OCR Unit 1 - Specimen paper SA:V question

http://www.ocr.org.uk/download/assess_mat/ocr_7742_sam_gce_unit_f211.pdf

Question 3)a)iii) - 'Single-celled organisms generally have a SA:V ratio more like that of sphere A than sphere B. Explain why.

The markscheme answer for this question was:

- living cells need to take in oxygen/nutrients and remove waste.
- reference to passive processes/diffusion
- rate of diffusion too slow if SA:V ratio too small.

Can someone briefly formulate an answer for me from this? I rambled on about how single-celled organisms are much smaller and have less volume so there's cells are nearer the surface and not deep within the body so their surface area is plentiful to their volume.. therefore completely missing the point.

I'm failing to see how the question is asking what it says in the mark scheme.

Thanks!!

Reply 1

LonelyLion02

So I know im ten years late but....

im also doing this q now in 2020 ahhahahhaha. If you'd have looked at the amount of marks, it was only worth two - one mark for saying single celled organisms are small like sphere A, and so have a large SA:V Ratio, and that this allows lots of diffusion to occur so that o2 and nutrients can go in and waste products can leave.

lmao id say i hope this helps but its been 10 years and i thought you'd just like to know the answer after all these years ahaha

hope this helps x (lol)