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AS Edexcel Biology Exams May 2011

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im thinking a little bit on the effects of CF, vitamin C practical, cvd treatments, maybe atherosclerosis. ive got a feeling a little bit on lipoproteins and carbohydrates.

There has been quite a bit on the heart recently and i don't think i have seen any questions on DNA replication so maybe that.

you know the water regulation stuff do we only need to know about CF patients' water regulation or a normal person with too much water/too little water aswell?

Reply 41

supersping

you know the water regulation stuff do we only need to know about CF patients' water regulation or a normal person with too much water/too little water aswell?

Reply 42

ilyking

Biology eh, the course forces you into rote memorization until the receptors in your brain begin to bleed and then they throw a random bubble graph question in your face which makes you drop that one grade because it was a 10 mark question and you miss your offers

:daydreaming:

Oh and everyone start memorizing, harder! your first memoroligy exam is in 18 hours. oops! I meant biology :biggrin:

Reply 43

ilyking

Original post by supersping

you know the water regulation stuff do we only need to know about CF patients' water regulation or a normal person with too much water/too little water aswell?

basically just memorize it all

Reply 44

fudgesundae

Original post by supersping

you know the water regulation stuff do we only need to know about CF patients' water regulation or a normal person with too much water/too little water aswell?

i dont know anything bout water regulation lol? what do you mean by that?

Reply 45

supersping

Original post by fudgesundae

i dont know anything bout water regulation lol? what do you mean by that?

the CFTR channel protein stuff .. like in a person with CF their CFTR channel is non functional or absent, the Na+ channel is permenantly open and water is continually removed from mucus by osmosis

Reply 46

fudgesundae

Original post by supersping

the CFTR channel protein stuff .. like in a person with CF their CFTR channel is non functional or absent, the Na+ channel is permenantly open and water is continually removed from mucus by osmosis

oh yeh sorry i know that. idk if there will be a question directly on that. There was a 5 mark question in the June 2010 paper. it was basically:

CFTR controls Cl- out of cell
also regulates ENaC which controls Na+ into cell
build up of ions means inside of cell has a lower water potential
water moves in by osmosis
thick mucus cannot be moved by cilia.

Reply 47

supersping

Original post by fudgesundae

yeah i saw that one so its not too likely to come up again this year right? i dont really get the stohl experiment, do you get it?

Reply 48

xshopoholicx

K SO BASICALY THIS IS THE THIRD TIME I AM TAKING THIS EXAM
the beetroot experiment has already been done
so has the permeability of membranes
and somatic and germ line therapy
and monohybrid inheritance

whats the difference between corellation and causation? (2)
whats the difference between endothelieum and epithelium? (2)
how is gas exchange adapted for diffusion? (6)
how does cf affect the digestive and respiratory and reproductive system? (9)
outline the procedure to find the vit.c content in juice?
why is the left ventricle wall thicker than the right?
whats the role of av valves?
3 factors that affect the chance of getting cvd?

Reply 49

taaaasha

Could anyone help me with the rates of reaction/enzyme core practical from topic 2?

Reply 50

High As A Kite

whats the difference between corellation and causation? (2)
- correlation is a 'link' it does not mean that one thing has definitely caused another. causation is a direct known cause - e.g) smoking causing lung cancer in an individual

whats the difference between endothelieum and epithelium? (2)
endothelium and epithelium are types of cells that just surround tissue .. on the inside is endothelium (blood vessel) and the and the outside is epithelium (intestine lining)

how is gas exchange adapted for diffusion? (6)
1) short diffusion distance
2) steep conc gradient
3) capillaries are 1 cell thick = rapid diffusion + the blood flow is slow = more time for diffusion

