A Level Edexcel SNAB Biology 6th June 2017 Discussion Thread PAPER 2 Watch

C_Yap
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Haven't found a thread for it yet, so decided to make one.

How did paper 2 go for you guys today? I personally found the 6 marker on malaria and Africa confusing at first, but then I eventually got it.
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bioenthusiast
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Wasn't awful but wasn't good. Same here about the 6 marker - I eventually clicked and talked about natural selection did you?? Also, for the other 6 marker on mitosis I accidentally talked about changing concentrations but reread the question and had to talk about changing time.

What do you think the grade boundaries will be like? Really hope they're low I want a B at least
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C_Yap
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(Original post by bioenthusiast)
Wasn't awful but wasn't good. Same here about the 6 marker - I eventually clicked and talked about natural selection did you?? Also, for the other 6 marker on mitosis I accidentally talked about changing concentrations but reread the question and had to talk about changing time.

What do you think the grade boundaries will be like? Really hope they're low I want a B at least
According to last year's grade boundaries, it was 57% between both papers for an A overall, so not that bad

Yes, I did mention parts about natural selection. What I did, was I compared the allele frequencies of those who are heterozygous, homozygous for condition, and homozygous without allele.

Heterozygous - Resistant to cerebral malaria and won't develop sickle cell anaemia. This will lead to an increase in heterozygous individuals, so frequency of allele will increase. More likely to survive and reproduce as they can survive against the selection pressure and pass on the sickle cell allele.

Homozygous - Likely to develop severe sickle cell anaemia, so frequency of the allele may decrease

Homozygous without allele - Will not develop sickle cell, but vulnerable to the malaria, which is endemic in the region. This may lead to a decrease of non-sickle cell alleles.

I have no idea if it's right haha.

Also, I think you will lose marks on the 6 marker where you mentioned concentration. You are likely to lose other marking points since your investigation doesn't actually answer the question.

Overall, I found it okay. I think i did get the Hardy Weinberg equation wrong. I got 192, how about you?
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bioenthusiast
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(Original post by Baaah)
According to last year's grade boundaries, it was 57% between both papers for an A overall, so not that bad

Yes, I did mention parts about natural selection. What I did, was I compared the allele frequencies of those who are heterozygous, homozygous for condition, and homozygous without allele.

Heterozygous - Resistant to cerebral malaria and won't develop sickle cell anaemia. This will lead to an increase in heterozygous individuals, so frequency of allele will increase. More likely to survive and reproduce as they can survive against the selection pressure and pass on the sickle cell allele.

Homozygous - Likely to develop severe sickle cell anaemia, so frequency of the allele may decrease

Homozygous without allele - Will not develop sickle cell, but vulnerable to the malaria, which is endemic in the region. This may lead to a decrease of non-sickle cell alleles.

I have no idea if it's right haha.

Also, I think you will lose marks on the 6 marker where you mentioned concentration. You are likely to lose other marking points since your investigation doesn't actually answer the question.

Overall, I found it okay. I think i did get the Hardy Weinberg equation wrong. I got 192, how about you?
Oh god I've completely messed up. Got 96 for Hardy but someone I know got 192 so you're probably right. And yeahfor the mitosis I corrected my errors by crossing out the concentration stuff but don't think I did well. It's annoying because I feel like the content of Biology isn't that difficult it's the exam questions. And despite doing all past papers since 2009 I still was unprepared. Just got to hope for low grade boundaries!!


Also, do you remember the values you got for the mitotic index and the percentage change on the stem cells ? Also for the 4 marker on stem cells did you talk about differential gene expression
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C_Yap
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(Original post by bioenthusiast)
Oh god I've completely messed up. Got 96 for Hardy but someone I know got 192 so you're probably right. And yeahfor the mitosis I corrected my errors by crossing out the concentration stuff but don't think I did well. It's annoying because I feel like the content of Biology isn't that difficult it's the exam questions. And despite doing all past papers since 2009 I still was unprepared. Just got to hope for low grade boundaries!!


Also, do you remember the values you got for the mitotic index and the percentage change on the stem cells ? Also for the 4 marker on stem cells did you talk about differential gene expression
For mitotic index, I don't remember exactly the value, but you just have to had up the numbers next to prophase, metaphase, anaphase and telophase, and then divide by the sum of all the numbers and then multiply by hundred.

Percentage change of stem cells was ridiculously low for me. I think I got 3.75 x 10^-5 % per year

For the 4 marker on stem cells, I talked about DNA methylation, histone modification, as well as the fact that the specialised cell produced is dependent on the level of epigenetic modifications found in the DNA.

