Specialised Exchange Surfaces

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Why is diffusion alone enough for single celled organisms, with gaseous exchange?
Relatively low metabolic activity so low oxygen demand and waste removal needed and large SA:V ratio
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Why can't larger organisms not rely on diffusion alone?
Because as they get larger, the cells form into tissues and organs, they require a lot more energy and oxygen, thus producing more waste, also the distance between lungs and cells that need O2 is too large for effective diffusion
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State 4 examples of characteristics in an effective gas exchange surface
Increased SA, Thin layers, Good blood supply and good ventilation
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Why is it important to have an increased SA?
It overcomes SA:V ratio issues in larger organisms, increasing the surface area also increases the SA:V ratio
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Why is it important to have thin layers?
There is a shorter diffusion pathway for gaseous exchange making it fast and efficient
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Why is it important to have a good blood supply?
It maintains a steep concentration gradient, making diffusion faster and more effective
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Why is it important to have good ventilation?
Similar to the blood supply, it maintains a concentration gradient
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Other cards in this set

Card 2

Front

Why can't larger organisms not rely on diffusion alone?

Back

Because as they get larger, the cells form into tissues and organs, they require a lot more energy and oxygen, thus producing more waste, also the distance between lungs and cells that need O2 is too large for effective diffusion

Card 3

Front

State 4 examples of characteristics in an effective gas exchange surface

Back

Preview of the front of card 3

Card 4

Front

Why is it important to have an increased SA?

Back

Preview of the front of card 4

Card 5

Front

Why is it important to have thin layers?

Back

Preview of the front of card 5
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