Biology

• Cells


  The smallest living unit in all organisms
• Cell division


  1. Mitosis

  2. Fully grown cell divides to form new cells
• Types of cells


  • Eukaryotic cells (with nucleus)
  • Prokaryotic cells (without nucleus)
• Types of organisms


  • Multicellular organisms (millions of cells)
  • Unicellular organisms (single cell)
• Cell membrane


  • Thin layer of protein and fat
  • Separates cell contents from surroundings
  • Partially permeable
• Cell wall


  • Surrounds plant cells
  • Made of cellulose
  • Strong and can withstand high pressure
  • Fully permeable
• Cytoplasm


  Liquid and solid part of cell containing dissolved substances
• Vacuole


  • Fluid-filled space in cell
  • Large and permanent in plant cells
  • Small and scattered in animal cells
• Chloroplast


  • Contains chlorophyll
  • Site of photosynthesis
• Mitochondria


  • Has two membranes
  • Site of aerobic respiration
  • More in cells needing more energy
• Ribosomes


  • Site of protein synthesis
• Nucleus


  • Contains DNA and genetic information
• Specialised cells


  • Ciliated cell
  • Neuron/Nerve cell
  • Red blood cell
  • Sperm cell
  • Egg cell
  • Root hair cell
  • Palisade cell
  • Guard cell
  • Xylem and phloem cells
• Cell organisation


  Cells -> Tissues -> Organs -> Systems -> Organism
• Tissues


  Groups of specialised cells carrying out the same function
• Organs


  Groups of different tissues working together to carry out a function
• Systems


  Groups of organs working together to carry out a function
• Organism


  All systems working together to support life
• Light microscope


  • Optical (eyepiece, objective lenses)
  • Illuminating (diaphragm, mirror/illuminator)
  • Mechanical (draw tube, body tube, knobs, nosepiece, stage, base)
• Resolution


  Ability of microscope to focus clearly on specimen
• Field of view


  Diameter of circular area seen through microscope
• Magnification


  Number of times image is enlarged compared to actual size
• To find actual size, calculate Image size/Magnification and then multiply by 1000