Cosmetology Test Scientific Concepts 5 — Questions and Answers
Question 1: What is the main active ingredient in most sodium hydroxide (lye) hair relaxers?
- Ammonium thioglycolate
- Sodium hydroxide (Correct answer)
- Hydrogen peroxide
- Sodium lauryl sulfate
Correct answer: Sodium hydroxide
Sodium hydroxide is the active ingredient in lye relaxers; it has a very high pH (above 12) that permanently straightens hair by breaking disulfide bonds.
Question 2: Which term describes the process of a substance passing from a higher concentration to a lower concentration across a semi-permeable membrane?
- Osmosis (Correct answer)
- Diffusion
- Absorption
- Evaporation
Correct answer: Osmosis
Osmosis is the movement of a solvent through a semi-permeable membrane from a region of lower solute concentration to higher solute concentration.
Question 3: What type of melanin produces red and yellow pigment in hair?
- Eumelanin
- Pheomelanin (Correct answer)
- Neuromelanin
- Carotene
Correct answer: Pheomelanin
Pheomelanin produces the red, yellow, and orange tones found in naturally red and blonde hair.
Question 4: In cosmetology, what does the term 'emulsification' refer to?
- The separation of oil and water
- The blending of two immiscible liquids into a stable mixture (Correct answer)
- The hardening of a liquid into a solid
- The evaporation of a solvent
Correct answer: The blending of two immiscible liquids into a stable mixture
Emulsification is the process of mixing two liquids that normally don't blend, like oil and water, using an emulsifying agent.
Question 5: Which nail structure contains blood vessels and nerves and is located beneath the nail plate?
- Lunula
- Nail bed (Correct answer)
- Hyponychium
- Eponychium
Correct answer: Nail bed
The nail bed lies directly beneath the nail plate and contains blood vessels and nerves that nourish the nail.
Question 6: What is the purpose of hydrogen peroxide (H₂O₂) in a two-part hair color system?
- To deposit pigment directly into the cortex
- To oxidize the color molecules and develop the color (Correct answer)
- To close the cuticle after coloring
- To remove natural pigment without any color addition
Correct answer: To oxidize the color molecules and develop the color
Hydrogen peroxide acts as the oxidizing developer that activates the color molecules and allows them to develop and deposit in the cortex.
Question 7: Which of the following best describes a surfactant's role in shampoo?
- It provides conditioning and smoothing to the cuticle
- It lowers the surface tension of water to lift dirt and oil (Correct answer)
- It raises the pH to open the cuticle for cleansing
- It adds fragrance and preserves the product
Correct answer: It lowers the surface tension of water to lift dirt and oil
Surfactants are amphiphilic molecules that reduce surface tension, allowing water to interact with and remove oils and debris from the hair.
Cosmetology Test Scientific Concepts 5
What is the main active ingredient in most sodium hydroxide (lye) hair relaxers?