key concepts

• Animal cell


  • Nucleus - stores genetic information
  • Cell membrane - controls what enters and exits
  • Mitochondria - responsible for respiration
  • Ribosomes - make essential proteins
  • Cytoplasm - where chemical reactions happen
• Plant cell


  • Cell wall - gives extra strength and protection
  • Vacuole - stores cell sap
  • Chloroplasts - for photosynthesis
• Bacteria cell


  • Flagellum - acts like a 'tail' for movement
  • DNA floats loose in cytoplasm
  • Plasmid loops - extra DNA
• Prokaryotic cells


  Smaller, simpler, no nucleus
• Eukaryotic cells


  Bigger, more complex, have a nucleus
• Sperm and egg cells

  • Haploid nucleus - half the normal number of chromosomes
  • Egg cell has lots of nutrients in cytoplasm
• Ciliated epithelial cell


  • Has hair-like cilia to help move substances along
• Light microscope


  Invented in 1500s, uses light beams, relatively low resolution, can view living cells
• Electron microscope


  Invented in 1930s, uses electron beams, higher resolution, cannot view living cells
• Total magnification


  Eyepiece lens magnification x Objective lens magnification
• Enzymes


  Biological catalysts made by living things, speed up reactions
• Enzyme active site


  Place where substrate fits in, highly specific
• Enzyme conditions


  • Optimum temperature
  • Denaturation at extreme temperatures
  • Optimum pH
• Increasing substrate concentration


  Increases enzyme activity until active sites are full
• Benedict's test for reducing sugars

  1. Add Benedict's reagent

  2. Heat gently

  3. Blue = low sugar, Orange-red = high sugar
• Biuret test for proteins

  1. Add potassium hydroxide

  2. Add copper sulfate

  3. Purple colour indicates presence of proteins
• Emulsion test for lipids

  1. Add ethanol, shake, pour into water

  2. Milky water indicates presence of lipids
• Iodine test for starch

  1. Add iodine

  2. Blue-black colour indicates presence of starch
• Calorimetry to measure food energy

  1. Set food alight

  2. Hold under copper cup of water

  3. Measure temperature change

  4. Calculate energy using specific heat capacity
• Diffusion


  Passive movement of particles from high to low concentration
• Active transport


  Movement of particles from low to high concentration, requires energy
• Osmosis


  Diffusion of water molecules from high to low concentration through a partially permeable membrane