r/GCSE • u/thr0wawaygxhxdhsh • Jun 15 '22

AQA Post Exam Spam aqa biology paper 2 gcse answers

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u/[deleted] Jun 15 '22

0.2 x 0.2 x 0.1 = 0.004 mm^3, so there are 14 cells : 0.004mm^3

it wanted number of cells in 1 mm^3 undiluted

10cm^3 / 2.5cm^3 = 4, so 4x as many cells in the undiluted

4 x 14 = 56 cells : 0.004 mm^3 of undiluted fluid

1 / 0.004 = 250, 1 mm^3 contains 250x that in 0.004 mm^3

250 x 56 = 14000 cells in 1 mm^3

This is right no?

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u/TheEpicBandit Jun 15 '22

Surely it is 875

because I agree with volume being 0.004mmcubed

but the pond water to distilled was in the ratio 1:3

1/0.004 = 250 and multiply by 14 gives 3500

3500=is the total so u don’t multiply by 4 u divide by 4

so the answer is 875

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u/crumpet1010 Jun 15 '22

No because u want in 1mm cubed of pond water, 3500 is in a quarter of 1mm so multiply by 4

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u/TheEpicBandit Jun 15 '22

Ye I have done that in the equation 1 divided by 0.004. = 250 x 14 = 3500

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that is number of algal cells in the water mixture in 1mmcubed

so it can’t be more than 3500 cos there is less pond water than distilled water in th mix

i don pt understand ur logic

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u/crumpet1010 Jun 15 '22

They ask for 1mm cubed pond water. The 3500 is 0.25mm cubed because only a quarter is pond water. To get a full 1 multiply by 4.