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Plants (Plant Meristems (Different meristems produce primary and secondary…

- - - - Derivative cells can diverge in structure and function even though they share a genome because of gene expression
  - - - production of a flower by shoot apical meristem stops the primary growth of the shoot
        
        annuals: complete life cycle in a year
        
        biennials: 2 growing seasons to complete their life cycle
        
        perennials: live many years
- - - - leaves develop from leaf primordia that grow on the side of a shoot's apical meristem
        
        apical dominance is the dormancy of auxillary buds from inhibition by an active apical bud
        
        growing auxillary bud gives rise to a lateral shoot with its own apical bud, leaves, and auxillary buds
      - intercalary meristems let damaged leaves rapidly regrow
  - - - vascular cambium adds wood and secondary phloem, increasing vascular flow and support
        
        as cells divide they increase the circumference of vascular cambium and add secondary xylem
        
        initial cells produced by vascular cambium produce vascular rays that connect secondary xylem and phloem
        
        as secondary growth continues, layers o wood accumulate, consisting of tracheids, vessel elements, and fibers
      - cork cambium produces waxy cells that protect stem from water loss and invasion
        
        contains suberin, a hydrophobic substance, that makes the periderm impermeable to water and gases
- - - - consists of alternating nodes and internodes.
      - apical bud: developing leaves and compact nodes and internodes in young shoots
    - - tall plants have a taproot system consisting of a taproot that prevents plant from falling over and lateral roots that absorb water and nutrients.
        
        smaller, shorter plants have a fibrous root system, or a net of thin, spread out roots that prevents soil erosion
      - root hairs: extensions of root epidermal cells that increase root surface area
    - - Vascular tissue system transports materials through plants and provides mechanical support
        
        xylem: brings water and dissolved minerals up from roots to shoots
        
        phloem: transports sugars (products of photosynthesis) from where they're made (leaves) to where they're needed
      - ground tissue system contains specialized cells for photosnythesis, short distance transportation, storage, or support
        
        cortex: ground tissue external to vascular tissue
        
        pith: ground tissue in vascular tissue
      - Dermal systems contain dermal tissue that serves as a protective covering
        
        epidermis in non-woody plants
        
        cuticle in leaves and stems prevents water loss
        
        periderm in woody plants replaces the epidermis in older stem and root regions
    - - parenchyma cells have thin, flexible primary walls and lack secondary walls. Synthesize and store products.
      - collenchyma cells support young parts of plant shoots. Provide support without restraining growth.
      - Schlerenchyma cells are more rigid than collenchyma cells because of ligmin polymers. Are schlerids and ribers that provide structure. May die and stay as skeleton of support.
      - water-conducting cells of xylem are fracheids and vessel elements that die at functional maturity.
      - sugar-conducting cells of phloem are sieve-tube elements that transport fluids between cells