AQA BIOL2 ~ 21 May 2012 ~ AS Biology

Original post by sophiakhan

can someone explain the immunological comparison of proteins please.

Lets say we want to compare humans (species A) with chimps (C) and a goldfish (D), we would have to do this via another species, such as a rabbit (B).

- The blood plasma of any species contains a protein called albumin.
- The albumin from A will be removed and injected into B.
- B will produce antibodies against the antigens on the surface of the protein (albumin.)
- The antibodies from B are collected and mixed with samples of albumin from species C and D.
- The antibodies will bind to complimentary antigens in the samples of albumin, producing a precipitate.
- The greater the number of complimentary antigens, the more precipitate is formed, so the more closely related the species are.
- Therefore from our example, A will be most closely related to C.

If that still doesnt make sense let me know :smile:

Original post by EffKayy

Can you please bullet point your notes for the symplast and apoplast pathway please! Have very little notes on them and i think its going to be a 6marker

Apoplast:
- This is the movement of water through the cellulose cell wall of adjacent cells.
- Water moves by cohesion (Attraction of water molecules to each other.)
- The cell walls are fully permeable across the root except for the endodermis.
- The impermeable casparian strip in the cell walls of the endodermis prevents passage of water and ions via apoplast.
- Therefore water and ions are forced to pass through the symplast pathway into cells
- This allows for some control of movement of water and ions in xylem.

Symplast:
- Movement of water through the cytoplasm in the cells, and through the plasmodesmata connecting cells.
- Water moves by osmosis.

Both of these occur down a water potential gradient and through the cortex cells.

(edited 11 years ago)

Reply 982

sophiakhan

Original post by Mocking_bird

Lets say we want to compare humans (species A) with chimps (C) and a goldfish (D), we would have to do this via another species, such as a rabbit (B).

- The blood plasma of any species contains a protein called albumin.
- The albumin from A will be removed and injected into B.
- B will produce antibodies against the antigens on the surface of the protein (albumin.)
- The antibodies from B are collected and mixed with samples of albumin from species C and D.
- The antibodies will bind to complimentary antigens in the samples of albumin, producing a precipitate.
- The greater the number of similar antigens, the more precipitate is formed, so the more closely related the species are.
- Therefore from our example, A will be most closely related to C.

If that still doesnt make sense let me know :smile:

Apoplast:
- This is the movement of water through the cellulose cell wall of adjacent cells.
- Water moves by cohesion (Attraction of water molecules to each other.)
- The cell walls are fully permeable across the root except for the endodermis.
- The impermeable casparian strip in the cell walls of the endodermis prevents passage of water and ions via apoplast.
- Therefore water and ions are forced to pass through the symplast pathway into cells
- This allows for some control of movement of water and ions in xylem.

Symplast:
- Movement of water through the cytoplasm in the cells, and through the plasmodesmata connecting cells.
- Water moves by osmosis.

Both of these occur down a water potential gradient and through the cortex cells.

Oh i get it now thankyou so much :smile:

Reply 983

EffKayy

16

Original post by Mocking_bird

x

Thank you so much you're a star!
Can we do questions and answers later? After I've revised a bit :wink:

hahaha
It's much easier to get full ums in this, so I hope I can do that - seen as though I messed up BIOL6X, oh dear.. =(

Reply 984

Prijosh

I took this exam in Jan 2012 and managed to get an A. My UMS was 130/140. So if there's any advice I can give, it would be to go through the legacy papers from june 05 onwards, and if you have the AQA Biology AS: Student's Book by Glenn Toole and Susan Toole, then attempt all the HSW and APP q's. You may notice a trend of similar questions. These are most likely to come up but in different scenario forms. Good luck!

Reply 985

Original post by sophiakhan

Oh i get it now thankyou so much :smile:

You're welcome :biggrin:

Original post by EffKayy

Thank you so much you're a star!
Can we do questions and answers later? After I've revised a bit :wink:

hahaha
It's much easier to get full ums in this, so I hope I can do that - seen as though I messed up BIOL6X, oh dear.. =(

For sure !
& Is that the empa? Was it tricky? :frown:

--------------------------
Also, does anyone know if the nelsons thorne book (or even just the exam style questions) is available anywhere on the interwebs? I was planning on taking it out the college library today but forgot.. woops.

