special surfaces for exchange

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  • Created by: EClou
  • Created on: 08-04-15 09:07
what 6 substances do all living cells require to survive and what era they used for?
1. oxygen - aerobic respiration, 2. glucose - energy source, 3. proteins - growth & repair, 4. fats - making membranes & energy store, 5. water, 6. minerals - maintain WP & help enzyme action and other aspects of metabolism
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in what 2 ways are these substances gained?
either absorbed from the surrounding environment or made inside the cytoplasm
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what is the metabolism?
all the chemical reactions that take place in the cells of an organism
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what are the waste products of living cells?
1. carbon dioxide, 2. oxygen, 3. ammonia/urea (- excess nitrogen)
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what type of organisms are able to exchange gases, nutrients and wastes across their outer surfaces?
small or single celled organisms.
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what kind of SA:V do these kind of organisms have?
LARGE surface are to volume ratios (- because they have a big surface area surrounding not much volume)
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why can larger organisms not use diffusion alone for the removal of waste products and absorption of key substances? (2)
they have a smaller SA:V - 1. some cells are deep within the body so the distance is too great, 2. difficult to exchange enough substances to supply a large volume through a smaller outer surface
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what 4 features do good exchange surfaces have?
1. large SA (e.g by folding in walls/membranes), 2. thin barrier - reduce diffusion distance, 3. fresh supply of molecules on one side - keep concentration high & maintain steep diff. grad., 4. removal of required molecules on other side
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give 4 examples of exchange surfaces in living organisms
1. small intestine, 2. liver, 3. root hairs, 4. hyphae (in fungi)
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what is gaseous exchange?
it is the movement of gases by diffusion between an organism and its environment across a barrier such as the alveolus wall.
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what is a surfactant
a substance produced by the lungs to reduce cohesive forces between water molecules
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why is this vital
otherwise the alveolus would collapse due to the cohesive force between he water molecules lining the air sac.
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what kind of diffusion gradient is required for rapid diffusion?
steep
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how is the high concentration of molecules on the supply side and the low concentration of molecules on the demand side maintained?
the action of the blood transport system and the ventilation/breathing movements
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what does ventilation ensure about oxygen?
the concentration of O2 in the air of the alveoli remains higher than the concentration in the blood.
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what does ventilation ensure about carbon dioxide?
the concentration is lower of CO2 in the air of the alveoli is lower than the concentration in the blood stream
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Card 2

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in what 2 ways are these substances gained?

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either absorbed from the surrounding environment or made inside the cytoplasm

Card 3

Front

what is the metabolism?

Back

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Card 4

Front

what are the waste products of living cells?

Back

Preview of the front of card 4

Card 5

Front

what type of organisms are able to exchange gases, nutrients and wastes across their outer surfaces?

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