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F215 - Revision thread 13th June 2011

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Reply 1060
Avatar for 786girl
786girl
has anyone got the green book by mary jones? on pg 223 theres a bit about "agent orange"...er do we need to know it? its quite boring and confusing..
Original post by 786girl
has anyone got the green book by mary jones? on pg 223 theres a bit about "agent orange"...er do we need to know it? its quite boring and confusing..


I'm not sure what agent orange is but it's not on the specification or in the cgp book, and i can't recall it being in the ocr textbook so i doubt it :smile:
Reply 1062
Avatar for jak67m
jak67m
2
Can someone please help me with Gene and body plans - Homeobox sequences!!!! dont understand it at all!!!

Just summarise the two pages on it... so i can atleast understand it.....PLEASEEEEEEEE!!!!
Reply 1063
Avatar for Tobia_s
Tobia_s
One of the last few spec points in the genomes & gene tech. topic asks for an 'outline' of how animals can be genetically engineered for xenotransplantation. I've looked at 2 textbooks now and there's no form of 'outline' in any of them; they just go on and on :zomg: about how rejection can occur and how there's organ shortage. All we need is a bloody outline of how the engineering can be done! :angry:

Apologies for the mini-rant lol

So has anybody got some sort of 'outline' for this? Would be much appreciated :smile:
Original post by 786girl
lol the genomes and gene therapy stuff is quite intetesting hehe

can someone help me with this:
-biological species concept & phylogenetic species concept (are we just meant to know about the difference?)

-genetic drift!

that is alll i promise!


The biological species concept groups organisms which can freely interbreed with each other to produce fertile offspring.
Problems with the biological species concept is that organisms may produce asexually (never with members of the same species), organisms may be extinct so we cannot study their reproductive behaviour, and it is unethical to breed them to see if tehy belong to the same species- e.g. humans and chimps share approx 94% of DNA but it would be unethical to interbreed them!

Whereas, the phlogenetic species concept is grouping organisms which have similar morphology (shape), physiology (biochemistry), embryology(pattern of development), same behaviour and occupy same/ similar ecological niche.

Problem with the phylogenetic species concept is thatit is difficult to judge how similar organisms need to be to be part of the same species. Hope this helps.
Original post by 786girl
and what about the Galapagos Island??! it says we need to know examples...ummm yeahh I havemt learnt any! I have a feeling they will ask about it!! eeeew I hate OCRs attempt at trying tp test "application of knowledge" just so that they can tick their own boxes!


I think if we just know some general points for example humans over exploit resources e.g. over fishing in the north sea, taking pearls from oysters and fresh water clams, humans introduce non native species onto the island e.g. goats- which trample on land, eat native species food supply, occupy territories etc. so out complete native species and habitat distruction and disturbance occurs by pollution, cutting down trees from agricultural land etc. we'll be fine.
This may have already come up, but could someone please explain muscle contraction?
Original post by fellowgrip
This may have already come up, but could someone please explain muscle contraction?


action potential arrives at neuromuscular junction, causing vesicles containing acetylcholine to fuse with the membrane, molecules of acetylcholine diffuse across the synapse, bind to receptors on the sarcolemma causing depolarisation of it. this depolarisation travels along the cell membrane (sarcolemma) and down into t systems/t tubules/tubules - whatever you wanna call them haha. This stimulates the release of Ca2+ ions from the sarcoplasmic reticulum. The Ca2+ ions bind to troponin, which changes its shape, which causes the tropomyosin to move, uncovering the binding site on actin for myosin.
this means a cross bridge forms between a head of myosin and the actin - ADP + Pi are released as this head group bends, pushing the thick filament (myosin) outwards (or i guess you could say actin is pulled inwards?)
the cross bridge breaks as new ATP attaches to the myosin head, which is then hydrolysed to ADP+Pi, and the head group bends back, ready to repeat to another binding site on actin further along, causing further contraction.
Reply 1068
Avatar for ekta9
ekta9
Original post by Tobia_s
One of the last few spec points in the genomes & gene tech. topic asks for an 'outline' of how animals can be genetically engineered for xenotransplantation. I've looked at 2 textbooks now and there's no form of 'outline' in any of them; they just go on and on :zomg: about how rejection can occur and how there's organ shortage. All we need is a bloody outline of how the engineering can be done! :angry:

Apologies for the mini-rant lol

So has anybody got some sort of 'outline' for this? Would be much appreciated :smile:


Do you have the CGP book? That explains it really well!

