Year 12s: what will be the first way you research your future options? >>

F215 - Revision thread 13th June 2011

Scroll to see replies

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.

Reply 3261

himmai

50/(296+50) = p^2 = 0.14450....

rootANS = p = 0.3801

q = 1 - 0.38 = 0.62

Reply 3262

ManPowa

Original post by Tetanus

OCR exams are done at the exact same time everywhere.

yep, thats right.

Reply 3263

mortysteve

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 :s-smilie:

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.

(edited 12 years ago)

Reply 3264

F.I

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

:colondollar:

Sorry, so angry!

Reply 3265

786girl

what is the final definite answer to the last question? theres a mixture of numbers ppl are giving...

Reply 3266

Cheekytart

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!!

Reply 3267

lmfw

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.

Reply 3268

ITZME123

what i dont get is, why are there less dominant than recessive ? :s-smilie:

50 dominant nd 296 recessive surely that makes NO logical sense.

Reply 3269

mortysteve

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.

(edited 12 years ago)

Reply 3270

mortysteve

Original post by ITZME123

what i dont get is, why are there less dominant than recessive ? :s-smilie:

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).

Reply 3271

Cheekytart

I coudve watched countryfile for a flaming month and passed that exam!
Flaming hedgehogs and ladybirds!

DOOOOOM U OCR!

Reply 3272

kwindsor

Original post by Tetanus

you are wrong.

nice and blunt there :hmpf:

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 :smile:

Reply 3273

susan23

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 :biggrin:

Reply 3274

Cheekytart

What did people think about the ladybirds question?
The the nitrogen cycle? WTF??/

Reply 3275

sportycricketer

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!

Reply 3276

jungdao

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."

Reply 3277

Kirbester

http://www.scribd.com/doc/57771557?secret_password=us1rkds87fp9rxnkn2p

You're welcome

Reply 3278

mortysteve

Original post by jungdao

Oops. You're correct. I meant in the other way around. ;p

Reply 3279

Sereni

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