PSI Barbering Practice Exam

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What substance lubricates the skin and preserves the softness of the hair?

Collagen
Melanin
Sebum
Keratin

The correct answer is: Sebum

Sebum is the oily substance produced by sebaceous glands in the skin. It plays a crucial role in lubricating the skin and keeping hair soft. This natural oil helps to prevent dryness and can protect the skin against external elements. When sebum is present, it creates a barrier on the skin’s surface, which is essential for maintaining hydration and preventing the entry of harmful microorganisms. Collagen is a protein that provides structure and elasticity to the skin, but it does not serve as a lubricant or moisturizer. Melanin is the pigment responsible for the color of skin and hair and has no role in lubrication. Keratin is a fibrous protein that forms the structural framework of hair and nails, contributing to their strength, but it does not have moisturizing properties like sebum. Therefore, sebum is specifically the substance that lubricates the skin and preserves the softness of the hair.