B2 cells and control

• What are the stages of the cell cycle in order?

  Interphase, prophase, metaphase, anaphase, telophase, cytokinesis
• What are the stages of mitosis in order?

  Prophase, metaphase, anaphase, telophase
• interphase:when normal cell process take place as well as DNA replication
• mitosis produces 2 genetically indentical daughter diploid cells
• prophase is when the nuclear membrane breaks down,DNA unwinds and condenese into chromatids and spindle fibres becom visible
• metaphase is when chromatids line up along the centre of the cell and spindle fibres attach to chromatids at the centre
• anaphase is when chromosomes are split and chromatids are pulled to the edges by spindle fibres
• telophase is when a nuclear membrane forms around each set of chromosomes
• cytokensis is when he cytoplasm is split to create two separate, genetically identical diploid cells
• three reasons why mitosis is important in living things:Growth, repair of tissues/organs, asexual reproduction
• Give 2 advantages of embryonic stem cells

  Easy to extract from embryo, produce any type of cell
• Give a disadvantage of embryonic stem cells

  The embryo is destroyed when the cells are removed
• Give a risk involved with all sorts of stem cells

  They may not stop dividing and so could cause cancer
• Advantage of stem cell treatment

  Faulty cells are replaced with healthy cells
• Advantages of using adult stem cells

  • No embryo is destroyed
  • If taken from the person to be treated will not cause rejection by the body
• Disadvantage of adult stem cells

  Produce only a few types of cell
• Embryonic stem cells

  Come from embryos at a very early stage of division (8 cells)
• Adult stem cells

  Come from bone marrow
• Meristems


  Found in rapidly growing parts of a plant e.g. tips of roots and shoots
• Types of neurone in a reflex arc

  • Sensory
  • Relay
  • Motor
• Part of a neurone that insulates it

  Myelin sheath
• Part of a neurone that carries impulses towards the cell body

  Dendron
• Part of a neurone that carries impulses away from the cell body

  Axon
• Gap between 2 neurones

  Synapse
• How impulses travel across a synapse

  Neurotransmitters diffuse across the gap
• Pathogens have anti gens which trigger the production of antibodies by lymphocytes