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• Microscopes


  Normal light microscope can see cells and nucleus, electron microscope can see subcellular structures in more detail
• Magnification


  Image size / Object size
• Cell types


  • Eukaryotic cells (have nucleus)
  • Prokaryotic cells (no nucleus)
• Eukaryotic cells


  • DNA is found in the nucleus
  • Examples: plant and animal cells
• Prokaryotic cells


  • DNA is found in a ring called a plasmid
  • No nucleus
• Cell structures


  • Cell membrane
  • Cell wall (plant cells and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (plant cells)
• Bacteria multiply by binary fission, doubling in number every 10 minutes
• Bacterial culture practical


  1. Lift lid towards flame to destroy air microbes

  2. Use sterilized equipment

  3. Put drop of bacteria or spread around

  4. Add antibiotic spots

  5. Seal dish with tape

  6. Incubate at 25°C
• Diploid cells


  Cells with 23 pairs of chromosomes (e.g. human body cells)
• Haploid cells


  Cells with 23 single chromosomes (e.g. gametes)
• Mitosis


  1. Genetic material duplicated

  2. Ribosomes and mitochondria doubled

  3. Nucleus breaks down

  4. Chromosomes pulled to opposite sides

  5. New nuclei form
• Specialized cells


  • Nerve cells
  • Muscle cells
  • Root hair cells
  • Xylem cells
  • Phloem cells
• Stem cells


  Unspecialized cells that can differentiate into specialized cells
• Diffusion


  Passive movement of molecules/particles from high to low concentration
• Osmosis


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


  1. Cut potato cylinders

  2. Weigh and place in sugar solutions

  3. Reweigh after a day

  4. Calculate % change in mass

  5. Plot against sugar concentration
• Active transport


  Using energy to move substances against a concentration gradient
• Tissues


  • Heart tissue
  • Digestive tissue
• Organs


  • Heart
  • Liver
  • Gallbladder
• Organ systems


  • Circulatory system
  • Digestive system
• Enzymes


  Biological catalysts that are specific to certain substrates
• Enzyme activity practical


  1. Mix amylase and starch

  2. Test for starch every 10 seconds with iodine

  3. Plot time taken to break down starch against temperature or pH
• Food tests


  • Iodine for starch
  • Benedict's solution for sugars
  • Biuret's reagent for proteins
  • Ethanol for lipids
• Respiratory system


  • Air moves down trachea, bronchi, bronchioles to alveoli
  • Oxygen diffuses into blood, carbon dioxide diffuses out
• Circulatory system


  • Double circulatory system - deoxygenated blood to lungs, oxygenated blood to body
  • Heart has 4 chambers and valves
  • Arteries carry oxygenated blood, veins carry deoxygenated blood
• Coronary arteries supply the heart muscle with oxygen
• Stents


  Tubes inserted into blood vessels to keep them open
• Statins


  Drugs that reduce cholesterol
• Heart valve replacement can be done with artificial valves
• Components of blood

  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Communicable diseases


  Diseases caused by external pathogens
• Non-communicable diseases


  Diseases caused by internal factors, e.g. cardiovascular disease, cancer, autoimmune conditions
• Coronary artery


  Delivers blood to the heart muscle to supply oxygen
• Heart attack


  Occurs when coronary arteries are blocked by buildup of fatty deposits, causing coronary heart disease (CHD)
• Stents


  Little tubes inserted into blood vessels to keep them open and allow blood flow
• Statins


  Drugs that reduce cholesterol, which reduces fatty deposits
• Faulty heart valves


  Result in backflow, can be replaced with artificial ones
• Blood


  Carries plasma, red blood cells, white blood cells (combat infections), and platelets (clot wounds)
• Cardiovascular disease (CVD)


  An example of a non-communicable disease, caused by factors within the body
• Examples of non-communicable diseases

  • Cardiovascular disease
  • Autoimmune conditions
  • Cancer