2.2 Adaptations for gas exchange INSECTS

Question 1

How are insects adapted for gas exchange?

Answer 1

Extensive network of branching tracheae and tracheoles provides a large surface area for diffusion of gases

Tracheoles deliver oxygen directly to the cells providing a short diffusion pathway

End of tracheoles filled with fluid - allows gases to dissolve before diffusing

Ventilation mechanism to maintain diffusion gradient

Question 2

Describe the insect ventilation mechanism

Answer 2

Abdomen enlarges increasing the volume

Pressure decreases

Air drawn in through the thoracic spiracles

During expiration, air is forced out through the abdominal spiracles as the abdomen contracts

Question 3

Where is the site of gas exchange in insects?

Answer 3

The tracheoles
When actively respiring, lactic acid builds up in the cells
Water is drawn out of the tracheoles, drawing more oxygen in

Question 4

How are insects adapted to a terrestrial environment?

Answer 4

-Impermeable cuticle to reduce water loss by evaporation
-Air enters through spiracles into branching network of trachea and tracheoles
-Spiracles close to limit evaporation of water and prevent dessication