Bio P1

• There are two types of microscopes: light microscope and electron microscope
• Light microscope

  • Magnifies up to 2,000 times
  • Resolves points 200 nanometers apart
  • Can use living samples
  • Produces coloured images
• Electron microscope

  • Magnifies up to 2 million times
  • Resolves points 0.2 nanometers apart
  • Requires dead samples
  • Produces black and white images
• Using the magnification equation

  1. Image size = Magnification x Object size

  2. Magnification = Image size / Object size

  3. Object size = Image size / Magnification
• Converting units

  • Centimetres to millimetres: multiply by 10
  • Micrometres to millimetres: divide by 1000
• Enzyme

  Biological catalyst that speeds up chemical reactions without being used up
• Enzyme active site

  • Biologically active part of the enzyme molecule where the substrate binds
• Enzyme-catalysed reaction

  1. Substrate binds to active site

  2. Forms enzyme-substrate complex

  3. Complex splits to form product
• Enzymes involved in digestion

  • Amylase (breaks down starch to glucose)
  • Proteases (break down proteins to amino acids)
  • Lipase (breaks down lipids to fatty acids and glycerol)
• As temperature increases

  Enzyme activity increases up to the optimum temperature, then decreases as the enzyme denatures
• As pH changes from the optimum

  Enzyme activity decreases as the enzyme denatures
• Testing for glucose

  1. Add Benedict's reagent and heat

  2. Brick red colour indicates presence of glucose
• Testing for starch

  1. Add iodine

  2. Blue-black colour indicates presence of starch
• Testing for proteins

  1. Add biuret reagent

  2. Purple colour indicates presence of proteins
• Testing for lipids

  1. Add ethanol, then water

  2. Milky white emulsion indicates presence of lipids
• Diffusion

  Net movement of particles from high to low concentration, no energy required
• Osmosis

  Net movement of water from high to low water potential across a partially permeable membrane
• Active transport

  Movement of substances against a concentration gradient, requires energy
• Diffusion

  1. High concentration of packing particles on one side of the room

  2. Moves across to the other side of the room

  3. Can smell it

  4. Passive process

  5. Does not require energy
• Osmosis

  The net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane
• Osmosis involves the movement of water, unlike diffusion which does not require a partially permeable membrane
• Diffusion through stomata


  Leaves the stomata from the leaf
• Active transport


  An active process that requires energy to move substances from an area of low concentration to an area of high concentration, against the concentration gradient
• Diffusion is suitable for single-celled organisms like amoeba because they have a large surface area to volume ratio, allowing fast diffusion
• Larger multicellular organisms have a smaller surface area to volume ratio, so diffusion is too slow and they have developed a circulatory system
• Chromosomes


  Where DNA is found, in pairs inside the nucleus of the cell
• Cell cycle


  The process by which a cell duplicates its genetic material and divides into two or more daughter cells
• Mitosis


  The type of cell division that produces genetically identical daughter cells for growth and repair
• Stages of mitosis


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Cytokinesis


  The physical division of the cytoplasm to form two daughter cells
• Growth


  An increase in size of an organism, either through an increase in cell number or cell size
• Stem cells


  Cells capable of becoming any other type of cell
• Differentiation


  The process by which a less specialized cell becomes a more specialized cell type
• Meristems


  Groups of cells found in plants that allow for continuous growth, as they can differentiate into any plant cell type
• Main parts of the brain

  • Cerebral cortex
  • Cerebellum
  • Medulla/brainstem
• Functions of the brain regions

  Cerebral cortex: emotions, memory, personality, behaviour

  Cerebellum: balance, posture

  Medulla/brainstem: controls breathing, heart rate, reflexes
• Examining the brain


  1. Brain surgery with electrodes

  2. CT scans

  3. PET scans
• Nerve cells (neurons)


  Have many dendrites for connections, a long axon to transmit impulses, and many mitochondria for energy
• Myelin sheath


  Fatty substance that insulates the axon to increase the speed of electrical impulse transmission
• Nervous system response


  1. Stimulus detected by receptors

  2. Electrical impulses along sensory neuron

  3. To central nervous system

  4. Electrical impulses along motor neuron

  5. To effector (muscle or gland)