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AQA BIOL4 ~ 11th June 2013 ~ A2 Biology

"If aerobic respiration had been investigated rather than anaerobic respiration, how would you expect the volume of gas collected at the same temperature to differ from results obtained from anaerobic test"

Markscheme
volume(s) less / no gas evolved;
aerobic respiration of glucose;
so volume CO2 evolved = volume of O2 taken in

In a previous similar question it wanted you to talk about rate of anaerobic respiration greater than aerobic thats why with aerobic you get less CO2 !?!?! im baffled

Reply 361

TheFootyKing19

10

I think the 5 markers may be on:
- Eutrophication
- Adv and Dis of either Artificial/Natural fertilisers
- Light Independent stage

Reply 362

MLogan

Original post by Scienceisgood

Compounds containing nitrogen broken down by saprobiotes' enzyme activity
Nitrogen fixing bacteria convert nitrogen into nitrogen containing compounds
Ammonia to Nitrites
Nitrites to nitrates
Nitrates absorbed by roots of plants by active transport
Nitrogen used/stored in plants when used in things such as production of DNA/Proteins

Am I right?

Make sure you mention Ammonia is oxidised into nitrites and further oxidised into nitrates by nitrifying bacteria.

Reply 363

Scienceisgood

21

Oh yeah, and guys who are having trouble remembering order of nitrogen cycle. Here is how I remember.

Ammonia begins with A and so comes first.
Then Nitrite turns into nitrate (i is number 1 in roman numerals)
Then follows by simple memory of nitrate. =)

Reply 364

emah123

5

How many past papers had everyone done?

Reply 365

Scienceisgood

21

Original post by emah123

How many past papers had everyone done?

Done the last 4 papers. Gonna keep the first few until tomorrow.
The grade boundaries for those are like 40/75 for an A. :eek:

(edited 10 years ago)

Reply 366

jonnyb123

9

Original post by Scienceisgood

Compounds containing nitrogen broken down by saprobiotes' enzyme activity
Nitrogen fixing bacteria convert nitrogen into nitrogen containing compounds
Ammonia to Nitrites
Nitrites to nitrates
Nitrates absorbed by roots of plants by active transport
Nitrogen used/stored in plants when used in things such as production of DNA/Proteins

Am I right?

Pretty sure the saprobionts break down the nitrogen containing compounds via extracellular digestion, by secreting digestive enzymes onto the material, like the saprobionts do in the Carbon Cycle, so that's another point

[edit] yup, it's been asked twice, the last two june papers, though it was only a marking point in june 2011. Still can't hurt to add it in.

Original post by emah123

How many past papers had everyone done?

All of them (from jan 2010 to jan 2013)...like 4 times...I'm so damn tired of bio4...

(edited 10 years ago)

Reply 367

TheFootyKing19

10

Do my predictions look ok for the 5 markers, scroll up?

Good luck :wink:

(edited 10 years ago)

Reply 368

popnit

14

Original post by laser174572

No, we don't cover kidneys. I've studied them a bit in my own time and before uni interviews, though, so if you want you can try messaging me your question and I can try answering it, always interesting to see what's on other exam boards :smile:

Posted from TSR Mobile

Ah okay, well just wondering if you can explain the process of selective reabsorption to me..Don't worry if you can't!

Reply 369

Scienceisgood

21

I have always called and spelled it Saprobiotes.
Will I get penalised for this?

Reply 370

Hannah_Boot

Hi! does anyone have the jan 2013 unit 4 paper? If so please could they post a link,

Thanks :smile:

Reply 371

Scienceisgood

21

Original post by jonnyb123

Pretty sure the saprobionts break down the nitrogen containing compounds via extracellular digestion, by secreting digestive enzymes onto the material, like the saprobionts do in the Carbon Cycle, so that's another point

[edit] yup, it's been asked twice, the last two june papers, though it was only a marking point in june 2011. Still can't hurt to add it in.

All of them (from jan 2010 to jan 2013)...like 4 times...I'm so damn tired of bio4...

If you want more questions, you can always follow this link and look at the questions on my thread. :smile:

(From the old spec)

http://www.thestudentroom.co.uk/showthread.php?t=2176162

Reply 372

Scienceisgood

21

Original post by Hannah_Boot

Hi! does anyone have the jan 2013 unit 4 paper? If so please could they post a link,

Thanks :smile:

Here.

AQA-BIOL4-QP-Jan13.pdf868.1KB

AQA-BIOL4-W-MS-Jan13.pdf105.2KB

Thank you! xxxxxxxxx

Original post by Hannah_Boot

Thank you! xxxxxxxxx

I want to know how I flopped on this paper so badly in January! DX
After getting my paper back, I thought I done so much better than I did when I finished this paper!!!!!!

Reply 375

kdk

I'm going to do my last past paper Jan 13 NOW!!!! :afraid:

I really dont think doing the past papers this time has helped me, because I tend to remember most of the answers since last time i've done them in December.
This one is the only one that I haven't seen the MS before!!!

Reply 376

Scienceisgood

21

Original post by kdk

I'm going to do my last past paper Jan 13 NOW!!!! :afraid:

I really dont think doing the past papers this time has helped me, because I tend to remember most of the answers since last time i've done them in December.
This one is the only one that I haven't seen the MS before!!!

It is, by far the nicest paper I have seen for unit 4.
How I flopped so badly I will never now.

Reply 377

Starlight94

Is this correct for nitrogen cycle? i'm finding it so hard to remember

Saprobionts break down nitrogen contaning compounds by secreting enzymes (extracellular digestion). Ammonium is converted to nitrite and then nitrate by nitrification. Nitrates are taken up by roots by active transport, ATP is required.

Where does denitrification come into this process? Confused

Reply 378

MLogan

Original post by Scienceisgood

I want to know how I flopped on this paper so badly in January! DX
After getting my paper back, I thought I done so much better than I did when I finished this paper!!!!!!

I was in the exact same situation as you! I thought the jan 13 paper went quite good but then on results day find out i got a C! Called my paper back to see i lost 13 marks on QS7 HSW :|

Reply 379

Starlight94

Also I struggle with the carbon cycle 5 markers about how carbon can be taken up my plants...?
Anyone know what to write for 5 marks but not too complicated? :/

AQA BIOL4 ~ 11th June 2013 ~ A2 Biology

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