gas exchange in insects

Question 1

how do insects avoid water loss via evaporation

Answer 1

insects posses a rigid chitin exoskeleton with a lipid layer that is impermeable to gasses and prevents water loss via evaporation

Question 2

what is the insects gas exchange system called

Answer 2

tracheal system

Question 3

how do insects lose water and how have they adapted a gas exchange system which minimises that

Answer 3

water evaporates off the surface of terrestrial insects. they have adapted gas exchange systems to minimise water loss;
-small surface area to volume ratio for water to evaporate from
-waterproof exosceleton
-small spiracles where gasses entre and water can evaporate, they open and close to reduce water loss due to evaporation

Question 4

how are the trachea supported

Answer 4

by strengthening rings of cartilage to prevent collapse

Question 5

describe the movement of gasses along a concentration gradient

Answer 5

when cells are respiring oxygen is used up and so its concentration towards the ends of the tracheoles falls. this creates a diffusion gradient that causes oxygen to diffuse from the atmosphere along the trachea and tracheoles to the cells. carbon dioxide is then produced by cells during respiration which creates a diffusion gradient in the opposite direction. This leads to the carbon dioxide to diffuse along the tracheoles and trachea back into the atmosphere.

Question 6

describe respiratory gas movement during periods of major activity

Answer 6

during periods of major activity the muscle cells around the tracheoles respire carrying out anaerobic respiration. This produces lactate which is soluble and lowers the water potential of the muscle cells. water then moves into the cells from the tracheoles via osmosis. the water in the ends of the tracheoles decreases in volume and in doing so draws air further into them. this means the final diffusion pathway is in a gas rather than a liquid leading to diffusion being more rapid.