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Title: Gas Exchange in Fish Gills - AQA AS Level Biology
Description: As title describes, concise notes covering Gas Exchange in Fish Gills under chapter 6 of the kerboodle AS level (new( spec Biology.

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Gas Exchange in Fish 
The System 
Firstly, water is taken in through the mouth of the fish and is passed over the gills
...
 
 

 
The Countercurrent Exchange Principle 

 
The arrows above show the direction of flow of two substances, one is water (blue arrow on top) 
and one is blood in the gill lamellae (purple arrow on bottom)
...
  
is​
 

The nature of the opposing direction of flow at work here means that the water always has a 
higher concentration of oxygen than the blood at any point in the flow
...
  
 
Due to the countercurrent nature of the water and blood flow, the water always has a higher 
concentration of oxygen than the blood​
 across the entire gill filament​

...
 
Large Concentration Gradient ­ is achieved by the countercurrent flow of the water and the 
blood, as at any one point, the water will have a higher concentration of oxygen than the blood it 
is closest to
...
 


Title: Gas Exchange in Fish Gills - AQA AS Level Biology
Description: As title describes, concise notes covering Gas Exchange in Fish Gills under chapter 6 of the kerboodle AS level (new( spec Biology.