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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

Can someone please indicate to me at what stage there are positive and negative feedback mechanisms occuring in the oestrous cycle. Thanks in advance :smile:

1st Negative Feedback: When the levels of oestrogen begin to rise just after the beginning of the cycle. This inhibits the release of FSH.

Positive Feedback: When the levels of oestrogen continue to rise and reach a critical point where oestrogen now stimulates the release of FSH and LH.

2nd Negative Feedback: Happens after ovulation where progesterone inhibits the production of LH and FSH.

Reply 2581

ynm1

Can someone please help me with question 4b)!!! Mark scheme is quite vague :frown:

http://filestore.aqa.org.uk/subjects/AQA-BIOL5-W-QP-JUN11.PDF

Reply 2582

MLogan

Original post by James A

1st Negative Feedback: When the levels of oestrogen begin to rise just after the beginning of the cycle. This inhibits the release of FSH.

Positive Feedback: When the levels of oestrogen continue to rise and reach a critical point where oestrogen now stimulates the release of FSH and LH.

2nd Negative Feedback: Happens after ovulation where progesterone inhibits the production of LH and FSH.

Thank you too :smile:

You know your stuff pretty well, Well done!

Reply 2583

SamEastie

2

Original post by MLogan

Thanks a lot :biggrin:

Would give +rep but finished it :|

no worries! i like my little red bar anyway.. :tongue:

Reply 2584

F1's Finest

21

Original post by MLogan

Thank you too :smile:

You know your stuff pretty well, Well done!

No worries.

Helping others on here also helps me to remember things too! Sharing info with others makes learning a two way process!

Reply 2585

06spam

Please could some one explain to be restriction mapping?? in particular question five on the June 2011 paper!!! pleasee!!

Reply 2586

dizzy17

for an adaptation of a fast twitch muscle fibre for anaerobic respiration, my book says thicker and more numerous myosin filaments. How does that exactly adapt it for this? Thanks for any help!

Reply 2587

F1's Finest

21

Original post by dizzy17

for an adaptation of a fast twitch muscle fibre for anaerobic respiration, my book says thicker and more numerous myosin filaments. How does that exactly adapt it for this? Thanks for any help!

Thicker filaments result in stronger contractions.

Stronger contractions are a property of fast twitch fibres.

Reply 2588

SamEastie

2

Original post by SamEastie

no worries! i like my little red bar anyway.. :tongue:

aha getting negged for that.. wow.

Reply 2589

FM1994

Can someone give me a list of the main synoptic topics for this exam?

Thanks

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Reply 2590

AVB

9

Original post by peebs123

Does anyone know what the grade boundaries were for the unit 5 specimen paper on the AQA website? :smile:

Anyone else find that paper really hard?

Did it today, and being honest I thought the actual paper wasn't that bad...

Both essay titles were awful though!

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Reply 2591

jonnyb123

9

So I thought in gel electrophoresis the sequence of bases in the original fragment was complementary to the sequence on the gel, because those are the complementary terminator nucleotides that binded to the original sequence. That's what it says on page 269 anyway (Nelson Thornes). But on the on the next page in question 3 the answers just correspond to the sequence on the gel, i.e. they aren't complementary...how do you know which one they are asking for?

Reply 2592

flyylikejetz

11

Original post by ynm1

Can someone please help me with question 4b)!!! Mark scheme is quite vague :frown:

http://filestore.aqa.org.uk/subjects/AQA-BIOL5-W-QP-JUN11.PDF

follow the story of increasing higher conc. to the critical point of oestrogen causes release of more LH & FSH (hence positive feedback). the key point its the increase in oestrogen that causes increase in LH. increase:increase instead of increase:decrease (Negative feedback)

Reply 2593

Anjna

9

can someone PLEASE explain q4aii) and why the answer is B? http://filestore.aqa.org.uk/subjects/AQA-BIOL5-W-QP-JUN11.PDF

Reply 2594

_sa

What are people predicting for the essay titles?
I'm thinking maybe one of them will be on ATP!

Reply 2595

Anjna

9

Original post by Anjna

can someone PLEASE explain q4aii) and why the answer is B? http://filestore.aqa.org.uk/subjects/AQA-BIOL5-W-QP-JUN11.PDF

anyone ?

Reply 2596

ahmmm

8

Original post by James A

No worries.

Helping others on here also helps me to remember things too! Sharing info with others makes learning a two way process!

are you only revising those 7 essays we were talking about the other day?

Reply 2597

ahmmm

8

Original post by _sa

What are people predicting for the essay titles?
I'm thinking maybe one of them will be on ATP!

i bladdy hope so !!

Reply 2598

DoeADeer

9

Original post by ahmmm

are you only revising those 7 essays we were talking about the other day?

Sorry to butt in, but where are these seven essays if you don't mind? :biggrin:

Reply 2599

gingerandice

1

Original post by dizzy17

for an adaptation of a fast twitch muscle fibre for anaerobic respiration, my book says thicker and more numerous myosin filaments. How does that exactly adapt it for this? Thanks for any help!

more powerful contractions

AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

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