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AQA A2 Biology BIOL5 - 17th June 2015

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adenly cyclase is mentioned in the revision guide by Collins which is what the examiners use for reference so i think it should be ok? however in mark schemes adenylate cyclase is only mentioned :s-smilie:

what on earth is adenylate cyclase????

Reply 1321

biojames

What is the repolarisation of the axon in an action potential ?

Reply 1322

aprocrastinator

Original post by kiwi8397

what on earth is adenylate cyclase????

it is activated when adrenaline binds with a receptor on a cell membrane and it converts ATP to cyclic AMP which activates enzymes involved with gluconeogenesis and glycogenolysis

Reply 1323

Ninainnarnia

Original post by kiwi8397

what on earth is adenylate cyclase????

When adrenaline or glucose binds to receptors on liver cell membranes:
-it activates advenylate cyclase
-this enzyme converts ATP to cAMP
-cAMP activates enzymes which convert glycogen to glucose (glycogenolysis)

Reply 1324

wrfrew

can someone please please explain the hormonal system vs local chemical mediators

Reply 1325

lucha

Original post by biojames

What is the repolarisation of the axon in an action potential ?

The potential of the axon is about +40mV. The peak of the curve. Na+ channels close and K+ open. K+ diffuse out of the axon. These positive ions leaving make the axon more negative. It is depolarised. It can be hyper polarised though it too many k+ leave. This helps in the unidirectionality of a nervous transmission though. Due to an action potential being unable to be fired. Hope this helps. Good luck!!

Reply 1326

naykaykay

any predictions on essay titles?

Reply 1327

DecantedOrange

Original post by kiwi8397

what on earth is adenylate cyclase????

Not in our spec, don't worry about it.

Reply 1328

DecantedOrange

After the horrendous Biol 4 exam and this horrid thing tomorrow I can kiss uni goodbye

Reply 1329

xSophie04x

what would i write about in this essay question :

'carbon dioxide can effect organisms directly and indirectly'

thanks! :smile:

Reply 1330

KatiexZoe

Original post by DecantedOrange

Not in our spec, don't worry about it.

I think it is!

Reply 1331

Redpurplelane

Original post by wrfrew

can someone please please explain the hormonal system vs local chemical mediators

Hormones travel in blood plasma and only affect cells with complementary receptors on their cell surface membranes.
LCM - travell by diffusion and affect cells in their immediate vicinity, Histamine for example, is released in response to an allergen such as pollen and causes dilation of small arterioles and increased permeability of capillaries,

Reply 1332

chemistrykid123

did you guys hear that proteins were on the stolen paper and won't be on this one

Reply 1333

Bustamove

Original post by chemistrykid123

did you guys hear that proteins were on the stolen paper and won't be on this one

there was a stolen paper?

Reply 1334

Redpurplelane

Original post by xSophie04x

what would i write about in this essay question :

'carbon dioxide can effect organisms directly and indirectly'

thanks! :smile:

- Physiology ; the effect of carbon dioxide on heart rate and enzymes (pH lowered), Hemoglobin affinity for oxygen and lung function/gas exchange
- Ecological - Carbon cycle, global warming
- Biochemistry - Photosynthesis

hope this helps

Reply 1335

Ninainnarnia

Original post by DecantedOrange

Not in our spec, don't worry about it.

It's definitely in the spec.

Reply 1336

chemistrykid123

Original post by Bustamove

there was a stolen paper?

yh the man demz jacked it blud #sillymandemz

Reply 1337

DecantedOrange

Original post by KatiexZoe

I think it is!

Cyclic AMP is and the secondary messenger model but that name isnt mentioned anywhere in the spec

Reply 1338

FrankiiWatson

Original post by KatiexZoe

I think it is!

It's in the second messenger system with adrenaline. When adrenaline binds to the receptors it activates adenylate cyclase which converts ATP into cAMP