Do fish have a large surface area to volume ratio?
No
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As their body surface is not an adequate gas exchange surface, what have they evolved?
A specialised internal gas exchange surface- gills
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Where does oxygenated water enter through and pass over?
It enters through the mouth and passes over the gills
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Where does deoxygenated water pass out of?
The operculum opening
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What is the operculum?
Muscular flap surrounding the gills
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Water flows in an opposite direction to the blood stream in the gill lamellae- what is this called?
Counter-current flow
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What is the benefit of a counter-current flow for gas exchange?
It maximises oxygen uptake as it ensures that a diffusion gradient is maintained along the whole length of the gill lamellae
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How is a diffusion gradient maintained throughout the whole length of the lamellae?
deoxygenated blood always meets water with lots oxygen in and hence oxygen diffuses from the water into the blood
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What percentage of oxygen is transferred from water to blood with a counter-current flow mechanism?
About 80%
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Name three components to a fish gill
- Gill bar - Gill filaments - Gill lamellae
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How do the gill lamellae increase the rate of diffusion?
They increase the surface area
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How do fish ventilate their gills?
They continuously open and close their mouths to allow oxygen-rich water to flow over their gills and the deoxygenated water to be pushed out through the operculum opening
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Why is gill ventilation important?
It helps maintain a steep diffusion gradient for maximum oxygen diffusion
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What active process is used with the operculum opening to push water out?
Mass transport
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Other cards in this set
Card 2
Front
Do fish have a large surface area to volume ratio?
Back
No
Card 3
Front
As their body surface is not an adequate gas exchange surface, what have they evolved?
Back
Card 4
Front
Where does oxygenated water enter through and pass over?
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