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  1. A

    A level Biology: Post your doubts here!

    I dont think the walls are partially permeable. Lignin is totally impermeable, and pits would allow the passage of all substances (as far as i know).. Anyways, i think abcde is right :)
  2. A

    Mathematics: Post your doubts here!

    No problem :)
  3. A

    A level Biology: Post your doubts here!

    But that still doesnt mean that osmosis occurs in the xylem :/
  4. A

    A level Biology: Post your doubts here!

    http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Biology%20%289700%29/9700_s11_qp_12.pdf In Q28... WHY do we include osmosis?? Xylem is dead, osmosis cant occur in osmosis since theres no partially permaeble membrane in the structure.. :/
  5. A

    Mathematics: Post your doubts here!

    P(X<6)=0.105 Let (6-mean)/sd be a P(Z<a)=0.105 a is negative (im not sure how you've been taught to determine whether a is -ve or +ve. What we do is that if both the sign is less than, i.e <, and the probability is less than 0.5, or if both are more than, then a is -ve) 1-...
  6. A

    Mathematics: Post your doubts here!

    p(x<6)= 63/600 p(z< (6-mean0/s.d) = 63/600 (i)Do the same for the other set of values. You'll get to equations. Solve them simultaneously to get the answer. (ii) P(X< mean-s.d) + P(X> mean + s.d) This gives u the probability of length being more than a s.d from the mean. Multiply the result by...
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    Mathematics: Post your doubts here!

    According to some friends of mine, using ES series calculators will straightaway result in a deduction of 10 marks. Is this true?? :O
  8. A

    Mathematics: Post your doubts here!

    Q. 5(b)(ii) The first digit has to be a 2 if we are to get a no. between 20,000 and 30,000. the no of ways the remaining 5 digits can be used= 5P4= 120 (c) The probability of placing a white tile ( or any other colored tile) first is 1/3. The second tile must not be white so P(not white)=1 -...
  9. A

    Mathematics: Post your doubts here!

    Q5.(i) Apply continuity correction. If u are rounding off a number to 84, it must be in the range 83.5<X<84.5. Now calculate the probability of the result ( by converting the data to normal distribution by subtracting mean from each value and dividing by standard deviation) (ii) Simply...
  10. A

    Physics: Post your doubts here!

    http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20%289702%29/9702_s03_qp_1.pdf Please help me out with Q20 asap. The answer is A.. :/
  11. A

    Some Different Notes & Website Are Available !!!

    Thank you for all the links you've posted. They really are helpful. :) But I still have a MAJOR issue when it comes to thermal physics ( esp in questions asking for evidence for strong,rigid bonds in solids,etc) can you PLEASE share any link that discusses this particular chapter in more detail...
  12. A

    Distinctions 2013

    Same is the case here :/.. my school isn't even sure if the list has been announced.
  13. A

    Distinctions 2013

    Do you have the link?
  14. A

    Distinctions 2013

    Can someone please post the list if it has been announced in Pakistan?
  15. A

    they*

    they*
    • aleezay
    • Profile post comment
  16. A

    Chemistry: Post your doubts here!

    But it says that the acid is in excess.. by what amount,we dont know.. shouldnt there be some other technique? Thank you for trying btw :)
  17. A

    Nope.. i tried but the wouldnt let us postpone the play :/ Next year IA :)

    Nope.. i tried but the wouldnt let us postpone the play :/ Next year IA :)
    • aleezay
    • Profile post comment
  18. A

    Hey! :) I forgot to tell you, I managed to convince a group of 4 for Briangle. :D

    Hey! :) I forgot to tell you, I managed to convince a group of 4 for Briangle. :D
    • aleezay
    • Profile post comment
  19. A

    Chemistry: Post your doubts here!

    Q. 2.80g of a group II metal carbonate, XCO3, is added to 50cm^3 of 2.00 moldm^-3 HCl (excess) in a plastic cup. the temperature rose by 9.7K. Calculatre the Mr of the carbonate. for this question, can we assume that q= sum of all the bond energies of bonds involved in the formula q=mcdT? I...
  20. A

    Chemistry: Post your doubts here!

    Wouldn't trichloromethane react with Br2.. the reaction would be somewhat similar to the addition reaction between alkenes and halogens.. except that this compound already is a halogenoalkene.. :/
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