Gas Exchange In Insects

Question 1

Describe the structure of the tracheal system in insects.

Answer 1

• spiracles as openings in the exoskeleton of insects
• the tracheae which extends from the spiracles and divides into tracheoles

Question 2

How does the tracheal system help the concentration gradient of insects

Answer 2

• when cells respire, they take up oxygen decreasing the concentration of oxygen n the tracheoles.
• this creates a concentration gradient which maximises the diffusion of oxygen from the air
• Cells also release carbon dioxide through respiration, increasing the concentration of CO2 in the tracheoles and therefore creating a concentration gradient and allowing the diffusion Of CO2 out of the tracheoles

Question 3

How does the tracheal system maximise the surface area of insects

Answer 3

There are many tracheoles which extend into a insects body and increase their SA

Question 4

How does the tracheal system decrease the diffusion distance of insects.

Answer 4

The tracheas are very close to cells, decreasing diffusion distance and maximising diffusion.

Question 5

How does the tracheal system increase mass transport

Answer 5

• The contraction of muscles in the insects can squeeze the trachea increasing the mass movement of air In and out of the tracheal system, maximising diffusion

Question 6

How does the end of tracheoles being filled with water increase gas exchange

Answer 6

• In periods of major activity, cells respire anerobically and produce lactic acid
• the lactic acid decreases the water potential of cells, so water osmoses from the tracheoles fluid into cells
• this decrease the volume of water in the tracheoles, drawing more air from the environment
• this increases the rate of diffusion

Question 7

What are the limitations of the tracheal system

Answer 7

the tracheal system is dependent on exchange from the environment, so diffusion distance is an important factor
- this means insects have to be small