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A2 Biology OCR June 2015 Revision Thread

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Original post by medactuary
wow how do you know that?! thank you!


Probably a future medic?
Original post by Shostakovish
Here is what I have learnt (quoted from my notes):
Gibberellins are plant hormones
They are synthesised throughout the stem and causes the cells to elongate...
Plant height is regulated by genes
Dominant allele = tall plant
recessive allele = short plant
dominant gene codes for an enzyme that catalyses the synthesis of activated gibberellins
Homozygous recesive plants can only produce inactive gibberellins, so the plant is short
If applied to dwarf plants activated gibberellins can normalise their size
Dwarfing can also be induced by treating plants with substances that prevent them forming activated gibberellins
Mechanism of gibberellin action...
1) activated gibberellin affects gene expression
2) it binds to receptors on the plasma membrane
3) this sets off a a cascade of reactions which lead to the breakdown of DELLA proteins
4) these DELLA proteins usually inhibit transcription factors, so when they are broken down the transcription factors are released and transcription of the gene can begin
5) this leads to stem elongation

Gibberellins
Increases yield of sugar from sugar cane - the sucrose is produced in the stem, the longer the stem the more sugar is stored
Gibberellins also stimulate seed germination
used in the brewing industry where they are sprayed in barley
the germinating grains produce enzymes that convert starch to maltose
yeast + maltose = alcohol

I think that is everything on Gibberellins!


You're a saint! Thank you so much fellow human. :biggrin:
Original post by hibaj
Who wants to teach me things about module 2 and 3 :|


Feel free to ask
Reply 4003
Actually, dismiss my other post. Its going be a long night but #BELIEVE
What's the difference between preservation and conservation?
Anyone else ****ting bricks right now and hoping to LEARN and REMEMBER everything by tomorrow morning?
All nighter time
i have done no past papers. Gonna do them all tonight.



Activate beast mode
Original post by BioAgent
I need to destroy this paper for my A but I dont think its gonna happen. :frown:


Same here :frown:


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Original post by baymax96
I'm just risking not learning it

a night of sleep will probably benefit me more than trying to cram a whole syllabus which I'm not going to remember

resigned to the fact I'll get a U


Thank f, im not the only one. *sighs with relief*
Original post by ecwsky
EVERYONE NEEDS SLEEP-don't do alnighters, do another hour, have a bath, you'll be fine


Not necessarily. I had LOADS to remember before my PE exam last week and I can safely say after going to be at 3 I woke up in the morning actually remembering at least half of what I went through, we all work differently, it's just most need their sleep to function
Original post by hukdealz
All nighter time
i have done no past papers. Gonna do them all tonight.



Activate beast mode


Good luck !


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does anyone know what to say about primate behaviour?
Original post by amorrison
Anyone else ****ting bricks right now and hoping to LEARN and REMEMBER everything by tomorrow morning?


:'( yes fcking bricking it


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Original post by amorrison
Anyone else ****ting bricks right now and hoping to LEARN and REMEMBER everything by tomorrow morning?


Yep, the sad thing is ill have to do the same thing tommorow night fory physics exam on thursday
Can anyone tell me the ratio for linkage. Is it 9:3:3:1 and also can someonr explain what a dihybrid is
LMFAO,,,cheer you all up a bit aha https://www.youtube.com/embed/ID6KY1QBR5s
Original post by doctor_2_be
At least u all were able to revise all day, I have a 1 year old son who's teething and took an hour to put to bed b4 I could do some proper revision.

I haven't even done a past paper yet.


i'll take him for you

neither have I, past papers aren't really crucial for OCR bio
Original post by claudiaelli
does anyone know what to say about primate behaviour?


1. Large groups allow for maximum hunting area covered so more food.
2. allogrooming- removes disease and improves health, whilst forming bonds between members.
3. Females and infants stay in the middle of the group with males on the outside, giving protection and having max. no of females for successful reproduction.
4. Male hierarchy asserted so no energy wasted on fighting.
Original post by claudiaelli
does anyone know what to say about primate behaviour?


the advantages of social behavior in primates: Primate stick together in groups.

Primates give birth to few young at a time to enhance group protection and so it can receive better maternal care.

The young can the learn vital survival skills from members of the group.

Knowledge of food sources can be shared within the group.

Better chance of detecting and surviving predation as group.
Reply 4019
Original post by Lychees
Can anyone tell me the ratio for linkage. Is it 9:3:3:1 and also can someonr explain what a dihybrid is


Dihybrid is the inheritance of two genes. 9:3:3:1 is for a heterozygous dihybrid

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