[hvcxxx]

I'm so nervous for this exam - I hate unit 4 with a passion!! Too much ecology and the questions can be so ambiguous! I think that's what tripped me up in January, it's just a pain in the arse having to juggle unit 4 and 5 revision. I feel so much more confident about unit 5!

Also, can someone please simply define nitrogen fixation and ammonification for me?

Is this right: Nitrogen fixation is where nitrogen-fixing bacteria fix gaseous nitrogen into nitrogen-containing compounds such as proteins. They live on the root nodules of leguminous plants and form a mutualistic relationship with them (e.g. give nitrogen-compounds in exchange for carbohydrates)
Does it also produce some kind of ammonia? So many sources say slightly different things it's so confusing

Also, what is the difference between ammonium and ammonia? Is ammonium the same as ammonium compounds?

[Belton42]

I really don't understand the grade boundaries for this unit. I was doing the unit 4 paper from June 2010 and got forty something out of 75, I assumed this was a B/low A but turns out an A* was 39/75. This can't be right... can it?

[umair.khan]

(Original post by jessplease)
thats amazing, do you know what his unit 5 essay prediction is yet, or are you going to ask that tomoz too?
Thanks!!

He gave us a sheet with questions that might come up, they mainly focus on energy transfer if im honest. There's this really awkward one he gave us and it hasnt come up before:
How does an oak tree grow?

How are you revising for the essay?

[umair.khan]

(Original post by Belton42)
I really don't understand the grade boundaries for this unit. I was doing the unit 4 paper from June 2010 and got forty something out of 75, I assumed this was a B/low A but turns out an A* was 39/75. This can't be right... can it?

That paper was extremely difficult, it really depends on how everyone finds it int he whole year. For example last years june 2011 paper was the easiest of biol4 papers apprantely, so the grade boundaries were pretty high aswell. As long as you do everything correctly, you should get the grade you want, although i have to say biol4 is the most borest unit ever

[Elzie]

Is anyone else getting sick of revision for this unit? :P I'm getting in that mood where I'm like "If I don't know it by now I'll never know it so what's the point?"

Absolutely bricking it!!!!

[yeebz93]

(Original post by jessplease)
http://www.school-portal.co.uk/Group...urceId=4497804

http://www.thestudentroom.co.uk/atta...6&d=1331386803

Have you got the mark scheme?

[kingam]

(Original post by Elzie)
Is anyone else getting sick of revision for this unit? :P I'm getting in that mood where I'm like "If I don't know it by now I'll never know it so what's the point?"

Absolutely bricking it!!!!

Same here , I need an A in it , fml
If not wont be going Uni

[Elzie]

(Original post by kingam)
Same here , I need an A in it , fml
If not wont be going Uni

Same!! I got an A in AS and A2 has suddenly become so hard!! I'm doing loads of past papers and I keep getting really high As, like 100UMS (which is like 53/75) but then I get into the exam and I just forget everything!! I start panicking because of the bloomin' time and those stupid 15 mark application questions!!

[jessplease]

(Original post by umair.khan)
He gave us a sheet with questions that might come up, they mainly focus on energy transfer if im honest. There's this really awkward one he gave us and it hasnt come up before:
How does an oak tree grow?

How are you revising for the essay?

Tbh, I've only been planning a few essays but seem to be focussing on other exams! What type of variations are there with energy transfers? Would ATP be an example? I'm gunna do so bad in this lol, and Oak tree waah, I hope they keep it simple!

[Elzie]

I've compiled my notes if anyone needs a condensed version of the textbook?

[jessplease]

(Original post by yeebz93)
Have you got the mark scheme?

The second link automatically downloads the markscheme

[wenger16]

(Original post by Elzie)
I've compiled my notes if anyone needs a condensed version of the textbook?

Thanks for this, i got my own notes but i like your typed up one better.

[ZeeBurb]

Any predictions on what will come up on this exam?

Like what wasn't in the last few papers that is bound to come up on this one?

[Kandy_Kain_94]

Struggling to revise for this exam. I only started revising today because I had psychology and English yesterday. Don't know whether to go over the whole content again or just do past papers?

[Rizzy J]

Can someone help me do qs 1cii and 2c on jan 11 paper please. Thanks

[umair.khan]

(Original post by Rizzy J)
Can someone help me do qs 1cii and 2c on jan 11 paper please. Thanks

1cii) 20000-5000=15000
(15000*107)+107000000= the answer, i dont have a calculator with me now lol, but im hoping this gives you the correct answer

2c) so q^2=0.16
q=0.4
since p+q=1
p=1-0.4=0.6

to get heterozygous you need to use 2pq
so 2pq=2*0.4*0.6
=0.48
=48% (im assuming they want the answer in % since the figures in the question are & )

Hope that helped you

[jessplease]

What do we need to know for biological control?

[narnia123]

(Original post by Kandy_Kain_94)
Struggling to revise for this exam. I only started revising today because I had psychology and English yesterday. Don't know whether to go over the whole content again or just do past papers?

With such a short amount of time left i'd say you would be better doing past papers and then that will give u an idea of the topics you need to go over the most and then cram like hell. im deading this paper..ideally i need an A

[Rizzy J]

(Original post by umair.khan)
1cii) 20000-5000=15000
(15000*107)+107000000= the answer, i dont have a calculator with me now lol, but im hoping this gives you the correct answer

2c) so q^2=0.16
q=0.4
since p+q=1
p=1-0.4=0.6

to get heterozygous you need to use 2pq
so 2pq=2*0.4*0.6
=0.48
=48% (im assuming they want the answer in % since the figures in the question are & )

Hope that helped you

Great thanks Helped me a lot

[excell]

Confident about this bar Hardy Weinberg. Can anyone else me out a bit, I get confused as to when it's p or p^2???

Does anyone know a good way to remember/how to tell which is it?