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king101
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#701
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#701
(Original post by bellaanne)
Maybe we can do past papers together to see where you're going wrong?
just a thought x
Yeh great idea! Pm me!

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erniiee
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#702
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#702
When are people planning on starting past papers seeing as there are only 4 :eek:
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lala12
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#703
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#703
(Original post by erniiee)
When are people planning on starting past papers seeing as there are only 4 :eek:
Is that including the specimen paper?
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master y
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#704
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#704
(Original post by erniiee)
When are people planning on starting past papers seeing as there are only 4 :eek:
err i've gone through a few already.... :L
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DELETED ACCOUNT
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#705
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#705
(Original post by erniiee)
When are people planning on starting past papers seeing as there are only 4 :eek:
I know!! Last week of revision and then I'll start!
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iop horray
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#706
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#706
Hi can some one please give me some feedback about my 25 mark essay as I have already done around 10 and have given around 4 of them to my teacher yet I haven't received any feedback; even though that was 3 weeks ago but anyways any feedback would be good and if you could give it an marking out of 25 would be wonderful , thanks.
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Where'sPerry?
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#707
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#707
(Original post by erniiee)
When are people planning on starting past papers seeing as there are only 4 :eek:
A day before the exam :teehee: Kidding, I'll probably start when there's about 2/3 weeks to go as there's only 4. At the moment I'm focusing on revising the synoptic stuff (units 1, 2 and 4) rather than actual unit 5 content. I've done some revision on that as I've gone along but I've not started revising it intensely yet. I prefer to begin the past papers only when I'm absolutely solid on the content.
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erniiee
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#708
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#708
(Original post by lala12)
Is that including the specimen paper?
It is indeed :/

(Original post by master y)
err i've gone through a few already.... :L
Lol, all of them?

(Original post by frogs r everywhere)
I know!! Last week of revision and then I'll start!
Cool. Yea, I think I'm going to max out on all of the application/HSW and exam style questions before I start past papers!

(Original post by Where'sPerry?)
A day before the exam :teehee: Kidding, I'll probably start when there's about 2/3 weeks to go as there's only 4. At the moment I'm focusing on revising the synoptic stuff (units 1, 2 and 4) rather than actual unit 5 content. I've done some revision on that as I've gone along but I've not started revising it intensely yet. I prefer to begin the past papers only when I'm absolutely solid on the content.
Thats exactly what I usually do it annoys me when teachers use past paper questions in class, especially as there are only 4 for this spec :/ in the mean time though, I'm gonna do legacy questions to brush up on my exam technique!
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sensei_mooni
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#709
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#709
(Original post by Rebeelouise)
these are the ones I have finished
thank you so much!!!
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Where'sPerry?
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#710
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#710
(Original post by erniiee)
Thats exactly what I usually do it annoys me when teachers use past paper questions in class, especially as there are only 4 for this spec :/ in the mean time though, I'm gonna do legacy questions to brush up on my exam technique!
Ohh I know, I'll probably end up working through a past paper and realise I've done about five of the questions already!

For unit 4 my teacher recommended using some of the relevant OCR questions once I'd run out of AQA ones, but I'm not sure how similar the two unit 5 specs are. I'll ask her if they're any use tomorrow.
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master y
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#711
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#711
(Original post by erniiee)
It is indeed :/



Lol, all of them?

yeah pretty much
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F1's Finest
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#712
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#712
Feeling really good about this exam actually

I keep on repeating this but I need to be fully focussed in the exams and I will be alright.

:ahee: :ahee:
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iop horray
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#713
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#713
Here is the essay. The biological importance molecular shape
The molecular shape of a biological substance is animportant feature as some of their functions are dependent upon it. There are numerous examples of these types ofbiological substances, such as: enzymes ( Globular proteins) ,starch and cellulose,hormones as well as the carrier proteins which are involved in active transportand facilitated diffusion.

Enzymes are globular proteins which increase the rate ofa chemical reaction without being used up themselves. They have the followingstructure of:
- The primary structure is a long chain of aminoacids which are held together by peptide bonds which form during a condensationreaction.
- The secondary structure is when the primary structurefolds in on itself and are held together by the development of hydrogen bonds.
- The tertiary structure is when the secondarystructure fold in on itself to form a more complex structure which are held inplace by the development of hydrogen bonds, ionic bonds and di sulphide bridgebonds.
- The quaternary structure is when a number ofpolypeptide chains are held together by numerous bonds, such as haemoglobin.
- Within these structures there is a slight dipwhich is known as the active site and is where the substrate molecule binds to.

