How are substances such as oxygen, carbon dioxide and digestive products moved around the body of small organisms?
Diffusion
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What is diffusion?
the movement of molecules or ions from a region of high concentration to low concentration by relatively slow random movement of molecules
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how are substances moved around the body of complex multicellular organisms?
They usually have blood to carry vital substances around their body and a heart to pump it instead of relying on diffusion. in other words they have a circulatory system.
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Open circulatory system: Blood circulates in large ...... spaces.
Open
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The hearts role in open circulatory systems?
A simple heart pumps blood out into cavities surrounding the animals organs. substances can diffuse between blood and cells. when heart relaxes- blood= drawn from cavity back to the heart through small valved openings along its length
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Closed circulatory system- the effect of having the blood enclosed in tubes?
higher blood pressure as blood is flowing along fairly narrow channels and not into large cavities
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Why is the closed circulatory system more affective than the open?
Due to the blood flowing along fairly narrow channels, the blood travels faster and so the blood system is more efficient at delivering substances around the body.
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Other cards in this set
Card 2
Front
How are substances such as oxygen, carbon dioxide and digestive products moved around the body of small organisms?
Back
Diffusion
Card 3
Front
What is diffusion?
Back
Card 4
Front
how are substances moved around the body of complex multicellular organisms?
Back
Card 5
Front
Open circulatory system: Blood circulates in large ...... spaces.
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