Growth and repair

• Growth


  Involving a permanent increase in cell number, size or mass
• Dry mass


  The mass of the body of an organism with all the water removed from it
• What is the most accurate way of measuring the growth of an organism?

  Dry mass

  Because all the water has been removed from the organism to leave just pure material
• What are the limitations of dry mass to measure the growth f an organism?

  • Removing water from an organism will kill it, so no further growth can be measured
  • There are ways around this but they are unethical, so scientists use less reliable indicators such as height and wet mass instead
• What do growth curves do?

  Show the growth throughout the life of an organism (the growth curves are very similar for most organisms)
• During what period does the largest amount of growth occur?

  During the development of the embryo
• Growth in plants

  • Mitosis continues throughout their life
  • Growth takes place in meristems
• Meristems


  Regions at the plant roots and shoots where the most mitosis and growth takes place
• Mitosis and age

  • In organisms that use mitosis, it does not stop, even when growth slows down or stops due to maturity
  • Mitosis continues until old age, where the number of dying cells outnumber the new cells being formed
• How can mitosis help damaged cells?

  If the skin is damaged, mitosis is triggered in nearby cells