Multiple choice

Which of the following excretory substances is not present in sebum?

  1. Wax

  2. Keratin

  3. Fatty acid

  4. Sterol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Keratin is an extremely strong protein, which is a major component in skin, hair, nails, hooves, horns and teeth. The amino acids which combine to form keratin have several unique properties, and depending on the levels of the various amino acids, keratin can be inflexible and hard, like hooves, or soft, as is the case with skin.

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