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AQA A2 Biol4 January 2012 pre- exam discussion

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Reply 60

yeebz93

I beg you email me these resources

Reply 61

clukas

We just finished the syllabus here as well. Just preparing for the A2 ISA which is on monday.

Reply 62

EffKayy

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL4-W-SQP-07.PDF
Can someone help me with 6? Why is the percentage of the black lady birds 51%? I did it and got 42% :s-smilie:

I got the red lady birds answer right though.

I assumed the black lady birds had heterozygous alleles, etc... so I did 0.7*0.3(*2)

Reply 63

SKPD11

Original post by EffKayy

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL4-W-SQP-07.PDF
Can someone help me with 6? Why is the percentage of the black lady birds 51%? I did it and got 42% :s-smilie:

I got the red lady birds answer right though.

I assumed the black lady birds had heterozygous alleles, etc... so I did 0.7*0.3(*2)

Your not supposed to work out the black ladybirds directly, you work out the red ladybird percentage and then take away from 100% to work out the black ladybird percentage . So like as you said the 49% for the red lady birds so the black ones are 51%

Reply 64

Master S P

Hey there,

Do those questions have answers to them though? :s-smilie:

Reply 65

tamii05

I'm doing this exam too. Just going over a few more topics and should be starting with exam papers this week. :s-smilie:

Reply 66

NutterFrutter

I'll be doing this exam. :yep:

Reply 67

EffKayy

Original post by NutterFrutter

I'll be doing this exam. :yep:

Have you tried the Jan 2010 paper yet? :colone:

Reply 68

NutterFrutter

Original post by EffKayy

Have you tried the Jan 2010 paper yet? :colone:

I've done some questions from it. Some of the questions are difficult to understand as to what they're asking for exactly but the paper isn't too bad.

Reply 69

EffKayy

Original post by NutterFrutter

I've done some questions from it. Some of the questions are difficult to understand as to what they're asking for exactly but the paper isn't too bad.

The latest papers (June 2011 and Jan 2011) have been much fairer so i'm hoping for something similar fingers crossed.
Yeah it was just the Hair tube question thing which was a bit mean and I got some of the first ones wrong o_O
The 15marks at the end are good though :smile:

Reply 70

handsome7654

Original post by EffKayy

This exam is just so stupid!! For some of the questions the mark scheme is ridiculous!! :mad:

Exactly :|

Any chance of uploading the material on here or pm'ing it :smile:

? thanks!

Reply 73

tamii05

Did the Jan '11 paper today as a mock. Didn't do very well I think. :redface:

Reply 74

Rahul.S

might do some work for this tonight.....got a mock tomorrow :yawn:

Reply 75

beckswilkinson

Can anyone find the 2011 June paper?!

Reply 76

tamii05

Original post by beckswilkinson

Can anyone find the 2011 June paper?!

I think only teachers can access that. Someone could have it though.

Reply 77

Apa

I took both my Unit 1 & 2 exams in June due to illness and I just completely failed on both of them. On every other exam I took in June I got an A and I have had a look at my paper and the mark scheme and my exam technique is just not at all what they're asking for. Has anyone else overcome problems with their exam techniques? I don't want to do the past papers too many times because once you've done a paper one and gone through the mark scheme any future attempts are obviously not going to be accurate of your knowledge.

Reply 78

Besakt

Original post by EffKayy

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL4-W-SQP-07.PDF
Can someone help me with 6? Why is the percentage of the black lady birds 51%? I did it and got 42% :s-smilie:

I got the red lady birds answer right though.

I assumed the black lady birds had heterozygous alleles, etc... so I did 0.7*0.3(*2)

The 2 equations you need to know are :

1. p + q = 1

2. p^2 + q^2 + 2pq = 1

p or B (dominant allele frequency ) = 1 - 0.7 = 0.3 (rearranged equation p + q = 1)
q or b (recessive allele frequency) = 0.7 this is give in the data
p^2 or B^2 (homozygous dominant Black) = 0.3^2 = 0.09
q^2 or b^2 (homozygous recessive Red) = 0.7^2 = 0.49
2pq or 2Bb (heterozygous, it is 2pq because you can have pq or qp Black) = 2 x 0.3 x 0.7 = 0.42

Just to check everything is right

Substitute numbers into equations:

1. 0.3 + 0.7 = 1

2. 0.09 + 0.49 + 0.42 = 1

Black ladybirds can have genotype B^2 or 2Bb (because B is the dominant allele) which 0.09 and 0.42 = 0.51

Red ladybirds can only have genotype bb as they have to be homozygous recessive which is 0.49

Then you just times it by a 100 to go from decimals to percentages

So 0.51 x 100 = 51% black ladybirds.
and 0.49 x 100 = 49% red ladybirds.

(edited 12 years ago)

Reply 79

Besakt

Original post by Apa

Yeah the AQA biology has a very awkward mark scheme, I suppose we just have to practice, I did the June 2011 exam paper as a mock and got 46/75 which is terrible because of poor exam technique, it is so annoying as you know the answer but because you haven't phrased the answer in the way they like you don't get the mark.