And same, the content is actually straightforward for Biology, but it is the exam technique that always catched me out. I think it's the main reason why the grade boundaries are low.
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bioenthusiast
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(Original post by Baaah)
For mitotic index, I don't remember exactly the value, but you just have to had up the numbers next to prophase, metaphase, anaphase and telophase, and then divide by the sum of all the numbers and then multiply by hundred.

Percentage change of stem cells was ridiculously low for me. I think I got 3.75 x 10^-5 % per year

For the 4 marker on stem cells, I talked about DNA methylation, histone modification, as well as the fact that the specialised cell produced is dependent on the level of epigenetic modifications found in the DNA.

And same, the content is actually straightforward for Biology, but it is the exam technique that always catched me out. I think it's the main reason why the grade boundaries are low.

Yeah I did the same for mitotic index I got 12.6% I think. And the stem cells one I forgot actually haha.

I talked about something difffenr for that one I talked about how activated genes transcribe mRNA which is then translated into proteins which modifies cell structure and function and cause differentiation. Also described how it was a pluripotent cell. I'm not sure I'm probably wrong
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heyheyhye
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(Original post by Baaah)
For mitotic index, I don't remember exactly the value, but you just have to had up the numbers next to prophase, metaphase, anaphase and telophase, and then divide by the sum of all the numbers and then multiply by hundred.

Percentage change of stem cells was ridiculously low for me. I think I got 3.75 x 10^-5 % per year

For the 4 marker on stem cells, I talked about DNA methylation, histone modification, as well as the fact that the specialised cell produced is dependent on the level of epigenetic modifications found in the DNA.

And same, the content is actually straightforward for Biology, but it is the exam technique that always catched me out. I think it's the main reason why the grade boundaries are low.
Wasn't the stem cell answer about the genes being switched on and so an active mRNA is transcripted and translated and a protein is synthesised that decides the structure and function of the cell.
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C_Yap
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(Original post by bioenthusiast)
Yeah I did the same for mitotic index I got 12.6% I think. And the stem cells one I forgot actually haha.

I talked about something difffenr for that one I talked about how activated genes transcribe mRNA which is then translated into proteins which modifies cell structure and function and cause differentiation. Also described how it was a pluripotent cell. I'm not sure I'm probably wrong
Your answers sounds more right than mine does...
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Yousman
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Unofficial Mark Scheme:
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bioenthusiast
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(Original post by heyheyhye)
Wasn't the stem cell answer about the genes being switched on and so an active mRNA is transcripted and translated and a protein is synthesised that decides the structure and function of the cell.

That's what I did
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C_Yap
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(Original post by heyheyhye)
Wasn't the stem cell answer about the genes being switched on and so an active mRNA is transcripted and translated and a protein is synthesised that decides the structure and function of the cell.
Yep, I got it wrong :/

Oh well, I did mention about genes being switched on/off, so I should get 1 mark at least...
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bioenthusiast
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(Original post by Baaah)
Your answers sounds more right than mine does...
No idea- I hope we both did well!!
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heyheyhye
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(Original post by bioenthusiast)
Yeah I did the same for mitotic index I got 12.6% I think. And the stem cells one I forgot actually haha.

I talked about something difffenr for that one I talked about how activated genes transcribe mRNA which is then translated into proteins which modifies cell structure and function and cause differentiation. Also described how it was a pluripotent cell. I'm not sure I'm probably wrong
I wrote the same
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bioenthusiast
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(Original post by heyheyhye)
I wrote the same
what did you get for mitotic index?
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heyheyhye
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(Original post by bioenthusiast)
what did you get for mitotic index?
I can't remember, I added all the number in prophase, metaphase, anaphase and telophase and divided it by the total and multiplied by 100
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Yousman
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(Original post by bioenthusiast)
Wasn't awful but wasn't good. Same here about the 6 marker - I eventually clicked and talked about natural selection did you?? Also, for the other 6 marker on mitosis I accidentally talked about changing concentrations but reread the question and had to talk about changing time.

What do you think the grade boundaries will be like? Really hope they're low I want a B at least

What was the answer to the 'IRAK 1 gene' question?
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heyheyhye
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Wha did you write for the starch question?
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bioenthusiast
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(Original post by Yousman)
What was the answer to the 'IRAK 1 gene' question?
That was hard. All I remember putting was that women have XX and men is XY so men would have lupus more than women as the IRAK gene is expressed no matter what if it's on X but for women it needs to be on both to be expressed. Idk I'm baffled
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(Original post by heyheyhye)
Wha did you write for the starch question?

Topic 1 style question
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(Original post by heyheyhye)
I wrote the same


Answer to the IRAK1 gene ?
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