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

where can we find the synoptic topics we need to know?
and omgg, you are sooo prepared dudee!

thaaaaaaaaaanks alooooot u r such a great person

Wow thank you so much thats really good advice
Also thanks for the link to the questions that Sir Redden suggested, really useful

if you find it could you post a link on here please? thanks

Sorry but can you send them to me as well? i mean if you not gonna upload them here
im a private student and got really few resources
thank you so much!

You would be doing me a massive favour if you could send me the notes too
Congrats on that awesome score.

thank u sooooooo much

Hi there, I saw you that you might be able to help with some revision materials etc? I'm so stressed with this exam and I only need a C, but I just can't get the questions right. I've learnt most of the stuff from the textbook but i'm finding it so difficult to apply it to the paper.
I literally just need like 55-60% (or higher )to be able to get what I need so I can go to uni..
Could you offer any advice?

Also would you be able to send me the revision notes today please? Would appreciate it!

BACKFLIP IS DA MAAAAN !!!

NOOOO myelin sheath is made up of schwaan cells ! it is wraped around axon MEMBRANE
this axon MEMBRANE is made up of phospholipid bilayer.!

no theyre made up of schwann cells which are made up of lipids. they act as electrical insulators preventing the movement of ions around the part its wrapped on the axon. there are breakages though that occur regularly which are called nodes of ranvier. only ions pass through the membrane at nodes of ranvier. this allows saltatory conduction, which is the 'jumping' of an impulse from node to node. this way the action potential travels much quicker than a regular wave.

Thank you both. So I am I correct in saying the myelin sheath prevents the transfer of all ions including sodium (na+) and potassium (k+) and the phopholipid bilayer which is present all along the neuron, allows the transfer of na and k but prevents large molecules from passing through?

the bilayer only allows flow of ions due to specific channels and carrier proteins. without those they would not be able to pass through because they are polar. only non polar molecules can pass through the membrane

This is going to sound so so stupid, but i'm the type of person who gets the difficult things right and gets the absoloute sitters wrong but

What is the difference between a polar and non-polar ion ?

ions are always polar. polar basically means it has a charge

Thank you. Needless to say, I didn't take Chemistry.