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

the evidence for it, do you thinkyou would need to know how to do the experiments

i checked in a book : answer:
Aerobic resp. can only take place when oygen is present. this is beacause oxygen is the final electorn acceptor from the electorn transport chain. if there is no oxygen, then electorns cannot be passed in the electorn carriers so they cannot accept any more from NAHD, so the NADH cannot be converted to NAD, therefore there is nothing left to pick up hydrogen from reactions of link and krebs, and the electron transport chain grinds to a halt !

sorry about spellings and hope this makes sense ! ^?!

Thanks you!!! made it so much easier for me to understand now

in the book it says evaluate so in the exam they will probably give us all the information and we will have to evaluate why it supports or doesnt support the evidence for chemiosmosis.

i've never seen a question for it so i might be wrong. however because it hasn't come up before you might aswell learn it just to be safe

Yeh, might aswel learn it! mmmm.. ihavent really seen any kidney processes, i think ultrafilteration came up, but none of the others in such details, i think PCT will come up !
can i explain it to you and you tel me whether i needa add anything?

and there's renal dialysis but i feel its going to chemiosmosis because last paper didnt have much respiration on it either

I think kidney's been on a fair bit in Jan and June so I can't see dialysis coming on but then again it might. Its not that bad I suppose. I think its been on before but the stuf about the HCG protein in urine for pregnancy tests is that how science works could come up? I remember seeing it on a past paper a while ago.

Has anyone uploaded the June 2011 paper with Mark scheme anywhere?

make sure you guys do the liver, that hasnt come up much

ocr don't put on certain topics for ages just so that people stop prediciting whats likely to come up. one example is the heart in f211 which hardly ever comes up whereas that xylem/phloem come up all the time lol----- i've had bad experiences lol

i dont really understand renal dyalysis to be honest but i'm going to learn it all before they exam. it was really unfair of ocr to put a 6 mark question on pregnancy testing-- most people just skip that bit.

i've uploaded the paper somewhere on this thread back in mid december

oh yeah I remember my friends complaining about the heart in F211 constantly. this paper usually feels fairly balanced in terms of whats on. The HCG one was unfair I remember doing that last year it was followed up with something about anabolic steroids. Dialysis doesn't seem so bad i can imagine a few marks being for each type, although if its a big marker specifically on one then Its a little tricky.

I haven't looked at the Excretion unit yet I wouldn't mind kidney failure coming up though that seems the easiest part of it. I'm a bit weary of homeostasis coming up though that type of stuff is really annoying and boring to revise, along with the fact it hasn't come up much, along with the liver like someone else said.

i forgot about homeostasis and all that endotherms and ectotherms-- that hasn't really come up either yet so it could possiblt be an essay question this year.

i'm going to revise homeostasis tonight and the liver and kindey failure tmoz

are you on a gap year?

yeh sure go for it, i've got a mark scheme for it awell so i'll mark it according to that
think of it as an 8 mark essay question.

make sure you name the process of how everything moves such as active transport, diffusion, passive diffusion etc

start it off by describing how the cells lining the filtrate in PCT are specalised for selective reabsorption

Anyone else done the specimen paper?

e i did.. i found it a bit difficult ! i got 47/60 =O !

Where do I find the specimen paper?

Thanks

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?

Don't forget the co-transporter proteins