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

1. Yes. In each topic, (5, 6, 7 and 8) in the spec, the first objective is that we know ALL HSW stuff. Stats tests are included. They better not ask any in this paper though!
2. I haven't found statistical tests(t-test) in the student book......so is it gonna come in unit 4 or 5?? But its part of unit 6(6BIO8) for sure!
3. (Original post by nightwalker123)
t-test is a statistical test that is applied to interval data. it can be applied to matched or idependant samples.
criteria for t-test:
1.samples are small(<30)
2.the population or population of differences(matched) are normaly distributed.
3.the standard deviation of the population is not known.

Eg. calculated t-value= 3.25 and the t-crit value (at 5% significance level)= 2.09.
In this example the positive value ot t (3.25) is greater than the t-crit value(2.09) so reject the null hypothesis and accept the alternative hypothesis.

hope that clears your doubt mate.
Thanks.
4. how are people actully prepering for the article bit ....apart from reading it which is sooooooooooooo boring....(quote me please)
5. unit 5 article??????...i think we really got to get discussin' soon.....
6. true....its gettin' late now!
7. (Original post by nightwalker123)
unit 5 article??????...i think we really got to get discussin' soon.....
I thought it was Unit 6 article??

Anyways, someone fire away with the "article" discussion please, and lets get a biology banter goin'
8. Well lets start.......

the first topic is about how scientists came about making the dancing worm and trying to use to technology in treating depression and Parkinson's disease.
Earlier scientists tried with electroconvulsive therapy, DBS and vagal nerve stimulation. Using electrodes to trigger an electric impulse in neurones was gr8 but it stimulates thousands of neurones together which contains both excitatory and inhibitatory neurones. This limited the use of electrodes in treating medical disorders as stimulating the right ones may cause stimulation of the wrong ones resulting in side effects such as memory loss!

The effects of DBS is sometimes funny and sad!.....it may sometimes electrify patients funny bones and make them laugh uncontrollably! and in other cases to weep!

I havent understood the vagal nerve stimulation thing...and is the STN part of hypothalamus?

Scientists now found membrane protein that respond to light! Engineering animals with these proteins can help scientists control individual neurones.

ChR2 from algae used to detect sunlight, is sensitive to blue light.
NpHR from desert-dwelling microbes are sensitive to yellow light and does the exact opposite of ChR2.
Engineering worm with both of them brings our dancing worm which dances with flashes of blue and yellow light.........lovely!!
9. (Original post by shuvo_roy)
Is the STN part of hypothalamus?
:
Its part of the Basal Ganglia, which is basically a big old load of grey matter right in the centre of the brain. It isn't actually part of the hypothalamus, but its strongly associated with the thalamus, hypothalamus and cerebral cortex.
10. We may be asked to suggest why the worm dances.
> photoreceptors (maybe mechanism similar to rod cells and rhodopsin)
> nerve impulses
> synpases
> muscle contraction
11. (Original post by JoshFlack)
Its part of the Basal Ganglia, which is basically a big old load of grey matter right in the centre of the brain. It isn't actually part of the hypothalamus, but its strongly associated with the thalamus, hypothalamus and cerebral cortex.
So, what does STN do? and whats vagal nerve stimulation......is vagal nerve called parasympathetic nerves??
12. Questions may also come from genetic engineering in animals.......what are used as vectors,etc.
13. (Original post by shuvo_roy)
So, what does STN do? and whats vagal nerve stimulation......is vagal nerve called parasympathetic nerves??
Thought I'd join in with this thread as I'm having to take this exam and pre-release as well
The STN is a part of the brain associated with movement, so the small electrode that is placed there creates its own electrical impulses that block or interfere with the impulses that cause the tremors or other parkinson's symptons, so it stops the tremors completely i think, but not without possible side effects...

The vagal nerve is the parasympathetic nerve that controls heart rate, so if the nerve is stimulated it will slow the HR. The VNS stimulates the vagas nerve at regular intervals in the day to lessen the frequency and intensity of seizures, and if a seizure is felt to be coming on they can turn the VNS on at that moment to help even more control the seizure.

Let me know if this helped
14. (Original post by Pi Face)
Thought I'd join in with this thread as I'm having to take this exam and pre-release as well
The STN is a part of the brain associated with movement, so the small electrode that is placed there creates its own electrical impulses that block or interfere with the impulses that cause the tremors or other parkinson's symptons, so it stops the tremors completely i think, but not without possible side effects...

The vagal nerve is the parasympathetic nerve that controls heart rate, so if the nerve is stimulated it will slow the HR. The VNS stimulates the vagas nerve at regular intervals in the day to lessen the frequency and intensity of seizures, and if a seizure is felt to be coming on they can turn the VNS on at that moment to help even more control the seizure.

Let me know if this helped
thanks man!

another question......why tremors occur? in parkinsons disease the substantia nigra is damaged and so less dopamine is produced. As a result less impulses flow across the synapse involving dopamine. This results in slowness of movements but why tremors occur?? is it because the cerebral cortex can no longer filter motor activities??
15. (Original post by shuvo_roy)
thanks man!

another question......why tremors occur? in parkinsons disease the substantia nigra is damaged and so less dopamine is produced. As a result less impulses flow across the synapse involving dopamine. This results in slowness of movements but why tremors occur?? is it because the cerebral cortex can no longer filter motor activities??
I don't think they actually know what the root cause of tremors are yet, but the best lead I think scientists have now is to do with the dopamine that you mentioned. Basically as you move, receptors in your joints and muscles relay information back and forth to the brain through the thalamus to make sure any movement is being carried out correctly. The loss of dopamine disrupts these relayed impulses and the operations of the thalamus. The brain no longer gets enough sensory feedback for how well movements are being carried out, so it can't adjust bad movements or control any slow or complex movements such as those of your hands and fingers. This is why they think the hands and fingers are the first and worst affected by Parkinson's.
16. I saw animals were mentioned and brain imaging.

This ties in with ethical implications+animals in research and fMRI.
17. Well can any1 summarize the ethical issues in using animals in lab experiments.......
the 1st one might come as "every organism has the right to live in this World! "
18. Can anyone send me a copy of the article because my school doesn't seem to want to give us it
19. It's right in the first post...
20. (Original post by Doughboy)
It's right in the first post...
Oh ok thanks. I didn't look properly

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