Xenotransplantation is about the transfer of cells and organs from animals to different species (humans!). Basically theres 2 ways how animals can be genetically engineered:
1) Genes for HUMAN cell surface proteins are INSERTED into animals DNA. This is to reduce the risk of transplant rejection.
2) Genes for ANIMAL cell surface proteins can be removed/inactivated so reduce risk of rejection.

That's just a short summary of it :smile:
Wakey wakey rise and shine peeps, we have a whole day of revision to get through :h:
Original post by heartskippedabeat
I think they just mean the transverse tubules :confused:


Yeh, T tubules make up the T system (lots oif them) I think :wink:
Original post by Kidms001
Wakey wakey rise and shine peeps, we have a whole day of revision to get through :h:


Can't wait :biggrin: :tongue:

I've done so much revision for this though, haven't even started on any of my other exams but I still feel like I know nothing :frown:
Just been looking through the spec AGAIN, and I'm not entirely sure on how much about the Galapagos we need to know.
I remember SNNIF ... like sniff, but not quite.
Sailors (They ate animals and took some away)
Non-Native animals (increase competition, eat native plants etc)
Non-Native Plants (Increase competition etc ...)
Increase (In population and tourism. BAD)
Fishing (Takes away native sealife)

Is that enough? Not enough?
Reply 1073
Avatar for Rosi M
Rosi M
11
Original post by ekta9
Do you have the CGP book? That explains it really well!

Xenotransplantation is about the transfer of cells and organs from animals to different species (humans!). Basically theres 2 ways how animals can be genetically engineered:
1) Genes for HUMAN cell surface proteins are INSERTED into animals DNA. This is to reduce the risk of transplant rejection.
2) Genes for ANIMAL cell surface proteins can be removed/inactivated so reduce risk of rejection.


Is this somatic cell gene therapy? So basically augmentation (inserting genes) and killing cells?

Do you not talk about germline cell gene therapy?
God im so confused when it comes to animals!
Reply 1074
Avatar for lmfw
lmfw
1
Original post by Rosi M
Is this somatic cell gene therapy? So basically augmentation (inserting genes) and killing cells?

Do you not talk about germline cell gene therapy?
God im so confused when it comes to animals!


This is completely of subject but I have just realised we have exactly the same GCSE grades, exactly the same AS grades and exactly the same A2 predictions. And, we're both going to Manchester Uni!!! haha, just thought you ought to know :smile:
Reply 1075
Avatar for Rosi M
Rosi M
11
Can somebody please define Conservation and Preservation? The book has a very long definition but im not sure if it fits mark schemes :s
Reply 1076
Avatar for Rosi M
Rosi M
11
Original post by lmfw
This is completely of subject but I have just realised we have exactly the same GCSE grades, exactly the same AS grades and exactly the same A2 predictions. And, we're both going to Manchester Uni!!! haha, just thought you ought to know :smile:


Haha wow your my long lost .. what do you call it? :tongue:

I'll see you at Manchester then as long as both of us dont fail this exam!!!! Which seems very likely for me at this rate!
Reply 1077
Avatar for lmfw
lmfw
1
Original post by Rosi M
Haha wow your my long lost .. what do you call it? :tongue:

I'll see you at Manchester then as long as both of us dont fail this exam!!!! Which seems very likely for me at this rate!


Well my offer's ABB :tongue:, noo failing we're going to Manchester! Good luck!
Original post by Rosi M
Can somebody please define Conservation and Preservation? The book has a very long definition but im not sure if it fits mark schemes :s


Conservation is the protection and management of ecosystems so that natural resources in them can be used without running out.
Preservation is the protection of ecosystems so they're kept exactly as they are. :smile:

If you look a couple of pages back, a few people have asked this question and have been given answers that are probably different from mine, so you could check those out for different wording and info :tongue:
Reply 1079
Avatar for Rosi M
Rosi M
11
Original post by heartskippedabeat
Conservation is the protection and management of ecosystems so that natural resources in them can be used without running out.
Preservation is the protection of ecosystems so they're kept exactly as they are. :smile:

If you look a couple of pages back, a few people have asked this question and have been given answers that are probably different from mine, so you could check those out for different wording and info :tongue:


Haha ahright ok thank you :smile: x

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