Final answer:
Natural barriers such as hair in animals and insulation in human-made structures protect against extreme temperatures by trapping air and utilizing its insulating properties.
Step-by-step explanation:
Various structures form natural barriers that protect living organisms from extreme temperatures and other environmental factors. Hair is one such example in animals, including humans, which helps trap a layer of warm air close to the skin, keeps the body warm, and provides a filter for particles.
This concept also applies to man-made structures, where materials such as insulation in buildings limit the conduction of heat, keeping interiors warm in winter and cool in summer. Additionally, adaptations like fur and feathers in animals trap air in small spaces, utilizing air's low conductivity to act as an insulator against cold environments. Humans have also designed buildings with features like double-paned windows and thermal mass to regulate temperature through insulation and reduce the need for additional heating or cooling.