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Edexcel A2 Biology Unit 5 (6BIO5) - 22/06/2011- OFFICIAL THREAD !

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Original post by iesians
i dont get that bit !! why is ENERGY needed to move something DOWN its gradient, isnt it only needed to move somethign AGAINST its gradient ..?hmmmmmmmmmmmm


i think sometimes energy is required to move things down the gradient if they are too large?
Original post by pandoraclaire
that is EXACTLY what i thought!!! i dont get it surely it makes no sense! I thought maybe they typed the A and B the wrong way round but im sure we would know about it if there was a mistake on a paper:s-smilie:


I haven't got the paper on me but if it's the question i'm thinking of check the order of A and B before and then after (once they replace the blocks). I think they changed them round so A is now on the right?
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iesians
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Original post by pandoraclaire
that is EXACTLY what i thought!!! i dont get it surely it makes no sense! I thought maybe they typed the A and B the wrong way round but im sure we would know about it if there was a mistake on a paper:s-smilie:


NO its totally correct !
when light was shone on the tip the auxins moved to B block as they are senstive to light.
and then when the blocks were kept on the shoot, B was place on the left(remember it has more auxins) so auxins now diffuse into the shoot evenly as no light is rpesent. but since B is on the left more auxins will move to the left side of shoot cause elongation here and cause the shoot to BEND towards right , cuz if left side grows more than right the shoot will bend to right only.
Original post by PlatypusPigeon
I haven't got the paper on me but if it's the question i'm thinking of check the order of A and B before and then after (once they replace the blocks). I think they changed them round so A is now on the right?


The thing is thought they had A closer to the left and then swapped them round so a was now on the right, but apparently the stem still grew to the left! it confused me so much :frown:
Original post by iesians
NO its totally correct !
when light was shone on the tip the auxins moved to B block as they are senstive to light.
and then when the blocks were kept on the shoot, B was place on the left(remember it has more auxins) so auxins now diffuse into the shoot evenly as no light is rpesent. but since B is on the left more auxins will move to the left side of shoot cause elongation here and cause the shoot to BEND towards right , cuz if left side grows more than right the shoot will bend to right only.


that's exactly what i thought should happen but in the mark scheme apparently it curves to the left
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iesians
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Original post by pandoraclaire
that's exactly what i thought should happen but in the mark scheme apparently it curves to the left


mark scheme says itll bend on right.:rolleyes:
http://www.edexcel.com/migrationdocuments/QP%20GCE%20Curriculum%202000/June%202011%20-%20MS/6BI05_01_rms_20110817.pdf
see the MS yourself in this link.
(edited 11 years ago)
Original post by iesians
mark scheme says itll bend on right.:rolleyes:


.. yeah just found that :P i was looking at the examiners report which has it bending to the left XD which is weird because it says it would get the marks :s-smilie:
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iesians
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Original post by pandoraclaire
.. yeah just found that :P i was looking at the examiners report which has it bending to the left XD which is weird because it says it would get the marks :s-smilie:


lol. dont confuse yourself unnecessarily.
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rohitbd
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Original post by pandoraclaire
.. yeah just found that :P i was looking at the examiners report which has it bending to the left XD which is weird because it says it would get the marks :s-smilie:

Thats interesting I just didn't get it.
Original post by iesians
lol. dont confuse yourself unnecessarily.


its my school website has all of them but pretty much named the same things so i opened the wrong one XD but yeah it said that showing it bending the wrong way would still get the marks... but then again i suppose thats good!
Original post by rohitbd
Thats interesting I just didn't get it.


basically because they are 2 different stages, the light is shone towards the side of the tip with the A block of agar and so more auxins are sent down into the B block so it would grow towards the light but as the blocks are changed around so are these signals and the auxins make the plant grow more on the left side showing it bending towards the right :smile:
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user3456
Am i right in thinking that at the ETC reduced FAD and reduced NAD offload two hydrogen atoms each?
Reply 4292
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lagoom
on the jan 12 paper 1aiii i don't understand how it's top to bottom wouldn't the light pass through the photoreceptors to the bipolar cells to the optic nerve to the brain?
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lagoom
Original post by user3456
Am i right in thinking that at the ETC reduced FAD and reduced NAD offload two hydrogen atoms each?

isn't it one each, they only pick up one
Reply 4294
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user3456
In my book it says " and since each molecule donates two hydrogen atoms, either donates 2 protons and 2 electrons at the same time.." ??????? :s-smilie:
Does anyone have the examiners report for Unit 5 June 2012? The damned Edexcel website won't let me access it.

By the way, try and calculate your bedtime so you wake up just after a sleep cycle has finished, so you don't feel like a zombie, and can read through some notes before the exam!
I've been using http://sleepyti.me/ for this, but you can calculate it yourself, since a sleep cycle lasts 90 mins.

That was slightly random, hopefully it helps someone though :biggrin:
Original post by lagoom
on the jan 12 paper 1aiii i don't understand how it's top to bottom wouldn't the light pass through the photoreceptors to the bipolar cells to the optic nerve to the brain?


Light has to come in from the top and hit the retina first, then it gets reflected back through the bipolar neurone to the optic nerve
Original post by lagoom
isn't it one each, they only pick up one


No, when they pick up hydrogens, they always pick up two each time.
Original post by user3456
Am i right in thinking that at the ETC reduced FAD and reduced NAD offload two hydrogen atoms each?


Er No. only one each, however 3 Reduced NAD and 1 Reduced FAD are made in the krebs cycle which then are used in Oxidative Phosphorylation so that's where you maybe confused? :smile:

EDIT: no forgot me, you are right :wink:
Original post by lagoom
on the jan 12 paper 1aiii i don't understand how it's top to bottom wouldn't the light pass through the photoreceptors to the bipolar cells to the optic nerve to the brain?


Light has to hit the retina first. Then it will be reflected back to the optic nerve. So it'll have to go from top to bottom.

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