Edexcel igcse biology may 2012 exam discussion

Original post by mynameisgrace

using them for what?!

Beer production may well come up. There's no way out here, really - you just have to memorize the list. And you may get a separate, lab-type experiment on fermentation (using yeast).

You should definitely have a few examples of human uses of bacteria (e.g. GM to produce insulin) and a few examples of GM plants as well (e.g. wheat, with increased drought resistance). I'm looking for a few examples of human uses of selective breeding (which has come up on past papers) ... does anyone have any?

Reply 62

OP

Original post by StUdEnTIGCSE

Well in the production of insulin(human --> Bacteria) I know there's a vector involved (Plasmid). But what about in transferring gene from plant to plant? Is there a vector involved? When must you transfer the gene? When its a zygote?Should we directly put gene into plant cell? And what is a transgenic organism? One who has received a gene from any another organism or from an organism of a different species? What is genetic modification - is it modifying genetic material and therefor producing a trangenic organism? It really confuses me! Thanks if you help!

For plant GM. DNA from another species is cut using restriction enzymes and joined into a plasmid from Agrobacterium by ligases forming the recombinant DNA. Leaf discs are placed in liquid containing the plasmids. These discs are then cultivated to make plants which have the modification. Hope this helps :smile:

Reply 63

mynameisgrace

Original post by sahajkaur

Yeast for beer, bacteria for insulin and yoghurt production and the mould Penicillium for the manufacture of Penicillin.

oooh okok! Thanks! :smile:

Reply 64

OP

Original post by Big-Daddy

Beer production may well come up. There's no way out here, really - you just have to memorize the list. And you may get a separate, lab-type experiment on fermentation (using yeast).

You should definitely have a few examples of human uses of bacteria (e.g. GM to produce insulin) and a few examples of GM plants as well (e.g. wheat, with increased drought resistance). I'm looking for a few examples of human uses of selective breeding (which has come up on past papers) ... does anyone have any?

Breeding bulls that have given cows with high milk yields with cows with high milk yields to produce high milk yields (haha!). Also breeding animals together to have more meat, better quality fur or lay more offspring :smile:

Reply 65

OP

Do we need to know the brain in much detail?

Reply 66

Umackjiggles

1

This is going to be a long post but here goes :

1. In plant - plant transfer you still use a plasmid which you take from Agrobacterium and use restriction endonucleases on both the desired gene and the plasmid. They then stick together one account of their "sticky ends" and you use DNA ligase to fix the backbone (phosphodiester links) of the plasmid. You then put the plasmid into a petri dish with leaf discs and wait for some of it to be taken up by the leaves. The leaves then grow into a new plant which has the desired gene.
2. The vector is the agrobacterium plasmid.
3. It never is a zygote. Zygote refers to the diploid cell formed immediately after the oocyte and sperm (or pollen in this case) nuclei fuse. Instead here you add the plasmid to the explants of the plant that are the leaves.
4. A transgenic organism is an organism that receives a gene from a different species.

Reply 67

Umackjiggles

1

PM me if you want me to go over it with more detail.

Reply 68

mynameisgrace

Original post by sahajkaur

Do we need to know the brain in much detail?

well i think we just need to know about the brain in the CNS and also about the hypothalamus and the pituitary gland and what they do.. and just things like the optic nerve carrying impulses to the brain. Heres the specification, check here:http://www.edexcel.com/migrationdocuments/IGCSE%20New%20IGCSE/IGCSE%20Biology%20(4BI0)%20Issue%202.pdf

Reply 69

OP

Original post by mynameisgrace

well i think we just need to know about the brain in the CNS and also about the hypothalamus and the pituitary gland and what they do.. and just things like the optic nerve carrying impulses to the brain. Heres the specification, check here:http://www.edexcel.com/migrationdocuments/IGCSE%20New%20IGCSE/IGCSE%20Biology%20(4BI0)%20Issue%202.pdf

Oh lol i know it in much more detail. what a waste :frown:

Reply 70

Original post by sahajkaur

Breeding bulls that have given cows with high milk yields with cows with high milk yields to produce high milk yields (haha!). Also breeding animals together to have more meat, better quality fur or lay more offspring :smile:

Thanks

Any specific examples for the breeding animals for more meat?

Also, when wheat is made drought resistant, is that an example of genetic modification or of selective breeding?

Reply 71

What do we think they might ask for the 6-markers?

Reply 72

OP

Original post by Big-Daddy

What do we think they might ask for the 6-markers?

thats the CORMS questions like experiments, exact questions are hard to say. And I would say things like pest and drought resistance is GM.

They breed chickens to have more meat on them :smile:

Reply 73

Tazxx_xx

Does anyone have the January 2012 papers?

Reply 74

Carmeee

Original post by Tazxx_xx

Does anyone have the January 2012 papers?

http://www.mediafire.com/?99hzey1atzs4s#k2kg38yffbha4
HERE YOU ARE,HOPE THIS HELP

Reply 75

muf_mur

19

Original post by Tazxx_xx

Does anyone have the January 2012 papers?

http://www.mediafire.com/?99hzey1atzs4s visit this link

Reply 76

RoyalBlue7

19

Original post by sahajkaur

For plant GM. DNA from another species is cut using restriction enzymes and joined into a plasmid from Agrobacterium by ligases forming the recombinant DNA. Leaf discs are placed in liquid containing the plasmids. These discs are then cultivated to make plants which have the modification. Hope this helps :smile:

Thanks it helps very much? By the way did I ask it from you? Ok i Don't know but thanks for the description

Reply 77

Original post by sahajkaur

thats the CORMS questions like experiments, exact questions are hard to say. And I would say things like pest and drought resistance is GM.

They breed chickens to have more meat on them :smile:

Thanks.

Reply 78

Tazxx_xx

http://www.scribd.com/doc/54629793/Edexcel-IGCSE-Biology-Revision-Notes
quite a useful website for revision notes.

Reply 79