gas exchange

Question 1

3 main features of an insects mass transport system:

• holes on the body’s surface…valves…gas…water
• large tubes…tissue
• smaller branches

Answer 1

• spiracles- holes on the body’s surface which is opened or closed by valves for gas or water exchange
• tracheae- large tubes extending throughout the body tissues, supported by ring to prevent collapse
• tracheoles-smaller tubes dividing off the tracheae

Question 2

explain the process of gas exchange in insects-
gas
diffuse
muscle

Answer 2

gases move in and out of the tracheae through spiracles
diffusion gradient allows oxygen to diffuse into the body tissue while co2 diffuses out
contraction of muscles in tracheae allows movement of air in and out

Question 3

why cant insects or fish use their bodies as an exchange surface?

Answer 3

insects-waterproof exoskeleton- chitin

fish-waterproof impermeable outer membrane and a small sa: vol ratio

Question 4

fish gas transport: describe 2 features

Answer 4

gills-supported by arches, have multiple projections of gill filaments which are stacked up in piles
lamellae-right angle to gill filaments- increase sa, blood and water flow across them in opposite directions

Question 5

process of gas exchange in fish:
first thing the fish does
what does the water do?
what passes over where?
waste...

Answer 5

fish opens its mouth, enables water to flow in, closes mouth to increase pressure
water passes over lamellae- oxygen diffuses into the bloodstream
waste co2 diffuses into the water and back out the gills

Question 6

counter current exchange:

Answer 6

maintains a concentration gradient as water is flowing opposite direction of blood- across the whole length of the lamellae.

Question 7

adaptations of plants for gas exchange

Answer 7

exchange gas through stomata
guard cells control opening and closing of stomata- helps prevent water loss by evaporation
thin and flat- short diffusion pathway- small sa: vol ratio
many pores on underside of leaf allow gasses to easily enter
air spaces in mesophyll allow gases to move around the leaf
hairy leaves trap water vapour-reduce water potential gradient

Question 8

human gas exchange- direction of gas

Answer 8

nasal cavity, trechea, bronchi, bronchioles. alveoli

Question 9

describe process of inspiration

Answer 9

external intercostal muscles contract, internals relax
ribs up and out-diaphragm contracts and flattens
increases thoracic volume, decreases air pressure in lungs, air moves into the lungs