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  1. I

    biology paper 1 doubts

    Yes, it does. But here's what you have to be very careful about: The protein found inside tissue fluid does not come from blood (capillaries). This is because proteins are extremely large molecules and are too big to fit through the pores of the capillaries to diffuse to the tissue fluid...
  2. I

    biology paper 1 doubts

    Pressure potential actually increases the water potential, so it is positive and not negative. The greater the pressure exerted, the higher the pressure potential. So the more turgid a cell is, the more positive is the pressure potential (and the higher the water potential).
  3. I

    biology paper 1 doubts

    The three of them are nearly identical. Here are the differences: 1) Blood has red blood cells; tissue fluid and lymph do not. 2) Lymph near the small intestine (lacteals) absorb lipids from our food, so they have a lot of fats 3) Lymph near the liver has a lot of protein. But most other lymph...
  4. I

    biology paper 1 doubts

    Could you please be a bit more specific, or point me to a certain past paper question?
  5. I

    biology paper 1 doubts

    Lymph has the exact same content as tissue fluid. It only has a different name because it is in a different vessel, that's all.
  6. I

    biology paper 1 doubts

    I answered this question already in page 2, and I'm not in the mood to type it all out again. So I'll just copy and paste it: ==================================================================================== A, B, C, and D are four different bases (adenine, guanine, cytosine, and thymine)...
  7. I

    biology paper 1 doubts

    Three main fluids: 1) Blood 2) Tissue fluid 3) Lymph Blood leaks from capillaries to the area surrounding the cells. This forms tissue fluid which bathes the cells. If blood kept on leaking, then there would be a build up of tissue fluid which may completely drain the blood vessels and cause a...
  8. I

    biology paper 1 doubts

    Bronchioles do not have any goblet cells, but all of them have cilia.
  9. I

    biology paper 1 doubts

    The question says from parent to child, not from parent to embryo or parent to foetus. EDIT: cholera can be transmitted through contaminated food AIDS can be transmitted through breast feeding TB can be transmitted when a mother coughs/sneezes next to her child. As you said, malaria needs a...
  10. I

    biology paper 1 doubts

    Epidermis is a squamous tissue. It's main function is to protect the system. Smooth muscle is important in the system to stretch (NOT contract) and recoil (NOT relax) during inhalation and exhalation. It's important to allow the maximum amount of oxygen to be transferred. EDIT: When smooth...
  11. I

    biology paper 1 doubts

    There are 46 chromosomes just before prophase. Every chromosome is made up of 2 chromatids. So you have a total of 46 x 2 = 92 chromatids just before prophase. Every chromatid contains one DNA molecule. There is no spindle present just before prophase. It starts forming by late prophase and...
  12. I

    biology paper 1 doubts

    No, what you're talking about is a peptide bond. Hydrogen bond is formed when a partially positive hydrogen atom in one molecule is bounded to a partially negative nitrogen, oxygen, or fluorine atom in another. This happens with a partially positive hydrogen atom in one amino acid binding with...
  13. I

    biology paper 1 doubts

    To be honest, I'm not exactly sure. I know it because our school teaches us biology much tougher than the AS. So I studied the AS material from my school book, not the Cambridge book. Our teacher just told us which chapters to study for, and that's what I did.
  14. I

    biology paper 1 doubts

    D is the structure of glycerol, not a natural alkyl group or one of its derivatives.
  15. I

    biology paper 1 doubts

    Yes, you're right. A habitat is where an organism lives. But if the tree carries out phtotosynthesis and absorbs water etc..., then it is more than "just a habitat". They're describing for you the role of the tree in the ecosystem which is its niche. ONE of its roles may be that it is a habitat...
  16. I

    biology paper 1 doubts

    During prophase, the chromosomes coil and condense, and they don't uncoil until the end of telophase. In prophase, the two chromatids are still held together by a centromere (5). After that, metaphase pulls all the chromosomes to the metaphase plate (imaginary line drawn through the...
  17. I

    biology paper 1 doubts

    Every single order of protein structure affects the shape of a protein (including the active site of an enzyme). Take it this way: with sickle cell anemia, one of the polar amino acids is replaced by a non-polar one. This changed the primary structure. Since the new amino acid is non polar, it...
  18. I

    biology paper 1 doubts

    The syllabus changed after 2006, so I only solved from 2007 and onwards.
  19. I

    biology paper 1 doubts

    I deleted my post. Here is exactly what I know: Stroke volume = end systolic volume - end diastolic volume End systolic volume = volume of blood after a contraction So even after the ventricle contracts, there will still be some blood left over (maybe not all the blood made it through past the...
  20. I

    biology paper 1 doubts

    The question states, "which range of partial pressures of oxygen produces the greatest change of percentage saturation haemoglobin per unit oxygen tension" So you have to find the greatest increase which is B.
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