bio paper 1

• Topics covered


  • Cells
  • Infection and response
  • Organization
  • Bioenergetics
• Animal and plant cells

  Organelles they both have: nucleus, cytoplasm, mitochondria, ribosomes, cell membrane
• Plant cells


  • Vacuole, cell wall, chloroplasts
• Eukaryotic cells


  DNA is inside the nucleus
• Prokaryotic cells


  DNA is not in a nucleus, it's in a plasmid
• Mitosis


  Chromosomes are copied and separated into two daughter nuclei
• Chromosomes in humans


  23 pairs, 46 total
• Meiosis


  DNA is copied and swapped, then divided into 4 gametes with half the information
• Stem cells


  Become specialized into different cell types
• Microscopy


  • Magnification = image size / object size
  • Nanometers are 1 million times smaller than millimeters
  • Micrometers are 1000 times smaller than millimeters
• Electron microscopes


  Have better resolution than light microscopes, can see organelles
• DNA


  Made of 4 bases, 3 bases code for an amino acid, many amino acids make a protein, many triplets make a gene
• Diffusion


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


  Diffusion of water through a semi-permeable membrane
• Osmosis practical


  Weigh potato cylinders in different sucrose solutions, measure change in mass
• Active transport


  Moving substances up a concentration gradient, requires energy
• Respiration


  Glucose + oxygen -> water + carbon dioxide, releases energy
• Photosynthesis


  Reverse of respiration, uses light energy to make glucose
• Factors affecting photosynthesis rate

  • Light intensity, temperature, carbon dioxide concentration
• Anaerobic respiration


  Glucose -> lactic acid, less energy released
• Metabolism


  Sum of all chemical reactions in the body
• Pathogens


  Bacteria, viruses, fungi, protists that cause infectious diseases
• Human defenses against pathogens


  • Skin
  • Platelets
  • Cilia
  • Mucus
  • Acid
• White blood cells


  • Phagocytes ingest pathogens, lymphocytes make antibodies
• Immunity


  Body remembers antibodies to fight pathogens it has encountered before
• Alexander Fleming discovered penicillin, the first antibiotic
• Antibiotics


  Kill bacteria but not viruses, overuse can lead to resistance
• Antibiotics practical


  Prepare agar plate, spread bacteria, add antibiotic discs
• Drug development process


  1. Test on tissue

  2. Animal trials

  3. Human blind trials

  4. Double blind trials
• Blind trials


  One group given actual drug, other group given placebo to avoid patient bias
• Double blind trials


  Similar to blind trials but doctors don't know which is control group, eliminates all bias
• Antibiotic testing process


  1. Prepare agar plate

  2. Spread bacteria like E. coli

  3. Place antibiotic discs on lawn

  4. Measure diameter of bacteria-free zones
• Aseptic technique


  Procedure to ensure no other bacteria enter the dish
• Monoclonal antibody production


  1. Inject mouse with antigen

  2. Extract white blood cells making antibody

  3. Fuse with tumor cell to create hybridomas

  4. Clone hybridomas and harvest antibodies
• Plant diseases


  • Virus (e.g. tobacco mosaic virus)
  • Fungus (e.g. rose black spots)
  • Mineral deficiencies
• Nitrate deficiency


  Causes stunted plant growth
• Magnesium deficiency


  Causes chlorosis (yellow leaves)
• Plant defences


  • Cell walls
  • Waxy cuticle
  • Trichomes
  • Antibacterial chemicals
• Transpiration


  1. Water evaporates from leaves

  2. Causes low pressure in plant

  3. Water osmoses into roots and rises up xylem
• Factors affecting transpiration


  • Temperature (higher = faster)
  • Wind/air flow (higher = faster)
  • Humidity (higher = slower)