Bios in 2 days lock in nigga

• 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 subcellular structures, has better resolving power and higher resolution
• Calculating cell size


  Magnification = image size / object size, so object size = image size / magnification
• Two main groups of cells

  • Eukaryotic cells (have a nucleus)
  • Prokaryotic cells (no nucleus, DNA in a ring called a plasmid)
• Subcellular structures


  • Cell membrane
  • Cell wall (in plant cells and most bacteria)
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Chloroplasts (in plant cells)
• Diffusion


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


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


  Cut equal size cylinders from potato, weigh, place in sugar solutions, reweigh after a day, calculate % change in mass, plot against sugar concentration to find no change point
• Active transport

  Movement of substances through a membrane against a concentration gradient, using energy
• Tissues


  Groups of similar connected cells
• Organs


  Groups of tissues working together
• Organ systems


  Groups of organs working together
• Digestion


  1. Physical digestion (breaking down food)

  2. Chemical digestion (enzymes breaking down food)
• Parts of a tooth

  • Enamel
  • Dentine
  • Pulp
  • Cementum
• Enzymes


  Biological catalysts that speed up reactions, specific to certain substrates
• Enzyme activity and temperature

  Increases with temperature until active site is denatured
• Enzyme activity and pH

  Optimum pH, too high or too low can denature enzyme
• Practical on enzyme activity

  Mix amylase and starch at different temperatures or pH, time how long for starch to be broken down, plot graph to find optimum
• Food tests


  • Iodine (starch)
  • Benedict's solution (sugars)
  • Biuret reagent (proteins)
  • Ethanol (lipids)
• Nutrients needed in a balanced diet

  • Carbohydrates (energy)
  • Fats/lipids (energy)
  • Proteins (growth and repair)
  • Vitamins (health)
  • Minerals (health)
  • Fibre (digestion)
  • Water
• Respiratory system


  Provides oxygen for respiration, not the same as respiration
• Breathing and gas exchange

  1. Air moves down trachea, bronchi, bronchioles to alveoli where gas exchange occurs

  2. Oxygen binds to haemoglobin in red blood cells and is transported to cells

  3. Carbon dioxide diffuses from cells into blood and is exhaled
• Circulatory system


  Double circulatory system, deoxygenated blood enters right side of heart, goes to lungs, oxygenated blood enters left side and is pumped to body
• Heart structure


  Right atrium and ventricle, left atrium and ventricle, valves to prevent backflow, left ventricle has thicker walls
• Blood vessels


  Arteries carry oxygenated blood away from heart, veins carry deoxygenated blood towards heart, capillaries allow diffusion
• Coronary arteries supply heart muscle with oxygen, blockage can cause heart attack
• Stents and statins can be used to treat coronary heart disease
• Plant organs


  • Leaves (photosynthesis, transpiration)
  • Roots (water and mineral absorption)
  • Xylem (unidirectional water transport)
  • Phloem (bidirectional food transport)
• Factors affecting transpiration rate

  Increased temperature, decreased humidity, increased air movement
• Lack of nitrate ions stunts plant growth, chlorosis is yellowing of leaves due to magnesium deficiency
• Leaf structure


  • Cuticle
  • Upper epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Vascular bundles
  • Lower epidermis with stomata
• Non-communicable diseases


  Caused by factors within the body, e.g. obesity, cancer
• Communicable diseases


  Caused by pathogens that enter the body, e.g. viral, bacterial, fungal, protist infections
• Types of pathogens


  • Viruses
  • Bacteria
  • Fungi
  • Protists
• Carcinogens increase cancer risk, benign cancers don't spread, malignant cancers do
• Viruses can't reproduce on their own, they inject genetic material into cells to make more copies
• Bacteria and fungi release toxins that damage body cells
• Protists like malaria parasite infect and destroy red blood cells
• Mosquitoes are the vector for malaria protist