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A level Biology: Post your doubts here!

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Can someone please tell me why the answer is C?:(:(
The width of a cell membrane is 7nm.. that's the reason why we use electron microscope to see it clearly. The white blood cells diameter can't be in mm.. if it were so, we would not need a microscope to view them . As for the alveoli their diameter too is in micrometers since we need a large surface area to volume ratio for quick diffusion across the alveolar walls.. You must have read that the smaller the surface area, the larger surface area to volume ratio. Hope this makes sense :)
 
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The width of a cell membrane is 7nm.. that's the reason why we use electron microscope to see it clearly. The white blood cells diameter can't be in mm.. if it were so, we would not need a microscope to view them . As for the alveoli their diameter too is in micrometers since we need a large surface area to volume ratio for quick diffusion across the alveolar walls.. You must have read that the smaller the surface area, the larger surface area to volume ratio. Hope this makes sense :)
Thanks, but they are asking about the cell wall(which is not 7nm)...and I didn't get the rest:(
 
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Thanks, but they are asking about the cell wall(which is not 7nm)...and I didn't get the rest:(
The diameter of cell walls in different organisms is not the same.. for example in prokaryotes it's diameter ranges from 5 to 80 nm and in eukaryotes it's about 1000 to 5000 nm thick. (I actually searched for it).. What did not you get dear? :) Can you please specify?
 
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Can someone please tell me why the answer is C?:(:(
Look, all the structures mentioned here in the MCQ can never be in mm because if they were in mm, you would have been able to see them with naked eye, but you aren't able to do so. So just eliminate all the options which quote 'mm' as the measuring unit. After elimination you'll notice that you're left with only option C.

Actually according to syllabus you're not expected to memorize the sizes of these. So you're to compare the structures mentioned and then deduce. Cell walls are obviously smaller than white blood cells or alveoli. So if you're measuring WBCs in micromemter, then cellwalls must be in nm. So you're to solve this by comparisons.
 
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Can someone pls solve oct/nov 2014 component 12 mcq for me...it's abt diploid and haploid cells with vague terming......sorry couldn't upload it
 
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