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<a https://www.thestudentroom.co.uk/showthread.php?t=7467335'> Year 12s: what will be the first way you research your future options? >>

A2 Biology OCR June 2015 Revision Thread

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Original post by Diamond Crafter
Same! I cracked Hardy Weinberg two nights ago so I'm hoping it comes up xD


Don't wanna burst your bubble but it's really unlikely to come up as it came up last year lol. Damn it :frown:
Original post by hajs
Quick Question... HEP.jpg


They can add a genetic marker and the more active the gene is, the more mRNA produced which cn be detected under uv light.

I'm assuming them extract the mRNA after that and yeah, that's something that's been dumbed down for our course
how do you work this out:

The human ABO blood groups are A, B, AB and O. They are determined by a singlegene with multiple alleles. IAand IBalleles are codominant, but both these alleles aredominant to the IOallele.

In a maternity ward, the identities of four babies became accidentally mixed up. TheABO blood groups of the babies were discovered to be O, A, B and AB. The ABOblood groups of the four sets of parents were determined and are shown in the tablebelow.

Complete the table to match each baby to its parents by indicating:

• the parental genotypes, using the symbols IA, IBand IO;
• the blood group of the baby which belongs to each set of parents

parental blood groups /parental genotypes/ baby blood group
O and O
AB and O
A and O
AB and A
What do we need to know for outining the role of ATP in muscle contraction
Original post by cinderella25
how do you work this out:<br />
<br />
The human ABO blood groups are A, B, AB and O. They are determined by a singlegene with multiple alleles. IAand IBalleles are codominant, but both these alleles aredominant to the IOallele. <br />
<br />
In a maternity ward, the identities of four babies became accidentally mixed up. TheABO blood groups of the babies were discovered to be O, A, B and AB. The ABOblood groups of the four sets of parents were determined and are shown in the tablebelow.<br />
<br />
Complete the table to match each baby to its parents by indicating:<br />
<br />
• the parental genotypes, using the symbols IA, IBand IO; <br />
• the blood group of the baby which belongs to each set of parents<br />
<br />
parental blood groups /parental genotypes/ baby blood group <br />
O and O<br />
AB and O<br />
A and O<br />
AB and A


O and O is obviously baby O

A and O is baby A as o and o is definitely o as that's homozygous recessive, even though there is a possibility these parents would produce an O baby

Which means that AB and O is likely to be baby B and Parent A and O are the ones to have baby A

AB and B have baby AB then
Original post by cr7alwayz
What do we need to know for outining the role of ATP in muscle contraction


ATP breaks the actin myosin cross bridge so myosin heads can bind to a different binding site and pull the actin filament along the myosin
Original post by ChoccyPhilly
O and O is obviously baby O

A and O is baby A as o and o is definitely o as that's homozygous recessive, even though there is a possibility these parents would produce an O baby

Which means that AB and O is likely to be baby B and Parent A and O are the ones to have baby A

AB and B have baby AB then


I get O and O = baby O
A and O = baby A

I just don't get the other two. How AB and O = baby B and AB and B = baby AB

how did you work that out
Original post by Diamond Crafter
Same! I cracked Hardy Weinberg two nights ago so I'm hoping it comes up xD


May you explain it please?
I know it's like p+q=1
and 2pq + blah
but how would I do this question?

1 in 2000 people have cystic fibrosis in the UK ff
Find the percentage of carriers :s-smilie:
Original post by cinderella25
I get O and O = baby O<br />
A and O = baby A<br />
<br />
I just don't get the other two. How AB and O = baby B and AB and B = baby AB<br />
<br />
how did you work that out


AB and O can be either baby A or baby B, right?

If parents A and O are baby A then therefore, parents AB and O must be baby B as baby A has been confirmed by other evidence.

In the same way that AB and B can be either AB or B, B has been confirmed previously from parents AB and O, so therefore, AB and B must be AB.

Also, no other parent combination can produce AB either as the rest have O as one of their parents, meaning you dint get codominance
Any predictions for the exam?
(edited 8 years ago)
Original post by ChoccyPhilly
AB and O can be either baby A or baby B, right?

If parents A and O are baby A then therefore, parents AB and O must be baby B as baby A has been confirmed by other evidence.

In the same way that AB and B can be either AB or B, B has been confirmed previously from parents AB and O, so therefore, AB and B must be AB.

Also, no other parent combination can produce AB either as the rest have O as one of their parents, meaning you dint get codominance


Thank you for your explanation it makes sense now!


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Original post by frozo123
May you explain it please?
I know it's like p+q=1
and 2pq + blah
but how would I do this question?

1 in 2000 people have cystic fibrosis in the UK ff
Find the percentage of carriers :s-smilie:


Ok, to find da carriers we need to know what 2pq is. 2pq is all da individuals who are heterozygous k. They carry one legit allele and one faulty allele

So we know dat q^2 would be 1 in 2000 i.e. 1/2000, which is 0.0005
Therefore q would be root 0.0005, which is 0.02236....

And you know dat p+q = 1 yeah
Dat means dat p would be 1-0.02236..., which is 0.977639...

Now all you gots to do is 2 times p times q, which is 2 x 0.977639... x 0.02236...

= 0.0437...

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(edited 8 years ago)
Original post by cinderella25
Any predictions for the exam?


Lots and lots of ecology... I think a big question on succssion
Original post by Prince edmund
Ok, to find da carriers we need to know what 2pq is. 2pq is all da individuals who are heterozygous k. They carry one legit allele and one faulty allele

So we know dat q^2 would be 1 in 2000 i.e. 1/2000, which is 0.0005
Therefore q would be root 0.0005, which is 0.02236....

And you know dat p+q = 1 yeah
Dat means dat p would be 1-0.02236..., which is 0.977639...

Now all you gots to do is 2 times p times q, which is 2 x 0.977639... x 0.02236...

= 0.0437...

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so is it 2pq= x
not pq= x/2 ?
Original post by ChoccyPhilly
Lots and lots of ecology... I think a big question on succssion


ugh :colonhash:
Original post by ChoccyPhilly
Lots and lots of ecology... I think a big question on succssion


That would be awesome! That's the easiest topic lol


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Original post by cinderella25
That would be awesome! That's the easiest topic lol<br />
<br />
<br />
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I hate ecology so much. Last years paper would be so ideal as the.long question was on transction and translation, which I really enjoy but I don't think we'll get a lot of genetics in our paper
The responding to the environments section is the easiest by far and away. Half of it is AS psychology. :biggrin:
Original post by ChoccyPhilly
I hate ecology so much. Last years paper would be so ideal as the.long question was on transction and translation, which I really enjoy but I don't think we'll get a lot of genetics in our paper


It is boring topic I have to agree but it is the easiest topic because you don't really have to learn a lot of keywords for it. It's the same as AS biodiversity just with a bit more info. You just need some keywords such as maintaining biodiversity etc and that's all lol

Yeah genetics is really cool but that all came last year so we will only get 2-3 marks questions for that. I am really dreading meiosis topic


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Original post by Diamond Crafter
The responding to the environments section is the easiest by far and away. Half of it is AS psychology. :biggrin:


Yeah and that will come up in the exam because it has lots of synoptic questions. So it's always good to learn that section


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