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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
  • Prokaryotic cells
• Eukaryotic cells


  • Have a nucleus where DNA is found
• Prokaryotic cells


  • Don't have a nucleus, DNA is in a ring called a plasmid
• Cell structures


  • Cell membrane
  • Cell wall (plant cells and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (plant cells)
• Bacterial binary fission


  1. Number of bacteria doubles every 10 minutes

  2. After 1 hour, 64 bacteria

  3. After 6 hours, 6.87 x 10^10 bacteria
• Practical on bacterial growth - use aseptic technique, incubate at 25°C, calculate area of growth or inhibition
• Diploid cells


  Cells with 23 pairs of chromosomes
• Haploid cells


  Cells with 23 single chromosomes
• Mitosis


  1. Genetic material duplicated

  2. Nucleus breaks down

  3. Chromosomes pulled to opposite sides

  4. New nuclei form
• Specialised cell types


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


  Unspecialised cells that can differentiate into various cell types
• Diffusion


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


  Diffusion of water across a semi-permeable membrane
• Factors affecting rate of diffusion/osmosis: concentration difference, temperature, surface area
• Practical on osmosis


  Cut potato cylinders, weigh, place in sugar solutions, reweigh, calculate % change in mass, plot graph to find no change 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 break down larger molecules into smaller ones
• Enzymes


  • Specific to certain substrates, work on a lock and key principle
  • Rate increases with temperature until denaturation, optimum temperature
  • Rate also affected by pH, optimum pH
• Practical on enzyme activity

  Mix amylase and starch, test for starch presence over time at different temperatures/pH, find optimum
• Food tests


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


  • Trachea
  • Bronchi
  • Bronchioles
  • Alveoli
• Breathing vs respiration


  Breathing provides oxygen for respiration in cells
• Gas exchange in alveoli

  Oxygen diffuses into blood, carbon dioxide diffuses out
• Components of blood


  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• Blood circulation


  1. Deoxygenated blood enters right atrium

  2. Pumped to lungs via pulmonary artery

  3. Oxygenated blood returns to left atrium

  4. Pumped to body via aorta
• Blood vessels


  • Arteries have thick walls, veins have valves
  • Capillaries are one cell thick
• Coronary artery


  Supplies blood to heart muscle
• Cardiovascular diseases are non-communicable, caused by factors within the body
• 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 and 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)


  Non-communicable disease caused by factors inside the body, e.g. obesity, diabetes, smoking