# BIOL4 Biology Unit 4 Exam - 13th June 2011 watch

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1. Remember kids: p=0.05 means the probability that the results are due to chance is 5%, and it's very important you remember to check the sign and the number. I remember a paper which decided to set the statistical test at p=0.5 (50%, which is ridiculous but...) somewhere which caught a lot of people out.
If you didn't know this by now I'm worried.

(Original post by SK-mar)
anyone super nervous haha?! its getting to that stage now... although its a nice feeling knowing we have the morning to relax a little....
Relax? Surely you jest. The morning is when you realise you've forgotten half the material and cram like hell. You just have longer to do the cramming in an afternoon. But longer to panic.
There are no winners.
Welcome to AQA Biology.
2. Thats whats i like to hear, although if it does, il be back for a negative rating
3. (Original post by Master.K)
True, but I guess you just have to try your best. Haha.
My prediction for 5 markers are either of these LIR..... Carbon/Nitrogen Cycle.....Eutrophication,....Fer tilisers....Chemical Pesticides.
yeh I'd say those few pretty fair guesses. I don't know what may come up, maybe something that will totally surprise us like, demographic transition model for human populations, or maybe a green house gases question.
4. (Original post by *Rainbow*)
If you give an example of a question you can't do i'll see whether I can help with it
cheers

ques 5 part b on the spec paper is the one i was doing but other than p+q=1 i dont no anything else.
5. (Original post by Zetsubeau)
Remember kids: p=0.05 means the probability that the results are due to chance is 5%, and it's very important you remember to check the sign and the number. I remember a paper which decided to set the statistical test at p=0.5 (50%, which is ridiculous but...) somewhere which caught a lot of people out.
If you didn't know this by now I'm worried.

Relax? Surely you jest. The morning is when you realise you've forgotten half the material and cram like hell. You just have longer to do the cramming in an afternoon. But longer to panic.
There are no winners.
Welcome to AQA Biology.
the thing i get confused on here is.... if the probability of something being due to chance is 5% or less - does that mean there is no significant statistical difference so we accept the results... or there is a significant statistical difference etc? confused.com
6. (Original post by SK-mar)
demographic transition model for human populations
Hope we get that one just because almost nobody will understand what this means.
The UMS system reminds me of Battle Royale sometimes.
7. (Original post by Zetsubeau)
Hope we get that one just because almost nobody will understand what this means.
The UMS system reminds me of Battle Royale sometimes.
haha....
8. nothing on muscles or how they work has come up yet has it? im hoping for that tomorrow...no wait today...
9. (Original post by Zetsubeau)
Remember kids: p=0.05 means the probability that the results are due to chance is 5%, and it's very important you remember to check the sign and the number. I remember a paper which decided to set the statistical test at p=0.5 (50%, which is ridiculous but...) somewhere which caught a lot of people out.
But if p <0.05 then its due to chance, and results are or are not significant?
nothing on muscles or how they work has come up yet has it? im hoping for that tomorrow...no wait today...
Muscles is unit 5
11. (Original post by SK-mar)
the thing i get confused on here is.... if the probability of something being due to chance is 5% or less - does that mean there is no significant statistical difference so we accept the results... or there is a significant statistical difference etc? confused.com
5% level is the level of critical value or whatever equivalent there is you chose to use in your statistical test, and the value varies depending on which (I've been revising Psychology and I can't remember whether it's higher or lower for each right now, annoyingly.)
If the critical value at p=0.05 was 0.1 and your test came up with 0.2, and it was one that needed it to be higher than the critical value, then it was be significant as 0.2>0.1. This means that the results are not due to chance, so you can reject the null hypothesis and accept the alternative hypothesis.
Correct me if I'm wrong, it's kinda late.
12. (Original post by Zetsubeau)
5% level is the level of critical value or whatever equivalent there is you chose to use in your statistical test, and the value varies depending on which (I've been revising Psychology and I can't remember whether it's higher or lower for each right now, annoyingly.)
If the critical value at p=0.05 was 0.1 and your test came up with 0.2, and it was one that needed it to be higher than the critical value, then it was be significant as 0.2>0.1. This means that the results are not due to chance, so you can reject the null hypothesis and accept the alternative hypothesis.
Correct me if I'm wrong, it's kinda late.
yeh i think i understand that mate! cheers... off to sleep now and up at 8.30 .... gonna get some last min revisionnn in before the exam... good luck!!!
13. (Original post by Rainbow249)
But if p <0.05 then its due to chance, and results are or are not significant?
My brain can't handle numbers. What is this I don't even.
p<0.05 means probability that the results are due to chance is less than 0.05. If it's less than 0.05 then it is less likely to be due to chance. If it's not due to chance, results are significant.
Again, correct me if I'm wrong.

