Gas Exchange And Water Loss In Insects

Question 1

Name the parts of the tracheal system

Answer 1

Spiracles
Trachea
Tracheoles

Question 2

Adaptations of Insects for gas exchange and water loss

Answer 2

Exoskeleton - impermeable to water, prevents water loss

Spiracles have valves - controls water loss

Spiracles have hairs - filters air to prevent clogging of the tracheal system which would reduce volume for gas exchange

Tracheal system is lined with single layer of cells to minimise diffusion pathway.

Question 3

Describe how respiratory gases move the an Insects tracheal system at rest

Answer 3

Oxygen diffuses from the atmosphere into the spiracles by simple diffusion. CO2 diffuses out into the atmosphere the same way.

Oxygen then diffuses into the trachea, Tracheoles then across the fluid at the ends of the Tracheoles and into the respiring cells for use in respiration

Oxygen is used up in respiration, creating a steep concentration gradient to allow diffusion to continue. CO2 is produced in respiration creating a concentration gradient in the opposite direction.

Question 4

Name and describe the 3 main ways respiratory gases are moved in an insect.

Answer 4

Along a diffusion gradient

Mass transport as mucle cless around trachea and tracheoles contract, increasing pressure in the tubes, forcing gases to move.

Fluid at the ends of tracheols is drawn into muscle cells during heightened activity. This is because lactic acid is produced in anaerobic respiration, lowering the water potential within the muscle cells. This draws the fluid into them, drawing air further into the tracheols. Allows final stage of diffusion into muscle cells to be over gas which is faster than over liquid.

Question 5

What is the trachea supported by to prevent collapse?

Answer 5

Rings of chitin.

Question 6

Limitations of the tracheal system

Answer 6

Relies on diffusion. For diffusion to be efficient it requires a shot diffusion pathway. This limits the size of Insects.