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BIOL4 Biology Unit 4 Exam - 13th June 2011

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Reply 740
Original post by FatalError
You don't need to know about specific disorders i think. I don't think it's only in men is it?
They are more likely to suffer from it because their sex chromosomes are not the typical bivalent so they are less likely to have the dominant allele to override the recessive allele.


Yeah because the X chromosome is bigger than the Y, the reccesive allele on the Y does not correspon to the homolgous part on the X chromosome, so men are more likely to get hameophilia
Reply 741
Anyone help me with an example of a biological agent and its prey??
Original post by Rickesh
I thought it was g m-2?


doesnt really matter now does it :rolleyes:
Original post by Rickesh
Why is haemophilia only in men?


Probably are more likely to be men

Maybe the allele causing the diesease is recessive!
I have actually lost the will to study this stupid module!
Original post by Rickesh
I thought it was g m-2?


It doesn't matter, the mark scheme will credit any units that have both mass and area in.

Original post by SK-mar
just out of question, what would be suitable cultural methods?


I'm guessing they mean something like manual removal of pests? Not really cultural though.
Original post by Rickesh
Why is haemophilia only in men?


The most common cause for hemophilia is a lack of Factor VIII production (the protein that causes clotting) and the gene locus for this protein is on the non-homologous part of the Y chromosome. You don't need to know that for the exam but that explains the sex linkage part.

Non-production of Factor VIII i.e. haemophilia is recessive, and therefore males are more likely to have haemophilia as they only have one X chromosome, and there's no homologous part on the Y chromosome which might have had a dominant allele.

You don't have to know any specific cases with sex linkage, just the general principle that males only have one X chromosome, no homologous part on the Y chromosome so no chance of there being a dominant allele along with the recessive allele. This means if the male inherits the recessive allele on the X chromosome from their mother it will be expressed in their phenotype.
Original post by dents
Anyone help me with an example of a biological agent and its prey??


Aphid or Greenfly is the pest, and Ladybird is the biological control predator.


About the probability and chance thing, is this right...

Probability less than 0.05, so results are not significant and any results were due to chance?
Reply 748
Jan 10 Question 2b i and ii. Could someone explain to me how theyve got the answer, cannot get my head round it it at all, and got a bad feeling it will pop up tommorow :frown:
Reply 749
anyone super nervous haha?! its getting to that stage now... although its a nice feeling knowing we have the morning to relax a little....
Reply 750
i dont understand hardy weinburg at all and am crap at maths can someone please help and give me an idea of what to do

worst thing is it nearly always comes up.
Original post by enjybenji
Jan 10 Question 2b i and ii. Could someone explain to me how theyve got the answer, cannot get my head round it it at all, and got a bad feeling it will pop up tommorow :frown:


There is no 2bi/ii there's only 2b. :s-smilie:
Reply 752
Im so nervous I can't concentrate on anything :/
Reply 753
My bad i meant jan 2011 sorry
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....


I'm not, because I know that every question is based on the data they give you.....Until the 5 markers at the back lol! :teehee:
Reply 755
Original post by Master.K
I'm not, because I know that every question is based on the data they give you.....Until the 5 markers at the back lol! :teehee:


yeh but the data questions are still mostly based on knowledge of the syllabus. application of that knowledge. Thing is, i know there are gonna be some strange questions as AQA usually get a few in, im just apprehensive as to what they're gonna be. I also hope that the last 5 markers are decent.
Original post by enjybenji
My bad i meant jan 2011 sorry


I'm almost certain that a pedigree diagram would not come up for the second time in a row.:smile:
Original post by SK-mar
yeh but the data questions are still mostly based on knowledge of the syllabus. application of that knowledge. Thing is, i know there are gonna be some strange questions as AQA usually get a few in, im just apprehensive as to what they're gonna be. I also hope that the last 5 markers are decent.


True, but I guess you just have to try your best. Haha. :p:
My prediction for 5 markers are either of these LIR..... Carbon/Nitrogen Cycle.....Eutrophication,....Fertilisers....Chemical Pesticides.
Reply 758
Original post by dents
i dont understand hardy weinburg at all and am crap at maths can someone please help and give me an idea of what to do

worst thing is it nearly always comes up.


If you give an example of a question you can't do i'll see whether I can help with it :smile:
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.

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