AQA Biology question help URGENT

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kathy9
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#1
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#1
The table below shows some features of gas exchange of a fish at rest.

Volume of oxygen absorbed by the gills from each dm3 of water /cm3 = 7
Mass of fish / kg = 0.4
Oxygen required by fish / cm3 kg–1 hour–1 = 90

(i) Calculate the volume of water that would have to pass over the gills each hour
to supply the oxygen required by the fish. Show your working.

Can anyone tell me how to work out this question.
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11wiltshirel
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#2
Report 4 years ago
#2
Mark Scheme:

Correct answer of 5.1 or 5.14 (dm3) = 2 marks;
One mark for incorrect answers that show 36 or 0.4 x 90 or 90 ÷ 7;
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kathy9
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#3
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#3
(Original post by 11wiltshirel)
Mark Scheme:

Correct answer of 5.1 or 5.14 (dm3) = 2 marks;
One mark for incorrect answers that show 36 or 0.4 x 90 or 90 ÷ 7;
Thanks, I'm still unsure how to get to the answer of 5.1
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westcw13
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#4
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#4
Fish need 90cm3 O2 per kg per hour

Fish weighs 0.4kg, so 0.4 x 90 = 36cm3 O2 needed per hour

7cm3 of O2 per dm3 water,
so 36cm3 / 7cm3 = 5.14... dm3 water
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kathy9
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#5
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#5
(Original post by westcw13)
Fish need 90cm3 O2 per kg per hour

Fish weighs 0.4kg, so 0.4 x 90 = 36cm3 O2 needed per hour

7cm3 of O2 per dm3 water,
so 36cm3 / 7cm3 = 5.14... dm3 water
Thanks!
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sabrine12
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#6
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#6
IS this an A Level Question ?
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kathy9
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#7
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#7
(Original post by sabrine12)
IS this an A Level Question ?
yeah
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stella90945
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#8
Report 1 year ago
#8
Hi,

Could you please explain why you did each step.

I think the 0.4 x 7 is to see the oxygen required for THIS fish but I don't understand why you divided it by 7 after that?
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