Final answer:
Carbohydrates are the macromolecules that principally constitute the extracellular polymeric substances in the extracellular matrix.
Step-by-step explanation:
The macromolecules that make up the majority of extracellular polymeric substances in the extracellular matrix are carbohydrates. These macromolecules, especially polysaccharides, provide structural support and are involved in various cellular functions.
Carbohydrates like cellulose in plants or chitin in arthropods are fundamental to the structure of cells and organisms. Additionally, the extracellular matrix is a network of proteins and carbohydrates that surrounds cells, further supporting the role of carbohydrates as a major component.