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  1. I

    AS Biology P1 MCQs Preparation Thread

    19) Lets review the length of spindle fibres during mitosis. During prophase, the two centrioles move to opposite ends of the nucleus and start building up the spindle fibres and it grows until metaphase. During metaphase, they are in their largest because they moved the chromosomes from one end...
  2. I

    AS Biology P1 MCQs Preparation Thread

    Condensation means that the DNA molecules get shorter and thicker (so that it can be viewed by a light microscope after appropriate staining)
  3. I

    AS Biology P1 MCQs Preparation Thread

    The only structural polysaccharide you are asked to know is cellulose, and that is made from beta-glucose like in B, not alpha-glucose like in A
  4. I

    AS Biology P1 MCQs Preparation Thread

    Pressure potential in a plant cell is how much a plant's cell membrane pushes a cell wall. This happens in a turgid cell. If a turgid cell is placed in a solution, water will leave by osmosis. This will continue to happen until the water potentials of the solution and the cell are the same. When...
  5. I

    AS Biology P1 MCQs Preparation Thread

    To clarify even further, plants have a lot of material that is completely useless to herbivores such as cell walls made of cellulose and chloroplasts. Most animals cannot digest cellulose, so it passes through the animal without being used. Secondary consumers eat the herbivores. Herbivores...
  6. I

    AS Biology P1 MCQs Preparation Thread

    During interphase, DNA replicates. During prophase, histones unwind the DNA so that they can be condensed. You don't need to know what histones are, just that they allow DNA to be condensed.
  7. I

    AS Biology P1 MCQs Preparation Thread

    From all the sunlight arriving at the plant, a lot is wasted from transpiration, the light misses the leaf, the light passes through the leaf without getting absorbed by the chloroplasts etc... so only 1% of the sunlight is actually used in photosynthesis (this is a number you must know from...
  8. I

    AS Biology P1 MCQs Preparation Thread

    1) Male bees are haploid, so they are NOT genetically identical. They are formed from diploid cells which have gone through independent assortment and crossing over to increase variation. Haploid cells produce other haploid cells by mitosis, not meiosis. If they were produced by meiosis, the 1n...
  9. I

    AS Biology P1 MCQs Preparation Thread

    From what I learnt in AP Biology, cholesterol is responsible for maintaining the fluidity of the membrane. Unsaturated tails just increase the fluidity. At high temperatures, the membrane is too fluid, so cholesterol stiffens the membrane, but at low temperatures, the membrane is too stiff, so...
  10. I

    AS Biology P1 MCQs Preparation Thread

    Technically, it can't just go from orange to green. So 2 is definitely out.
  11. I

    AS Biology P1 MCQs Preparation Thread

    There are questions when they put a tiny meter calibrated in 0.1mm divisions right above a graticule with 100 units. In this case, 0.1 mm normally take up 40 units. So if 0.1 mm takes 40 units, 1 unit would be 0.1/40 = 0.0025 mm = 2.5 micrometers in length.
  12. I

    AS Biology P1 MCQs Preparation Thread

    You can't fix a cell by making a new one. However, you can repair a TISSUE by replacing a damaged cell
  13. I

    AS Biology P1 MCQs Preparation Thread

    A pyramid of energy shows the energy of an organism in a trophic level. So to get that, you should multiply the biomass of one individual by the number of individuals (to get the total biomass) The results are: P: 1000 Q: 50 R: 1 S: 900000 Arrange them in a pyramid, and you'll find out that...
  14. I

    AS Biology P1 MCQs Preparation Thread

    According to the fluid-mosaic model, the more unsaturated phospholipids there are (i.e. phospholipids with a double bond in them), the more "fluid" the membrane is. In cold conditions, we all get stiffer, right? Even membranes! So if membranes want to be less stiff in the cold, they should...
  15. I

    AS Biology P1 MCQs Preparation Thread

    magnification = size of image/actual size of specimen For example, the actual size of a plant cell is 150 micrometers, but when you measure the cell with a ruler, you find out that it is 6 cm. First, convert both measurements to the same units. In this case, 6 cm = 60,000 micrometers. So the...
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    AS Biology P1 MCQs Preparation Thread

    If you sterilize the blood by heating, you would also denature the enzyme, so you can't use that. If you want to test the activity of an enzyme, you need to see how fast it works by adding a substrate. An inhibitor STOPS the action of enzymes, so we do not need that.
  17. I

    AS Biology P1 MCQs Preparation Thread

    I'll try to clarify this point: A cell wall always allows water to pass through. But once it is completely full of water (turgid), then no more water can pass through.
  18. I

    AS Biology P1 MCQs Preparation Thread

    38) C 39) A 40) A I'm not 100% sure of the answers though
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