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# Biology aqa question help watch

1. Hello all,
If anyone can help here I would very grateful.
I don't have a clue as to how to arrive at this answer:
Calculate the ratio of the mean rate of uptake of chloride ions in the first hour to the rate of uptake of chloride ions in the second hour for group B plants.

At 60 minutes the total uptake of chloride ions was 360 and at 120 minutes it was 470. The answer is 3.3:1.
2. Okay so,

Your mean rate of uptake of sodium ions in the first hour is 360. Simple.

You then have to find the mean rate of uptake of sodium ions in the second hour, this is where you need to know that your looking from 60 -120 (You do not include the 360 in the first value)

On your graph you read 470, so 470 - 360 (to make it just the second hour uptake) this brings you to an answer of 110.

Now all you need to do is divide 360(first hour) by 110(second hour) this brings you to an answer of 3.27 (Round up to 3.3)

It's hard to explain but hope it made some sort of sense
3. Ah yes I see thnks a lot. The mark scheme itself doesn't show how to arrive at the answer but you have shown how. Thanks!

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Updated: February 9, 2018
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