module 3 - 7.1 specialised exchange surfaces Flashcards

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1
Q

why do we need to exchange material?

A

for survival e.g. food, oxygen, water

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2
Q

what is the main thing that all organisms need to exchange?

A

gas (CO2, O2)

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3
Q

why cant we diffuse oxygen and carbon dioxide through the skin?

A

too thick, diffusion distance too great

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4
Q

what features must an effective gas exchange system have?

A

concentration gradient
SA:V ratio
moist inner wall of alveoli (turns gas to aqueous solution)

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5
Q

what are some reasons for exchange systems?

A
  • large multicellular organisms have a small SA:V
  • cells in center of organism wouldn’t receive any materials if multicellular organs survived on diffusion alone
  • multicellular organisms have high metabolic rate
  • need to exchange lots of materials fast
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6
Q

what makes the exchange of substances by diffusion easier?

A

larger the SA:V

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7
Q

why do multicellular organisms require specialist exchange surfaces?

A

they have a small SA:V

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8
Q

why can single celled organisms survive using diffusion alone?

A

because its a shorter diffusion pathway between cytoplasm and edge

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9
Q

what does a steep gradient mean for diffusion?

A

faster diffusion

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10
Q

how does large SA make gas exchange more efficient?

A

provides larger area for material exchange to occur

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11
Q

how do thin layers make gas exchange more efficient?

A

creates a short diffusion distance for gases, increases speed of exchange

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12
Q

how does blood supply make gas exchange more efficient?

A

constant blood supply maintains large diffusion gradient, makes sure exchanged substances are constantly moving to area needed

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13
Q

how does ventilation make gas exchange more effeicient?

A

maintains diffusion gradient, makes process faster & more efficient

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