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A2 Biology OCR June 2015 Revision Thread

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Original post by it's a me, mario
How comes youre not sure what's in f214 and whats in f215?

Surely you have the ocr textbook, no?

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Yeah I just didn't realise what was in what exam :/
Original post by alexthehuman
Im sorry if this has already been asked but im new to the thread. I can't find the 2014 f214 paper anywhere. Does anyone have it or know what the big questions were?


There were a lot of questions about vegetables

Like onions and asparagus and shiz

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Reply 1902
Original post by hajs
After a prolonged period of fasting, glycogen levels in the liver are depleted. However the liver can still produce glucose by the process of gluconeogenesis. Describe one way in which this is done?

Anyone gonna try to answer that? I found it really difficult lol..


Protein can be converted to glucose in glucogenesis
Reply 1903
Does cyclic and non-cyclic photophosphorylation occur at the same time? And if so, how does it work because in cyclic PSI electrons are returned to PSI, but in non-cyclic, PSI gets electrons from PSII?
Reply 1904
Original post by nk96
Does cyclic and non-cyclic photophosphorylation occur at the same time? And if so, how does it work because in cyclic PSI electrons are returned to PSI, but in non-cyclic, PSI gets electrons from PSII?


In non-cyclic, water undergos photolysis to form H+ and electrons
Photolysis is splitting of water using light

The electrons from water replace those lost from PSII
Original post by baymax96
Please can someone give a detailed summary of selective reabsorption in the pct. I'm so confused by it :confused: :'(

Sodium/potassium ion pump actively removes Na+ from cells lining pct
Na enter back the cell in association with glucose through cotransporter proteins
Glucose diffuses back into the blood
Water potential in filtrate increases
H20 enters cells by osmosis
Can someone please explain all the G words for me please, getting a little confused :/ (like glycogenesis etc)
Original post by hajs
After a prolonged period of fasting, glycogen levels in the liver are depleted. However the liver can still produce glucose by the process of gluconeogenesis. Describe one way in which this is done?

Anyone gonna try to answer that? I found it really difficult lol..



Gluconeogenesis from fatty acids right? was this a PPQ?
Any predictions for tomorrow? :smile:
Lol as if some guy on here was supposedly revising the f215 topics for the exam tomorrow!! thats jokes
Original post by coolerthanbeans
amino acids + fats = glucose
= gluconeogenesis :smile:


Glucose isn't made by a reaction between amino acids and fats. It's fats and/or amino acids entering the krebs cycle and then doing glycolysis in reverse (bar a few reactions) to form glucose. The two don't bind together.
Original post by RichBitch
What's the vagus nerve and what does it do???


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The vagus nerve (also know as the decelerator nerve) connects the medulla oblongata in the brain to the sinoatrial node (SAN) in the heart. Action potentials are sent down it to decrease the frequency of contractions of the heart muscle, reducing the heart rate. The opposite is the accelerator nerve which is the same except action potentials sent down it increase the frequency of contractions, raising heart rate.
Reply 1912
Original post by Lighfy
Can't glucose be produced by combining fatty acids and amino acids together? :s-smilie:


Original post by Munrot07
Gluconeogenesis is the process of converting amino acids, fats and nucleic acids into glucose. Certain amino acids can be bled into the krebs cycle and then go through reverse glycolysis (bar a few reactions) and are turned back to glucose. Pyrimidines can do this as well (purines can not).


Thats what i thought. The answer however is...
either
deaminationof amino acids / removal of NH2 from amino acids ;
pyruvate/ carbon skeleton / AW ;
triosephosphate / TP ;condensation/ increasing number of carbon atoms ;
or
breakdownof, lipid / triglyceride ;
glycerol;
triosephosphate / TP ;
condensation/ increasing number of carbon atoms ; max3
Original post by alexthehuman
Im sorry if this has already been asked but im new to the thread. I can't find the 2014 f214 paper anywhere. Does anyone have it or know what the big questions were?


Bro, you can find the june 2014 papers here

http://www.thebiotutor.com/past-papers3.html

:yes:

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Reply 1914
Original post by ZQ110
In non-cyclic, water undergos photolysis to form H+ and electrons
Photolysis is splitting of water using light

The electrons from water replace those lost from PSII


My main Q was do they occur at the same time.
Original post by loperdoper
I'm going to assume the main point is that not all the water is lost in the descending limb. The water potential gradient is there, but by the time it's passed into the ascending limb some of it hasn't diffused out into the capillaries yet. That's why ADH can have an affect to vary it - not all of the water diffuses out of the collecting duct either, so aquaporins can help it along a bit more.


http://www.thebiotutor.com/past-papers3.html


Amazing! Thank you so much
Reply 1916
Original post by lawalke
Gluconeogenesis from fatty acids right? was this a PPQ?


One of the q's on the old spec
Original post by domcandrews
Lol as if some guy on here was supposedly revising the f215 topics for the exam tomorrow!! thats jokes


What's F215? :/
Original post by PropaneHorcrux
Can someone please explain all the G words for me please, getting a little confused :/ (like glycogenesis etc)


Gluconeogenesis- Production of 'new' glucose - genesis- think formation

Glycogenolysis- Break down of glycogen- Lysis= Breakdown Glyco- like glycogen

Glycogenesis- Production of glycogen - like i said before -gylco= glycogen Genesis- formation

Hope this helps :smile:
Original post by PropaneHorcrux
Can someone please explain all the G words for me please, getting a little confused :/ (like glycogenesis etc)


Glucose - a carbohydrate
Glycogen - animal carbohydrate storage molecule
Glucagon - hormone that increases blood glucose
Glycolysis - Breaking down of glucose to form pyruvate, first stage of respiration
Glycogenolysis - Breaking down of glycogen to glucose
Glycogenesis - Glycogen synthesis from glucose
Gluconeogenesis - Formation of new glucose from animo acids and fatty acids.

I think that's all :smile:

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