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AQA A LEVEL BIOLOGY: Can anyone explain how/why this is the answer?

I have a test coming up soon for the respiration topic and I'm doing some past paper questions. I had this question (images attached) about finding the rate of reaction for the first 40 minutes of a reaction.

To my knowledge, the rate of reaction is change in product/change in time. I got the answer of 0.0775 by dividing 3.1 by 40. As you can see on the mark scheme, I would have received one mark.

I'm not sure how I am supposed to arrive at the 2 mark answer of 0.0155. I tried to make sense of it and 0.0155 is 0.0775/5 but I don't see why I would divide my result by 5?

Is it possible someone could take a look and explain how I would arrive at the 2 mark answer and how I went wrong?
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Avatar for Ro-Z.707
Ro-Z.707
9
Original post by nikiej028
I have a test coming up soon for the respiration topic and I'm doing some past paper questions. I had this question (images attached) about finding the rate of reaction for the first 40 minutes of a reaction.

To my knowledge, the rate of reaction is change in product/change in time. I got the answer of 0.0775 by dividing 3.1 by 40. As you can see on the mark scheme, I would have received one mark.

I'm not sure how I am supposed to arrive at the 2 mark answer of 0.0155. I tried to make sense of it and 0.0155 is 0.0775/5 but I don't see why I would divide my result by 5?

Is it possible someone could take a look and explain how I would arrive at the 2 mark answer and how I went wrong?

Hello i'm not sure if ive done this right but you did the correct thing which is 3.1 / 40 to get 0.0775 cm3 per minute (min-1) however you need to get the per gram (g-1) which is shown in the question units so there must be a gram/ weight value somewhere in the question which results in you dividing 0.0775 by 5 to get the 2nd mark and the correct answer.
Reply 2
Avatar for nikiej028
nikiej028
OP
7
Original post by Ro-Z.707
Hello i'm not sure if ive done this right but you did the correct thing which is 3.1 / 40 to get 0.0775 cm3 per minute (min-1) however you need to get the per gram (g-1) which is shown in the question units so there must be a gram/ weight value somewhere in the question which results in you dividing 0.0775 by 5 to get the 2nd mark and the correct answer.

thank you, I'll take another look at the question

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