AQA Biology A2 Unit 5: Control in Cells and In Organisms - 23rd June 2016

Oh god the essay.
I've been trying but I can't do it in under an hour.

Keep practising and decide whether you're writing stuff that is irrelevant. I don't know what you're told at your centre, but we're told to just focus on writing 5/6 paragraphs, each with two good pieces of a level information. So when you're writing, decide when you've written two good pieces, stop, and move on to the next topic. Getting feedback is also really important, so keep writing them and getting them marked, this will help you decide whether something will get you the marks or not.

Reply 21

username1308238

8

What sort of essay predictions do you all have?

I was thinking something maybe like negative feedback (not too synoptic) or DNA. Or perhaps a horrible ecology one, I really haven't a clue really...

I find that a good way to prepare for essays is to just find a random title, and spend max 5 minutes planning it - bullet points the topics, an intro and conclusion, and just keep doing it, you'll see overlap in topics, and how synoptic certain essays are

All the best with revision, there's still plenty of time :smile:

Reply 22

joshwan

Not saying it's a wise idea to do this, but can any of you think of the possible essay questions that will come up? (using the previous ones as indication of what may be repeated or has yet to be asked)

If you have any ideas let me know and I will be happy to do a kind of essay plan with you over DM :smile:

happy revising (don't let gene/DNA technology kill you pls)

Reply 23

Zuzuvela

2

Original post by DanMargetts

What sort of essay predictions do you all have?

I was thinking something maybe like negative feedback (not too synoptic) or DNA. Or perhaps a horrible ecology one, I really haven't a clue really...

I find that a good way to prepare for essays is to just find a random title, and spend max 5 minutes planning it - bullet points the topics, an intro and conclusion, and just keep doing it, you'll see overlap in topics, and how synoptic certain essays are

All the best with revision, there's still plenty of time :smile:

Original post by joshwan

Not saying it's a wise idea to do this, but can any of you think of the possible essay questions that will come up? (using the previous ones as indication of what may be repeated or has yet to be asked)

If you have any ideas let me know and I will be happy to do a kind of essay plan with you over DM :smile:

happy revising (don't let gene/DNA technology kill you pls)

Original post by pineneedles

Keep practising and decide whether you're writing stuff that is irrelevant. I don't know what you're told at your centre, but we're told to just focus on writing 5/6 paragraphs, each with two good pieces of a level information. So when you're writing, decide when you've written two good pieces, stop, and move on to the next topic. Getting feedback is also really important, so keep writing them and getting them marked, this will help you decide whether something will get you the marks or not.

Too early to publish predictions now. My teacher has got at least one of the 2 right for the last 3 or 4 years. Pollock Biology is also good.

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Reply 24

thenextchemist

21

I feel lik DNA tech is deffo gonna come up

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Reply 25

cherrybanana

2

Please can someone explain HOW you work out the answer for these two questions about the Polymerase Chain Reaction?

1) How many DNA molecules will have been produced from one molecule of DNA after 6 complete cycles?

And this is a different question from a past paper:

2) One cycle of the polymerase chain reaction takes 5 minutes to complete. Starting with a single gene, calculate the number of copies of the gene produced in 40 minutes.

I have seen two different formulas used to work PCR questions out. One of them is 2^n where n is the number of cycles. Another is 2^n+1 where n is also the number of PCR cycles. I am very confused about which to use.

Reply 26

cherrybanana

2

Also, can someone please explain how the answer to this is 62%?????

Original post by cherrybanana

Please can someone explain HOW you work out the answer for these two questions about the Polymerase Chain Reaction?

1) How many DNA molecules will have been produced from one molecule of DNA after 6 complete cycles?

And this is a different question from a past paper:

2) One cycle of the polymerase chain reaction takes 5 minutes to complete. Starting with a single gene, calculate the number of copies of the gene produced in 40 minutes.

I have seen two different formulas used to work PCR questions out. One of them is 2^n where n is the number of cycles. Another is 2^n+1 where n is also the number of PCR cycles. I am very confused about which to use.

