Edexcel igcse biology may 2012 exam discussion

hey guys, i have mine tomorrow at 9am. feeling pretty confident but I still can't really get my mind around the whole 'micropropagation' and 'hydroponics'. if any of you could help me out, that'd be lovely! thanks :-)

So nervous for this... Good luck to everyone! When can we discuss the paper?

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.

Super thanks. do they teach you this at school.
But in a marksheme they defined transgenic animal as one which had recombinant Dna transferred into, not necessarily from another species - which contradicts the specification.

And another question - for the designing experiment question must or mustn't we write in prose. can we write it in CORMS form or is it a must to write in prose.
Anyone answering will do me great help!!

Super thanks. do they teach you this at school.
But in a marksheme they defined transgenic animal as one which had recombinant Dna transferred into, not necessarily from another species - which contradicts the specification.

And another question - for the designing experiment question must or mustn't we write in prose. can we write it in CORMS form or is it a must to write in prose.
Anyone answering will do me great help!!

does anyone have any tips on how to answer the "Describe the results / graph" questions? They are really annoying.

If they are two markers I say how it increases/decreases and steeply or quite gradually and then saying it levels off after (give value here). Thats the shape of most graphs :P
And for describe results I usually splat and hope, seems to work

does anyone have any tips on how to answer the "Describe the results / graph" questions? They are really annoying.

Haha, you find the easiest questions hard ... and the hardest ones easy.

I would say "the rate of photosynthesis increases with increasing temperature up to 40 deg C, above which the rate begins to decrease (as the enzymes for photosynthesis begin to have the shape of their active sites changed), and finally (as the enzymes are denatured) the rate of photosynthesis reaches 0 at 80 deg C" (for example). The points I have in brackets wouldn't be necessary for a "describe" question.

If they are two markers I say how it increases/decreases and steeply or quite gradually and then saying it levels off after (give value here). Thats the shape of most graphs :P
And for describe results I usually splat and hope, seems to work

does anyone have any tips on how to answer the "Describe the results / graph" questions? They are really annoying.