Cosmetology · Hair and Scalp Science

Hair and the outer skin and nails are all composed largely of the same protein, which is:

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Correct answer

Keratin

A Collagen
B Keratin
C Hemoglobin
D Insulin

Why this is the answer

Hair, the outermost layer of skin, and the nails are all composed largely of keratin, a tough, fibrous, insoluble protein. Keratin gives these structures their strength and protective qualities. This shared composition is why hair and nails are both classified as keratinized structures. (Collagen is a structural protein of the dermis; hemoglobin and insulin are unrelated body proteins.) Recognizing keratin as the common protein of hair, nails, and the skin's surface links several scientific-concepts topics tested on the exam.

Source: Scientific Concepts — Keratinized Structures

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About this topic: Hair and Scalp Science

Hair and scalp science covers the structure of the hair (cuticle, cortex, medulla), the follicle and growth cycle, hair types and the common scalp and hair disorders — which can be treated in the salon and which must be referred. This is one of 9 Scientific Concepts questions on hair and scalp science, each with a full explanation on a single study page.

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Hair and the outer skin and nails are all composed largely of the same protein, which is:

Why this is the answer

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About this topic: Hair and Scalp Science

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