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Edexcel 6BIO5 ~ 20h June 2014 ~ A2 Biology

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Reply 720

han55

Original post by Rz_22

Thank you so so much! :smile:

Pr and Pfr are the photoreceptors in the plant that detect light.
Pr absorbs red light and Pfr absorbs far red light
When one form of the pigment absorbs light, it is concerted reversibly to the other form.
These phytochromes enable the plant to respond to changes in day length.

I don't get how this links in with the tropism stuff or are supposed to revise them as two different things?

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i have never heard of any of that oh my, to my knowledge, it hasn't come up in any past papers?

Reply 721

Rz_22

Original post by haniie219

i have never heard of any of that oh my, to my knowledge, it hasn't come up in any past papers?

It has come up in January 2011 paper- the question about day lengths and detection of environmental cues :/

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Reply 722

corrgeorgia

Original post by Rz_22

It is on the specification 'explain how genes can be switched on and off by DNA transcription factors including hormones'

Do you want me to explain each of them? :smile:

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Yes please but aren't they enhancement drugs how do they link in with transcription factors? :P thankyou :smile:

Reply 723

Rz_22

Original post by corrgeorgia

Yes please but aren't they enhancement drugs how do they link in with transcription factors? :P thankyou :smile:

So anabolic steroids are similar in structure to the male testosterone hormone. They bind with the receptors on the cell surface membrane. This complex then enters the cell and enters the nucleus. This acts as a transcription factor switching on particular genes linked to protein synthesis. This means that the mRNA formed is different and so when it is translated different proteins result. These proteins mean that bigger and stronger muscles result.

Erythropoietin: peptide hormone which binds to the cell surface membrane receptor. This activates a second messenger inside the cell which triggers a protein kinase cascade and the final product enters the nucleus acting as a transcription factor. This switches on particular genes related to the synthesis of enzymes to make more red blood cells. More red blood cells mean oxygen can be carried more efficiently but this makes the blood thick so it can lead to strokes and heart attacks due to the blood clotting

Hope that helps :smile:

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Reply 724

han55

Original post by Rz_22

It has come up in January 2011 paper- the question about day lengths and detection of environmental cues :/

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oh goodness, i better try and learn it then :/

Reply 725

han55

Does anyone have notes on the spirometer experiment? My teacher forgot to do it :/ i have no idea what it is.

Reply 726

corrgeorgia

Original post by Rz_22

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Thanks very much, its very insightful! Good luck for Friday (although you seem to not need it) ! :smile:

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Reply 727

Rz_22

Original post by corrgeorgia

Thanks very much, its very insightful! Good luck for Friday (although you seem to not need it) ! :smile:

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Haha thank you- good luck to you too! I feel I was more prepared for unit 4, so scared! :frown:

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Reply 728

diggy

Ok i need a D for my to get a B overall, halfway through the spec, got an E on a past paper yesterday, there's still hope

#Prayforyungdiggy

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Reply 729

acer0951

Can anybody tell me why the Hela cells grow faster in space\ zero gravity? Confused the shizzle out of me

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Reply 730

alicja_p

Original post by diggy

Ok i need a D for my to get a B overall, halfway through the spec, got an E on a past paper yesterday, there's still hope

#Prayforyungdiggy

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What a lucky bastard :frown:

I need an A to get a B, just got a C in a past paper - obviously scaled down grade boundaries (did well considering I did 5 out of 6 questions hahah)

Reply 731

justanotherindigo

Original post by diggy

Ok i need a D for my to get a B overall, halfway through the spec, got an E on a past paper yesterday, there's still hope

#Prayforyungdiggy

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Same! I guess that I just need to go through the spec more thoroughly, but there's still hope :smile:

Reply 732

warmhugs

What has been the hardest bio paper yet? And what was the mark for an a?
Thanks in advance!

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Reply 733

Katy4341

I don't know if I'm really over thinking the pre release question. After having limited time in class, and resources I'm not sure what to look at. I've looked at mitosis, enzymes, ethical issues, virus/bacteria, protein synthesis etc. maybe this will be enough but any ideas from anyone else. Probably worrying about nothing but I'd rather be over prepared than under!

Reply 734

Just ZK

anyone who have stafford valentines questions and answers related to the scientific article????? :sad:

Reply 735

polka dots :)

Could someone please help me with this. It's a picture of a diagram in the CGP revision guide. I don't understand why the direction of light is the opposite way to the direction of the impulse??

It's probably really simple! Thank you!

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Reply 736