OCR Biology Unifying Concepts today...

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crana
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#41
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#41
(Original post by Tanaz)
btw, what did every1 put for the genetic question on central concept paper(the first paper).. i mean the question with at A ac as thing??!!where u had to write the six possible genotype any phenotype?!!.. was it multiple allele?? caz i put A as ac, A as as, A ac ac, as ac ac, and so on!!..but it doesnt look right :confused: ...
sorry but I think you were wrong..

The 6 combinations were:

A as

A A

A ac

as as

as ac

ac ac

I am not sure how on earth you would get combinations of 3 alleles. We have chromosomes in pairs, so any combination (and I am positive the question meant "of two alleles") would have to be an even number anyway..
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xk8
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#42
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#42
hmm... can't quite work out how i did in that unifying paper, i don't feel like i wrote bout much from my biology2 text book! can i just ask (cos its gonna bug me!) why on earth you use a the nicotine plant with a leaf cut off as the control? lol only worth a mark but its stuck in my mind!
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kingpong
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#43
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#43
(Original post by xk8)
hmm... can't quite work out how i did in that unifying paper, i don't feel like i wrote bout much from my biology2 text book! can i just ask (cos its gonna bug me!) why on earth you use a the nicotine plant with a leaf cut off as the control? lol only worth a mark but its stuck in my mind!
I totally guessed that the leaf punctured would eventually fall off (abcisic acid etc), so the % nicotene for the biomass would be equivilant for both.
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crana
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(Original post by kingpong)
I totally guessed that the leaf punctured would eventually fall off (abcisic acid etc), so the % nicotene for the biomass would be equivilant for both.
that doesnt really make sense though. The nicotine is, as you say, a % - so it doesnt matter if the biomasses differ (which they inevitably will, even if you slice a leaf off)..

unless you mean some other way it would make them equivalent?

rosie
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adrian
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#45
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#45
(Original post by xk8)
hmm... can't quite work out how i did in that unifying paper, i don't feel like i wrote bout much from my biology2 text book! can i just ask (cos its gonna bug me!) why on earth you use a the nicotine plant with a leaf cut off as the control? lol only worth a mark but its stuck in my mind!

I put that a leaf was cut off because realistically some plants from the forest will not have all their leaves due to animals eating it. So this was done to mimic a life-like situation to make the test more valid.
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charlord
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#46
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(Original post by kingpong)
I totally guessed that the leaf punctured would eventually fall off (abcisic acid etc), so the % nicotene for the biomass would be equivilant for both.
oh bum...i said because it was a known quantity or something
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crana
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#47
I said it was to control the variable of a leaf being removed...

but now I can't remember if the organism thingy actually removed a leaf or just damaged it?

rosie
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ThunderCat8
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#48
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#48
I said to remove the leaf instead as insects may have punctured the leaves without the scientists knowing. lol, ******** i know!
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starcrossed
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#49
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#49
lol, i wrote exactly the same thing lol
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emzie
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#50
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#50
i didnt know that one, said it may contain SOME nicotine, and so to remove it to ensure a fair test.
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kingpong
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#51
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#51
(Original post by crana)
that doesnt really make sense though. The nicotine is, as you say, a % - so it doesnt matter if the biomasses differ (which they inevitably will, even if you slice a leaf off)..

unless you mean some other way it would make them equivalent?

rosie
Yeah, it was a crappy answer, but it was all I could think of.

It was just based on the presumtion that the damaged leaf would fall off after it had been punctured etc., therefore the biomass of the two plants would be equivilant, since I don't know whether leaves have a greater concentration of nicotene. If they do have a higher/lower conc, then if the control plant was left with an extra leaf the % nicotene/mass would be messed up.

I dunno, bad question. I really couldn't think of any other reasion that would cause them to remove a leaf.
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ResidentEvil
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#52
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#52
let's just settle it, that paper sucks! they better lower the raw marks to get a decent UMS, but I doubt it coz there are those annoying individuals who are amazing at interpreting random data.