The way in which the enzymes function is by the substratebinding to the enzymes active site which in turn forms an enzyme substratecomplex. Then when this substrate complex forms it causes the bond within thesubstrate molecule to become weaker which would thus lower the activationenergy of the molecule and thus increases the overall rate of the chemicalreaction. Each substrate molecule has a specific enzyme which it binds to dueto its active site providing it a complementary fit. There are numerous factorssuch as temperature and Ph which alter the shape of the functions of theenzymes active site which in a way would prevent an enzyme-substrate complex toform and thus causing the enzyme to be unable to function. This is the mainreason why the molecular structure of enzyme is important to its function. The wayin which a change in Ph cause the enzyme to be unable to function is by itchanging the concentration of hydrogen ions within the solution and thuschanging the charge on the active site so that the substrate molecule is unableto attach to it and allowing a substrate complex to form. Whereas thetemperature only comes into account when it is increased beyond the optimum andcause the hydrogen bonds, ionic bonds and disulphide bridge bonds to gain somuch kinetic energy that they vibrate to the extent of breakage. This would inturn change the tertiary structure of the enzyme which would in turn mean thatit wouldn’t be able to provide a complementary fit to the substrate moleculeany more so an enzyme-substrate complex wouldn’t be able to form. Although thisdoesn’t necessary mean that the enzymes active site has a ridged structure asaccording to the induced fit theory it doesn’t. As the induced fit theorystates that the enzymes active site would change shape so that it becomes more complementaryto the substrate molecule. However if the enzymes active site does change shapeit may mean that it’s active site could change in a way which allows it to havean more complementary fit to an completely different substrate molecule andconsequently having an different effect than it was initially meant to do.

Another biological molecule which structure is importantto its functions is cellulose and starch. Starch is a polysaccharide which ismade up of a long chain of alpha glucose molecules which coil together in atight coils. The coil structure of the starch molecule allows it to be more adaptedto its structure of storage in plants. As the cellulose molecule is insoluble sodoesn’t have an overall osmotic effect and so don’t drawn water into the cellalso it is compact. This allows more starch to be stored in comparison with thevolume. Whereas the cellulose molecule an polysaccharide which is made up of anlong chain of beta glucose molecules which at attached inversely for every betaglucose molecule. The structure of the cellulose molecules is long chains ofthese polysaccharides running along parallel to each other and there arehydrogen bond cross bridges which form between these cellulose molecules. This featureallows them to withstand high tensile strengths which helps its function as acell wall of the plant cell. Therefore the structure of the cellulose andstarch is complementary to their structure.

Hormones are other biological molecules where theirstructure is important to their function. Hormones are chemicals which areproduced and is the sole means of communication within the hormone system. One ofthe means in which the hormones function is by the second messenger model whichis when the actual hormone is the first model messenger and it binds to thebinding site of the receptor present along the plasma membrane of the targetcell. This forms a receptor-hormone complex to form which would activate anenzyme within the target cell which would produce the second messenger. The secondmessenger would produce the required changes inside the cell which wouldproduce the required response. For example the case of adrenaline which the responseis the conversion of glycogen to glucose. Therefore the main way in whichhormones function by attaching to the binding site on the receptor, so the bindingsite of the receptor requires to have a complementary fit to the hormones, inthe similar way in which the shape of the antibody molecules require to have ancomplementary shape to the binding site of the receptors present along theplasma membrane of the T cells and the B cells. When the antibody-receptorcomplex forms it would activate the T cells and B cells so that they are ableto overcome the foreign substance detected by the immune system. Although ifthe hormone didn’t have a complementary shape to the binding site of thereceptor it would result in a hormone-receptor complex not forming thereforethe hormone wouldn’t be able to carry out their function which could have badconsequences. For example if the hormone which is known as insulin wasn’t ableto bind to the binging site of the receptor present along the plasma membraneof the muscle and liver cells then it would decrease the glucose uptake. Thereforethe blood glucose level would remain high which would result in the tissuefluid having a lower water potential as the cells. So water would move out ofthe cells via osmosis which would cause the cell to shrivel up and consequentlynot allow the cell to function properly. Therefore the biological shape of thehormones are important to its function.

