Topic 1 - Cell biology

• How do light microscopes form an image of an object?

  They use a beam of light.
• What is the maximum magnification of light microscopes?

  2000x
• What are the advantages of using a light microscope?

  • Relatively cheap
  • Can be used anywhere
  • Can magnify live specimens
• How do electron microscopes form an image of a specimen?

  They use a beam of electrons.
• What is the maximum magnification of electron microscopes?

  200,000 times
• What are the disadvantages of using an electron microscope?

  • Large
  • Very expensive
  • Must be kept in special rooms
• What is resolution in microscopy?

  The ability to distinguish between two separate points.
• What is the average size of an animal cell?

  10-30 micrometres long.
• What is the average size of a plant cell?

  10-100 micrometres long.
• What are eukaryotes?

  Cells that have a nucleus, cell membrane, and cytoplasm, such as plant and animal cells.
• What is a prokaryote?

  A single-celled organism made up of a prokaryotic cell, smaller and simpler than eukaryotic cells.
• What are the adaptations of nerve cells?

  • Axon that carries nerve impulses
  • Synapse to pass electrical impulses
• What are the adaptations of muscle cells?

  • Many mitochondria for energy
  • Glycogen for cellular respiration
• What are the adaptations of sperm cells?

  • Loads of mitochondria for tail movement
  • Acrosome with digestive enzymes
  • Large nucleus with genetic information
• What are the adaptations of root hair cells?

  • Large permanent vacuole for water movement
  • Mitochondria for active transport energy
• What are the adaptations of photosynthetic cells?

  • Positioned in layers for light intake
  • Large permanent vacuole for rigidity
• What are the adaptations of xylem cells?

  • Spirals and rings of lignin for strength
• What are the adaptations of phloem cells?

  • Cytoplasm removed for sugar movement
  • Companion cells for support
• What is diffusion?

  The movement of particles from high to low concentration.
• What is osmosis?

  The movement of water particles from a dilute to a concentrated solution across a membrane.
• What is a dilute solution?

  High concentration of water and low concentration of sugar.
• What is a concentrated solution?

  Low concentration of water and high concentration of sugar.
• What is an isotonic solution?

  When the concentration of solutes outside is the same as inside.
• What is a hypertonic solution?

  When the concentration of solutes outside is higher than inside.
• What is a hypotonic solution?

  When the concentration of solutes outside is lower than inside.
• What may happen to a cell in a hypotonic solution?

  Water will move in, and the cell may swell and burst.
• What may happen to a cell in a hypertonic solution?

  Water will move out, and the cell may shrivel and die.
• What is active transport?

  The movement of particles from low to high concentration using energy.
• What are the adaptations for exchanging materials?

  • Thin membrane for short diffusion path
  • Efficient blood supply for steep concentration gradient
  • Ventilation for steep concentration gradient
• What are additional adaptations of nerve cells?

  • Lots of dendrites for connections
• What are additional adaptations of muscle cells?

  • Special proteins that slide to contract
• What are additional adaptations of sperm cells?

  • Long tail for movement
• What are additional adaptations of root hair cells?

  • Large surface area for absorption
• What are additional adaptations of photosynthetic cells?

  • Contain many chloroplasts for sunlight absorption
• What are additional adaptations of xylem cells?

  • Form long hollow tubes for water and mineral flow
• How do light microscopes form an image of an object?

  They use a beam of light.
• What are additional adaptations of phloem cells?

  • Cell wall has holes like a sieve for sugar movement
• What is the maximum magnification of light microscopes?

  2000x
• What are additional adaptations of phloem cells?

  • Large surface area for efficient transport
• What are the advantages of using a light microscope?

  • Relatively cheap
  • Can be used anywhere
  • Can magnify live specimens