Gas exchange in insects (sub topic 6)

Question 1

What features increase the rate of diffusion?

Answer 1

-large surface area
-short diffusion pathway
-steep concentration gradient

Question 2

How do single-celled organisms absorb and release gases?

Answer 2

-diffusion through their cell-surface membranes
-because of large surface area, a thin surface and a short diffusion pathway

Question 3

How do waxy exoskeleton help insects?

Answer 3

–protection
-retention of water

Question 4

What system do insects use to exchange gases?

Answer 4

-tracheal system

Question 5

Describe the tracheae in insects.

Answer 5

-air-filled network of tubes
-supported by strengthened rings to prevent them collapsing
-divide into smaller dead-end (tracheoles)

Question 6

How does gas exchange happen in insects?

Answer 6

-Air moves through pores in exoskeleton called spiracles
-O2 goes down concentration gradient to cells
-tracheae branch to tracheoles (thin, permeable walls)
- O2 diffuses directly from tracheoles into respiring cells
-CO2 moves from spiracles to be released

Question 7

How can contraction of muscles in insects move gasses?

Answer 7

-squeeze of trachea enabling mass movements of air in and out
-speeds up the exchange of respiratory gases

Question 8

Why are ends of the tracheoles are filled with water in insects ?

Answer 8

-at major activity insects cells undergo anaerobic respiration
-which produces lactate and lowers water potential of cells
-water moves into cells via osmosis, lowering volume of water in tracheoles by draws air in
-which means diffusion is more rapid