Insects

• What type of environment do most insects inhabit?

  Terrestrial
• Why do terrestrial organisms, including insects, face dehydration?

  Water evaporates from their body surface
• What is required for efficient gas exchange in insects?

  A thin, permeable surface with a large area
• How have insects adapted to reduce water loss?

  By evolving a rigid waterproof exoskeleton
• What is the structure that covers the exoskeleton of insects?

  Cuticle
• Why can't insects use their body surface for gas exchange?

  They have a small surface area to volume ratio
• What are the paired holes used for gas exchange in insects called?

  Spiracles
• What do spiracles lead into for gas exchange?

  A system of branched, chitin-lined air tubes
• How do spiracles function during gas exchange?

  They open and close like valves
• What do resting insects rely on for gas exchange?

  Diffusion to take in oxygen and remove carbon dioxide
• What happens to the abdomen during insect flight to aid gas exchange?

  Movements of the abdomen ventilate the tracheae
• What are the ends of the tracheae called?

  Tracheoles
• Where does gas exchange take place in insects?

  At the end of the tracheoles
• How does oxygen reach the cells in insects?

  It passes directly to the cells
• What is the maximum diameter of muscle fibers connected to tracheoles?

  20µm
• Why is the diffusion path for gaseous exchange short in insects?

  Muscle fibers are small in diameter
• What happens to fluid levels in tracheoles during flight?

  Fluid levels decrease, increasing surface area
• How does the compression and expansion of the abdomen affect ventilation?

  It ventilates the tracheal system
• What does the expansion of the abdomen do to the thorax spiracles?

  Thorax spiracles open to allow air in
• What occurs when the abdomen is compressed in insects?

  Abdominal spiracles open to expel air
• What is the process of ventilation in the tracheal system of insects?

  • Compression and expansion of the abdomen
  • Spiracles open and close to regulate airflow
  • Air enters through thorax spiracles and exits through abdominal spiracles
• How do the structures involved in gas exchange in insects work together?

  • Spiracles allow air entry and exit
  • Tracheae transport air to tracheoles
  • Tracheoles facilitate direct gas exchange with cells