Bio paper 1

• Animal cell


  Looks like a fried egg, has a big border and a small compartment in the middle which is the nucleus that controls the activities of the cell, surrounded by cytoplasm where chemical reactions take place, has a cell membrane that controls entry and exit of substances
• Mitochondria


  • Powerhouse of the cell, creates energy via aerobic respiration
• Ribosomes


  • Responsible for protein synthesis
• Plant cell


  Very rectangular in shape due to the cell wall that surrounds it and supports the cell, has a vacuole in the middle containing cell sap, has a nucleus squeezed into one corner, has mitochondria and chloroplasts for photosynthesis
• Bacterial cell


  Has a cell wall, a flagella to help it move, no distinct nucleus but instead has a nucleoid with genetic information, may have additional structures like a capsule or slime coat
• Sperm cell


  • Characteristic whiplash tail to help it swim, central portion packed with mitochondria for energy, head containing genetic information and enzymes in the acrosome to break down the egg's outer casing
• Egg cell


  • Haploid nucleus with one set of chromosomes, lots of cytoplasm containing nutrients for the future embryo, a jelly coat that hardens after fertilisation to prevent other sperm from entering
• Cells lining the oviduct

  • Have cilia that waft back and forth to move the egg along the oviduct
• Ciliated cells in the trachea

  • Have cilia that trap pathogens and particulates in mucus and move them out of the trachea
• Organelle


  Small structure found inside a cell
• Cell


  Group of organelles working together to perform the same function
• Tissue


  Group of cells working together to perform the same function
• Organ


  Group of tissues working together to perform the same function
• Organ system


  Group of organs working together to perform the same function
• Light microscope


  Microscope found in classrooms, can magnify up to 2000 times and has a resolving power of 200 nanometers
• Electron microscope


  Microscope found in scientific laboratories, can magnify up to 2 million times and has a resolving power of 0.2 nanometers, can only view dead samples
• Using the magnification equation


  1. Image size = Magnification x Object size

  2. Magnification = Image size / Object size

  3. Object size = Image size / Magnification
• Enzyme


  Biological catalyst that speeds up the rate of a chemical reaction without being used up
• Enzyme active site


  • The biologically active part of the enzyme molecule where the substrate binds
• Enzyme catalysis


  1. Substrate binds to active site to form enzyme-substrate complex

  2. Complex splits to form product
• Digestive enzymes


  • Amylase (breaks down starch into glucose)
  • Proteases (break down proteins into amino acids)
  • Lipase (breaks down lipids/fats into fatty acids and glycerol)
• Increasing temperature


  Increases enzyme activity up to the optimum temperature, then activity decreases as the enzyme denatures
• Changing pH


  Affects enzyme activity, each enzyme has an optimum pH range
• Testing for glucose


  Add Benedict's reagent and heat, brick red colour indicates presence of glucose
• Testing for starch


  Add iodine, blue-black colour indicates presence of starch
• Testing for proteins

  Add biuret reagent, purple colour indicates presence of proteins
• Testing for fats


  Add ethanol, then water, milky white emulsion indicates presence of fats
• Diffusion

  Net movement of particles from high to low concentration, passive process
• Osmosis

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


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


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

  2. Moves the cross 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
• If there's no partially permeable membrane, it's not osmosis, it's just diffusion
• Diffusion


  Leaves the stomata from a leaf
• Active transport


  An active process that requires energy to move from an area of low concentration to an area of high concentration, against the concentration gradient
• Protozoa


  • Amoeba
• Amoeba


  • A single-celled organism that can use diffusion to obtain all the nutrients it needs
  • Diffusion is appropriate because the amoeba has 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, requiring a circulatory system
• Chromosomes

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