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  1. I

    Biology 33, how was it?

    1) You're supposed to draw a graph of activity (y-axis) vs. pH(x-axis). You're also supposed to draw two lines and you must have a way of identifying which line represents which sample (and of course, you must show a key or label). What I did was plot the leaf points with crosses and the bark...
  2. I

    Biology P33 8 Nov

    1) Concentrations are supposed to be reduced by 0.1%, so if anything is rounded to that, I don't think it's fair to deduct more than 1 mark. Also, last time I checked, ecf was applicable, do there's no way you could lose too many marks 2) It's literally impossible for every single students to...
  3. I

    Biology p33 on 8 November thursday

    Here are the most common points they ask for: 1) Calculating actual size of a specimen from a magnified sample 2) Drawing a plan diagram 3) Using a light microscope 4) Comparing and contrasting two tissues from different organisms 5) Finding sources of error in an experiment and suggesting...
  4. I

    biology paper 1 doubts

    1) Volcanic eruptions don't necessarily have to kill bacteria, as they can sometimes have enzymes which are suited to high temperatures (especially archea) 2) Volcanic activity enriches soil, so it would be full of nitrifying bacteria 3) Obviously, volcanic eruptions would kill all animals and...
  5. I

    Biology P11 , HOW WAS IT?

    Okay, I'm seeing a lot of confusion over here, so I'll try to clarify a few things: 1) Fatty acids AND glucose BOTH have C=O bonds (Fatty acids are carboxylic acids and the STRUCTURAL formula of glucose has C=O). Glycerol is propan-1,2,3-triol, so that's 3 -OH groups, but no C=O groups. 2)...
  6. I

    AS Biology P1 MCQs Preparation Thread

    Sucrose is NOT a reducing sugar; however, after it is hydrolyzed, it produces glucose and fructose. Both of which are reducing sugars.
  7. I

    AS Biology P1 MCQs Preparation Thread

    Lysosomes have the highest hydrolytic activity because their function is to break down (hydrolize) wastes or any unwanted material. Mitochondria hydrolyzes glucose during respiration, but this is nowhere near the amount of hydrolysis in lysosomes. The nucleus does have a little bit of...
  8. I

    AS Biology P1 MCQs Preparation Thread

    The second sentence says it all: "They develop from unfertilized eggs" That means that they have gone through meiosis which means that chromosomes have crossed-over and have gone through independent assortment (mixing up of genes from the original gametes)
  9. I

    AS Biology P1 MCQs Preparation Thread

    Big circle in the middle is most likely the alveolus, and the cells around it are probably RBCs. The little black dots are air molecules, I think.
  10. I

    AS Biology P1 MCQs Preparation Thread

    pretty much :)
  11. I

    AS Biology P1 MCQs Preparation Thread

    Which one are you talking about?
  12. I

    AS Biology P1 MCQs Preparation Thread

    Centrioles replicate just before cell division, and they move apart in the beginning of cell division to form spindle fibres
  13. I

    AS Biology P1 MCQs Preparation Thread

    2.5 cm: diameter of aorta 1.8 cm: diameter of trachea 1.2 cm: diameter of bronchus 2 mm: thickness of aorta 0.01-0.2 mm: diameter of xylem vessels 250 μm: diameter of alveolus 200μm: average length of unicellular organism (e.g. Paramecium) 100 μm: smallest object visible with the eye only 40 μm...
  14. I

    AS Biology P1 MCQs Preparation Thread

    The leaf is actively photosynthesizing, so it is producing a lot of glucose. This dissolves immediately in the water which reduces the water potential.
  15. I

    AS Biology P1 MCQs Preparation Thread

    Mitochondria are 0.5-1 micrometers long. It CAN be viewed by a light microscope, BUT ONLY at a magnification of x750 or greater, NOT at x400. As everyone else said, chloroplasts are slightly visible, but the nucleus and the vacuoles are completely visible after staining.
  16. I

    AS Biology P1 MCQs Preparation Thread

    Disulphide is definitely the strongest, followed by ionic. As for hydrophobic and hydrogen bonds, that depends on the sequence of amino acids. A single hydrogen bond is very weak, so unless there are several of them, then it is the weakest. Hydrophobic interactions depend on the size of the...
  17. I

    AS Biology P1 MCQs Preparation Thread

    QRS represents ventricular systole, so P and T must be ventricular diastole
  18. I

    AS Biology P1 MCQs Preparation Thread

    Assume 100 kJ of light enters the system. From the diagram, 1.75 kJ would be the net productivity. Also, the diagram says that 0.75kJ would be incorporated into the primary consumers. So the ratio of the two values would give you the proportion of net productivities. That would be 0.75/1.75...
  19. I

    AS Biology P1 MCQs Preparation Thread

    I posted that table in my reply :)
  20. I

    AS Biology P1 MCQs Preparation Thread

    Cholera can be passed through food/contaminated water HIV/AIDS can be passed through breast-feeding Malaria needs a mosquito to transfer Plasmodium (cannot pass from human to human directly) Tuberculosis can be passed by sneezing/coughing
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