It's so unfair really, coz it's kinda not really testing Biology knowledge, but testing memory (e.g. how much information u can absorb from the paragraph without re-reading it), a bit of maths (although I dont mind that ), english language, working under time pressure, writing speed, reading speed, and analysation skills - and then they'll throw in like one small biology question to make it a "biology" exam.

I mean look at the chemistry synoptic for ****s sake, that involves last year's work and throws in a bit of extra for u to learn - i.e. it is chemistry overall. Therefore it's a sensible paper without having to really confuse u.

There's also that thing with the content in biology that really pisses me off. Biology there is like TWICE to write and literally TWICE to read in comparison to chemistry, yet u get the same time limit? how unfair is that? Biology's only advantage is they give many "alternative" answers, but still, for chemistry u still get some alternatives, and the examiner can still decide to give u a mark for an appropriate point. Also Biology's so-called alternative answers are usually directly related to the other points anyway, so it's not really an "alternative".

Anyway my rant is over, Biology OCR should think of a new strategy. oh I also forgot, what's with the biology practicals always involving bloody chemicals? Do they always rely on chemistry to do jack all "science"?
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crana
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(Original post by kingpong)
Yeah, it was a crappy answer, but it was all I could think of.

It was just based on the presumtion that the damaged leaf would fall off after it had been punctured etc., therefore the biomass of the two plants would be equivilant, since I don't know whether leaves have a greater concentration of nicotene. If they do have a higher/lower conc, then if the control plant was left with an extra leaf the % nicotene/mass would be messed up.

I dunno, bad question. I really couldn't think of any other reasion that would cause them to remove a leaf.
ah well my answer was really crap so. i love the way almost everyone has come up with something completely different for this!

I think though that they didn't count the no. of leaves of the plant, so like they didnt have punctured one with 9 leaves then remove one from a 10 leaf plant to make them the same.

On reflection Id have referred to the bit about slicing with a sharp blade in the question. But a bit late now

rosie
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Meghan
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#54
(Original post by adrian)
Wrote about depolarisation, repolarisation, refractory period, -70mV changing to +40mv, Voltage gated channels sodium/potassium pump. That's all I can remember at the mo.
that's what I wrote about
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Meghan
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#55
(Original post by crana)
The 6 combinations were: A as - A A - A ac - as as - as ac - ac ac

I am not sure how on earth you would get combinations of 3 alleles. We have chromosomes in pairs, so any combination (and I am positive the question meant "of two alleles") would have to be an even number anyway..
the answers you got were what i wrote - the correct answer

it's impossible to have combinations of the three alleles in this case - only the two.
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kingpong
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#56
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#56
(Original post by Meghan)
that's what I wrote about
But why??

It wasn't a nerve transmission question, was it?

Surely the diffusion of Na+ between the cells, causing depolarising of the sarcoplasmic reticulum was enough? I didn't read it as a 'nerous transmission along a neurone' question. Hmmmm.
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Meghan
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#57
(Original post by kingpong)
It wasn't a nerve transmission question, was it?
to be honest, I've completely forgotten about it all now, and I couldn't care less :rolleyes: but that is what i wrote about.
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adrian
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#58
(Original post by kingpong)
But why??

It wasn't a nerve transmission question, was it?

Surely the diffusion of Na+ between the cells, causing depolarising of the sarcoplasmic reticulum was enough? I didn't read it as a 'nerous transmission along a neurone' question. Hmmmm.
No it wasn't a question on nerve transmission. If it were then the answer would have to include something about transmittor neurones and also about receptors on the post-synaptic membrane. But any it's all over and done with. No point in crying over spilt milk eh
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Meghan
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#59
(Original post by adrian)
If it were then the answer would have to include something about transmittor neurones and also about receptors on the post-synaptic membrane.
also pieces of information i wrote about...

but nevertheless, it's been and gone. I'm just thankful that friday is my last ever biology exam!
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kingpong
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#60
(Original post by adrian)
No it wasn't a question on nerve transmission. If it were then the answer would have to include something about transmittor neurones and also about receptors on the post-synaptic membrane. But any it's all over and done with. No point in crying over spilt milk eh
I think you misinterpreted me. I'm still not sure what the question was asking for, dunno what's right, what's wrong.
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