Paper 1 - bio

• 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 like the animal cell, also has mitochondria and chloroplasts where photosynthesis takes place
• Bacterial cell


  Has a distinct cell wall, may have a flagella to help it move, has 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


  • Can magnify up to 2000 times, can see living samples in colour
• Electron microscope


  • Can magnify up to 2 million times, can see much finer detail but only in black and white, requires dead samples
• Using the magnification equation

  1. Magnification = Image size / Object size

  2. Image size = Magnification x Object size

  3. Object size = Image size / Magnification
• The image of a cell in a book is 48 cm in length, but the real cell is only 120 μm. The magnification is 400 times.
• The diameter of a capillary in a micrograph measures 5 mm, and the magnification is 1000 times. The actual diameter of the capillary is 5 μm.
• 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

  2. Forms enzyme-substrate complex

  3. Complex splits to form product
• Amylase


  Enzyme that catalyses the breakdown of starch into glucose
• Protease


  Enzyme that catalyses the breakdown of proteins into amino acids
• Lipase


  Enzyme that catalyses the breakdown of 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, with each enzyme having 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 particles on one side of the room

  2. Particles move to the other side of the room

  3. Passive process, 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


  The net movement from an area of low concentration to an area of high concentration, against the concentration gradient, requiring energy
• Amoeba


  • Single-celled organism that can use diffusion to obtain all the nutrients it needs