A2 Biology OCR June 2015 Revision Thread

It does make me feel kind of better that everyone else is cramming too.
Don't worry guys.
FIGHT.
We can do this.
WE CAN DO THIS.

Reply 3821

wanna get laid

2

Original post by peanutcracker20

anyone wanna go through nitrogen cycle and that stuff cannot do it

Ok

- plants cant use nitrogen gas cos it's unreactive innit
- nitrogen fixing bacteria convert nitrogen gas to ammonium ions
- ammonium ions are converted to nitrite ions by nitrosomonas bacteria
- nitrite is converted to nitrate by nitrobacter bacteria
- plants take up nitrate to synthesise amino acids and shiz for nucleic acids
- denitrifying bacteria convert nitrate ions back into nitrogen gas

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(edited 8 years ago)

Reply 3822

Riya1

Original post by domcandrews

Yes very true! Running on about 4 hours sleep over the past 2 days, gonna have to be 0 hours sleep tonight, to try and get some marks tomorrow

i think its better if you first look at every past papers with essay based questions 8 marks each, write them down in separate paper or print it out and learn them by heart and look at the diagram anotations in the book eg: brain one

http://www.physicsandmathstutor.com/biology-revision/ocr-unit-5/
this might be helpful too if u r trying to cram everything
and do try to get some sleep otherwise brain might not function properly tomorrow.

Reply 3823

Riya1

http://www.thestudentroom.co.uk/showthread.php?t=1296764 guys the condensed note is posted in this room if you havent got them yet. do have a look as it covers everything and is very useful

Reply 3824

domcandrews

2

Original post by Riya1

i think its better if you first look at every past papers with essay based questions 8 marks each, write them down in separate paper or print it out and learn them by heart and look at the diagram anotations in the book eg: brain one

http://www.physicsandmathstutor.com/biology-revision/ocr-unit-5/
this might be helpful too if u r trying to cram everything
and do try to get some sleep otherwise brain might not function properly tomorrow.

Ok will do that! Thanks, yeah will see how much I get done!

Reply 3825

ooxbridge

6

Original post by ChoccyPhilly

This is my last proper exam, so u have nothing to lilolose by doing an all nighter, aside from a place in uni

same here, can make up for sleep lost after the exam lol

Reply 3826

corey7695

11

Original post by Nadwuar

Yeah I use that for inter but if the question asks for different examples of both type of competition what should I use for intra, I don't want to repeat something I would've already mentioned if you know what I mean

couldn't you just use any species you want since every one will have intraspecific competition?

The only thing keeping me motivated is the fact that this is my last exam! Then I'm going on a Netflix marathon...can't wait! :biggrin:

Reply 3829

Nadwuar

2

Guys do any of you have any set mark scheme answers if they we're to ask how to use genetic engineering to make golden rice. I've seen the insulin one which is quite lengthy but for golden rice all I can see in the textbook is something to do with phytoene and crtl or whatever

Reply 3830

shalalondon

2

Stages in meiosis I and what happens in each stage

Original post by tewas

Anybody have any questions they want answered?

Reply 3831

Ned Stark

3

I've given up on past papers and am doing a Queen karaoke marathon.

Reply 3832

peanutcracker20

2

Original post by domcandrews

Yes very true! Running on about 4 hours sleep over the past 2 days, gonna have to be 0 hours sleep tonight, to try and get some marks tomorrow

thats just my plan and then will sleep for a day after the exam and do nothing at all

Reply 3833

wanna get laid

2

Original post by Nadwuar

Guys do any of you have any set mark scheme answers if they we're to ask how to use genetic engineering to make golden rice. I've seen the insulin one which is quite lengthy but for golden rice all I can see in the textbook is something to do with phytoene and crtl or whatever

Lemme explain to ya bro. Got no mark scheme fam, sorry yeh

So basically yeah, in rice, beta carotene doesnt accumulate in the endosperm (the part that is eaten)

So what we gotta do is put in some genes to make the metabolic pathway work.

You get a gene from daffodil plants and put in rice genome. When this gene is expressed, it produces dat enzyme called phytoene synthase. This converts phytoene into lycopene

And you get dat gene from soil bacteria and put it in the genome. When this gene is expressed, it produces the crt1 enzyme, which converts lycopene into beta carotene

So now youll have the rice producing beta carotene in the endosperm
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Reply 3834

Nadwuar

2

Original post by wanna get laid

Lemme explain to ya bro. Got no mark scheme fam, sorry yeh

So basically yeah, in rice, beta carotene doesnt accumulate in the endosperm (the part that is eaten)

So what we gotta do is put in some genes to make the metabolic pathway work.

You get a gene from daffodil plants and put in rice genome. When this gene is expressed, it produces dat enzyme called phytoene synthase. This converts phytoene into lycopene

And you get dat gene from soil bacteria and put it in the genome. When this gene is expressed, it produces the crt1 enzyme, which converts lycopene into beta carotene

So now youll have the rice producing beta carotene in the endosperm
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Safe blud, mans just trynna get an A outchea u get me fam?

Reply 3835

Shanahey

8

Why is batch culture more suitable for producing secondary metabolites and not primary?

Thanks

Reply 3836

Malawasheree

1

Lost my notes for Plant Responses :frown:

Could anyone go over the role of auxins in phototropism and how they promote the loosening of the cell wall?

Reply 3837

ishackm

5

Original post by Ned Stark

Dude it's not worth it, you'll do better with a night's rest.

i dont want to fail came this far

Reply 3838

wanna get laid

2

Original post by Malawasheree

Lost my notes for Plant Responses :frown:

Could anyone go over the role of auxins in phototropism and how they promote the loosening of the cell wall?

Ok fam, lemme help you out yeh

So basically auxin travels by active transport/diffusion to the cells in the zone of elongation. Auxin makes the cell walls stretchy and promotes the active transport of protons into the cell wall. This lowers the pH. The pH is now at an optimum for the wall-loosening enzymes (expansins) to work.

When light shines on one side of the shoot, auxins travel to the shaded side. This makes the shaded side elongate, and therefore pushes the shoot towards the light source fam

Dat cool now?

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