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Discussion in 'International A And AS Level' started by ahmed abdulla, May 25, 2013.
oh im so sorry :O i forgot to write the year umm may/june 2011 varient 12 ....
This is the easiest method ever lol.
37. Sickle cell anaemia is the genetically inherited condition, so the answers can only be either B or C. Cholera bacteria invade gut cells, so the answer is C.
36. Cholera and TB are both infectious and bacterial. A shows this.
31. Because the apoplast pathways gets blocked by suberin, water has to take the symplast way via the plasmodesmata.
23. There are 2 hydrogen bonds between A and T and 3 hydrogen bonds between C and G.
17. The solute concentration outside is low, therefore the water potential is high, therefore water enters the cell and that causes the pressure potential to increase.
14. B is wrong; K.E. is highest when the temperate is highest. The temperature isn't highest at Q. C is wrong & D is wrong. That leaves A.
7. 1 & 3. That's something you have to memorise.
5. 1 RBC - (7x10^-6)m, so x RBCs - (2x10^-2)m.
4. PROKARYOTES do not have cellulose cell walls; that leaves C.
ThANKS but umm
in 36....they r also transmitted by airborn droplets?No?
31. dn shudnt it b by plasmodesmeta ...y symplats :O its frm sytoplasm to cytoplasm ryt?
14. y C n D are wrong ?
7.ok ill memmorize it bt what are these structure 1 is Alpha glucose nd 3 is what?
36. No. The cholera bacteria is not trasmitted by air droplets; only the TB bacteria is.
31. Plasmodesmata is not a pathway. The symplast pathway includes the way through plasmodesmata.
14. C is wrong because R is the point of optimum activity. D is wrong; S is not the very end of the curve, it's before the end.
7. 3 is fructose.
Got it ^_^ thankyou so much!
http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_s07_qp_1.pdf
Question 24. The answer is C. Can anyone explain? I chose B, because I thought that the amount of glucose absorbed also depends on the cell surface area, because the higher the surface area, the more the transport proteins, so more glucose is absorbed.
Question 26. It may well be C, so what's the trick?
can someone do with oc/nov 2011 varient 12
q 19 , 20 , 23 & 39
Ans 19 - D -> Its only after all the Separation has taken place , The cytoplasm Start to divide to form two cells
20- C -> it says Reduction Division so Count all the chromosome and double it to get the diploid number
23-A -> this Cuz the amino acid is shown twice for different base pairs
39-C -> ammonification is when ammonium ion are converted to nitrates by nitrifying bacteria ( nitrite is intermediate compound )
can someone help with http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s11_qp_13.pdf
Question 3 , 13 , 15 , 16 29
with explanation please
24. B & C can both be correct if you look at the first column only, but since there's also the second column to consider, you have to choose between the two. B can't be correct because hormone detectors are located on the cell surface membrane, therefore hormone detection has only to do with the cell surface area, not the volume.
26. It can't be C; the water potential is 0 in pure water. Xylem contains dissolved mineral ions, and not just pure water.
3. Cell 3 is a xylem vessel, therefore has to have a lower water potential than both 1 & 2.
13. The cell surface membrance doesn't 'allow for intracellular transport'; it allows for intercellular transport, i.e. transport of materials from cell to cell, not within the cell. Glycoproteins mainly exist as antigen detectors; the carbohydrate chain has the additional benefit of providing stability. Antigen detectors don't need to be present inside the cell, because they're already present on the outside. Both have sites for enzyme attachment; remember the cristae of the mitochondria are there to provide a larger surface area for reactions to occur. Statement D is irrelevant because cells are the ones that produce lysosomes so they know better whether organelles need to be broken down or other substances outside the cell.
15. The organelles referred to in the question are the cisternae of the Gogli apparatus.
16. Not A because excess mucus is secreted when people smoke, not when they stop smoking. Not B because macrophages go to the lungs when there's many bacteria there and that happens when excess mucus trickles down into the lungs. Excess mucus will be there only when a person smokes. Not C because the lumen diameter is not increased by not smoking; it's just not decreased.
29. Bonds between complementary bases break twice, once when the DNA molecule is being cut open for transcription, and once when the RNA nucleotides are cut away from the DNA nucleotides. Both of these are joined by complementary base pairing.
20. 12000/2 because it's double-stranded. 6000/3 because 3 bases (and therefore 3 nucleotides) will code for 1 amino acid.
Can anyone explain me question 25?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_1.pdf
The answer is D. Why would the circumference increase if no water flows through the xylem? Circumference is directly proportional to diameter, so I can't figure out why would diameter increase when no water flows
so someone can help me with paper 1 bio ?have so many doubts
Now I have a really interesting question here.
Check Q38 from here: http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w09_qp_11.pdf
Answer is C - the niche.
Check Q40 from here http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_13.pdf
Answer is C - the ecosystem.
Now which is correct?
i was wondering about this too! i would say ecosystem, seeing as that's the latest answer. and if you read the examiner's report, "Many candidates did not use all the information provided and incorrectly selected option A." http://papers.xtremepapers.com/CIE/...A and AS Level/Biology (9700)/9700_w12_er.pdf
can anyone help with question 29 and 30?
http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w11_qp_12.pdf
for 30, how are 2 and 4 supporting evidence?
q29 - water potential is most negative when it has the most sucrose concentration. Since sucrose is produced at the leaf, B would be the correct choice. A cannot be correct because if the mesophyll cell was indeed the most negative, water would pass into the cell which is not what the cell needs. For mass translocation to occur, B needs to be more negative, so that the sucrose travels downwards towards the roots to relieve the hydrostatic pressure.
q30 - When cutting the stem near base, the pressure difference would become different, which forces sap out of the stem. For the fourth statement - Although there is a high humidity, transpiration is still occurring because pressure at the roots is higher, so water would pass upwards.
Hey guyss !! Please I need Help !! After solving almost all of the pastpapers, I got shocked when I answered November 2012 V12. Questions 16, 24 and 33 !!! Please Help me my exam is in a couple of days. In question 16, The cholestrol decreases the fluidity of the membrane not increases it, right?? Question 24,I don't understand it at all. Question 33, How come the deposition of fatty materials in ARTERIES and veins does not contribute to heart failure??
http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_12.pdf
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