Year 10 biology

• Eukaryotic cells


  Include animal and plant cells
• Structures of an animal cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Differences between plant and animal cells

  • Chloroplasts
  • Permanent vacuole
  • Cell wall
• Similarities between plant and animal cells: both have nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
• Prokaryotic cells


  Do not have a true nucleus, have a single strand of DNA that floats in the cytoplasm, contain plasmids which are small rings of DNA, are much smaller than eukaryotic cells
• Specialized cells


  Cells that have differentiated to become specialized to do a particular function or role
• Palisade cells


  • Found at the top of the leaf, absorb light for photosynthesis, have lots of chloroplasts, have a regular shape
• Xylem cells


  • Movement of water, made of dead cells, waterproof, go from root to leaf
• Phloem cells


  • Move sugars and amino acids, made of living cells, require energy from respiration
• Root hair cells


  • Have a large surface area, have very thin walls, allow water and mineral ions to be absorbed
• Sperm cells


  • Fertilize egg cell, have a tail that can move due to mitochondria, have enzymes in the head to break down egg surface
• Muscle cells


  • Contract to move the body, have filaments that slide over each other, need lots of mitochondria and glucose for energy
• Nerve cells


  • Very long and thin, insulated to carry electrical impulses, connect to each other
• There is a required practical to observe animal and plant cells
• Adding up marginal utility for each unit gives total utility
• Light microscope


  Microscope that uses light to magnify and observe cells and organisms
• Light microscope


  • Eyepiece
  • Objective lenses (can rotate to increase magnification)
  • Stage
  • Stage clips
  • Microscope slide
  • Light
  • Focusing wheel (fine or coarse)
• Magnification


  Making the image larger than the actual size
• Resolution


  The degree of detail, how well the microscope distinguishes between two close points
• Magnification increases


  Image becomes much bigger than actual size
• Resolution is high


  Image is clearer and more detailed
• Resolution is low


  Image is less clear and less detailed, tends to be blurry
• Light microscope


  • Can view living cells/organisms
  • Generally lower magnification and resolution than electron microscopes
• Electron microscope


  • Uses electrons instead of light
  • Specimens must be dead due to vacuum
  • Much higher magnification and resolution than light microscopes
  • Very expensive and require extensive training
• Advantages of light microscope

  • Can study living cells
  • Cheap
  • Portable
• Disadvantages of light microscope

  • Lower magnification
  • Lower resolution
• Advantages of electron microscope

  • Higher magnification
  • Higher resolution
• Disadvantages of electron microscope

  • Cannot study living cells
  • Very expensive
  • Not portable
  • Require extensive training
• Human eye


  Can see large cells (50-100 micrometers)
• Light microscope


  Maximum resolution of 200 nanometers, maximum magnification of 2000x
• Electron microscope


  Maximum resolution of 50 picometers, can study small subcellular structures
• Calculating magnification


  1. Measure image size

  2. Divide by actual size
• To convert micrometers to millimeters, divide by 1000
• To convert millimeters to micrometers, multiply by 1000
• Standard form is used for very small or very large measurements
• Exam checkpoint 1


  • Image size: 112 mm

  Actual size: 280 micrometers

  Magnification = 112,000 micrometers / 280 micrometers = 400x
• Exam checkpoint 2


  • Scale bar: 0.1 mm

  Measured scale bar: 40 mm

  Magnification = 40 mm / 0.1 mm = 400x
• Pathogens


  Microbes or microorganisms that cause infectious disease
• Types of pathogens


  • Viruses
  • Bacteria
  • Protists
  • Fungi
• Viruses


  • Not cells, much smaller than bacteria, invade cells and replicate, burst out of cells releasing new viruses