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A2 Biology OCR June 2015 Revision Thread

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Could someone please explain the leaf disc experiment in photosynthesis to me?
Original post by Asif_m96
My prediction on what will come up:
Photosynthesis experiment (either leaf disks or photsynthometer)
Adrenaline
Diabetes
Thermoregulation
Heart
Respiration ( 1 markers)
Role of Synapse
Possibly kidneys and regulation of blood glucose conc...


Didn't role of synapse come up in June 2014 though?
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tewas
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Original post by Asif_m96
My prediction on what will come up:
Photosynthesis experiment (either leaf disks or photsynthometer)
Adrenaline
Diabetes
Thermoregulation
Heart
Respiration ( 1 markers)
Role of Synapse
Possibly kidneys and regulation of blood glucose conc...


what could come up in thermoregulation/heart and adrenaline?
Original post by cinderella25
I'd like to add action potentials, synapses, properties of ATP, respiration experiments, and diagram of mitochondria, some suggest questions on disruption of synaptic transmission


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What respiration experiments are there, do we need to know them?
Original post by coolerthanbeans
Primary: location of the reaction centre, this is where light energy is absorbed to excite electrons so that they can pass into the electron transport chain.
It's found in the centre of photosystems.
Contains Chlorophyll A, P680,P700

Accessory: absorbs light energy of a wide range of wavelengths, absorbs any light energy that the primary pigment can't. Then transfers this light energy to the primary pigment.
Surrounds the primary pigment in the photosystem.
Contains chlorophyll B, Xanthophyll and Carotenoid.

Hope that helps! :smile:



Thank you so much! That's brilliant! :smile:
Original post by normalman
where in the Kidney is PH lowest??!!?!?


The medulla, hence why water moves out of the descending limb by osmosis. :wink:
Original post by gh1290
When GP is converted to TP in the calvin cycle, are two molecules of ATP and two molecules of NADPH used or is it just one molecule of each, as my two text books have different numbers, thanks


two since there are two gp molecules
Original post by Asif_m96
My prediction on what will come up:
Photosynthesis experiment (either leaf disks or photsynthometer)
Adrenaline
Diabetes
Thermoregulation
Heart
Respiration ( 1 markers)
Role of Synapse
Possibly kidneys and regulation of blood glucose conc...


Could you please explain the leaf disk or photosynthometer experiment please?
Original post by EllieTaorps
The medulla, hence why water moves out of the descending limb by osmosis. :wink:


Ph?????? why ph isnt it about water potential?
My predictions:
Heart rate
cAMP
Thermoregulation
Photosynthesis experiment
Insulin secreted from Beta cells
Original post by baffledchick
Could you please explain the leaf disk or photosynthometer experiment please?


take a syringe half full of hydrogenate carbonate.... put leaf discs into them. Put your finger on the end of the syringe and pull the plunger. This causes them to sink as spongy mesophyll air is replaced by the hydrogente carbonate solution. Shine a white light on it and it should rise up again ( as co2 from the hydrogen carbonate is used up and oxygen is produced). Measure the time as the time it takes to rise is proportional to photosynthesis rate..then you change the factor you want to investigate.
Original post by games211
take a syringe half full of hydrogenate carbonate.... put leaf discs into them. Put your finger on the end of the syringe and pull the plunger. This causes them to sink as spongy mesophyll air is replaced by the hydrogente carbonate solution. Shine a white light on it and it should rise up again ( as co2 from the hydrogen carbonate is used up and oxygen is produced). Measure the time as the time it takes to rise is proportional to photosynthesis rate..then you change the factor you want to investigate.


Thank youuu
Leaf disk experiment:
Get leaf disks from a plant ( same size and same part of plant)
Place in a syringe filled with dilute NaHCo3.
Hold upright and pull on the plunger... This increases density of disks as air is removed.
Transfer contents in a beaker illuminates with light.
Time how long it takes to float to the surface.

Why does it float?
Because as it photosynthesises it releases O2 therefore density decreases.


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http://us21.chatzy.com/67830706460982
Can someone please summarise what we need to know about Endotherms and Ectotherms?
including how they regulate body temperature
I am not being rude or anything but why can't people just look in the book to find the answers to some of the simple qs being asked? Some of the questions being asked can easily be found in the book...................................................... like i said not being rude or anything..
Original post by abOO
LIR was a main part in the JUne 2014 paper, dont think it will come up again this year


Hopefully they will go for Non cyclic photophosphorylation this time! But Calvin cycle has a wider range of questions to ask tbh
Original post by games211
I am not being rude or anything but why can't people just look in the book to find the answers to some of the simple qs being asked? Some of the questions being asked can easily be found in the book...................................................... like i said not being rude or anything..


I agree. The question about endotherms and ectotherms is explained in the book
Please can someone give a detailed summary of selective reabsorption in the pct. I'm so confused by it :confused: :'(
Original post by Asif_m96
My prediction on what will come up:
Photosynthesis experiment (either leaf disks or photsynthometer)
Adrenaline
Diabetes
Thermoregulation
Heart
Respiration ( 1 markers)
Role of Synapse
Possibly kidneys and regulation of blood glucose conc...


Thanks for this, but last year there was a 3 marker on roles of synapse, a QWC on regulation of blood glucose concentration (5 marker?) and q's some on diabetes ain't it?

But i agree with the thermoreg., adrenaline, heart and repiration :smile:

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