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Gnome :)
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#1281
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#1281
(Original post by RachelG_)
Hey, can someone please explain to me the difference between multipotent and pluripotent cells? Thanks
Basically pluripotent means a cell which can differentiate into any body cell, such as embryonic stem cells. Multipotent cells can differentiate, but are more limited e.g. adult hematopoietic stem cells in bone marrow are only able to differentiate into the various blood cells
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Kutie Karen
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#1282
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(Original post by emah123)
have you done some revision already or starting?
Yes I have started but it just too much to do in too little time. Need some kind of guidance on the best way to prepare especially the essay.
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Jammie Dodgers
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#1283
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(Original post by JoshL123)
Just from generally reading it, prior to the question, it states that "The insertion of the DNA copy in one of the host cell’s genes may cause the cell to
make a non-functional protein."

I haven't checked the mark scheme but from what that suggests it must be a tumour suppressor gene. Oncogenes, undergo mutations as to produce a proto-oncogenes, which can function via two methods - producing excessive amounts of the growth factor (that would then bind with the receptors of the cells causing it to grow and divide), or permanently activating the receptors found upon the cell surface membrane (bringing about the same response). Because the question states a non-functional protein, it cant be the proto-oncogene, as that would result in the coding for a protein (that opposes what the question states). I don't ink I would have actually got that one in the exam :/
Isn't it proto-oncogenes undergo mutation to produce oncogenes, the other way around?
This question also has me puzzled.
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Tikara
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#1284
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#1284
Anyone worried about not enough questions? (these were taken off exmpro)

Old Spec. relevant questions (NO MARK SCHEMES)
285 Unit 5 Questions, 40 Essay Questions:


http://www.newgrounds.com/dump/downl...ead54555cae705
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Mocking_bird
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#1285
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#1285
(Original post by Kutie Karen)
Yes I have started but it just too much to do in too little time. Need some kind of guidance on the best way to prepare especially the essay.
There is no way there is too little time... you'll be fine!
3 and a bit weeks time is honestly plenty to get everything revised.
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Scienceisgood
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#1286
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#1286
(Original post by Tikara)
Anyone worried about not enough questions? (these were taken off exmpro)

Old Spec. relevant questions (NO MARK SCHEMES)
285 Unit 5 Questions, 40 Essay Questions:


http://www.newgrounds.com/dump/downl...ead54555cae705
I love people like you! Always trying to help people. - Mark Schemes included on my skydrive if people go looking for them. =)
I would strongly advice people to use these, however, if you want them divided into sections, please check out my skydrive.

https://skydrive.live.com/?cid=AB9A5...012167BC%21111

Divided into DNA, Neurons/Synapses, Negative Feedback and Homeostasis.
I have taken out the essays because the mark scheme is the same thing for hundreds of pages!
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Tikara
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#1287
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#1287
(Original post by Scienceisgood)
I love people like you! Always trying to help people. - Mark Schemes included on my skydrive if people go looking for them. =)
I would strongly advice people to use these, however, if you want them divided into sections, please check out my skydrive.

https://skydrive.live.com/?cid=AB9A5...012167BC%21111

Divided into DNA, Neurons/Synapses, Negative Feedback and Homeostasis.
I have taken out the essays because the mark scheme is the same thing for hundreds of pages!
Yes!! awesome mate , yeah - if anyone downloads it, it has all questions on one file then a few sections w/ mark schemes in separate files

thanks alot man, I was worrying about not having mark schemes!
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xoxoxoxoxox
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#1288
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#1288
hey guys..
Initially i thought the more unsuitable an environment to more the species moves and changes directions it says in aqa book...

However doing an past question on kinses, its in your aqa text book . End of Chapter questions. Page 153. question 1. chaper9.. their is a question about a louse, and it says in a favorable environment the louse changes direction more frequently, so its likely to say in that condition..
so confused..!!
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Chewy29
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#1289
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#1289
Does anyone know where I can get the nelson thornes answers to the examination questions for this unit.

Posted from TSR Mobile
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Mocking_bird
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#1290
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#1290
(Original post by xoxoxoxoxox)
hey guys..
Initially i thought the more unsuitable an environment to more the species moves and changes directions it says in aqa book...

However doing an past question on kinses, its in your aqa text book . End of Chapter questions. Page 153. question 1. chaper9.. their is a question about a louse, and it says in a favorable environment the louse changes direction more frequently, so its likely to say in that condition..
so confused..!!
In a favourable condition the louse will increase its rate of turning but decrease its movement so its more likely to stay in favourable conditions.

Theres been some debate about what Nelson Thorne have said but the above is the notes from my teachers.
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Tikara
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#1291
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#1291
(Original post by Chewy29)
Does anyone know where I can get the nelson thornes answers to the examination questions for this unit.

Posted from TSR Mobile
all on the first post on this thread
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Chewy29
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#1292
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#1292
(Original post by Tikara)
all on the first post on this thread
Thanks

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xoxoxoxoxox
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#1293
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#1293
Thank you very much, for making this much more clearer for me.. Mocking_bird
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A sheesh
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#1294
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#1294
I had an exam and then went school next day and when I got into bio, Lund out I had a mock
was so unprepared and thought I failed but surprisingly got a high C

hopefully I can get the mid B i need
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A sheesh
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#1295
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#1295
Found*
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dizzy17
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#1296
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#1296
are people doing wider reading on any parts of the spec in particular? there's just so much I don't know where to start!
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samfreak
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#1297
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#1297
(Original post by Tikara)
omg my school are doing the same thing it's so frustrating- I refused to do the mock today though (maybe that was bad of me) but I'm terrified at the lack of exam practice I'm gonna get as most my final revision is learning from past papers (

if you want some extra questions I have a .zip full of them cause I was worried about proper exam practice :P (most don't have the answers though)

There are a list of essay questions somewhere as well on an aqa document - I can't find it right now though
do u still hav the aqa document

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Tikara
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#1298
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#1298
(Original post by samfreak)
do u still hav the aqa document

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here are the aqa stuff I was on about : http://www.thestudentroom.co.uk/show...postcount=1060

and extra questions (around 40 in this zip) : http://www.thestudentroom.co.uk/show...postcount=1285
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helpme456
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#1299
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What is the refractory period, is it when the membrane is hyperpolarised or when the protein channels are resetting?

also I understand how this can make impulses discrete but how does this make them unidirectional?
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Tikara
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#1300
(Original post by helpme456)
What is the refractory period, is it when the membrane is hyperpolarised or when the protein channels are resetting?

also I understand how this can make impulses discrete but how does this make them unidirectional?
It's when the protein channels (the voltage gated ones) can't be opened/are resting. I think the whole refractory period is from resting potential to resting potential again- but I'm not completely sure about this :P

Well, if you depolarise the axon in the middle of a neurone, the action potential actually moves both ways but only triggers acetyl choline at the synaptic knob end.

What it means by unidirectional is that due to the refractory period, each action potential doesn't cause another action potential the opposite way back as protein channels are closed until the depolarisation has passed them.

Someone correct me if I'm wrong- anyway hope this helped mate
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