bio

• All life consists of cells
• Light microscope


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


  Can see finer details and organelles, has better resolving power and higher resolution
• Magnification


  Image size / object size
• Eukaryotic cells


  Have a nucleus where DNA is found (e.g. plant and animal cells)
• Prokaryotic cells


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


  • Cell membrane
  • Cell wall (in plant cells and bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (in plant cells)
• Binary fission


  Bacteria multiply, number doubles every 10 minutes
• After 1 hour, 1 bacterium becomes 64
• After 6 hours, 1 bacterium becomes 6.87 x 10^10
• Practical on bacterial growth

  Aseptic technique, incubate at 25°C, calculate area of growth or inhibition
• Diploid cells


  Have 23 pairs of chromosomes
• Haploid cells


  Have 23 chromosomes (e.g. gametes)
• Mitosis


  Genetic material duplicates, nucleus divides, two identical cells formed
• Specialised cells


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


  Unspecialised cells that can differentiate
• Diffusion


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


  Diffusion of water across a semi-permeable membrane
• Practical on osmosis


  Cut potato cylinders, weigh, place in sugar solutions, reweigh, calculate % change in mass
• Active transport


  Using energy to move substances against a concentration gradient
• Tissues


  • Heart
  • Digestive
  • Circulatory
• Enzymes


  Biological catalysts that are specific to certain substrates
• Practical on enzyme activity

  Mix amylase and starch, test for starch using iodine, measure time taken, plot against temperature or pH
• Food tests: iodine (starch), Benedict's (sugars), Biuret (proteins), ethanol (lipids)
• Respiration


  Provides energy for cells, different to breathing
• Breathing


  Air moves down trachea, bronchi, bronchioles to alveoli for gas exchange
• Double circulatory system


  Blood enters heart twice per cycle, deoxygenated to lungs, oxygenated to body
• Arteries


  Carry blood away from the heart, have thick walls
• Veins


  Carry blood towards the heart, have thin walls and valves
• Coronary arteries supply the heart muscle with oxygen</b>
• Cardiovascular disease


  Non-communicable disease affecting the heart and blood vessels
• Diffusion of molecules in and out of cells

  • Fast
• Heart


  A muscle that needs its own supply of oxygen and blood to keep pumping
• Coronary artery


  Delivers blood to the heart muscle
• Coronary arteries are blocked by fatty deposits


  Can cause a heart attack, which is coronary heart disease (CHD)
• Stents


  Little tubes inserted into blood vessels to keep them open so blood can flow
• Statins


  Drugs that reduce cholesterol, which in turn 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 inside the body