(Original post by Rainbow249)
Muscles is unit 5
Annoyingly.
Muscles or ecology? Gee I wonder what I'd prefer.
14. (Original post by dents)
cheers

ques 5 part b on the spec paper is the one i was doing but other than p+q=1 i dont no anything else.
Heyy Yeah that questions a bit sneaky

basically: In order for the recessive allele to be expressed you must have homozygous recessive right? So it can only be q^2 .We know that q (the recessive) is 0.7 so 0.7^2 = 0.49 from the longer equatio psquared + 2pq + qsquared = 1 (you need to learn this eqn it's in your textbook) so anyways

0.49 x 100 to make it a percentage is 49% for the red (recessive)

Then we move on to the dominant. Since a dominant allele can be expressed even when heterozygous 2pq or psquared will be black so 2x 0.3 x 0.7 = 0.42 + 0.3squared = 0.51 x100 = 51%

Hence 51% black 49% red.
15. (Original post by *Rainbow*)
Heyy Yeah that questions a bit sneaky

basically: In order for the recessive allele to be expressed you must have homozygous recessive right? So it can only be q^2 .We know that q (the recessive) is 0.7 so 0.7^2 = 0.49 from the longer equatio psquared + 2pq + qsquared = 1 (you need to learn this eqn it's in your textbook) so anyways

0.49 x 100 to make it a percentage is 49% for the red (recessive)

Then we move on to the dominant. Since a dominant allele can be expressed even when heterozygous 2pq or psquared will be black so 2x 0.3 x 0.7 = 0.42 + 0.3squared = 0.51 x100 = 51%

Hence 51% black 49% red.
I have a feeling this will never stick for me. I understand the basic idea but the mechanics just sort of dance circles around me.
The reasons to hate ecology just pile up.
But let me try and get it through my head here.
p+q=1 because 1 that totals all possible combinations. That's the easy bit.
p^2 and q^2 are the homozygotes while 2pq is heterozygotes? Because p^2 accounts for two dominants, q^2 all recessives, and pq only covers one half, so you multiply by two? This is where I run out of skills a bit.
If you want to find just the recessive, you need q^2, because you can only get recessive expressed in a qq (less qq more pewpew). If q=0.7 then q^2 is whatever, you say 0.49 so I'm saying that. That's obviously 49% of the population.
For dominant to be expressed, assuming it's not co-dominant, you add up all the remaining? So that'd be 51%?
Assuming I'm right, what situations are we likely to come across where it's harder than this?
16. could someone explain the nitrogen cycle to me please? i keep getting mixed up! gosh i need to sleep...
17. (Original post by sms21)
could someone explain the nitrogen cycle to me please? i keep getting mixed up! gosh i need to sleep...
What's your mental version of it?
18. (Original post by Zetsubeau)
I have a feeling this will never stick for me. I understand the basic idea but the mechanics just sort of dance circles around me.
The reasons to hate ecology just pile up.
But let me try and get it through my head here.
p+q=1 because 1 that totals all possible combinations. That's the easy bit.
p^2 and q^2 are the homozygotes while 2pq is heterozygotes? Because p^2 accounts for two dominants, q^2 all recessives, and pq only covers one half, so you multiply by two? This is where I run out of skills a bit.
If you want to find just the recessive, you need q^2, because you can only get recessive expressed in a qq (less qq more pewpew). If q=0.7 then q^2 is whatever, you say 0.49 so I'm saying that. That's obviously 49% of the population.
For dominant to be expressed, assuming it's not co-dominant, you add up all the remaining? So that'd be 51%?
Assuming I'm right, what situations are we likely to come across where it's harder than this?
Yeah sounds like you've got it fine! Dont worry too much.. well as long as you know the above you'll be fine this one was a 2 mark question sometimes there are 3 mrks available but i dont think ive seen higher.
Anyhooo

Good luck! Maybe see you on here tomorrow morning? Haha last second revision my forte Good night I have to try force myself to sleep now. All the best

*LOL at the 7 thing wouldnt even have noticed!
Also edited 7 mins ago :O must be fate
19. Good luck all. I'm in AS but i'm doing this next jan!
You'll all be finee
20. guys are you doing pastpapers or going through your notes

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