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A2 Biology OCR June 2015 Revision Thread

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Original post by ChoccyPhilly
June 11

Why doesn't anyone believe me? ;_;


I can't find which question you mean? It's not that i didn't believe you, i was just checking in the paper to see if i'd made a mistake :smile: My teacher said today we're not required to know an example of positive feedback, just be able to recognize a given example of it. It was possible he made a mistake though.
Original post by maisie__x
I can't find which question you mean? It's not that i didn't believe you, i was just checking in the paper to see if i'd made a mistake :smile: My teacher said today we're not required to know an example of positive feedback, just be able to recognize a given example of it. It was possible he made a mistake though.


It's on the very last page which has lots of writing on it as they're definitions
Original post by ChoccyPhilly
It's on the very last page which has lots of writing on it as they're definitions


Yeah that's exactly the kind of question i mean :smile: They can give us an example of positive feedback and you get a mark for saying that it is.
But what i meant is you wouldn't get a question saying 'what is an example of positive feedback' where you have to make your own example.
Original post by ChoccyPhilly
I think you're confused as to what chain termination actually is. You do this before electrophoerisis and a computer should be able to read the nucleotides at the cathode (?) end of the gel, which will give you your sequence. Essentially, the computer works it out during gel electropherisis.

After that you have a bunch on DNA fragments (as you can't sequence the whole thing st once), you'll see where each fragment overlaps with one another and put them in order to get your full genome



Omg so confused right now , so you're basically describing sanger sequencing ???!

0890-3670-040927-44-1-1.png
guys is convergence and intergration the same in terms of role of synapses? One markscheme says convergence and the other says intergration....I'm so lost!
Original post by TheLegalDealer
Omg so confused right now , so you're basically describing sanger sequencing ???!
0890-3670-040927-44-1-1.png


I dnt think we have to know that. As far my book goes, they might lump that and chain termination method as one thing. I certainly though that was the chain termination method.
Original post by kewla1
guys is convergence and intergration the same in terms of role of synapses? One markscheme says convergence and the other says intergration....I'm so lost!


Convergence amplifies a stimulus, whereas integration brings impulses from different parts of the body? I might be wrong on the latter
Original post by ChoccyPhilly
I dnt think we have to know that. As far my book goes, they might lump that and chain termination method as one thing. I certainly though that was the chain termination method.


It's the same thing just different names
Does anyone also know why sometimes summation is allowed in the markscheme as a role of synapses, and sometimes not?! :s-smilie:
Original post by TheLegalDealer
It's the same thing just different names


Alright thanks, also do you know why summation is only credited in some markschemes? I find it confusing when role of synapses come up but summation is credited in some papers but not others
Original post by TheLegalDealer
It's the same thing just different names


Ahh I see.

I just wanted to highlight that you don't do PCR, then electrophoresis and THEN chain termination, chain termination IS PCR, electrophoresis and then the computer reads off your nucleotides
How difficult is it to get a B/C in this exam? I've revised excretion thoroughly and photosynthesis needs refreshing but not respiration and communication, would a day be enough and a past paper or two?
Original post by ChoccyPhilly
Ahh I see.

I just wanted to highlight that you don't do PCR, then electrophoresis and THEN chain termination, chain termination IS PCR, electrophoresis and then the computer reads off your nucleotides


Ive been confused this whole time for no good reason haha ! Just to make clear I dont have to mention BACs at all when sequencing a genome ?
Predictions?!!??!!???
Original post by TheLegalDealer
Ive been confused this whole time for no good reason haha ! Just to make clear I dont have to mention BACs at all when sequencing a genome ?

You seem so fearful of it haha. I think plasmid will be good enough :smile:
Original post by maisie__x
If you get B's in your retakes and a high A in f214 you would get a B overall. I'd estimate about 440 UMS. (480 is an A) B's at AS and then a B in F215 gives you 75% of your grade already as a B. :smile: You could get an A with an A in f215


Sorry to butt in here, if I have a low B at AS and a high A in the practical for A2 and I get a C in bio 5 and a B in bio 4 what would I get overall?
Original post by baffledchick
Sorry to butt in here, if I have a low B at AS and a high A in the practical for A2 and I get a C in bio 5 and a B in bio 4 what would I get overall?


Hello :smile: Assuming you were only just on a B last year and that get on the marks of a B and a C this year you would be two UMS away from having a B overall. So you'd probably get a B if you can just get an extra mark somewhere :smile:

Just in case you wondered how i worked this out;

F211 B last year was 63, add 105 from a B in F212, add a B in AS coursework 42. Then adding a guess of 55 UMS in your A2 coursework gives 265. If you get a B and a C this year adds a further 90 and 63 UMS giving 418 in total :smile: The boundary for a B is 420. Hope that helped! :smile:
are there any predictions for the f214 exam? or can literally anything come up? :smile:
Original post by maisie__x
Hello :smile: Assuming you were only just on a B last year and that get on the marks of a B and a C this year you would be two UMS away from having a B overall. So you'd probably get a B if you can just get an extra mark somewhere :smile:

Just in case you wondered how i worked this out;

F211 B last year was 63, add 105 from a B in F212, add a B in AS coursework 42. Then adding a guess of 55 UMS in your A2 coursework gives 265. If you get a B and a C this year adds a further 90 and 63 UMS giving 418 in total :smile: The boundary for a B is 420. Hope that helped! :smile:


Thank you! So I've actually got my UMS for AS it's 212, so I'll use that and work it out, thank youuu :smile:
Original post by kewla1
guys is convergence and intergration the same in terms of role of synapses? One markscheme says convergence and the other says intergration....I'm so lost!


Convergence and divergence are both forms of integration I believe.


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