GSCE Biology

• Plant cell


  • Organelle for aerobic respiration: mitochondria
  • Organelle for protein synthesis: ribosomes
  • Organelle for photosynthesis: chloroplasts
• Diffusion


  The spreading out of the particles of any gas or liquid from an area of high concentration to an area of lower concentration
• A human skin cell contains 46 chromosomes (23 pairs)
• A human gamete contains 23 chromosomes (single)
• Xylem


  Tubes that transport water up the stem of a plant
• Objective lens


  Purpose: To form and magnify an image of the specimen
• Osmosis


  The movement of water molecules from an area of high water concentration to an area of lower water concentration across a partially permeable membrane
• Substances transported into/out of animal cells by diffusion


  • Oxygen
  • Carbon dioxide
  • Amino acids
• Phloem


  Tubes that transport food around the plant
• Mitosis


  Produces new cells for growth and repair
• Cell division in mitosis

  1. Chromosomes line up and copies are pulled apart

  2. Nuclear membranes form around the chromosomes

  3. Cell splits into two identical 'daughter' cells
• Embryonic stem cells


  Undifferentiated cells found in the early embryo
• Medical conditions that could be treated with embryonic stem cells


  • Diabetes
  • Spinal injuries/paralysis
• Acrosome


  Contains enzymes that digest through the egg cell membrane, helping the sperm cell carry out its function
• Animal cell


  • Organelle for aerobic respiration: mitochondria
  • Organelle that controls movement of substances: cell membrane
  • Organelle that contains genetic information: nucleus
• Root hair cell


  Adapted to have a large surface area for rapid absorption of water and mineral ions from the soil
• Prokaryotic vs Eukaryotic cells

  Bacterial cells are smaller, lack a nucleus, mitochondria, and chloroplasts, but have plasmids with extra DNA
• Active transport vs Diffusion

  Active transport moves against a concentration gradient and requires energy, while diffusion moves down a concentration gradient
• Adaptations of exchange surfaces

  • Large surface area
  • Thin walls
  • Moist/good blood supply (animals)
• Some people object to embryonic stem cell research because they believe all embryos have the potential to become a human being
• A mouse has a bigger surface area to volume ratio than an elephant
• Adult stem cells


  Found in the bone marrow, can only turn into certain cell types
• Units


  • mm: millimetres
  • μm: micrometres
  • nm: nanometres
  • pm: picometres
• Magnification equation


  Magnification = image size / real size
• Advantages of cloning plants from meristem cells


  • Farmers can produce clones of a desired plant quickly and cheaply
  • Saves rare species from extinction
• 2500 in standard form is 2.5 x 10^3
• 0.003 in standard form is 3 x 10^-3
• 4,200,000 in standard form is 4.2 x 10^6
• 0.00000006 in standard form is 6 x 10^-8
• Active transport in plants


  To obtain mineral ions from the soil
• Active transport in animals


  To absorb nutrients (e.g. glucose) from the small intestine when they are at low concentrations
• Plant cell


  Typical plant cell structure
• Anaerobic respiration


  Occurs in the cytoplasm
• Protein synthesis


  Occurs in the ribosomes
• Photosynthesis


  Occurs in the chloroplasts
• Sperm cell


  • Acrosome helps digest through egg cell membrane
• Human skin cell


  Contains 46 chromosomes (23 pairs)
• Human gamete


  Contains 23 chromosomes (single)
• Preparing an uncontaminated bacterial culture


  1. Sterilise equipment

  2. Inoculate plate quickly

  3. Secure lid
• Sugar and water molecules