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Competition - post a photo you've taken of nature >>

helpp bio question

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Kalabamboo
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Anyone please ???? :frown:
8417FBCB-32CE-4EA1-8EEB-4B2EB8EEE08D.jpg.jpeg

✋😠we don’t accept bad conduct on these forums
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Kalabamboo
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anyone please ? help
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Avatar for Mk1237
Mk1237
10
Original post by Kalabamboo
anyone please ? help


Don't you have the mark scheme for it?
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Kalabamboo
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Original post by Mk1237
Don't you have the mark scheme for it?

yhh but I don't understand it
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Mk1237
10
Original post by Kalabamboo
yhh but I don't understand it


Whats the answer?
Original post by Kalabamboo
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ok so there were three theories to explain replication:
Semi-conservative where the daughter dna molecules contain one old and one new strand.
Conservative where one completely new dna molecule would be made from an old one
Dispersive where each new molecule would be made of old bits and new bits scattered randomly throughout the molecule.
if the replication was conservative then you would expect to see two separate bands of DNA in gen 1, one band containing original 15N DNA and one containing new 14N DNA. If the replication was dispersive then you shouldn't see separate bands of DNA forming in any generation. So results support the suggestion that dna replicates semi conservatively because gen1 would contain 100% hybrid dna were all dna contains 1 old and 1 new so no possibility of separation into layers. Gen2 would contain 50% hybrid dna and 50% completely 14N DNA and so on.
Heavy nitrogen species form band at bottom.
Light nitrogen bacteria form band at top as its lighter.

Semi conservative is where its a bit of both so the band ends up in the middle. Where heavy nitrogen bacteria is exposed to light nitrogen and so both is mixed to form 'medium heavy' bacteria.

Just remember the weight of the nitrogen.

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