Science

• Red blood cells


  More space for haemoglobin
• Similarities between red blood cells and root hair cells

  Both have shapes that provide high surface area to volume ratio
• Differences between red blood cells and root hair cells


  • Red blood cells have no nucleus, root hair cells have nucleus
  • Red blood cells have no cell wall, root hair cells have cell wall
• Cell wall


  Gives cell structure and support
• Mitochondrion

  Conducts respiration to release energy from sugar, to be used for growth and repair
• Root hair cell


  Increases surface area to volume ratio of cell to efficiently absorb water and mineral salts from the soil
• Chloroplast


  Contains chlorophyll to help trap sunlight for photosynthesis
• Atom


  Subatomic particle with proton, neutron, and electron
• Proton is always the smaller number (atomic number)
• Mass number = Protons + Neutrons (nucleon number)
• Periodic table


  • Vertical -> group (similar chemical properties)
  • Elements on left side are metals, right side non-metals
• Particulate nature of matter

  Weaker attractive forces
• Diffusion of bromine gas in air


  Bromine gas diffuses upwards, air particles diffuse downwards until evenly distributed
• Temperature affecting rate of diffusion


  Higher temperature, particles gain more kinetic energy, move around at higher speed
• States of matter

  • Solid: fixed shape, fixed volume, cannot be compressed
  • Liquid: no fixed shape, fixed volume, cannot be compressed
  • Gas: no fixed shape, no fixed volume, can be compressed
• Kinetic particle energy

  • Solid: particles in fixed positions
  • Liquid: particles can roll and slide randomly
  • Gas: particles move quickly in any direction
• Particles gain heat energy which is converted to kinetic energy, causing more vibration
• During melting, temperature remains constant as heat energy is used to weaken attractive forces between particles
• Element


  A pure chemical substance that cannot be broken down into simpler substances by chemical processes
• Compound


  A pure chemical substance formed when two or more elements are chemically combined in a fixed ratio
• Mixture


  Contains two or more components (elements and/or compounds) mixed together in any proportion
• Mixtures can be separated by physical processes, compounds can only be separated by chemical means
• Mixtures do not have a sharp melting point and boiling point, compounds do
• W is compressible at 80% because it is a gas, and gases can be compressed easily as the particles are far apart with a lot of empty space between them
• Red blood cells are red because they have haemoglobin
• Solubility of X at 60°C for 100g = 36g, for 250g = 90g