Final answer:
Hair and fingernails are not composed of a protein called cuticle; rather, they are made of a tough protein named keratin, which gives them strength and enables them to protect and enhance sensation.
Step-by-step explanation:
The statement that both hair and fingernails are composed of a protein called cuticle is false. Both hair and nails are actually made of a tough protein called keratin. Keratin is crucial as it provides the toughness needed for the protective and functional roles that hair and nails play. The hair serves many purposes including acting as a filter and keeping the body warm, while fingernails serve as protective plates over the fingertips and enhance sensation by acting as a counterforce during physical interactions with objects. Keratin is a key structural material in the epidermis, and it is what makes the nails hard yet flexible.