Insects Gas Exchange Flashcards
Why do single-celled organisms have a large surface area to volume ratio?
They are small
How is oxygen absorbed by single celled organism?
By diffusion across their body surface
What feature of an insects body surface allows it to absorb oxygen?
It is covered only by a cell-surface membrane
Does carbon dioxide move out of an insect the same way oxygen moves in?
Yes
Is a living cell being surrounded by a cell wall an additional barrier to the diffusion of gases?
No
Why does the increase in surface area required for gas exchange in an insect conflict with conserving water?
Because the water will evaporate from it
What do insects use for gas exchange?
Tracheae- Internal network of tubes
What prevents the tracheae from collapsing?
Strengthened rings
What dead end tubes are the tracheae divided into?
Tracheoles
Why do tracheoles extend throughout all the body tissues of an insect?
Atmospheric air with oxygen is brought directly to the respiring tissues - short diffusion pathway from a tracheole to any body cell
What 3 ways do respiratory gases move in and out of the tracheal system?
- Along a diffusion gradient
- Mass transport
- The ends of the tracheoles are filled with water
Why does the concentration of oxygen at the end of the tracheoles decrease?
Cells are respiring
What does the diffusion gradient created cause?
Gaseous oxygen to diffuse from the atmosphere along the trachea and tracheoles to the cells
When is carbon dioxide produced by cells?
During respiration
What does the larger concentration of Carbon dioxide create?
A diffusion gradient in the opposite direction
What direction does carbon dioxide travel due to the reverse diffusion gradient?
From the ends of the cells to the atmosphere
How do muscles in the tracheae create mass transport?
Contraction of muscles squeezes the trachea which enables the mass movement of air in and out
What effect does mass transport have on gas exchange?
Speeds up gas exchange
How does anaerobic respiration lower the water potential of the muscle cells
Produces lactate which is soluble to lowers the water potential
How does water move into the cells from the tracheoles?
Osmosis
How does the movement of water draw air in?
The water decreases in volume due to osmosis so draws air in
In what state is the final diffusion pathway - and is therefore quicker?
In a gas phase rather than a liquid phase
What downside does the ends of the tracheoles being filled with water have?
Has greater water evaporation
How are spiracles opened?
Valves
Why do insects keep their spiracles closed?
Prevents water loss
What is a limitation of the tracheal system?
It relies mostly on diffusion to exchange gases
Why are insects of small size?
Creates a short diffusion pathway for efficient diffusion
What is the size that the insects can attain limited by?
The length of the diffusion pathway
