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AQA Biol4 15th June 2012

Can someone please explain to me Hardy-Weinberg, giving me a worked example? I really don't understand it...

you need to remember his four assumptions eg: no mutation, selction etc
the two equations p + q = 1
p2 +q2 + 2pq =1

hope it s hepls in terms of what is required of you....

Reply 181

g00d4u

Original post by narnia123

This is how i did it:
0.33=frequency in london so therefore h=0.33 and H=0.67
Hardy Weinberg = p^2+2pq+q^2
where 2pq = heterozygous
heterozygous = 2(0.67x0.33)
=0.4422
=44%
I hope that makes sense, im crap at explaining things lol (i hope it's right too)

You done a preety good job.....coz I am crap at understanding.... lol

Reply 182

g00d4u

Hi everyone lets get this discussion started one day left before the exam....
any suggestions what may be on the last few question....or any tricks to understand the questions...coz I can't undersatnd what is being asked of me.... plase help... :redface:

Reply 183

navarre

20

Original post by g00d4u

you need to remember his four assumptions eg: no mutation, selction etc
the two equations p + q = 1
p2 +q2 + 2pq =1

hope it s hepls in terms of what is required of you....

I get the equation, I just don't get what do to with it with a question...

Reply 184

g00d4u

Original post by navarre

I get the equation, I just don't get what do to with it with a question...

If they ask you to work out:
allele frequency
p + q = 1
genotype frequency
p2 + q2 +2pq = 1
the percentage of a population that has a certain genotype
this can be tricky!
can be a combination of both and has to be a percentage

look up some of the different examples.... one in the specimen is soo vague.....coz its AQA.....

Reply 185

. . .

Original post by navarre

I get the equation, I just don't get what do to with it with a question...

Give an example of a question you don't understand.

Reply 186

username570910

2

I've compiled some key points using previous mark schemes. Hope it helps! :smile:

(edited 11 years ago)

Unit 4 Key Points.pdf96.9KB

Reply 187

Kandy_Kain_94

16

Can anyone give me an answer for 6(b) please? :smile:

http://intranet.xaverian.ac.uk/private/resources/datastor/Academic/10-SM/Biology/A2/Biol%204%20Populations%20&%20Environment/Exam%20Papers/Biol%204%202011%20Jan%20QP.pdf

Reply 188

canthardlywait

Original post by leeandrewarmstrong

I've compiled some key points using previous mark schemes. Hope it helps! :smile:

Thank you, this looks very useful.

Reply 189

jessplease

Original post by leeandrewarmstrong

I've compiled some key points using previous mark schemes. Hope it helps! :smile:

I've done that too, some of my points are exactly the same ahah, it really helps!

Reply 190

Bright.Inspiration.

10

Original post by leeandrewarmstrong

I've compiled some key points using previous mark schemes. Hope it helps! :smile:

Thank you for sharing this :smile:

Reply 191

Mina!SS

does anyone have the mark scheme for the specimen 2009 -2010 and january 2012 paper?

(edited 11 years ago)

Reply 192

canthardlywait

Original post by Mina!SS

does anyone have the mark scheme for the specimen 2009 -2010 and january 2012 paper?

Jan 2012: http://www.thestudentroom.co.uk/attachment.php?attachmentid=135846&d=1331386803

Reply 193

JasonDream

Original post by leeandrewarmstrong

I've compiled some key points using previous mark schemes. Hope it helps! :smile:

Unit 5 too please :biggrin:

this is very helpful

Reply 194

canthardlywait

Original post by Mina!SS

does anyone have the mark scheme for the specimen 2009 -2010 and january 2012 paper?

Specimen paper MS
http://www.thomas-reddington.com/uploads/7/7/8/3/778329/bio_u4_ms_specimen.pdf

Reply 195

navarre

20

Original post by . .

Give an example of a question you don't understand.

This is one:

Sea otters were close to extinction at the start of the 20th century. Following a ban
on hunting sea otters, the sizes of their populations began to increase. Scientists
studied the frequencies of two alleles of a gene in one population of sea otters.
The dominant allele, T, codes for an enzyme. The other allele, t, is recessive and
does not produce a functional enzyme.
In a population of sea otters, the allele frequency for the recessive allele, t, was found
to be 0.2.
6 (a) (i) Use the Hardy-Weinberg equation to calculate the percentage of homozygous
recessive sea otters in this population. Show your working.

Reply 196

sara.xx

Original post by leeandrewarmstrong

i've compiled some key points using previous mark schemes. Hope it helps! :smile:

thankyou ! :d <3

Reply 197

. . .

Original post by navarre

This is one:

Sea otters were close to extinction at the start of the 20th century. Following a ban
on hunting sea otters, the sizes of their populations began to increase. Scientists
studied the frequencies of two alleles of a gene in one population of sea otters.
The dominant allele, T, codes for an enzyme. The other allele, t, is recessive and
does not produce a functional enzyme.
In a population of sea otters, the allele frequency for the recessive allele, t, was found
to be 0.2.
6 (a) (i) Use the Hardy-Weinberg equation to calculate the percentage of homozygous
recessive sea otters in this population. Show your working.

The HW equations is p²+2pq+q²=1
p = Dominant allele frequency which is the same as T
q = Recessive allele frequency which is the same as t

Homozygous recessive is qq or tt
Heterozygous is pq or Tt
Homozygous dominant is pp or TT

If t = 0.2 then q must = 0.2
Homozygous recessive is qq or tt so that is 0.2 x 0.2 (0.2²) which = 0.04

Reply 198

ecokid

1

What's everyones plan for the last 24hr? I think I'm going to split my time to repeating some of the harder exam papers and making sure I have memorised equations and such.

Reply 199

narnia123

4

Original post by ecokid

What's everyones plan for the last 24hr? I think I'm going to split my time to repeating some of the harder exam papers and making sure I have memorised equations and such.

Past papers galore tomorrow! go over agriculture crap and make sure i know it,

AQA Biol4 15th June 2012

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