Gas exchange in insects

Question 1

Anatomy of a insect

Answer 1

Exoskeleton of chitin
Lipid layer - prevents water by evaporation

Question 2

Gas exchange relies on what in insects

Answer 2

Diffusion and is only possible due to a short diffusion pathway

Question 3

Goals of an insects gas exchange

Answer 3

Maintain the perfect balance of oxygen uptake and minimising water loss

Question 4

Spiracles

Answer 4

Round valve-like openings along abdomen ( Can close and open to stop water loss evaporating)
Oxygen can diffuse in down its concentration gradient
Carbon dioxide can diffuse out along up the concentration gradient

Question 5

Trachea

Answer 5

Network of internal air filled tracheae
Extend throughout into tissues
Delivered oxygen to respiring cells
Branches off into tracheoles

Question 6

Three ways of moving gas in insects

Answer 6

Simple diffusion
Mass transport
Insect in flight

Question 7

Simple diffusion

Answer 7

Oxygen diffuses in down concentration gradient
Carbon dioxide diffuse out along concentration gradient
Large SA:V ratio

Question 8

Mass transport

Answer 8

Contracts and relaxed abdomen muscles
Compresses tracheae
Raises pressure in the body and forces air out the body down the pressure gradient
Increases removal of carbon dioxide
Energy demand and respiration levels are highest

Question 9

Insect in flight

Answer 9

Respire anaerobically
This produced lactic acid
Lactic acid lowers water potential of cells
Water at the end of tracheoles moves into cells by osmosis
More air at the end of tracheoles and less pressure
Oxygen and carbon dioxide diffuse in and out faster,
This is because air travels faster in gas then liquid

Question 10

Insect adaptation for gas exchange

Answer 10

Tracheoles have thin walls - This shortens diffusion pathway
Tracheoles are highly branched - Increases SA : V ratio