np man 
Anywayz I was having trouble with the June 08 paper.. Plz help
Q12,18,20,21,26,27
I know they're a lot, so ure help will be much appreciated 
dont worries bro thats why we are here
Q12: ok it tells you that they increased the temp by 10, so that means that rate of raction will double ( therefore the curve must be steeper)
then it tells you that they added extra substrate so that means amount of product must be more!! so the only curve which is steeper AND has more product than X is curve B
Q18:
1) forms cells of equal size to the parent cell ( definantely wrong cuz the daughter cells are always smaller )
2) forms genetically identical cells ( this is right as it contains the same DNA sequences o genetically identical )
3) semi-conservative replication of DNA ( this has nothing to do with the mitotic cell cycle, as the DNA is replicated in the interstage ( before entering mitosis), and this is probabley where you got confused )
so the right answer is only 2)
Q20: so from your knowledge about metaphase, the centrioles are at opposite poles, and the sister chromatids arrange themselves on the equator of the cell, etc. so now the cell will be entering anaphase
so the distance between centromeres and poles of spindle decreases as know the cell is in anaphase stage where the chromatids will split appart ( so this part is 1 on the graph )
and the distance between centromeres of sister chromatids increases because they are being pulled towards opposite poles ( so this is 2 on the graph)
and the distance between poles of spindle will also increase in disance cuz they are also at opposite poles now ( this is 3 on the graph )
Q21:
ok so here is the DNA codon from the question, so if you transcribe it it will give the mRNA ( so im goind to transcribe it under the original codon )
T C C
A C T C G A T G C
A G G U G A U G A G C U A C G ( transcribed part )
ok so if a mutation occurs in the bold part and the (C) switches with (T) then the stop codon ( UAG ) would be formed
so answer is B
Q26: if look at the options u have:
A cohesive tension forces increased during the day ( if cohesive forces between water molecules increase then more water would move through the xylem, increasing the diameter of tree, this is the right answer)
B mass flow of sucrose increased during the night ( if sucrose was being transported at the night then the diameter of the tree must increase, but in the in the graph it decreases at night, so this answer is wrong )
C root pressure decreased during the day ( if root pressure decreased that means less water would be transported in the day so the diameter of tree would decrease, but it increases in the day, so this answer is wrong! )
D thermal expansion and contraction of water in the tree ( expansion and contraction of water does not neccesrially mean that the amount of water transported would increase or decrease, so this answer is wrong as well )
Q27: ok its askin about the solute potential in the phloem SEIVE TUBES, so it has to be low otherwise assimilates would not move inside the seive tube
and lignification is only found on xylem vessels, so lignification must be absent! so answer is C
finally im done, damn that was loooooonnnngg!!!!!
hope this helped..
