BIOLOGY

• Types of cells


  • Animal cells
  • Plant cells
• Organelles in both animal and plant cells

  • Nucleus
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Cell membrane
• Plant cells


  • Vacuole
  • Cell wall made of cellulose
  • Chloroplasts
• Eukaryotic cells


  Cells with DNA inside a nucleus
• Prokaryotic cells


  Cells with DNA not in a nucleus, like bacteria
• Mitosis


  1. Chromosomes copied

  2. Chromosomes line up in middle

  3. Chromosomes pulled apart

  4. Daughter nuclei formed
• Humans have 23 pairs of chromosomes (46 total)
• Meiosis


  1. DNA copied

  2. Chromosomes swap information

  3. Two daughter nuclei formed

  4. Four gametes formed with half the information
• Stem cells


  Cells that can become specialised cell types
• Magnification


  Image size / Object size
• Nanometers


  One million times smaller than millimeters
• Micrometers


  One thousand times smaller than millimeters
• Light microscopes


  • Can see cells but not individual organelles
• Electron microscopes


  • Can see individual organelles with much better resolution
• DNA


  Made up of 4 bases (A, T, C, G) that code for amino acids and proteins
• Diffusion


  Particles move from high to low concentration, no energy required
• Osmosis


  Diffusion of water through a semi-permeable membrane
• Active transport


  Movement of substances against a concentration gradient, requires energy
• Respiration


  Glucose + Oxygen -> Water + Carbon dioxide, releases energy
• Photosynthesis


  Carbon dioxide + Water -> Glucose, requires light energy
• Iodine test turns starch purple
• Factors affecting rate of photosynthesis

  • Light intensity
  • Temperature
  • Carbon dioxide concentration
• Limiting factor in photosynthesis is never the factor on the x-axis
• Anaerobic respiration


  Glucose -> Lactic acid, less energy released
• Increased heart rate and breathing rate during exercise to supply more oxygen
• Metabolism


  Sum of all chemical reactions in the body
• Types of pathogens


  • Bacteria
  • Viruses
  • Fungi
  • Protists
• Human defences against pathogens


  • Skin
  • Platelets
  • Cilia
  • Mucus
  • Stomach acid
  • Phagocytes
  • Lymphocytes
• Antibodies


  Bind to antigens on pathogens, causing them to clump together
• Vaccination


  Injecting dead or inert pathogens to stimulate antibody production
• Alexander Fleming discovered penicillin, the first antibiotic
• Antibiotics don't kill viruses, only bacteria
• Overuse of antibiotics can lead to bacterial resistance
• Drug development


  1. Discovery

  2. Development

  3. Trials (animal, human, blind, double-blind)

  4. Manufacture

  5. Review
• Drug development process


  1. Test on tissue

  2. Animal trials

  3. Human blind trials

  4. Double blind trials

  5. Manufacture and review
• In blind trials, one group gets the actual drug and the other group gets a placebo to avoid patient bias
• In double blind trials, even the doctors don't know which group is the control group to eliminate any bias
• Antibiotic testing procedure


  1. Prepare agar plate

  2. Spread bacteria like E. coli

  3. Use Bunsen flame for aseptic technique

  4. Place antibiotic discs on lawn

  5. Measure diameter of inhibition zones
• Monoclonal antibodies


  Antibodies manufactured by fusing mouse white blood cells with tumor cells to target specific cells or chemicals
• Plant diseases


  • Viral (e.g. tobacco mosaic virus)
  • Fungal (e.g. rose black spots)
  • Mineral deficiencies (e.g. nitrate, magnesium)