The shape of the carrier proteins which are involved in activetransport and facilitated diffusion are important to their function. Facilitateddiffusion is when molecules diffuse along the concentration gradient and itoccurs at specific points of the plasma membrane and with specific molecules. Whereasactive transport is when molecules move against of the concentration gradientvia carrier protein. By this it is usually due to the shape of the carrierproteins changing shape. As with active transport the ATP molecule would turninto ATP and an inorganic phosphate molecules which would bind to the carrierprotein so that it changes shape in a way which would allow the carrier proteinto open and consequently allow molecules to move against the concentrationgradient. Whereas with facilitated diffusion the specific ion binds to thecarrier protein so that it changes shape in a way which would allow thespecific ion to move across the plasma membrane. Therefore the biological shapeof some molecules are important to their function.
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Tikara
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#714
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#714
anyone got a list of essay questions not in the past papers? I'm the most worried about this section tbh
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Maid Marian
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#715
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#715
I am so going to fail on this essay. I can't remember anything from units 1-4 let alone anything in enough detail to write an essay on it! :confused:

Urgh

What're the negs for??:mad:
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erniiee
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#716
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#716
(Original post by Where'sPerry?)
Ohh I know, I'll probably end up working through a past paper and realise I've done about five of the questions already!

For unit 4 my teacher recommended using some of the relevant OCR questions once I'd run out of AQA ones, but I'm not sure how similar the two unit 5 specs are. I'll ask her if they're any use tomorrow.

Haha its so annoying :lol: today my teacher gave me a set of questions on restriction mapping from a past paper :grumble: why don't they understand our predicament?!

That's a good point. I think I'll just stick to old spec questions, but I'm sure a lot of the content overlaps in different courses!

(Original post by master y)
yeah pretty much
Aha, well there a lots of old spec questions on this site: http://www.freeexampapers.com/#/A Level
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F1's Finest
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#717
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#717
(Original post by iop horray)
Here is the essay.

You need to include some things outside of the spec.
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MLogan
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#718
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#718
Planning on doing an essay per day from tomorrow Hopefully would get the hand of it by june! Can someone give me a rough indication on how i go about writing the essay : roughly how many points, how in depth do i go, what to write in intro and conclusion!

Thanks guys
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k1rby
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#719
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#719
(Original post by MLogan)
Planning on doing an essay per day from tomorrow Hopefully would get the hand of it by june! Can someone give me a rough indication on how i go about writing the essay : roughly how many points, how in depth do i go, what to write in intro and conclusion!

Thanks guys
You should aim for 5 paragraphs. 4 of the paragraphs should contain at least 4 detailed unique points each from the specification. The 5th paragraph should have at least 2 points about something not in the specification. Don't bother with introduction and conclusion as you get no marks for it. For full breadth marks, aim to cover 3 different chapters/topics of specification in the 4 paragraphs to be sure. Aim for at least 3 A4 pages.
Read this for loads of information about how they mark the essays and what they are looking for: http://filestore.aqa.org.uk/subjects...W-TRB-OGME.PDF
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Where'sPerry?
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#720
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#720
(Original post by k1rby)
You should aim for 5 paragraphs. 4 of the paragraphs should contain at least 4 detailed unique points each from the specification. The 5th paragraph should have at least 2 points about something not in the specification. Don't bother with introduction and conclusion as you get no marks for it. For full breadth marks, aim to cover 3 different chapters/topics of specification in the 4 paragraphs to be sure. Aim for at least 3 A4 pages.
Read this for loads of information about how they mark the essays and what they are looking for: http://filestore.aqa.org.uk/subjects...W-TRB-OGME.PDF
Thank you for this. My teacher has always made me write a conclusion in my essays, even marking me down for not having them! Pretty annoying. I feel fine about the majority of the essay, but the off-spec stuff worries me. I've been collecting small bits of info from beyond the spec all year but I feel I don't have enough. Where has everyone been finding that sort of stuff?
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