Edexcel A2 Biology exams (6BIO4) 25th January 2012 exam discussion

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What really irritates me about Biology A-Level as a whole is that the marks aren't rewarded for knowledge / answering the question - but rather merely stating what the mark scheme says.

I've found on a few occasions that my answer most definitely answers the question, but receives few marks as the points don't match the mark scheme.

How are people revising best for the January unit then? Past papers?

Reply 61

This Honest

Original post by AdamBeee

Anyone got any ideas on topics that are very likely to come up? Maybe if they haven't come up for many years?

something about the immune system has to come up- it's such a big topic

Reply 62

scoutzawwar

Original post by This Honest

something about the immune system has to come up- it's such a big topic

And the Calvin Cycle... that is also quite complex.

Reply 63

leogirl1992

I have a question here. what is the difference between the humoral response and the cell-mediated response in the topic immunity?

thanks!

Reply 64

leogirl1992

Original post by claire4095

Unit 4 in January 2011 was really difficult, i think it was the way they worded the questions. June 2011 was still difficult but the questions were kind of more straight forward... hopefully for you guys youll get a nicer paper :P good luck!
c xxx

I know , right? :/
there are times when I thought why am I giving the same answer to different question. and I have to read the question again and again.

really have to do this :/ if not then scared that you are not answering what they want.

Reply 65

SLlewellyn

Original post by leogirl1992

I have a question here. what is the difference between the humoral response and the cell-mediated response in the topic immunity?

thanks!

The humoral response is split into two stages:
T-helper activation stage + the effector stage

The first stage involves T-helper cells binding to the APC and creating more T-helper cells and clones of the helper cells. The second stage involves T-helper cells (potentially from the first stage) differentiating into B-memory cells or B-effector cells; the latter of which differentiate to become plasma cells (and ultimately antibodies).

The cell-mediated response is also happening at the time of infection - but is significantly quicker at fighting the infection - a T-killer binds to the APC and differentiates into T-killer memory cells or more T-killer cells. If it's the latter, it effectively 'kills' the cell through lysis.

In summary:
Humoral - Two stages, Products: Helper Cells, Antibodies, Long Term
Cell-Mediated - One stage, Product: Killer Cells, When the H. response wouldn't be effective, Short Term

Reply 66

tal_786

can anyone explain the photosystems in the LDR of Photosynthesis? i know there are PSI and PSII but what exactly are they involved in?

Reply 67

SnailFace

Original post by tal_786

can anyone explain the photosystems in the LDR of Photosynthesis? i know there are PSI and PSII but what exactly are they involved in?

What on earth.

:s-smilie:

Ok, I'm failing this one.

Reply 68

leogirl1992

Original post by tal_786

can anyone explain the photosystems in the LDR of Photosynthesis? i know there are PSI and PSII but what exactly are they involved in?

Everything (the LDR) happens at the same time but normally we will start with the PS II and then PS I.

Firstly, the light energy is absorbed by the the photosynthetic pigments in PS I and PS II and this light energy is transferred to the primary pigment in the reaction centre of the these photosystems of the PS I and PS II.

The transferring of this energy causes the electrons in the chlorophyll to become excited and are raised to a higher energy level, and so are emitted.

These electrons from PS II are transferred along a system of electron carriers
(ETC) and at the same time, energy is released. This energy is used to phosphorylate ADP to form ATP.

so, these electrons from PS II will replace the electrons lost in PS I

Meanwhile, the electrons produced during photolysis of water will replace the electrons lost in PS II

Eqn of photolysis of water:

H2O --> 2e- + 2H+ + 1/2 O2

hope this helps.

Reply 69

leogirl1992

Original post by claire4095

Hey, at first i did dreadfully in unit 4, but then i got my head down and got a B in the resit! Unit 5 i got 105 so an A :smile:

and tips for the article:
Make a list of the keywords in each section and make sure you know what they all mean and where they appear in the article.
Try to make links to AS biology in the article as it is a synoptic paper. eg transcripton and translation.
hmm... you dont need to know if off by heart, as you will get a fresh copy in the exam!
C xxxx

thanks a lot. But I am having a problem here. I kept reading the article a few times, but only managed to come up with only 2 or 3 questions.

any advice on this?

Reply 70

*_*

Original post by SnailFace

What on earth.

:s-smilie:

Ok, I'm failing this one.

Are you doing SNAB? I'm pretty sure PSI and II are extra in that, but there are points for them on the mark scheme of some questions (although there can be 10 marking points for a 5 mark question, so you can get all the marks elsewhere)

Reply 71

aym3n

okay so i started my biology and i dont get whether i do or dont do the global warming debate and stuff ? :s...i mean i get that its there in the spec. but what exactly should i do about it..its mostly all experiments and data analysis ..if anyone could help me...

Reply 72

Nix-j-c

Is it just me or does the forensics bit seems like they didn't have enough content so randomly stuck it in? Although most of it is quite interesting the stuff with the entomology graphs is a nightmare!

(edited 12 years ago)

Reply 73

claire4095

Thankss

as long as you revise, i dont see why you wouldnt :P good luck!! xx

Original post by Hanz_a93

Thanks for all that! :smile:

and gratz on ur marks there really good! , hopefully ill get them too! x

Reply 74

claire4095

I've messaged you :smile:

Original post by leogirl1992

thanks a lot. But I am having a problem here. I kept reading the article a few times, but only managed to come up with only 2 or 3 questions.

any advice on this?

Reply 75

.snowflake.

Original post by Nix-j-c

Is it jsut me or does the ofrensics bit seems like they didn't have enough content so randomly stuck it in? Although most of it is quite interesting the stuff with the entomology graphs is a nightmare!

personally the entomology isnt too bad, how much thats down to the fact I self taught that as i wasnt in that lesson. I honestly thought it would be more interesting. its not. Does anyone else have days where they wonder what possessed them to pick biology?