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A2 Biology OCR June 2015 Revision Thread

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Original post by Hilton184
Convergence and divergence are both forms of integration I believe.


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Convergence and integration are the same thing but I stick with integration as its what they ask for in most MS
Can someone summarise the main points about the DRD4 receptor for me please. I don't really understand what we have to know about it
Original post by TheLegalDealer
Convergence and integration are the same thing but I stick with integration as its what they ask for in most MS


Source?

I've been lead to believe convergence and divergence occur by the mechanism of integration.

PS
June 2014 wanted convergence, with no mention of integration.

I deduced that integration covers both convergence and divergence from my textbook, it is not explicitly stated in many places across the Internet, but nor is the reverse. See point 2 on this picture:


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(edited 8 years ago)
Original post by Hilton184
Source?

I've been lead to believe convergence and divergence occur by the mechanism of integration.

PS
June 2014 wanted convergence, with no mention of integration.

I deduced that integration covers both convergence and divergence from my textbook, it is not explicitly stated in many places across the Internet, but nor in the reverse. See point 2 on this picture:


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ImageUploadedByStudent Room1433530169.502218.jpg


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What do we need to know abhor kidney failure??? Like the methods is it just renal dialysis??? And what about it
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nk96
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Predictions for F214 and F215?

Anything your teachers have maybe suggested or you have a strong feeling about?
has anyone got the step by step process of the light dependent reaction and the light independent reaction? :smile:
In the book, in section 1.1.9, it refers to low level stimuli when talking of summation and filtering out signals. I thought that with the all-or-nothing nature of impulses that all action potentials were of the same strength or 'level'? When it says low-level stimulus, is that the same as infrequent?
any predictions for the F214 exam??
Is selective reabsorption the same in the PCT and DCT or are there any minor differences?
Original post by ChoccyPhilly
Is selective reabsorption the same in the PCT and DCT or are there any minor differences?


ALL glucose and amino acids are reabsorbed in the PCT as well as ~85% of the water

DCT is adjustment in levels of salt dependent on the needs of the body at the time
Does anyone have the June 2014 f214 paper
wht would you say if you had to compare a myelinated and non myelinated neurone ?
Can someone please explain 'action potentials' im getting really pissed off trying to understand that ****. In one narration it says the membrane is impermeable to Na+ but then it says 'Na ion channels open so the membrane becomes more permeable' where have the Na ion channels come from ffs. Any help will be much appreciated.
Original post by Missy1x
wht would you say if you had to compare a myelinated and non myelinated neurone ?




you could say in myelinated the speed of conduction is much faster because the myelinated sheath is an insulated layer that stops the ions from leaving as they cant diffuse through except at the nodes of ranvier where saltatory conduction happens. something like that :smile:
Original post by CaliSurf'
Can someone please explain 'action potentials' im getting really pissed off trying to understand that ****. In one narration it says the membrane is impermeable to Na+ but then it says 'Na ion channels open so the membrane becomes more permeable' where have the Na ion channels come from ffs. Any help will be much appreciated.


At resting potential the sodium ions are closed and potassium ions are open therefore the cell is permeable to potassium ions and impermeable to sodium ions.

In order for a cell to be stimulated, a stimulus is intiated then sodium ions channels will open causing depolarisation, If it is above the intensity is above the threshold potential at -50mV then voltages gates sodium ions open and there is an influx of sodium ions.
Hope that makes it clearer?
The OCR textbook has a pretty good comparison table for them in the back, where the spread answers are, stuff like how many Schwann cells per neurone (one loosely wrapped for unmyelinated), function (movement vs digestion and breathing), where they're found, relative lengths and speed of transmission. If you don't have the textbook or can't find it just say! :smile:
Original post by chinapicke
At resting potential the sodium ions are closed and potassium ions are open therefore the cell is permeable to potassium ions and impermeable to sodium ions.

In order for a cell to be stimulated, a stimulus is intiated then sodium ions channels will open causing depolarisation, If it is above the intensity is above the threshold potential at -50mV then voltages gates sodium ions open and there is an influx of sodium ions.
Hope that makes it clearer?


thank you :smile: it makes more sense. if i can ask, how did you manage to learn it?
Original post by maisie__x
Yeah that's exactly the kind of question i mean :smile: They can give us an example of positive feedback and you get a mark for saying that it is.
But what i meant is you wouldn't get a question saying 'what is an example of positive feedback' where you have to make your own example.


We need to know the definition and also we need to know about transmission of an action potential along a neurone which is positive feedback. So just in case they do ask, there's an example :wink:
(edited 8 years ago)
Original post by CaliSurf'
thank you :smile: it makes more sense. if i can ask, how did you manage to learn it?


From the ocr textbook and also from YouTube videos they help so much more for a visual learner if you are one :smile:

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