Gas exchange

Question 1

How does oxygen in the air reach capillaries surrounding alveoli in the lungs

Answer 1

Trachea - Bronchi - Bronchioles 
Down a pressure gradient 
Down a diffusion gradient 
Across alveolar epithelium 
Across capillary epithelium

Question 2

Describe the movement of oxygen into an insect when it is at rest

Answer 2

Oxygen used in aerobic respiration
Oxygen concentration established
So oxygen diffuses in

Question 3

Describe the effect of abdominal pumping

Answer 3

Abdominal pumping is linked to CO2 release
Pumping raises prsssure in the body
CO2 is pushed out of the body down a pressure gradient

Question 4

Give 3 ways in which an insects tracheal system is adapted for efficient gas exchange

Answer 4

1. Tracheoles have thin walls so short
diffusion distance to cells;
2. Highly branched so short diffusion distance to
cells;
3. Highly branched/large number of
tracheoles so large surface area for gas
exchange