insects

Question 1

gaseous exchange systems in insects

Answer 1

• many insects are very active during parts of their life cycles so they require a lot of oxygen .
• though the have a tough exoskeleton where no gaseous exchange can take place. They do not have blood pigments that can carry oxygen either.
• insects have evolved a system where oxygen is directly delivered to the cells and to remove carbo dioxide in the same way.

Question 2

spiracles

Answer 2

• along the thorax and abdomen of most insects are small opening called spiracles
• air enters and leaves the system through spiracles but water is also lost.
• like mammals, insects need to maximize the efficiency of gaseous exchange e but minimize the loss of water.
• spiracles can be opened and closed with sphincters, they are kept closed as much as possible to minimize water loss.
• when an insect is inactive and doesn’t need much oxygen, the spiracles will be closed most of the time, when more oxygen is needed the spiracles will open.

Question 3

tracheae

Answer 3

• leading away from the spiracles are the tracheae which are the large tubes and carry air into the body.
• the tubes are lined with spirals of chitin which keep them open. Chitin is relatively impermeable so little gas exchange happens in the tracheae.