AQA AS Biology unit 1 25th May 2010 Watch

VULGAR123
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#81
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#81
(Original post by hallie.x)
in theory i understand the biolgy behind everything
but AQA's stupid questions confuse me

HARDCORE REVISION TONIGHT!
Yeah AQA papers are so difficult they like to test our application so there's hardly any recall questions instead we have to apply the knowledge!
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princessjuicy
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#82
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#82
how many mm is a nano meter? thanks
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alwaysanigel247
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#83
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(Original post by VULGAR123)
I am having problems understanding the B cells in immunity do they have antigens on their surfaces?
yeh they do! i got very confused on that!!!

also do mitrochondria release or produce atp?
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LettersFromTheSky
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#84
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(Original post by I_Need_To_Revise)
Anyone have any guesses on what the 5 markers will be at the end?
In jan 2010 it was on the cardiac cycle and i think myocardial infarction...
In jan 09 the five markers were on Cholera and microscopes and in jun 09 on digestion.

Jan 2010 was like you say Cardiac Cycle and how atheroma leads to myocardial infarction, so Id take a guess at saying that this paper's 5 markers wont be on heart stuff, Immunity has yet to come up and I dont think they usually ask lung stuff for long questions! But who knows!
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VULGAR123
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Yeah i find the whole B cell stuff incredibly confusing!

ATP is produced in the mitochondria from carbohydrates..i was wrong before lol
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CHEM1STRY
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(Original post by alwaysanigel247)
yeh they do! i got very confused on that!!!

also do mitrochondria release or produce atp?
produce
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CHEM1STRY
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(Original post by VULGAR123)
Yeah i find the whole B cell stuff incredibly confusing!

ATP is a form of energy so i'm guessing it's released because energy can't be produced
No it's a molecule so they produce it, but it releases energy
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INeedToRevise
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(Original post by alwaysanigel247)
yeh they do! i got very confused on that!!!

also do mitrochondria release or produce atp?
Mitochondria release energy. If you write produce you won't get the mark. It was in the markscheme for June 2009 paper.
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VULGAR123
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My textbook says Mitochondria produce ATP
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Scrubby
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It's either going to be something on lungs, cells or immuntiy. More specifically cell-mediated and humoral responses or absoprtion in epithelial cells or phospholipid bilayer or maybe phagocytosis. Just guessing. I'd say absorption or specifically the sodium potassium pump may come up. that hasn't really come up has it? I hope it does as I have that **** dooown.

Also for the mitochondria question it says this: Mitochondria produce ATP/release energy; So either is fine tbh.
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LettersFromTheSky
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(Original post by alwaysanigel247)
yeh they do! i got very confused on that!!!

also do mitrochondria release or produce atp?
A lot of mark scheme answers Ive seen say mitochondria for the production of atp.
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CHEM1STRY
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#92
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(Original post by I_Need_To_Revise)
Mitochondria release energy. If you write produce you won't get the mark. It was in the markscheme for June 2009 paper.
They release energy but produce atp
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T.S
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what type of question do you think they could ask for the 5 mark one if it was immunity??

and can someone help me because im confused with cholera..i just need a quick discription of what it does and what happens 2 the chloride ions?
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LettersFromTheSky
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(Original post by Scrubby)
It's either going to be something on lungs, cells or immuntiy. More specifically cell-mediated and humoral responses or absoprtion in epithelial cells or phospholipid bilayer or maybe phagocytosis. Just guessing. I'd say absorption or specifically the sodium potassium pump may come up. that hasn't really come up has it? I hope it does as I have that **** dooown.
Ahhh the Sodium Pottassium pump, Im so crap at that!

Immunity im not exactly great at but I think i more or less know phagocytosis, cell mediated response and humoral response
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T.S
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#95
(Original post by Scrubby)
It's either going to be something on lungs, cells or immuntiy. More specifically cell-mediated and humoral responses or absoprtion in epithelial cells or phospholipid bilayer or maybe phagocytosis. Just guessing. I'd say absorption or specifically the sodium potassium pump may come up. that hasn't really come up has it? I hope it does as I have that **** dooown.

Also for the mitochondria question it says this: Mitochondria produce ATP/release energy; So either is fine tbh.

heyyy
can u help me with the sodium potassium pump part! what do u think
is a good answa?
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Scrubby
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(Original post by LettersFromTheSky)
Ahhh the Sodium Pottassium pump, Im so crap at that!

Immunity im not exactly great at but I think i more or less know phagocytosis, cell mediated response and humoral response
Nah I just checked and it's the last question for the June 09 paper
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Scrubby
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(Original post by T.S)
heyyy
can u help me with the sodium potassium pump part! what do u think
is a good answa?
It doesn't look like it'll come up but here's the mark scheme answer:

Glucose moves in with sodium (into epithelial cell);
Via (carrier/channel) protein/symport;
Sodium removed (from epithelial cell) by active
transport/sodium-potassium pump;
Into blood;
Maintaining low concentration of sodium (in epithelial cell) /
maintaining sodium concentration gradient (between lumen
and epithelial cell);
Glucose moves into blood;
By (facilitated) diffusion;

Seems fairly thorough. I might have mentioned that it uses a different carrier protein for each movement in/out of the cell though.
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T.S
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(Original post by Scrubby)
It doesn't look like it'll come up but here's the mark scheme answer:

Glucose moves in with sodium (into epithelial cell);
Via (carrier/channel) protein/symport;
Sodium removed (from epithelial cell) by active
transport/sodium-potassium pump;
Into blood;
Maintaining low concentration of sodium (in epithelial cell) /
maintaining sodium concentration gradient (between lumen
and epithelial cell);
Glucose moves into blood;
By (facilitated) diffusion;

Seems fairly thorough. I might have mentioned that it uses a different carrier protein for each movement in/out of the cell though.

okk thanks!
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Lee :D
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They're nowhere near as bad as the A2 papers though

I've completely forgot most of the Unit 1 stuff, and only just realised how close the exam is... Guess I've got a lot to learn tonight >.<
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CHEM1STRY
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#100
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(Original post by T.S)
what type of question do you think they could ask for the 5 mark one if it was immunity??

and can someone help me because im confused with cholera..i just need a quick discription of what it does and what happens 2 the chloride ions?
Cholera is caused by Vibrio Cholerae. It propels itself through the mucus lining the epithelial cells in the intestine in a corkscrew like motion with its flagellum. Here it secretes a toxin in two parts.

One part binds to the glycolipids on the CSM of the epithelial cells. The receptors have a very specific shape and the toxin is only complementary shape to these receptors so only affects epithelial cells. Another part causes the release of cyclic AMP which causes the chloride ion channels to open.

Cl- ions flood out of the cells into the ileum, followed by Na+ ions to neutralise the building potential difference across the CSM. This lowers the water potential in the ileum and raises it in the epithelial cells. Hence water moves out of the epithelial cells via osmosis.

There is now a conc. gradient of ions from surrounding tissues to the epithelial cells, causing them to diffuse from the tissues to the epithelial cells. This raises their water potential so water moves via osmosis from tissues and blood to epithelial cells then into the ileum, causing dehydration and diarrohea.
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