# F215 - Revision thread 13th June 2011 watch

1. (Original post by 786girl)
WAITT

has everyone in the world done the paper???

we dont want people looking at the paper = doing well = raising grade boundaries = we all die
!!!!

just checkinggg
OCR exams are done at the exact same time everywhere.
2. 50/(296+50) = p^2 = 0.14450....

rootANS = p = 0.3801

q = 1 - 0.38 = 0.62
3. (Original post by Tetanus)
OCR exams are done at the exact same time everywhere.
yep, thats right.
4. (Original post by eddie90)
for the evaluation of his conclusion i said that his statement was true cause it does show an increase at high altitudes possibly cause the black are better adapted to survive than reds but i said the conclusion was wrong as at high altitudes it doesnt cause them to survive it helps them too would i get any marks for saying that lol?
His statement was wrong as correlation does not imply causality. There is a relationship, but that's not to say that it's a causal relationship.

Not sure if there'll be a "Award true if qualified" on the mark scheme.

(Original post by kwindsor)
gotta disagree with you on this one, there were only 3 marks and it seems you've over complicated it a bit. also if you do 50/392 it's not .08%
of course i could be wrong but this is just my opinion.
One mark for method (or failing that, for figuring out that q^2 = 0.855).
One mark for p.
One mark for q.

Total population was 346.
The 50 black ladybirds can be either BB or Bb (not just BB). Thus, p^2 + 2pq should roughly (50/346). Which it does.
5. (Original post by ManPowa)
I believe this thread is in it's log growth phase. Just sayin' haha :P
Hopefully OCR is heading towards the decline/DEATH phase

Sorry, so angry!
6. what is the final definite answer to the last question? theres a mixture of numbers ppl are giving...
7. Honestly, I thought the paper was absolutley horrible, horrific, ****ing load of crap!
How can ocr do this to us, Im just praying that the grade boundaries are gna b low!
there was no biology in there except the two big question!
Everyone, complain to Ocr right now! let your voices b heard!!
8. (Original post by 786girl)
what is the final definite answer to the last question? theres a mixture of numbers ppl are giving...
0.92 and 0.08 for definite.
9. what i dont get is, why are there less dominant than recessive ? 50 dominant nd 296 recessive surely that makes NO logical sense.
10. (Original post by himmai)
50/(296+50) = p^2 = 0.14450....

rootANS = p = 0.3801

q = 1 - 0.38 = 0.62
You did what I did.

Unfortunately, the population of bb ladybirds was 296, not 50.
11. (Original post by ITZME123)
what i dont get is, why are there less dominant than recessive ? 50 dominant nd 296 recessive surely that makes NO logical sense.
Dominant doesn't mean that it's the most frequent allele; just that it is expressed in both heterozygous (Bb) and homozygous dominant (BB).
12. I coudve watched countryfile for a flaming month and passed that exam!

DOOOOOM U OCR!
13. (Original post by Tetanus)
you are wrong.
nice and blunt there

it's only 3 marks at the end of the day, and i'm sure those who got .86 and .14 will have got method marks
14. ok guys lets just forget about it and stop post-morteming the exam because we cant change what we wrote. just hope grade boundaries are low and hope that the examiners die by E.coli cucumber spread and lets forget about it. Summer awaits us
The the nitrogen cycle? WTF??/
16. (Original post by mortysteve)
You did what I did.

Unfortunately, the population of bb ladybirds was 50, not 296.
Thats what I did first as well but later realised it was the other the way round!
17. (Original post by mortysteve)
You did what I did.

Unfortunately, the population of bb ladybirds was 50, not 296.
Straight from the exam paper:

"The red form of the ladybird is therefore homozygous recessive at this locus (bb).

The data in Table 7.1 give the total number of the red form of ladybird found as 296, and
the total number of the black form of ladybird as 50."
18. http://www.scribd.com/doc/57771557?s...ds87fp9rxnkn2p

You're welcome
19. (Original post by jungdao)
Straight from the exam paper:

"The red form of the ladybird is therefore homozygous recessive at this locus (bb).

The data in Table 7.1 give the total number of the red form of ladybird found as 296, and
the total number of the black form of ladybird as 50."
Oops. You're correct. I meant in the other way around. ;p
20. (Original post by himmai)
50/(296+50) = p^2 = 0.14450....

rootANS = p = 0.3801

q = 1 - 0.38 = 0.62
But 50/292 is not p^2, it is p^2 + 2pq. Because P is the DOMINANT allele and so is always expressed. You had to use the other number to work it out because that represents the genotype qq

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