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  1. I

    Biology 33, how was it?

    It's literally impossible for every single students to get identical seeds. So we're definitely going to get different very different answers estimating the concentration of reducing sugars. Mine, for example, was around 0.44%, other students in my class got between 0.2% to 0.5%. It really...
  2. I

    biology paper 1 doubts

    I'm not really sure if you've studied A2 Biology yet, but as a result of independent assortment and crossing over, the gametes an organism produces would be all very different. To explain this simpler, we all have two sets of genes, one from our mother and the other from our father. During...
  3. I

    biology paper 1 doubts

    Okay, so you measured the size to be 4 mm, that's equal to 4x10^6 nm = 4,000,000 nm This is the image size. What you want to find is the actual size. From your equation, magnification = image size/actual size Rearranging that equation gives you actual size = image size/magnification...
  4. I

    biology paper 1 doubts

    Yes, you've just explained what happens to the centromere. Think of a centromere as the bond between two chromatids, so when the centromere breaks (or, divides in this case), you'll have separate chromatids. Normally, after DNA replication, the two chromatids are held by a centromere to form a...
  5. I

    biology paper 1 doubts

    According to my book, five: 1) Into a cell in the alveolar wall 2) Out of a cell in the alveolar wall 3) Into a cell in the capillary wall 4) Out of a cell in the capillary wall 5) Into a red blood cell.
  6. I

    A level Biology: Post your doubts here!

    Both. For example, respiratory bronchioles don't have any smooth muscle, but terminal bronchioles do. That's why if they ask for the presence of smooth muscles in bronchioles, both answers are accepted.
  7. I

    Biology 33, how was it?

    You're supposed to join the points by two lines (one going up and the other going down). I also made the line slightly curved near the top as I think the graph should be differentiable at all points (so no sharp corners).
  8. I

    Biology 33, how was it?

    The syllabus changed completely at 2007, so they're getting different questions starting May/June '07. I'd recommend doing both past papers and studying the syllabus. If you don't have time to do both, then I would prefer if you study the syllabus rather than solving past papers. If you really...
  9. I

    Biology 33, how was it?

    Umm, let's see: Benedict's solution was supposed to be kept anywhere between 80 and 100 degrees (anything written in between would be acceptable) You're supposed to take 2 cm3 from each solution and 2cm3 (or more) from benedict's Table: Headings: concentrations of R, volume of solution, volume...
  10. I

    Biology 33, how was it?

    Then both of you should receive full credit, although honestly, you didn't have to write all that. They asked for modifications of the original experiment, so you only have to write what did you change. But don't worry, you'll still get all the marks :)
  11. I

    biology paper 1 doubts

    More water for the potato cylinder, but less water remaining in solution. It's just like a sponge absorbing water. The sponge holds more water, but the quantity of water in the surroundings is reduced. Makes sense?
  12. I

    Biology 33, how was it?

    I answered that question right here: http://www.xtremepapers.com/community/threads/biology-p33-8-nov.21164/page-7 I'm the 2nd post
  13. I

    Biology P33 8 Nov

    Idolfanatic95 is right, but you have to be more specific. You have to keep concentrations of solutions, number and size of seeds, and pH of the solutions constant. You have to make a few test tubes heated to different temperatures by using a thermostatically controlled water bath or an electric...
  14. I

    biology paper 1 doubts

    How could it be D? If water moves in the potato cylinder, then the solution would be more concentrated (same amount of solute, but with a reduced volume, and since concentration is inversely proportional to volume, concentration increases). If the solution is more concentrated, it would have a...
  15. I

    Biology 33, how was it?

    xtremeforums: looking at mark schemes, they normally provide a range of values which are acceptable. However, if they required a very accurate answer, yours would be correct.
  16. I

    Biology 33, how was it?

    You could have written millions of differences: 1) Fig 2.4 has a larger/wider pith 2) Fig 2.4 has a smaller cortex 3) Fig 2.4 has more collenchyma than parenchyma cells (and K1 had less collenchyma than parenchyma) 4) Vascular bundle was spread as a ring in K1, but in fig 2.4, it was in bundles...
  17. I

    Biology 33, how was it?

    Calibration: Every unit on the stage micrometer was 0.01 mm The stage micrometer was 4 units long on the eyepiece graticule So you're supposed to divide 0.1 mm by 4 to get 0.0025 mm Also, you're supposed to convert it to a more suitable unit by multiplying 0.0025 mm by 1000 to get 2.5 micrometres.
  18. I

    Biology P33 8 Nov

    Looking at mark schemes, they only credit similarities if they ask for them.
  19. I

    Biology P33 8 Nov

    The usage of lumen is right in TCHS's case. It refers to the hollow space in the vessel. However, you cannot fairly compare as their magnifications could be different. We have no information about that, so there's no way we can be sure.
  20. I

    Biology P33 8 Nov

    Idolfantic95, you can't say that pith is not present. What I did is say that the pith in K1 is smaller than the pith is Fig 2.4
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