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OCR Biology F214 Communication, Homeostasis and Energy Wed 25 Jan 2012

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Reply 220
Hey, I'm stuck on a respiratory substrates question. Why do lipids have a higher energy value than proteins, carbs etc...?
Lipids when hydrolysed contain more hydrogen atoms than the above. But these are atoms not hydrogen IONS (pumped in Oxdative phosph.) I'm confused... It would be grateful if someone could help me. Thanks.
Original post by Lalaa
Selective reabsorption occrus in the PCT . Here more water, glucose, salts and amino acids are reabsorped.

The linings of the PCT are specalised for this process. The membrane folds in forming ( hair like? finger like? ) , this icnrease surface area, so maximum level of reabsorption occrus.
The side at which the capilaries run, there are sodium pumps which are actively pumping out Na+ from the tubles.
this reduces conc. of Na+ inside the membrane? so more Na+ enter the membrane assosiated with Glucose and amino acids via facillated diffusion.
conc rises inside the cell, so glucose and AA leave the cell via active transport?
this lowers water potential iside the membrane so water eneters via osmosis, and large molecules enter via endocytosis.
Water can be reabsopred into the blood via osmosis.




is that okay? :colondollar:



'this reduces conc. of Na+ inside the membrane? so more Na+ enter the membrane assosiated with Glucose and amino acids via facillated diffusion'

the co-transporter proteins are embedded on the membrane which is in contact with the tubule fluid. these co-transporter proteins are Na+ ion channels which allow glucose or amino acids to diffuse into the cell inconjuction with the Na+ ion by facilitated diffusion.

you can also mention the Na/k ion pumps uses atp so the cells lining the pct also containing a lot of mitochondria needed for respiration to occour to produce ATP energy needed to pump Na+ ions out of the cell.

the rest is fine

here's the mark scheme: http://gryphonscience.files.wordpress.com/2010/12/l_gce_biology_3881_7881_ms_jan_10.pdf

question 4c
Reply 222
Original post by undertaker1
'this reduces conc. of Na+ inside the membrane? so more Na+ enter the membrane assosiated with Glucose and amino acids via facillated diffusion'

the co-transporter proteins are embedded on the membrane which is in contact with the tubule fluid. these co-transporter proteins are Na+ ion channels which allow glucose or amino acids to diffuse into the cell inconjuction with the Na+ ion by facilitated diffusion.

you can also mention the Na/k ion pumps uses atp so the cells lining the pct also containing a lot of mitochondria needed for respiration to occour to produce ATP energy needed to pump Na+ ions out of the cell.

the rest is fine

here's the mark scheme: http://gryphonscience.files.wordpress.com/2010/12/l_gce_biology_3881_7881_ms_jan_10.pdf

question 4c




Thank you for your helpp!!
Is that mark scheme from legacy?
Original post by Lalaa
Thank you for your helpp!!
Is that mark scheme from legacy?


yeh--- i really hope that question comes up
Reply 224
Original post by undertaker1
yeh--- i really hope that question comes up


it aint been mentioned once in the last 2 years ! so hopefullyy!
i hate it when they mix respiration and photosynthesis together! so confusing !

and the worst, when they bring up stomata ( unit 1 stuff ) :mad:
Reply 225
Original post by forex
Hey, I'm stuck on a respiratory substrates question. Why do lipids have a higher energy value than proteins, carbs etc...?
Lipids when hydrolysed contain more hydrogen atoms than the above. But these are atoms not hydrogen IONS (pumped in Oxdative phosph.) I'm confused... It would be grateful if someone could help me. Thanks.


i think its:

lipids release more hydrogen atoms, so more can bind to NAD to make it reduced?!, and so more hydrogen/ NADH is transported from krebs to Oxidative phops., and here NADH makes h+ e- which are used...

make any sense ? =P
ectotherms bask on a rock in the morning to absorb heat from the sun to maintain body temperature.

does anyone know why the rock is warmer than the ground,
Original post by undertaker1
ectotherms bask on a rock in the morning to absorb heat from the sun to maintain body temperature.

does anyone know why the rock is warmer than the ground,


the ground is warm as well as the rock?
both absorb heat from the sun.

you're second attempt f214 right? what do you predict bro
Reply 228
Original post by undertaker1
ectotherms bask on a rock in the morning to absorb heat from the sun to maintain body temperature.

does anyone know why the rock is warmer than the ground,


i dont think they necessarily have to bask on a rock..
in the OCR book it says: in order to warm up they will bask in the sun or lie on warm surfaces.?
Reply 229
in the Jan 2011 paper, it said:

suggest where ADH is removed from the blood AND describe what then happens to the ADH molecule?
in the mark scheme it said: ADH as hormone, and ADH as protein, and had steps for each... would you need to do both these things to get 3 marks ? =|


Q4D
Original post by Lalaa
in the Jan 2011 paper, it said:

suggest where ADH is removed from the blood AND describe what then happens to the ADH molecule?
in the mark scheme it said: ADH as hormone, and ADH as protein, and had steps for each... would you need to do both these things to get 3 marks ? =|


Q4D


nah because ADH is a protein hormone you can either think of it as just a hormone or protein
edit: you cant mix and match
(edited 12 years ago)
Reply 231
Original post by undertaker1
nah because ADH is a protein hormone you can either think of it as just a hormone or protein
edit: you cant mix and match


Ohhh right... thanksss ! Hav you done this paper?
Original post by Lalaa
Ohhh right... thanksss ! Hav you done this paper?


no not yet but i had a look at the mark scheme
hows everyone revising for this: are they using the big book or revision guides or a combination of both
Original post by undertaker1
hows everyone revising for this: are they using the big book or revision guides or a combination of both

i bought the CGP one but it doesnt seem to have enough info
i started using the big purple one, its much better
what about u?
Original post by Bi0logical
i bought the CGP one but it doesnt seem to have enough info
i started using the big purple one, its much better
what about u?


CGP is rubbish for this module but i recommend it for F215

I'm using the big book aswell as the cgp book
Reply 236
Original post by shyro1000
Anyone else done the specimen paper?


where did you get it!?!?!
Reply 237
Any predictions for the most likely topics coming up?
Reply 238
Original post by atman7
Only started revising this yesterday (yikes) but its my second time and i know a fair bit. Just a quick question, when blood glucose conc is too low the Glucagon binds to the Glucagon receptor on the hepatocyte but what enzyme converts the ATP into cAMP? is it Adenyl Cyclase again as it was the enzyme for when Insulin binds with the hepatocyte.


Adenyl Cyclase is the enzyme which converts ATP > cAMP for glucagon and adrenaline but NOT for insulin- the OCR text book made a mistake- researchers still dont know the enzyme for when insulin binds to a receptor.
whats the answer for that stupid seal question??????????????????????????

what did everyone put down before looking at the mark scheme

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