332A Hair Science and Structure 4 — Questions and Answers
Question 1: What is the typical rate of hair growth per month on the human scalp?
- 0.5 cm
- 1.25 cm (Correct answer)
- 2.5 cm
- 5 cm
Correct answer: 1.25 cm
Scalp hair grows at an average rate of approximately 1.25 cm (half an inch) per month, or about 15 cm (6 inches) per year.
Question 2: Which amino acid is most responsible for the formation of disulfide bonds in hair?
- Alanine
- Glycine
- Cysteine (Correct answer)
- Tyrosine
Correct answer: Cysteine
Cysteine is a sulfur-containing amino acid. The sulfur atoms in two cysteine molecules bond together to form the strong disulfide bonds that give hair its shape and strength.
Question 3: What is the term for the degree of coarseness or fineness of individual hair strands?
- Density
- Texture (Correct answer)
- Porosity
- Elasticity
Correct answer: Texture
Texture refers to the diameter or thickness of individual hair strands. It is classified as fine, medium, or coarse and affects how hair responds to chemical services.
Question 4: What does hair porosity refer to?
- The number of hairs per square centimetre
- The ability of hair to absorb and retain moisture (Correct answer)
- The natural curl pattern of the hair
- The rate at which hair grows
Correct answer: The ability of hair to absorb and retain moisture
Porosity is the hair's ability to absorb and retain moisture. It is determined by the condition of the cuticle layer — raised cuticles mean high porosity, flat cuticles mean low porosity.
Question 5: Which layer of the skin contains the hair follicle?
- Epidermis only
- Dermis (Correct answer)
- Hypodermis only
- Stratum corneum
Correct answer: Dermis
Hair follicles are rooted in the dermis, the second layer of the skin. The dermis contains connective tissue, blood vessels, and the structures that support hair growth.
Question 6: What is the hair bulb?
- The visible part of the hair above the skin
- The club-shaped structure at the lower end of the hair root (Correct answer)
- The oil gland attached to the follicle
- The muscle that makes hair stand up
Correct answer: The club-shaped structure at the lower end of the hair root
The hair bulb is the rounded, club-shaped structure at the base of the hair root that surrounds the dermal papilla. It contains matrix cells that produce new hair growth.
332A Hair Science and Structure 4
What is the typical rate of hair growth per month on the human scalp?