Gas exchange in fish

Question 1

Three parts of the fish gills

Answer 1

Gill arch , gill filaments and lamellae

Question 2

Where does diffusion happen in fish

Answer 2

Specifically in the lamellae

Question 3

How does oxygen diffuse into a fish

Answer 3

Fish opens mouth to let water in. The water contains a higher concentration of oxygen compared to the capillaries deoxygenated blood. Oxygen from the water diffuses into the capillaries down its concentration gradient

Question 4

How does carbon dioxide diffuse out of a fish

Answer 4

Carbon dioxide diffuses into the water because fish is constantly respiring so the concentration of carbon dioxide is higher in the blood than in the water

Question 5

Three adaptation of fish gills that increase gas exchange

Answer 5

Large SA:V Ratio
Short diffusion distance
Counter-current flow

Question 6

Counter-current flow

Answer 6

The water that is flowing in the the fish flows in opposite direction to the blood. Blood is never 100% oxygenated as blood is always passing water with higher oxygen concentration. This ensures a concentration gradient is maintained across the entire lamella. (Dexoygenated blood is constantly passing oxygenated water)

Question 7

Large SA:V ratio

Answer 7

Many long and thin gill filaments covered in many lamellae (capillaries)
The more gill filaments and lamellae the larger SA:V ratio the increased rate of gas exchange

Question 8

Short diffusion distance

Answer 8

Capillaries in every lamella and lamella are very thin

Question 9

Why must fish that swim faster have a larger surface area of gills

Answer 9

They need to respire faster for a faster rate of muscle contraction in the fish. So they need to uptake more oxygen by diffusion to do respiration at a faster rate. A larger surface area of gills helps diffuse more oxygen into the fish