Stem Cells

• What is a stem cell?

  undifferentiated cell that can differentiate into one or more specialised cell types
• What are adult stem cells?

  stem cells from adults that can only differentiate into certain specialised cells
• Where can adult stem cells be found?

  bone marrow
• What are embryonic stem cells?

  stem cells from embryos that can differentiate into any specialised cell
• Where are embryonic stem cells found?

  early human embryos (usually from spare embryos from fertility clinics)
• Give one advantage of using adult stem cells.

  fewer ethical issues as obtained from adults who can consent to their use
• Give two disadvantages of using adult stem cells.

  • can take a long time for a suitable donor to be found

  • can only differentiate into some specialised cell types, so treat fewer diseases
• Give two advantages of using embryonic stem cells.

  • can differentiate into any specialised cell, so can be used to treat many diseases

  • easier to obtain as they are found in spare embryos from fertility clinics
• Give two disadvantages of using embryonic stem cells.

  • ethical issues surrounding their use, as every embryo is a potential life

  • potential risks involved with treatments, such as transfer of viral infections
• What do egg and sperm cells fuse to form?


  a Zygote
• What does the zygote divide many time to form?

  a ball of cells - embryo
• What are the inner layers of the embryo called?

  embryonic stem cells
• What do the layers of the cells in the embryo do?

  Differentiate into all the cells the body needs.
• When do we say cells have differentiated?

  when the stem cells change into all the different types of body cell (e.g. nerve cells or muscle cells)
• What can adult stem cells in the bone marrow change into?

  other types of cell (e.g. blood cells)
• What can human stem cells be used to treat? (3)

  • paralysis - differentiating into new nerve cells
  • macular degeneration in the eye
  • diabetes - producing cells sensitive to blood sugar & can produce insulin
• What are the benefits of cloning plant? (4)

  • rare plants saved from extinction
  • large populations of genetically identical plants can be produced for scientific research
  • large numbers of exotic plants can be produced for sale (horticulture)
  • plants can be produced with special features, such as resistance to disease (agriculture)