Science Olympiad Integumentary System Practice Test 2025 – Complete Prep Guide

The correct answer is elastin. Elastin fibers are a specific type of protein found in the extracellular matrix of connective tissues, including the skin. They are characterized by their ability to stretch and return to their original shape, providing the skin with the necessary elasticity. This elasticity allows the skin to maintain its shape and resilience after being stretched or compressed.

Elastin works in conjunction with collagen, which is more densely packed and provides structural support and strength, but does not give the same elastic properties. While collagen is critical for maintaining the overall structure and firmness of the skin, it does not offer the same flexibility as elastin.

Fibronectin is a glycoprotein that plays a role in cell adhesion and also in wound healing but does not directly contribute to the skin's elasticity. Reticulin, on the other hand, refers to a type of collagen fiber that forms a mesh-like network, providing support and structure but lacks the elastic properties associated with elastin. Therefore, elastin’s unique properties make it the essential fiber for providing elasticity in the skin.