[Campbell Biology P.1000] Focusing on respiration and gas exchange, explain why it is improba... | Practice Question

Focusing on respiration and gas exchange, explain why it is improbable for insects to achieve the giant sizes seen in fictional monsters like Mothra.

  • A: Insect exoskeletons would become too heavy to support large bodies, hindering movement.
  • B: The tracheal system, which relies on diffusion for gas transport, would be inefficient over long distances.
  • C: Their open circulatory systems are incapable of supplying enough nutrients to very large tissues.
  • D: Giant insects would generate too much metabolic heat, leading to overheating without specialized cooling mechanisms.

Explanation

Insects primarily use a tracheal system for gas exchange, which consists of a network of tubes that extend throughout the body. This system relies heavily on diffusion to transport gases, especially in smaller insects. For larger organisms, the distance over which gases would need to diffuse becomes too great for this method to be efficient enough to meet metabolic demands. This is a fundamental physiological limitation that makes giant insect sizes improbable.