Which extracellular glycoprotein helps animal cells attach to the extracellular matrix?

Fibronectin is the correct answer because it is a type of extracellular glycoprotein that plays a crucial role in cellular adhesion to the extracellular matrix (ECM). Fibronectin helps anchor cells to the ECM by binding to integrins, which are membrane receptors on the surface of the cell. This interaction facilitates cell attachment, growth, migration, and differentiation, all of which are essential processes for tissue development and repair.

In contrast, catalase is an enzyme that helps break down hydrogen peroxide into water and oxygen and does not play a role in cell attachment. Elastin is another protein found in the ECM, but its primary function is to provide elasticity to tissues, not necessarily to mediate cell attachment. Chaperonins are a class of proteins that assist in the proper folding of other proteins within the cell, and they do not have functions related to cell adhesion to the ECM. Therefore, the unique functions of fibronectin in enabling cell attachment distinguish it as the correct choice.