how does cf affect the digestive and respiratory and reproductive system? (9)
a) resp = sticky mucus builds up airways of the lungs = reduces SA for gaseous exchange of the bronchiles. any pathogens inhaled or already hidden in the body are provided with a warm and ideal enviroment to reproduce and cause infections. the bodies immune system is blocked as WBCs cannot attack the pathogens because they cant navigate through the sticky mucus. also, the cillia of the lungs are unable to move the mucus along and into the stomach where it is normally destroyed due to the acidic conditions and digestive enzymes
b) repro: women = sperm cannot travel from the cervix to the oviducts = no fertilisation
men = the vas deferens is blocked with sticky mucus = sperm cannot get from testes to outside the penis.. :/

outline the procedure to find the vit.c content in juice?
about to read this

why is the left ventricle wall thicker than the right?
the left ventricle is under a lot more pressure as it has to pump harder to get blood around the whole body - as opposed to just the pulmonary artery (which the r. ventricle does).

whats the role of av valves?
prevent backflow of blood from the pulmonary artery and aorta from the r and l ventricle respectively -

3 factors that affect the chance of getting cvd?
lifestyle choices (smoking, poor diet), age, inherited genes

please correct if wrong and im really sorry about spelling + giving model answers - im still revising a few bits atm! so it was rushed

(edited 12 years ago)

Reply 51

cylon

can someone tell me what should we know about Meselson–Stahl experiment ? and what do they ask for?

Reply 52

xshopoholicx

Original post by ilyking

biology eh, the course forces you into rote memorization until the receptors in your brain begin to bleed and then they throw a random bubble graph question in your face which makes you drop that one grade because it was a 10 mark question and you miss your offers

:daydreaming:

Oh and everyone start memorizing, harder! Your first memoroligy exam is in 18 hours. Oops! I meant biology :d

so true
this is the third time
1st time i got an e
second time i got a b

Reply 53

xshopoholicx

Original post by cylon

can someone tell me what should we know about meselson–stahl experiment ? And what do they ask for?

basically we now know that dna relplication is semi conservative and we need to understand the procedure of the nitrogen broths

Reply 54

High As A Kite

how are you lot on your knowledge about proteins and amino acids?

all the bonds and different kinds etc. ?

Reply 55

cylon

Original post by xshopoholicx

basically we now know that dna relplication is semi conservative and we need to understand the procedure of the nitrogen broths

so after like 3 generations after mixing the DNA strands from both nitrogens do which one will be wider the heavy one in the middle or the light one in the upper side?

Reply 56

Panda29

hey guys when answering a core practicals questions.. do we need to write how much of something we need to put? or can we just state the steps? thanks.

Reply 57

Nator

Original post by Shippy

Yeah i've put a lot of effort into revising how it affects the digestive system rather than reproductive system :smile:

would you need to say about the digestive enzymes being trapped behind mucus in the pancreatic duct causing cysts? or just about malabsorption?

Nice

And the pancreatic duct just becomes blocked with mucus so no enzymes can be delivered, and cysts form on the pancreas which inhibit enzyme production, that's all you need to know :smile:

Reply 58

TheApex

Aha feeling prepared for this tomorrow. Got an E in January, but just did the Jan 2009 past paper and got an A (only just scraped in at the bare minimum mark needed for an A though, 52), so I'm much better prepared than I was in January. I don't know any practicals, but I know enough about the units to get a good grade without needing to know the practical procedures. Some of it is common sense though, so I'm sure I'll pick up a few marks here and there.

Gonna revise some more, then do one more past paper later tonight (Jan 2010), and then read over my notes after, read my notes in the morning and then off to the exam to get that A grade!

Reply 59

Shippy

I got a D in january, but I wasn't far off a C. Really hoping to get a B which is all I need really. Done mind maps covering everything, made extra notes on things i'm a bit unsure of. Completed all past papers but haven't marked 2010 ones :/ did the specimen paper in the snab revision book and nearly got full marks but only because all the questions were from past papers i'd done a load of times and knew the answers off by heart! Felt a bit of a cheat :P gonna read over all my notes once more tonight, then again tomorrow morning! Good luck everyone! :smile: