Untitled

• Light microscope


  Can see cells and maybe the nucleus, but not subcellular structures
• Electron microscope


  Can see much finer details and subcellular structures, has better resolving power and higher resolution
• Calculating cell size


  1. Measure image size

  2. Divide by magnification
• 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
• Subcellular structures


  • Cell membrane
  • Cell wall
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts
  • Vacuole
• Bacterial binary fission


  1. Number doubles every 10 minutes

  2. After 1 hour, 64 bacteria

  3. After 6 hours, 6.87 x 10^10 bacteria
• Practical: Bacterial culture on agar

  1. Use aseptic technique

  2. Lift lid towards flame

  3. Use sterilized equipment

  4. Incubate at 25°C
• Measuring bacterial culture


  1. Calculate size from initial drop or area where bacteria didn't grow

  2. Use πr^2 or πd^2/4 to calculate area
• Human cells


  • Have 23 pairs of chromosomes (diploid)
  • Gametes have 23 chromosomes (haploid)
• Cell division by mitosis

  1. Genetic material duplicated

  2. Ribosomes and mitochondria doubled

  3. Nucleus breaks down

  4. Chromosomes pulled to opposite sides

  5. New nuclei form
• Specialised cell types


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


  Unspecialised cells that can differentiate into various cell types
• Diffusion


  Movement of molecules/particles from high to low concentration, down concentration gradient, passive process
• Osmosis


  Diffusion of water across a semi-permeable membrane
• Practical: Osmosis in potato cylinders

  1. Cut equal size cylinders

  2. Weigh and place in sugar solutions

  3. Reweigh after a day

  4. Calculate percentage 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 break down larger molecules into smaller ones
  • Work on a lock and key principle with substrates
• Enzyme activity


  • Increases with temperature until denaturation
  • Affected by pH, optimum pH for activity
• Practical: Investigating enzyme activity

  1. Mix enzyme and substrate

  2. Test for product formation over time

  3. Plot time taken vs temperature or pH

  4. Identify optimum conditions
• 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

  1. Oxygen diffuses into blood

  2. Carbon dioxide diffuses out
• Components of blood


  • Red blood cells
  • Plasma
  • White blood cells
  • Platelets
• Double circulatory system


  Blood enters heart twice per cycle
• Heart structures


  • Right atrium
  • Right ventricle
  • Pulmonary artery
  • Pulmonary vein
  • Left atrium
  • Left ventricle
  • Aorta
• Coronary arteries


  Supply oxygen to heart muscle
• Cardiovascular disease


  Example of a non-communicable disease
• Communicable diseases have causes from outside the body
• Coronary artery

  Delivers blood to the heart muscle to supply oxygen
• Coronary heart disease (CHD)


  Occurs when coronary arteries are blocked by fatty deposits, causing a heart attack
• Stent


  A small tube 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
• Cardiovascular (CV) disease


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