AQA Biology A2 Unit 4: Populations and Environment - 16th June 2016

Hi, can someone go through this really quick for me please.

Polydactyly in cats is an inherited condition in which cats have extra toes. The allele forpolydactyly is dominant.4 (d) (i) In a population, 19% of cats had extra toes. Use the Hardy-Weinberg equation tocalculate the frequency of the recessive allele for this gene in this population.Show your working.

p^2 + 2pq + q^2= 1

as the allele for polydactyl is dominant, we can assume that p^2 and 2pq= 19% or 0.19.

To work out q^2= 1-0.19= 0.81
then to work out the frequency of the recessive allele= square root of 0.81 =0.9 (q)

I think that is right! Will have to check the mark scheme but when I checked it against the HW equation it was correct

Reply 41

hopingmedicinae

4

Original post by KatieAlicexxx

p^2 + 2pq + q^2= 1

as the allele for polydactyl is dominant, we can assume that p^2 and 2pq= 19% or 0.19.

To work out q^2= 1-0.19= 0.81
then to work out the frequency of the recessive allele= square root of 0.81 =0.9 (q)

I think that is right! Will have to check the mark scheme but when I checked it against the HW equation it was correct

Thankyou so much!

What I was thinking was that P^2 + 2PQ together = 0.19 so how did we know what P^2 is on it's own. But it's the frequency of an allele so it would be the same either way. Not sure if that makes sense, but thanks for the help anyway!

Reply 42

kkboyk

21

Original post by KatieAlicexxx

Biology is one of those subjects that takes so much motivation to revise for! I know the feeling. I need an A but motivation is low!!Posted from TSR Mobile

I used to like this subject until A2 (+_+) Have you done any past papers yet?

Original post by pineneedles

Starting is the hardest part. Go ahead and do a past paper, find your weak topics and go from there. Think about how good it'll feel when you get your A 😃Posted from TSR Mobile

Rather than doing past papers, I am planning on doing past paper questions by topic every morning after covering a particular topic until a few days before the exam, so then I could start past papers.There's so much to remember.

Reply 43

Questioner1234

7

Original post by Bloom77

Thank you
I've done some of these
Are these from old papers spec B
The old papers from spec A are much harder

Posted from TSR Mobile

Really? I think the spec A ones(BYA5 mostly) are much simpler than both old B spec and current spec. They tended to have straightforward biology knowledge questions whereas much of B spec and most of the current spec is how science works and context questions.

Posted from TSR Mobile

Reply 44

Supermanxxxxxx

5

Anyone got any tips for this exam

Posted from TSR Mobile

Reply 45

Oliver_1_2

1

Original post by Supermanxxxxxx

Anyone got any tips for this exam

Posted from TSR Mobile

Yeah, revise lots

Reply 46

Supermanxxxxxx

5

Original post by Oliver_1_2

Yeah, revise lots

What about the hsw questions

Posted from TSR Mobile

Reply 47

cherrybanana

2

Can anyone explain why the curve drawn would be concave and what even this would look like?

Reply 48

cherrybanana

2

Also, how would you calculate the answer for this? the answer is in the yellow box!

Reply 49

kkboyk

21

Original post by Supermanxxxxxx

Anyone got any tips for this exam

Posted from TSR Mobile

Practice doing questions involving graphs and data, as it makes most of the unit 4 papers. Also remember these key points.
Also ensure that you read the question properly and know what it is asking, before attempting it.

Reply 50

pineneedles

14

Original post by cherrybanana

Can anyone explain why the curve drawn would be concave and what even this would look like?

The curve labeled H = 0.1 is a concave survival curve. The one in the question would pass through (50%, 40) because the life expectancy is 40 years old
PMC3378582_pone.0039479.g003.png

Posted from TSR Mobile

(edited 7 years ago)

Reply 51

pineneedles

14

Original post by cherrybanana

Also, how would you calculate the answer for this? the answer is in the yellow box!

First you would read from the graph the rate of oxygen intake at 0.6 ms-1. For the regular swimmer this is 2 dm3min-1.
Work out how long it takes the swimmer to swim 300m :
300/0.6 = 500 second
In minutes : 8 1/3 mins or 25/3 minutes
Multiply this by the rate of oxygen intake:
2 * 25/3 = 50/3 =16.7 dm

Posted from TSR Mobile

Reply 52

cherrybanana

2

Original post by pineneedles

First you would read from the graph the rate of oxygen intake at 0.6 ms-1. For the regular swimmer this is 2 dm3min-1.
Work out how long it takes the swimmer to swim 300m :
300/0.6 = 500 second
In minutes : 8 1/3 mins or 25/3 minutes
Multiply this by the rate of oxygen intake:
2 * 25/3 = 50/3 =16.7 dm

Posted from TSR Mobile

Thanks soooo much! I totally understand it now! :smile:

Reply 53

cherrybanana

2

How is this answer achieved anyone? :smile:

Reply 54

ssamarai

2

Original post by cherrybanana

How is this answer achieved anyone? :smile:

208-203 in order to find in the difference in biomass for the green shoots (which shows how much it's increased), which gives you 5 and then divide by 10 because it's from 10-20 years and you're finding the rate per year.

Reply 55

Boundless_x

16

Anyone have predictions for the 5 markers??

Reply 56

KatieAlicexxx

10

Original post by kkboyk

I used to like this subject until A2 (+_+) Have you done any past papers yet? Rather than doing past papers, I am planning on doing past paper questions by topic every morning after covering a particular topic until a few days before the exam, so then I could start past papers.There's so much to remember.

Sorry, I dont think I saw this! I have done past papers- almost all of them for unit 4 and 3 of them for unit 5 (one was a mock last week). Luckily I'm getting high marks in them but thats kind of a curse too because I'm like "I dont need to revise this, I'm good at it" but 100% can guarantee my mind will go blank on the day!
My teacher has got together packs of 100 marks worth of questions for each topic from the old spec and the human biology spec so we can have the past paper questions too. Its useful to do those let me tell you!
Biology is literally the subject that I have the most information for. Even psychology, where you have to know 60 studies for one exam in detail has less information than bio!!

Reply 57

cherrybanana

2

Original post by ssamarai

208-203 in order to find in the difference in biomass for the green shoots (which shows how much it's increased), which gives you 5 and then divide by 10 because it's from 10-20 years and you're finding the rate per year.

Got it - thank you! :smile:

Reply 58

cherrybanana

2

Can anyone please explain how this answer (in red) was achieved? :smile:

Reply 59

kkboyk

21

Original post by KatieAlicexxx

Sorry, I dont think I saw this! I have done past papers- almost all of them for unit 4 and 3 of them for unit 5 (one was a mock last week). Luckily I'm getting high marks in them but thats kind of a curse too because I'm like "I dont need to revise this, I'm good at it" but 100% can guarantee my mind will go blank on the day!
My teacher has got together packs of 100 marks worth of questions for each topic from the old spec and the human biology spec so we can have the past paper questions too. Its useful to do those let me tell you!
Biology is literally the subject that I have the most information for. Even psychology, where you have to know 60 studies for one exam in detail has less information than bio!!

It's ok

What would you say would be your biggest weakness in unit 4? For me it has to be the questions involving us to interpret a particular graph/table, and infer what its showing.

I always thought that Psychology has twice as much info than Biology. I'm so glad I've dropped all essay based subject purely because I can never finish a bunch of essays in time, plus the content is too much for me (+_+).

AQA Biology A2 Unit 4: Populations and Environment - 16th June 2016

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