National Occupational Competency Testing Institute (NOCTI) Cosmetology Practice Exam

Which element is considered the most important in the composition of hair?

1. Hydrogen

2. Oxygen

3. Nitrogen

4. Carbon

The correct answer is: Carbon

The most important element in the composition of hair is carbon. Hair is primarily made up of a protein called keratin, which is rich in amino acids, and these amino acids contain carbon as a fundamental building block. Carbon atoms form the backbone of the keratin structure, allowing for the formation of strong and flexible fibers that make up the hair strand. The presence of carbon is essential not only for the structural integrity of hair but also for its ability to bond with other elements, which affects its overall characteristics, such as strength and texture. In contrast, while hydrogen, oxygen, and nitrogen are also components of hair, they play subsidiary roles in the stability, hydration, and structure of keratin. Hydrogen, for example, contributes to the overall bonding and molecular structure but does not serve as the foundational element in the same way that carbon does. Similarly, oxygen is primarily involved in the water content and metabolic processes, and nitrogen is found in the amino acids that make up proteins, but they are not the primary constituents of hair fibers themselves. Thus, carbon's role as the primary component in the architecture of hair emphasizes its importance in the composition of hair.