BIOLOGY SCIENCE

• 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
• Triplets of DNA bases


  Code for amino acids that make up proteins
• Genes


  Long sequences of DNA triplets that code for specific traits
• Diffusion


  Movement of particles from high to low concentration, no energy required
• Osmosis


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


  Weigh potato cylinders before and after soaking in sucrose solutions
• Active transport


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


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


  Carbon dioxide + Water -> Glucose, using light energy
• Starch test


  Iodine turns purple when added to starch
• Photosynthesis rate practical


  Measure oxygen bubbles produced by pond weed under different light intensities
• Limiting factor for photosynthesis rate

  Not the factor on the x-axis, must be something else
• Anaerobic respiration


  Glucose -> Lactic acid, less energy released
• During exercise


  Heart rate and breathing rate increase
• Metabolism


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


  • Bacteria
  • Viruses
  • Fungi
  • Protists
• Disease caused by a protist


  • Malaria
• Defences against pathogens


  • Skin
  • Platelets
  • Cilia
  • Mucus
  • Acid
• Types of white blood cells

  • Phagocytes
  • Lymphocytes
• Phagocytes


  Non-specific cells that ingest and destroy pathogens
• Lymphocytes


  Specific cells that make antibodies to target pathogens
• Immunity


  Body remembers how to make antibodies for a pathogen
• Vaccination


  Injecting dead or inert pathogens to stimulate antibody production
• Alexander Fleming discovered penicillin, one of the first antibiotics
• Antibiotics


  Kill bacteria but not viruses
• Overuse of antibiotics can lead to bacterial resistance