3.1.1f) The mechanisms of ventilation and gas exchange in bony fish and insects

Question 1

Gaseous exchange systems in insects

Answer 1

Land-dwelling animals - high oxygen requirements
Tough exoskeleton - little or no gaseous exchange can take place
Evolved gaseous exchange systems to deliver oxygen directly to cells and carbon dioxide removed in the same way

Question 2

Insect gaseous exchange process

Answer 2

Spiracles
Tracheae
Tracheae fluid

Question 3

Spiracles

Answer 3

Found along the thorax and abdomen
Air enters but some water is also lost
Sphincters - open & close spiracles
Spiracle sphincters kept closed to minimise water loss
When oxygen demands increase or carbon dioxide levels build up more of the spiracles open

Question 4

Tracheae

Answer 4

1m in diameter - largest in the insect respiratory system
Carry air into the body
Run into and along the body of the insect
Lined with chitin - support keeping them open
Impermeable to gases
Divide into tracheoles

Question 5

Tracheoles

Answer 5

0.6-0.8um
no chitin - permeable to gases
Where most gaseous exchange takes place
Number of tracheoles - large surface area
Oxygen diffuses in the moisture on the walls of the tracheoles & dissolves into the surrounding cells

Question 6

Tracheal fluid

Answer 6

Found at the end of tracheoles
Limits the penetration of air for diffusion