AQA AS Biology Unit 2 - 1 June 2015

Reply 380

future doctor x

2

Original post by Clovers

Hi guys, quick question ... for meiosis, apart from meiosis 1 and meiosis 2 do we need to know other steps?
Thanks :yy:

No for meiosis in the aqa spec all we need to know is a general understanding of meiosis 1 and 2 and crossing over and independent segregation no need to know any other stages
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Reply 381

SamuelSingleton

13

Original post by ALevelBro

Can you please explain transcription/translation/replication in simple terms?

Transcription and translation is A2 so don't bother eith that there's no easy way to explain that in simple terms

Replication: DNA molecule unwound and unzipped by dna helicase which breaks weak hydrogen bonds between strands
Each strand acts as a template for free floating dna nucleotides to form new hydrogen bonds between complementary base pairs (at and cg)
Adjacent nucleotides are joined together by DNA polymerase which reforms strong covalent phosphodiester bonds
Semi conservatives replication

Reply 382

ALevelBro

2

Original post by SamuelSingleton

Transcription and translation is A2 so don't bother eith that there's no easy way to explain that in simple terms

Replication: DNA molecule unwound and unzipped by dna helicase which breaks weak hydrogen bonds between strands
Each strand acts as a template for free floating dna nucleotides to form new hydrogen bonds between complementary base pairs (at and cg)
Adjacent nucleotides are joined together by DNA polymerase which reforms strong covalent phosphodiester bonds
Semi conservatives replication

Thanks a lot mate!

Reply 383

AshcaanH

2

Original post by maggie43

i thought this was one easier

Depends on who you are. I, personally, prefer it.

Reply 384

future doctor x

2

Original post by Jess_P

Does anyone have any notes on selective breeding? I cant seem to find any anywhere... :redface:

I have some notes bt I dont know if they would help and sorry for the pen over it

20150530_164611.jpg311.3KB

20150530_164622.jpg249.2KB

Reply 385

Tplox

2

jan 10 biol2
q 9d calculation, can someone help?
http://filestore.aqa.org.uk/subjects/AQA-BIOL2-W-QP-JAN10.PDF

Reply 386

Crambo-clink

8

Original post by lunaa.lovegood

http://filestore.aqa.org.uk/subjects/AQA-BIOL2-W-MS-JUN10.PDF

can anyone explain why, for q4c, the diameter/radius/area of the capillary tube must be measured, too (to calculate the rate of water uptake)?

I'm assuming so that you can work out the volume of the capillary tube.

Reply 387

SamuelSingleton

13

Original post by Tplox

jan 10 biol2
q 9d calculation, can someone help?
http://filestore.aqa.org.uk/subjects/AQA-BIOL2-W-QP-JAN10.PDF

calculate the % decrease in volume without the drug
so without its 372
with its 87

(372-87)/372 *100 =76.6% decrease

(edited 8 years ago)

Reply 388

Clovers

2

Original post by AshcaanH

If you understand those two steps you should be good!

Hmmm ... thanks :biggrin:

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Reply 389

Clovers

2

[QUOTE="x;56359975" future="future" doctor="doctor"]

Original post by Clovers

Hi guys, quick question ... for meiosis, apart from meiosis 1 and meiosis 2 do we need to know other steps?
Thanks :yy:

No for meiosis in the aqa spec all we need to know is a general understanding of meiosis 1 and 2 and crossing over and independent segregation no need to know any other stages
Posted from TSR Mobile[Oasisosis]

Okay thanks! :biggrin:

thats a relief

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Reply 390

SamuelSingleton

13

[QUOTE="Clovers;56360377"]

Original post by future doctor x

Okay thanks! :biggrin:

thats a relief

Posted from TSR Mobile

well you do still need to know the steps of producing haploid cells... that would include same stages as mitosis but with the added steps of genetic variation

Reply 391

turtle294

2

Hey does anyone know how to calculate the answer for number 4bii on the June 2011 paper??? Would be much appreciated x

Reply 392

Tplox

2

Original post by SamuelSingleton

calculate the % decrease in volume without the drug
so without its 372
with its 87

(372-87)/372 *100 =76.6% decrease

cheers bossman.

Reply 393

Tplox

2

Original post by turtle294

Hey does anyone know how to calculate the answer for number 4bii on the June 2011 paper??? Would be much appreciated x

it takes 3 cycles long
2 cells,4 cells ,8 cells

3 x 258 mins = 774 mins

258 mins comes from in the questions, 4hrs 18 - change to mins

Reply 394

Clovers

2

[QUOTE="SamuelSingleton;56360553"]

Original post by Clovers

well you do still need to know the steps of producing haploid cells... that would include same stages as mitosis but with the added steps of genetic variation

Yes I'm okay with that in terms of meiosis 1&2 where 1 increases genetic variation by independent segregation and recombination by crossing over and splits cells into two and meiosis 2 which is similar to mitosis and produces four gametes with haploid chomosomes; 23. Is that all? In added detail as well!

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Reply 395

turtle294

2

Original post by Tplox

it takes 3 cycles long
2 cells,4 cells ,8 cells

3 x 258 mins = 774 mins

258 mins comes from in the questions, 4hrs 18 - change to mins

Oh my god you life saver, thank you!!

Reply 396

djhodnett

9

so any predictions for the 6 marker for this paper?

Reply 397

blueberry389

8

http://filestore.aqa.org.uk/subjects/AQA-BIOL2-W-MS-JAN11.PDF
can anyone explain why in q8c it's epithelium but not endothelium?

Reply 398

cherrybanana

2

Help! Can someone please draw this?

Reply 399

turtle294

2

Original post by djhodnett

so any predictions for the 6 marker for this paper?

I'm thinking maybe adaptations of xerophytes (probably too easy) or adaptations of starch that make it suited to its role? Not sure it could be anything...

AQA AS Biology Unit 2 - 1 June 2015

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