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  1. Z

    Biology A2 Paper 4 Thread (1st June 2011)

    could someone please post a reply to my questions in this post: viewtopic.php?f=26&t=8640&start=50
  2. Z

    Biology A2 Paper 4 Thread (1st June 2011)

    Plant growth regulators are basically plant hormones. We need to know about three plant hormones: (i) Auxin (specifically IAA) (ii) Gibberellic acid (GA) (iii) Abscissic acid (very confusing spelling) (i) Auxin There are several chemicals known as auxins, in our case it is IAA. Auxins are...
  3. Z

    Biology P4 random notes

    I haven't found anything satisfactory on the role of Distal Convoluted Tubules. So, I would like to post what I have understood, please correct the mistakes in my answer: DCT conceptually behaves both as the ascending loop of Henle and Distal convoluted tubule (i) Reabsorption of sodium ions in...
  4. Z

    Biology P4 random notes

    how many layers of podocytes are there?? From what I understand , podocytes wrap around the basement memabrane surrounding the capillaries of the glomerulus. But now I read that podocytes form the wall of the renal capsule too. So, are there two layers of basement membrane and two layers of...
  5. Z

    Biology P4 random notes

    okay, lemme put my question in another way. Suppose we have genes ABCDE in a part of the chromosome. A and B being close together are linked and thus form a linkage group. So, if crossing over occurs, it is highly probable that AB will be translocate together. So, how is the linkage group...
  6. Z

    Biology P4 random notes

    What prompted me to ask the question was the fact that if they are "linked together" as in they are close together on chromosome and thus have high probability of being inherited together, why are they broken? Shouldn't it be more probabilistic that the linked genes be inherited together and it...
  7. Z

    Biology P4 random notes

    how meiosis results in genetic variation
  8. Z

    Biology P4 random notes

    what is a linkage group and how does crossing over break linkage groups??
  9. Z

    Biology P4 random notes

    need to be more specific buddy
  10. Z

    Biology P4 random notes

    Some examples of effect of environment on phenotype: (i) Height of plants and humans determined by their nutrient intake (ii) While both worker and queen bee develop from fertilized egg, in order to become queen she is well fed during her larva stage (iii) Temperature makes the primrose plant to...
  11. Z

    Biology P4 random notes

    Mutations: Mutation refers to random, unpredictable changes in the nucleotide sequences of a gene or the number of chromosomes of a cell Causes of mutations: -Spontaneous mutations (Mutations occurring naturally during replication) (i) Background mutation (ii) Tautomeric shifts (iii)...
  12. Z

    Stats

    yeah, I already realized that. I screwed it!
  13. Z

    Biology P4 random notes

    ah, I got confused by wikipedia. It seems to have grouped mitosis and interphase together into the cell cycle but I thought it had included interphase it under mitosis
  14. Z

    Biology P4 random notes

    why don't you simply answer my question??? :D
  15. Z

    Biology P4 random notes

    Am I right in stating that interphase is a stage of mitosis but cytokinesis is not Also, is it correct to state that both interphase and cytokinesis are not the stages of meiosis
  16. Z

    Biology P4 random notes

    To sum up: Oxygen debt simply is the volume of oxygen required to allow the oxidation of all lactate back to to pyruvate by the liver cells.Usually, about 20% of pyruvate so formed is oxidised to CO2 and H2O by the regular aerobic oxidation. The remainder of pyruvate is converted to glucose by...
  17. Z

    Biology P4 random notes

    Your definition made it clearer. If we suppose that ATP should be going in the direction of formation of ADP by hydrolysis, this happens very quickly as it is an immediate source of energy being catalysed by enzyme ATPase. Then, the opposite direction becomes reformation of ATP from ADP. And the...
  18. Z

    Biology P4 random notes

    yep! :D what about the enzyme involved in photolysis?
  19. Z

    Biology P4 random notes

    I am not sure if I understand that! :(
  20. Z

    Biology P4 random notes

    What does "high turnover" mean in the context of ATP?? :no:
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