What is important when it comes to exchanging substances (especially CO2 and O2) with the surroundings and then moving them around the body?
Size
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Give an example of a unicellular (one-celled) organism.
Amoeba - its non photosynthetic and gains its energy by eating smaller organisms such as bacteria & it lives in fresh water.
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What serves as the site of gaseous exchange and why?
The cell surface membrane because its surface area is large enough to provide sufficient oxygen for respiration and for the removal of carbon dioxide.
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What's the definition of Gaseous exchange?
The diffusion of oxygen and carbon dioxide between an organism and its environment.
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Give the definition of a gas exchange surface.
Past of the body where gas is exchanged.
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For unicellular organisms, where is their gas exchanged?
All over the whole body.
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For fish, where is their gas exchanged?
In their gills.
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For mammals, where is their gas exchanged?
In the lungs.
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Why do large multicellular organisms (e.g. fish) not have a sufficient body surface to to act as the site of gaseous exchange?
Because there isn't enough surface to absorb the oxygen required. (This is why animals have lungs or gills with large surface areas as sites of gaseous exchange)
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Give an example of a specialised surface for exchange int he human body.
The lining of the gut has a large surface area for the absorption of digested food.
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How do you calculate the surface area to volume ratio?
calculate the surface area and then the volume. Next, put them into a ratio (you can do this by dividing the surface area by the volume) e.g. 6:1
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How do you calculate the surface area of a cube / object?
area of one side x number of sides
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how do you calculate the volume of a cube / object?
length x height x width
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Do small organisms have a large or small surface area to volume ratio and why?
Small organisms have a large surface area to volume ratio because they use their whole body for gaseous exchange.
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Do large organisms have a large or small surface area to volume ratio and why?
Large organisms have a small surface area to volume ratio because they have specialised surfaces for exchange e.g. gills / lungs.
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Other cards in this set
Card 2
Front
What is important when it comes to exchanging substances (especially CO2 and O2) with the surroundings and then moving them around the body?
Back
Size
Card 3
Front
Give an example of a unicellular (one-celled) organism.
Back
Card 4
Front
What serves as the site of gaseous exchange and why?
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