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Alevel Biology
Topic 3
Gas exchange in fish
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Created by
Laura Ladhams
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Cards (23)
Why can't fish simply diffuse oxygen across their surface?
They have a small
surface area to volume ratio
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What is the gas exchange surface in fish?
The
gills
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How much less oxygen does water contain compared to air?
30
times less oxygen
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What are the three key features of every gas exchange surface?
Large
surface area
, short
diffusion distance
, concentration gradient
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What adaptations do fish gills have for gas exchange?
Large surface area due to
gill filaments
Short
diffusion distance
from thin gill
lamellae
Counter current flow
to maintain concentration gradient
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How is the rate of diffusion calculated in gas exchange?
Using
Fick's law
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How many layers of gills do fish have on each side of their head?
Four
layers
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What are the structures on the gills called that increase surface area?
Gill filaments
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How are gill lamellae positioned in relation to gill filaments?
At
right angles
to the gill filaments
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Where does gas exchange occur in fish gills?
On the
gill lamellae
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What is the role of the capillary network in gill lamellae?
It provides a short
diffusion distance
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What is the counter current flow in fish gills?
Water flows opposite to blood in
capillaries
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Why is counter current flow advantageous for fish?
It prevents
equilibrium
, maintaining diffusion
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What happens in concurrent flow compared to counter current flow?
Equilibrium
is reached, stopping diffusion
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What is the saturation level of water entering the gills?
100%
saturation with oxygen
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How does the oxygen concentration change as water flows over the gills?
It decreases from
100%
to near 0%
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What is the significance of maintaining a diffusion gradient in fish gills?
It allows continuous
oxygen uptake
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What are the three features of gas exchange surfaces in fish?
Large
surface area to volume ratio
Short
diffusion distance
Mechanism to maintain
concentration gradients
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What is the advantage of counter current flow over concurrent flow?
It maintains diffusion across the entire
lamellae
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What is the role of gill lamellae in fish gills?
They facilitate
gas exchange
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What is the primary function of gills in fish?
To facilitate
gas exchange
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How does the structure of gills contribute to their function?
They provide a large surface area for
diffusion
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How does the design of gills prevent reaching equilibrium?
Counter current flow
keeps
oxygen concentration gradient
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