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

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Original post by jam277
I need help in the brain bit. What are the main things that we need to know for the CT, MRI and fMRI scanning?


CT:
-uses X-rays
-produces cross-section images of the brain
-different densities of tissue absorb different amounts of radiation and show up as different colours
-shows major structures in the brain without much detail
-used to tell the extent of an abnormality and its location in the brain
-loss of a function may be associated with the abnormality seen

MRI:
-uses radio waves
-cross-section images
-tissues seen in much more detail
-extent of abnormality and location
-loss of a function may be associated with the abnormality seen

fMRI:
-like MRI but show changes in brain activity as they happen
-more oxygenated blood flows to active brain areas, these areas show up in a different colour
-identify parts of the brain associated with a function whilst it is performed in the scanner
-study diseases caused by abnormal brain activity rather than structure


:awesome: CGP
Original post by whizz-kid
thats wat i thought aswell arent they


introns are transcribed but they're not translated... introns are cut out of mRNA during splicing..
you are welcome
Homeostasis questions.rtf1108.7KB
Homeostasis ms.rtf19.6KB
Muscle & Joints questions.rtf1338.1KB
Muscle & Joints ms.rtf25.4KB
Original post by whizz-kid
thats wat i thought aswell arent they


Yeah I'm pretty sure they are.

Original post by memomemootoo
...


Omgg thank you sooo much for the muscle questions. :biggrin: I've been looking for some for so long and I couldn't find them. Where did you find them, if you don't mind me asking.
Reply 1964
Avatar for jklm123
jklm123
what do we have to know about action potentials? orange book is making it too confusing
Think of an mRNA sequence as a magazine..... a magazine has got useless advertisements that no one reads (the introns) and the articles that are read (exons).....

Introns have to be transcribed and they are spliced out by protein complexes in post transcriptional modification
Original post by InItToWinItGetIt?
Omgg thank you sooo much for the muscle questions. :biggrin: I've been looking for some for so long and I couldn't find them. Where did you find them, if you don't mind me asking.


you are welcome)) ...my kind school gave them me ...also, if you're desperate for questions on any other topics let me know and i'll try to upload them aswell...
Revising won't help for these exams, there are just going to be some bull**** questions which are ambiguous and require no biological knowledge, in unit 4 they asked you to guess whether you think prescriptions for antibiotics will go below a certain number, and they gave you 4 sets of points which gave a weak negative correlation... FOR 3 MARKS!
Original post by memomemootoo
you are welcome)) ...my kind school gave them me ...also, if you're desperate for questions on any other topics let me know and i'll try to upload them aswell...


Have you got any on the role nature/nurture on the brain? Knowing edexcel they will throw up a ton of waffle.
Reply 1969
Avatar for Samia99
Samia99
Original post by Engineer31
Revising won't help for these exams, there are just going to be some bull**** questions which are ambiguous and require no biological knowledge, in unit 4 they asked you to guess whether you think prescriptions for antibiotics will go below a certain number, and they gave you 4 sets of points which gave a weak negative correlation... FOR 3 MARKS!


Lol totallllyy! I f0und the Wavelength Q ridiculous!

*Sigh* .. But just can't sit around Doing nothing :/

Article help needed!
Any1n?
Original post by jklm123
what do we have to know about action potentials? orange book is making it too confusing


firstly, this is how depolarisation happens:
stimulus arrives
soduim channels in the cell membrane open
sodium ions flow in
the inside of the cell become increasingly positive
more sodium ion channels open
the cell is then depolarised up to around +45mV
sodium channels close and potassium channels open
potassium ions exit the cell causing it to become increasingly negative
hyperpolarisation occurs (also known as the refractory period, time is needed for the cation channels to close...)
the resting potential of -70mV is then reached

...in action potentials the sodium ions at the start diffuse sideways causing the area of depolarisation to move across the axon

also you need to know this:
-when the cell is at rest the resting potential is reached by pumping out 3 sodium ions for every 2 potassium ions which enter
-the action potentials are unidirectional and discrete due to the refractory period
-saltatory conduction happens in myolinated axons where depolarisation can only occur at the nodes of ranvier (where sodium channels are situated)
-saltatory conduction is faster than what happens in non-myolinated neurones
Reply 1971
Avatar for Fifi93
Fifi93
Original post by jklm123
what do we have to know about action potentials? orange book is making it too confusing


We have to know how they're caused, all the stages, depolarisation, repolarisation, hyperpolarisation and restoring resting potential. I once saw a question where you had to identify the stages from a graph of Voltage and time. Try to remember whether the Na or K channels are open, that comes up quite regularly.
hey guys..how s everybody preparing 4 the paper? anybody have any notes or something for the article?
Original post by InItToWinItGetIt?
Have you got any on the role nature/nurture on the brain? Knowing edexcel they will throw up a ton of waffle.

do you mean the stuff on habituation and cute little kittens with sewn up eyes?

if yes then i've got some questions but they're too heavy to upload on here... i can try sending them to your email if you like..?
Nervous system ms.rtf142.4KB
Original post by memomemootoo
CT:
-uses X-rays
-produces cross-section images of the brain
-different densities of tissue absorb different amounts of radiation and show up as different colours
-shows major structures in the brain without much detail
-used to tell the extent of an abnormality and its location in the brain
-loss of a function may be associated with the abnormality seen

MRI:
-uses radio waves
-cross-section images
-tissues seen in much more detail
-extent of abnormality and location
-loss of a function may be associated with the abnormality seen

fMRI:
-like MRI but show changes in brain activity as they happen
-more oxygenated blood flows to active brain areas, these areas show up in a different colour
-identify parts of the brain associated with a function whilst it is performed in the scanner
-study diseases caused by abnormal brain activity rather than structure


:awesome: CGP


:biggrin:
Original post by memomemootoo
do you mean the stuff on habituation and cute little kittens with sewn up eyes?

if yes then i've got some questions but they're too heavy to upload on here... i can try sending them to your email if you like..?


I've got questions on those I think. I meant like, the role of twin studies, people with damaged brains etc.

Thanks for offering the other questions though, very nice of you. :smile:
Reply 1976
Avatar for samima1
samima1
Hey guys, which practicals do we need to know?

Thanks x
Original post by samima1
hey guys, which practicals do we need to know?

Thanks x


habituation, spirometer, respirometer
Reply 1978
Avatar for samima1
samima1
Original post by darkiee
habituation, spirometer, respirometer


Thanks!! :smile:
guys anything for the article pleeeeeeeeeease!

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