength?

The strength of wood primarily comes from cellulose, a complex carbohydrate that forms the structural framework of plant cells. Cellulose molecules are long chains of glucose units and are arranged in a way that provides significant tensile strength; this arrangement allows wood to resist bending and deformation under load. The high molecular weight and crystalline structure of cellulose contribute to its strength, making it an essential component of wood fibers.

Lignin, while also important in wood, primarily serves to bind cellulose fibers together and provide rigidity, but it does not have the same tensile strength that cellulose possesses. Hemoglobin is a protein found in blood responsible for oxygen transport and is not related to the structural qualities of wood. Chlorophyll is the green pigment involved in photosynthesis and has no structural role within the wood itself. Therefore, cellulose is the key substance that imparts strength to wood.