b5

b5

1. how do organisms develop?

   • cell specialisation
     • start as zygotes
       • fertilised egg cell
     • make new cells through mitosis
       • this creates an embryo
     • cells change during mitosis to adapt to jobs
       • differentiated
     • red and white blood cells
       • red carries oxygen
         • surface area allows for efficient absorption
       • white is important for the immune system
         • fight pathogens
           • engulf them
           • produce antibodies
             • requires a lot of energy
   • how cells differentiate
     • only carries out jobs it is specialised to do
     • genes in the dna are turned on and off
     • dna
   • cell adaptations
     • unicellular
     • multicellular
     • specialised jobs
     • adapted to different fucntions
     • tissue - group of cells
     • organ is made up of tissues

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4. stem cells

   • fertilisation
     • sex cells
       • sperm and eggs
       • fertilisation
       • haploid
     • fertilised sex cell is a zygote
     • turns into embryo
   • what are stem cells?
     • embryonic stem cells
       • before differentiation
     • adult stem cells
       • not differentiated
       • can be differentiated
   • the importance of stem cells
     • give rise to the entire body
     • can reproduce themselves
       • cell division
     • research
       • treatments

5. stem cells in plants

   • plant cells
     • palisade cells
       • top of leaves
         • get light
       • full of chloroplasts
     • xylem cells
       • carry water and mineral salts
       • form together to make long tubes
         • xylem tissue
     • phloem cells
   • cell division in plants
     • differentiated cells cannot divide anymore
     • cells in meristems can divide
     • divide by mitosis
       • become two identical daughter cells
         • separated by a cell plate that later becomes a cell wall
         • can either divide again or differentiate
   • cell specialization in plants
     • meristems
       • found in the tips of shoots, roots, buds and flowering parts
     • plants constantly grow

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7. mitosis

8. plant clones

   • plants from cuttings
     • end of the shoot in moist earth
       • roots grow and a plant does too
     • exact copy/clone
   • tissue culture
     • saves time and money
     • take bits of plant tissue
       • from the root or stem
       • treat with enzymes to separate the cells
       • placed individually on nutrient jelly
         • contains plant hormones
   • tissue culture using meristem cells
     • auxins
       • chemical messages
         • coordinate growth
     • auxin effects all cells
       • elongates cells

9. plant development

   • how lights affect plants

10. meiosis