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AQA BIOL2~3rd June 2013~AS Biology (Now Closed)

Reply 380

Scienceisgood

21

Original post by lauraaaaa

Ooh ****! My mock exam is tomorrow! :frown:

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I know this may be asking a lot but, if you manage to get a soft copy of the paper from a teacher after your mock, could you please put it here?
I want to see how well I do on it as it is the only paper I haven't done yet (aside from the specimen paper).

Reply 381

username504651

20

Original post by Scienceisgood

I know this may be asking a lot but, if you manage to get a soft copy of the paper from a teacher after your mock, could you please put it here?
I want to see how well I do on it as it is the only paper I haven't done yet (aside from the specimen paper).

I can try but I won't get the results back until next week. Plus I don't know what the protocol is for uploading papers that aren't on the aqa website as I remember in December time the forum strictly said not to upload the last paper as people do their mocks at different times.

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Reply 382

Hamzi

2

I made this simplified version of the comparison of immunological response to proteins...you might find it useful.

Reply 383

FutureMedic1009

2

Original post by Hamzi

I made this simplified version of the comparison of immunological response to proteins...you might find it useful.

That's very useful thanks

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Reply 384

p.mods

Original post by kiyubi

this is a bio2 thread but i presume everyone has done the bio1 exam 2013

heres the mark scheme

Do you have the January 2013 unit 2 mark scheme please?

Reply 385

science-oliver

11

I know this is the wrong thread but some of you are taking biol1 this summer and this thread seems more active than the biol1 thread and seems to give good responses, I was just wondering about two questions, in the nelson thorbes aqa book it says 'chest infections increase the risk of emphysema ( it actually says COPD but that includes emphysema)' and I was just wondering how. Also the larger lung stuctures such as the trachea require cartilage so prevents trachea collapsing in on itself' and I was just wondering why the trachea is more susceptible to collapse than smaller structures such as the bronchioles, thankyou

Reply 386

Sophie1994

6

Original post by Scienceisgood

I know this may be asking a lot but, if you manage to get a soft copy of the paper from a teacher after your mock, could you please put it here?
I want to see how well I do on it as it is the only paper I haven't done yet (aside from the specimen paper).

Can you upload the specimen paper please?

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Reply 387

Scienceisgood

21

Original post by Sophie1994

Can you upload the specimen paper please?

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Here you go. :smile:

Good luck in your exam. =)

Unit 2 Specimen Paper.pdf309.3KB

Unit 2 Specimen MS.pdf112.7KB

Reply 388

Sophie1994

6

Original post by Scienceisgood

Here you go. :smile:

Good luck in your exam. =)

Thank you very much, and you too! :biggrin:

I want more pratice doing exam questions but the past papers are limited from jun09 - jan13. Does anyone know what papers from the old spec I can use? :tongue:

Reply 389

science-oliver

11

Can someone explain to me how transpiration pull, puts the xylem under tension?!? I thought it was that during cohesion tension the, when water molecules are pulled up the xylem the hydrogen bonds are under tension by the strain of the water molecule above it pulling on the hydrogen bond (causing the hydrogen bond tension) meaning the water molecule below is pulled up. So what's this about in the nelson thornes aqa book saying about the xylem vessel being under tension? Please someone correct my wrong thinking!

Reply 390

FutureMedic1009

2

Original post by science-oliver

Can someone explain to me how transpiration pull, puts the xylem under tension?!? I thought it was that during cohesion tension the, when water molecules are pulled up the xylem the hydrogen bonds are under tension by the strain of the water molecule above it pulling on the hydrogen bond (causing the hydrogen bond tension) meaning the water molecule below is pulled up. So what's this about in the nelson thornes aqa book saying about the xylem vessel being under tension? Please someone correct my wrong thinking!

http://www.youtube.com/watch?v=bsY8j8f54I0

Watch that video,it's very helpful in understanding the movement of water in plants :smile:

Reply 391

science-oliver

11

Original post by FutureMedic1009

http://www.youtube.com/watch?v=bsY8j8f54I0

Watch that video,it's very helpful in understanding the movement of water in plants :smile:

Hello, it was a good video! But I'm going to be really annoying now, I don't understand still, how tension is caused in the xylem vessel from the transpirational pull, and to be fair I don't really know what the definition of tension is in the case of transpiration, I am genuinely struggling, could you help? :smile:

Reply 392

FutureMedic1009

2

Original post by science-oliver

Hello, it was a good video! But I'm going to be really annoying now, I don't understand still, how tension is caused in the xylem vessel from the transpirational pull, and to be fair I don't really know what the definition of tension is in the case of transpiration, I am genuinely struggling, could you help? :smile:

No don't worry it's not annoying :smile:

the more q's the better! Erm just hold on for a bit I'm a bit busy ATM i'll respond in a hour

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Reply 393

Nina8

8

Hey saw your message, thought I can help. I remember it through 3 steps

- When stomata are open the water vapor diffuses down the water potential gradient from the air spaces to the atmosphere.
- Most water evaporates from the surface of the spongy mesophyll cells into the air spaces making the water potential more NEGATIVE.
- This loss of water at the top will create this suction force inside the xylem vessel as water molecules are pulled along its by its cohesive forces to where they are needed :smile:

)

x

Reply 394

Suzanna5678

Can someone write a 6 mark model answer on apoplastic and sympoplastic pathways. It hasn't come up before so got a strong feeling it could be the 6 marker

Reply 395

Nina8

8

Water movement occurs through two pathways in a leaf. In the apoplastic pathway the water molecules will move through the plasmodemata in the cell walls. As water molecules are cohesive, they will stick together and a continuos stream is pulled across the endodermal cells until it reaches the casparian strip. It is blocked by the waxy layer of suberin which lies on top, making it water repellant. The symplastic pathway involves water moving through the cytoplasm of cells from a region of higher water potential to a region of lower water potential by osmosis down a water potential gradient. It is not stopped by the Casparian strip, and so water from the apoplast pathway combines with the symplast pathway and is pushed in the cell membrane along with mineral ions

:smile:

Reply 396

Suzanna5678

Original post by Nina8

Water movement occurs through two pathways in a leaf. In the apoplastic pathway the water molecules will move through the plasmodemata in the cell walls. As water molecules are cohesive, they will stick together and a continuos stream is pulled across the endodermal cells until it reaches the casparian strip. It is blocked by the waxy layer of suberin which lies on top, making it water repellant. The symplastic pathway involves water moving through the cytoplasm of cells from a region of higher water potential to a region of lower water potential by osmosis down a water potential gradient. It is not stopped by the Casparian strip, and so water from the apoplast pathway combines with the symplast pathway and is pushed in the cell membrane along with mineral ions

:smile:

thank you! I thought water is stopped by the casparian strip??