4.3 Gas Exchange (fish)

Question 1

gas exchange in fish

Answer 1

fish are waterproof because of their scales
they have small surface area to volume ratio hence why they have a gas exchange surface which is the gills

for gas exchange all species must always have
short diffusion distance
maintained a concentration gradient

Question 2

fish gill anatomy

Answer 2

the four layers of gills on both sides of the head

the gills are made up of stacks of gill filaments

each gill filament is covered in gill lamellae, which is perpendicular to the filament

this creates a large surface area

when fish open their mouth, water washes in and over the gills and then out through a hole in the sides of their head called the operculum

Question 3

adaptations for efficent gas exchange

Answer 3

large surface area- many gill filaments covered in many gill lamellae

short diffusion distance due to a capilary network in every lamellae and very thin gill lamellae

maintains concentration gradient= countercurrent flow mechanism.

Question 4

counter current exchange principle

Answer 4

this is when water flows over the gills in the opposite direction to the flow of blood in the capillaries

counter current flow ensures that equilibruim is not reached

this ensures that a diffusion gradient is maintained across the entire length of the gill lamellae.

Question 5

Explain how gills are adapted for gas exchange.

Answer 5

the large surface area of the gills.
thin for shorter diffusion distance
countercurrent to maintain concentration gradient