Insects

• What do insects lack for gas exchange?

  Insects do not have lungs
• What do insects have instead of blood?

  Insects have haemolymph
• How is gas exchanged in insects?

  Gas is exchanged directly to tissues
• Why do insects have a large surface area?

  To facilitate gas exchange
• What are the main structures involved in insect gas exchange?

  Trachea and tracheoles
• What adaptations do insects have for efficient gas exchange?

  • Walls of tracheoles are one cell thick
  • Tracheoles are highly branched
  • Short diffusion pathway for rapid diffusion
  • Insects move their abdomen which maintains concentration gradient during activity
• How does the structure of tracheoles aid in gas exchange?

  They provide a large surface area for diffusion
• How does oxygen enter the insect gas exchange system?

  Oxygen moves into spiracles down the concentration gradient
• What role do tracheae play in gas exchange?

  They transport oxygen to tracheoles
• Why is the diffusion pathway short in insects?

  Tracheole walls are one cell thick
• How does fluid in tracheoles affect gas exchange during activity?

  • Fluid moves closer to muscle during activity
  • Increases surface area for gas exchange
  • Enhances efficiency of oxygen delivery
• How do insects limit water loss during gas exchange?

  They can close spiracles to reduce water loss
• What is the function of hairs around spiracles?

  They trap water to reduce water loss
• What is the role of the chitin exoskeleton in insects?

  It prevents evaporation of water
• What are the limitations to gas exchange in insects?

  • Need short diffusion pathways to all cells
  • Limits the size of insects
• Why were fossilized insects larger than modern insects?

  Higher concentration of oxygen in the atmosphere
• How does a steeper concentration gradient affect diffusion?

  It increases the rate of diffusion
• What happens to the rate of diffusion of oxygen with higher atmospheric oxygen levels?

  The rate of diffusion would be quicker