(edited 11 years ago)

Reply 986

Original post by EffKayy

Thank you so much you're a star!
Can we do questions and answers later? After I've revised a bit :wink:

hahaha
It's much easier to get full ums in this, so I hope I can do that - seen as though I messed up BIOL6X, oh dear.. =(

if its that easy, then get full ums.

Reply 987

Original post by Mocking_bird

You're welcome :biggrin:

For sure !
& Is that the empa? Was it tricky? :frown:

--------------------------
Also, does anyone know if the nelsons thorne book (or even just the exam style questions) is available anywhere on the interwebs? I was planning on taking it out the college library today but forgot.. woops.

hey, later tonight can we do some questions again, i have my exam monday

Reply 988

swiftylol

18

Original post by EffKayy

Bad times.

How you feeling about this exam - prepared?

Almost finished prep, just gotta do the Jan12 paper :colone:

Reply 989

Original post by dongonaeatu

hey, later tonight can we do some questions again, i have my exam monday

We all have the exam monday. :erm:

I'll be doing some with Effkayy so feel free to answer them too.

Reply 990

EffKayy

16

Original post by Mocking_bird

You're welcome :biggrin:

For sure !
& Is that the empa? Was it tricky? :frown:

--------------------------
Also, does anyone know if the nelsons thorne book (or even just the exam style questions) is available anywhere on the interwebs? I was planning on taking it out the college library today but forgot.. woops.

Yeah task 3 was awful. You did the ISA didn't you ? How did you do?

Original post by dongonaeatu

if its that easy, then get full ums.

Hopefuly I will. I seriously cannot be asked with your sarcastic/pathetic comments and you annoying the **** out of people, i.e. mockingbird. If you haven't got anything decent to say piss the **** off. And we all have the exam on monday, awks.
/rantover.

Reply 991

Original post by Mocking_bird

We all have the exam monday. :erm:

I'll be doing some with Effkayy so feel free to answer them too.

ok thank you. I had my maths exam today. I think i got a B. Hopefully i can better grades, its just i always seem to screw up in exams :frown:

Reply 992

Original post by EffKayy

Yeah task 3 was awful. You did the ISA didn't you ? How did you do?

Hopefuly I will. I seriously cannot be asked with your sarcastic/pathetic comments and you annoying the **** out of people, i.e. mockingbird. If you haven't got anything decent to say piss the **** off. And we all have the exam on monday, awks.
/rantover.

There's no need for that attitude.

Reply 993

EffKayy

16

Original post by swiftylol

Almost finished prep, just gotta do the Jan12 paper :colone:

I liked the jan12 paper, got 79/85 which was 140 :smile:

How did the unit 1 resit go? (I stalked the thread ¬_¬ ) haha

EDIT: Negged? K. lol

(edited 11 years ago)

Reply 994

Original post by EffKayy

I liked the jan12 paper, got 79/85 which was 140 :smile:

How did the unit 1 resit go? (I stalked the thread ¬_¬ ) haha

One of the biology teachers at my college wrote the Jan 12 paper. But, he's known for his "fair" papers, so i'm just really hoping the person who writes ours is fair!

Reply 995

Madara

Can anyone explain the phases of mitosis, the cell cycle and interphase?

Reply 996

pjanoo

2

Original post by Prijosh

I took this exam in Jan 2012 and managed to get an A. My UMS was 130/140. So if there's any advice I can give, it would be to go through the legacy papers from june 05 onwards, and if you have the AQA Biology AS: Student's Book by Glenn Toole and Susan Toole, then attempt all the HSW and APP q's. You may notice a trend of similar questions. These are most likely to come up but in different scenario forms. Good luck!

hey, where can I find these legacy papers?

Reply 997