Gas exchange in insects, fish & plants

Question 1

How gills are adapted for gas exchange

Answer 1

-Many lamellae-increase SA
-Walls of lamellae are very thin-short diffusion pathway
-Counter current system-maintains concentration gradient for o2 along the whole length of the gill
-Large blood supply to lamellae

Question 2

Couneter courrent system

Answer 2

-Blood flows in the opposite direction to water
-Equilibrium never reached
-More O2 diffuses into blood

Question 3

Spiracles

Answer 3

Tiny openings on the abdomen, where gase enters & exits
-Open and close by muscle contractions to minimise water loss

Question 4

Trachea

Answer 4

Tubes that carry air from spiacles to tracheols
-Chintin to prevent collapsing

Question 5

Tracheols

Answer 5

Highly brached tubes that are the site of gase exchange with cells
-Thin walls, short diff pathway
-Highly branched, large SA
-Penetrate directly into tissue, reduces diffusion distance

Question 6

Gas exchange in insects

Answer 6

1. O2 diffuses into insects through spiracles
2. PPo2 is lower in cells than in tracheoles, so o2 diffuses into cells
   -O2 used by the cells maintaining gradient
   -CO2 moves in the opposite direction

Question 7

Gas exchange in insects during exercise

Answer 7

Tracheal fluid moves into tissues to increase diffusion and SA for gas exchange