• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Search results

  1. Z

    Biology P4 random notes

    what I mean was, I needed explanation for: adpatation summation discrimination
  2. Z

    Biology P4 random notes

    The only chapter where I think we might come across photons is Photosynthesis. But we don't need to mention photons there either. Mention of energy of light, frequency and wavelength is adequate
  3. Z

    Biology P4 random notes

    EXPLANATION REQUIRED FOR THE ADVANTAGES!!!!!!!!!!
  4. Z

    Biology P4 random notes

    okay, I will try to get back with the answer as soon as I can
  5. Z

    Biology P4 random notes

    do you mean the need for the synapse such as summation, one directional impulse etc. If that is the case then we share the same boat. Am not very sure about that section either!
  6. Z

    Biology P4 random notes

    there is no restriction on the choice of the endangered species. You could choose a plant if you wanted to!
  7. Z

    Biology A2 Paper 4 Thread (1st June 2011)

    variation is what makes selection meaningful. Variation can be thought of as "choices". If there is no variation (no options) ,selection wouldn't mean anything as any action of choosing would result in the same type of object being chosen. Thus, variation is the raw material upon which selection...
  8. Z

    Biology P4 random notes

    Structure of a maize grain (grain is a fruit and not a seed): - The fruit is called "caryopsis and conatins a single monocotyledonous seed. In maize, each ovary contained a single ovule, so each fruit contains a single seed. In maize, the fruit wall (pericarp) and the seed coat (testa) are...
  9. Z

    Biology P4 random notes

    Outbreeding depression: Offspring from crosses betn individuals from population have lower fitness thatn progeny from crosses between individual of the same population (as opposed to inbreeding depression) Outbreeders are plants that do not normally self pollinate. If they are dioeciour or...
  10. Z

    Biology P4 random notes

    The main aim of the adaptations of wind pollinating flowers is to maximise exposure to the air of the pollen producing anthers and the pollen collecting stigmas
  11. Z

    Biology P4 random notes

    Treatment of cancer using MAb: -MAbs can be bonded to molecules of cancer drugs (MAbs bonded to drugs known as "magic bullets") -The MAb then injected into the patient -They attach only to the surface of the cancer cells, delivering the drug to them. The drug therefore destroys the cancer cells...
  12. Z

    Biology P4 random notes

    I am SERIOUSLY confused about how a biosensor works. Different books and mark schemes seem to present different methods. Which one are we supposed to stick to?? - Enzyme glucose oxidase immobilised in a protective gel matrix made of cellophane acetate - glucose oxidised to gluconic acid and...
  13. Z

    Biology P4 random notes

    Why enzyme immobilisation enhances enzyme stability: Stability of an enzyme: Its ability to retain its tertiary structure so that it can be effective under a wide range of conditions The surface on which the enzyme is immobilized is responsible for retaining the structure in the enzyme through...
  14. Z

    Biology P4 random notes

    Horizontal transfer: Horizontal gene transfer (HGT), also lateral gene transfer (LGT), is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism. By contrast, vertical transfer occurs when an organism receives genetic...
  15. Z

    Biology P4 random notes

    Inhibition of the active site of the enzyme transpeptidase by penicillin is irreversible competitive inhibition. Now, why is it irreversible?
  16. Z

    Biology P4 random notes

    Metabolite: Intermediates and products of metabolism. (i) Primary metabolite: Directly involved in growth, development, and reproduction. Alcohol is an example of primary metabolite produced in large scale by industrial microbiology. Produced during the active growh phase known as exponential...
  17. Z

    Biology P4 random notes

    Bioleaching: -Some bacteria are chemoautotrophic i.e.they derive their energy via breakdown of inorganic chemicals. The microbial oxidation process involved in bioleaching occurs at the cell membrane of the bacteria. The electrons pass into the cells and are used in biochemical processes to...
  18. Z

    Biology P4 random notes

    I don't know what COC means and I have already posted note on sympatric speciation somewhere in this thread
  19. Z

    Biology P4 random notes

    @mukesh: Oestrogen inhibits the secretion of BOTH FSH and LH. It inhibits the Gonadotrophin Releasing Hormone production by hypothalamus. GnRH is the hormone that makes the the anterior pituitary gland release gonadotrophic peptide hormones called FSH and LH. Pills lower the level of both FSH...
  20. Z

    Biology P4 random notes

    that reminds me of something else too, very high level of oestrogen stimulates hypothalamus to produce a high level of LH as evident on day 14
Top