Which type of collagen is primarily found in skin, tendon, and bone?

• A. Type II
• B. Type I
• C. Type III
• D. Type IV

Answer: (B)

Type I collagen forms thick fibrils that give tissues like skin, tendons, and bone their strength and ability to resist pulling forces. In the skin, Type I collagen is the main component of the dermal layer, providing the tensile strength that prevents tearing. Tendons rely on it for their high tensile strength to transmit muscle force to bone, and bone contains a Type I–rich organic matrix that supports mineralization and toughness.

In contrast, Type II collagen is the main component of cartilage, Type III forms reticular fibers in many soft tissues (and is prominent during wound healing), and Type IV makes up basement membranes. This distribution explains why Type I is the best fit for skin, tendon, and bone.