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A level Biology: Post your doubts here!

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If they had sank to the bottom,why would their be only a single organelle present?
They said in the question that they sank to the bottom, the reason it would be a single organelle is because when they are spun in the centrifuge the heaviest one is removed first
 
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Guys is it necessary to draw double line to show cell wall in cell drawings or is one line okay?
 
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Guys is it necessary to draw double line to show cell wall in cell drawings or is one line okay?
No you must draw the cell wall as double lines very close to each other and make sure that it is at constant thickness. Like this :

high-power-1.png
 
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Guys pls help!!!!
 

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Thanks really useful :)
but are cells supposed to share their cell walls with other cells like this one?
Maybe that is overlapping of cells but we are supposed to draw them like that ONLY IF THEY APPEAR to be like that
 
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Guys don't u think so this statement is wrong? Like N14 to be transferred to N15.
 

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Can someone pls clarify me what is the min n max number of hydrogen bonds in a length of DNA containing 700 base pairs? It's really confusing sometimes they say min 1400 or 700 :(
 
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Can someone pls clarify me what is the min n max number of hydrogen bonds in a length of DNA containing 700 base pairs? It's really confusing sometimes they say min 1400 or 700 :(
Hmm what??.
1 base pair means A-T or C-G.A-T base pair have 2 hydrogen bonds and C-G base pair have 3 hydrogen bonds.

You want minimum number of hydrogen bonds?.So 700 base pairs into 2 (considering all base pairs are A-T)=1400.This answer is confirmed from the mark scheme..
And max 700 into 3 =2100
 
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Hmm what??.
1 base pair means A-T or C-G.A-T base pair have 2 hydrogen bonds and C-G base pair have 3 hydrogen bonds.

You want minimum number of hydrogen bonds?.So 700 base pairs into 2 (considering all base pairs are A-T)=1400.This answer is confirmed from the mark scheme..
And max 700 into 3 =2100
But in M/J/13/P13/q24 says it's B i.e 700
 
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