1) the formula is always 2^n
n being the number of cycles
So it would be 2^6 = 64

2) 1 cycle = 5 minutes
So 40 minutes = 8 cycles
So 2^8 = 256 genes
(I'm not sure about this one, please let me know)

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Reply 28

cherrybanana

2

Thanks so much! Those are both the right answers but I'm just abit confused because this website presents a different formula: 2^n+1

http://vlab.amrita.edu/?sub=3&brch=186&sim=321&cnt=1

Reply 29

thenextchemist

21

Original post by cherrybanana

Thanks so much! Those are both the right answers but I'm just abit confused because this website presents a different formula: 2^n+1

http://vlab.amrita.edu/?sub=3&brch=186&sim=321&cnt=1

Hmm
I'm not sure tbh
I don't think that's correct
It maybe for another process perhaps in addition to pcr
Or they may have included the original gene from the DNA

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Reply 30

cherrybanana

2

Original post by Bloom77

Hmm
I'm not sure tbh
I don't think that's correct
It maybe for another process perhaps in addition to pcr
Or they may have included the original gene from the DNA

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Ohh ok thank youuu :smile:

Reply 31

cherrybanana

2

Can anyone please explain this? :frown:

I really don't understand the answer (in red)

Hey guys. I ma doing the past papers without the essay atm so 75 Marks and i am wondering how would i mark my paper cos obvs grade boundaries incl essay so total 100 marks. well confused. ik its pribs a dumb question. Also hate the essay and i am putting off practising even tho i rly need to kick myself and do it.

Reply 33

thenextchemist

21

What exactly is the process of tissue fluid used for?

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Reply 34

Jessica Starfell

2

Calculate your mark as a % ,eg 56/74 is 75% then just convert the grade boundaries to a percentage. (64/100 would be 64 %) :P

Reply 35

charlie2466

12

Original post by cherrybanana

Can anyone please explain this? :frown:

I really don't understand the answer (in red)

Hi

this thread -> http://www.thestudentroom.co.uk/showthread.php?t=2708523 <- asks about that question and gives an explanation for it :smile:

Reply 36

cherrybanana

2

Original post by charlieecooperr

Hi

this thread -> http://www.thestudentroom.co.uk/showthread.php?t=2708523 <- asks about that question and gives an explanation for it :smile:

Thank youuu!

I still don't understand it though its so confusing! :frown:

Reply 37

weevilspongebob

2

Original post by Jessica Starfell

Calculate your mark as a % ,eg 56/74 is 75% then just convert the grade boundaries to a percentage. (64/100 would be 64 %) :P

Thnks

ngl though In am so fed up of bio but I really need to pull my socks up and revise DNA Tech i find it so difficult. Also do essay practise :frown:

BOOHOO

Reply 38

pineneedles

14

Original post by Bloom77

What exactly is the process of tissue fluid used for?

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I'll check in a minute, but I think its function is to aid the diffusion of substances to and from cells to the blood stream. So rather than needing a separate vessel to every cell in the body, oxygen can simply diffuse out of the capillaries into the tissue fluid, meaning that all the surrounding cells are supplied with oxygen. Likewise with waste products from the cells.

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Reply 39

Student1234510

hi, I understand that sodium, glucose and amino acids move into the cuboidal cells from the PCT by secondary active transport and how amino acids and glucose move in through co-transporters (sodium/amino acids and sodium/glucose co-transporters) using sodiums concentration gradient. But I don't understand how the potassium ions get in from the tubule? Is it by simple diffusion? I also understand that potassium moves into the cuboidal cells (from the interstitial fluid) via sodium/potassium pumps which use ATP to pump one sodium ion out of the cuboidal cells per pump into the interstitial fluid and then two potassium ions in not using ATP as the release of the phosphate from ATP in the cell to pump the one sodium out already made the conformational change so essentially potassium gets a free ride back into the cell (by acive transport). Thanks in advance.

(edited 7 years ago)

AQA Biology A2 Unit 5: Control in Cells and In Organisms - 23rd June 2016

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