Unit 1

• What are all living things made of?

  Cells
• Why can't we see cells with the naked eye?

  Because cells are very small
• How can we see cells if they are so small?

  By using instruments that magnify them
• What are the three types of magnifying instruments used in life sciences?

  • Hand lens
  • Light microscope
  • Scanning electron microscope
• What is the magnifying power of a hand lens?

  Low magnifying power
• What is the magnifying power range of a light microscope?

  70x to 2000x
• What is the magnifying power range of a scanning electron microscope?

  1000x to 100,000x
• What is the purpose of staining chemicals in microscopy?

  To make different structures in cells visible
• What is the main difference between light microscopes and electron microscopes?

  Electron microscopes have a much higher magnifying power
• What do electron microscopes use to magnify objects?

  A beam of electrons focused by electromagnets
• What do scanning electron microscopes (SEMs) do?

  They scan the surface of cells
• What is the significance of transmission electron microscopes (TEMs)?

  They allow us to see much smaller structures inside cells
• What are the main points of cell theory?

  • All living things consist of one or more cells.
  • Cells are the smallest living things (the basic unit of life).
  • All cells arise from pre-existing cells.
  • Cells contain inherited information for growth, development, and specialized functions.
• Who was the first person to observe living cells using a microscope?

  Antonie van Leeuwenhoek
• What did Matthias Schleiden claim in 1838?

  That all plants are made of cells
• What did Theodor Schwann report in 1839?

  That all animals are also made of cells
• What did Robert Hooke observe in 1665?

  Very thin sections of cork
• What did Hooke call the tiny box-like structures he observed?

  Cellulae
• What does the term "naked eye" refer to?

  Looking at something without the aid of a magnifying instrument
• What are the parts of a light microscope and their functions?

  • Eyepiece: Magnifies the image
  • Objective lenses: Provide different magnifications
  • Stage: Holds the slide
  • Light source: Illuminates the specimen
  • Focus knobs: Adjust the clarity of the image