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• Unicellular organisms


  Single cell must perform all functions to stay alive
• Multicellular organisms


  Each cell performs a special role, which can give rise to different levels of function
• Levels of function in multicellular organisms

  • Tissue level (cells of one type organised to perform specific function)
  • Organ level (tissues of different types can be put into organs that perform a specific function)
  • Cellular level
  • System level (different organs that perform major life supporting functions)
• Parts of a system that work together to carry out a specific function

  • Specialised cells
  • Tissues
  • Organs
• Plant systems, organs and tissues

  • Shoot system
  • Root system
• Organs within the shoot system

  • Stems
  • Leaves
  • Reproductive organs (flowers and fruits)
• Organs within the root system

  • Root
  • Lateral roots
  • Root hairs
• Meristematic tissue


  Cells that undergo cell division and are found in the tips of roots and shoots, responsible for increase in length of the stems and roots (apical meristems) and along the length of stems and roots, responsible for increase in girth (lateral meristems)
• Permanent tissue


  Cells that no longer divide, including dermal, ground and vascular tissues
• Dermal tissues


  • Epidermal tissue - flattened cells forming the outer layer of stems and leaves
• Ground tissues


  • Parenchyma - living thin-walled cells, site of photosynthesis and storage
  • Collenchyma - elongated living cells with thick but flexible primary cell walls, provide support
  • Sclerenchyma - cells with thickened secondary walls, provide rigidity and strength
• Vascular tissues


  • Xylem - transports water and dissolved minerals
  • Phloem - transports sugars and other organic compounds
• Xylem


  Composed of hollow dead cells with thick lignin-hardened walls that transport water and dissolved minerals
• Phloem


  Composed of living cells that transport sugars and other organic compounds
• Tracheids


  Dead cells that taper at the ends and connect to form a continuous column, have thickened cell walls for structural support
• Vessel elements


  Dead cells that form a continuous wide pipe-like structure, have thick and strong secondary walls, have perforation plates at junctions
• Plants only use 5% of water taken up by the roots, the remaining passes straight up and back out into the atmosphere through transpiration
• Transpiration


  The process of water loss from plants as water vapour
• Factors affecting rate of transpiration

  High temperature, wind and water availability increase transpiration, high humidity decreases it
• Water movement in plants

  1. Absorbed by root hairs from soil

  2. Moves into xylem tissue

  3. Transported through the plant
• Stomata


  Small holes located mainly in the lower epidermis of leaves where water vapour diffuses from leaves to air
• Guard cells


  Cells that surround the stomata and cause them to open and close
• Stomata opening and closing

  In sunlight, guard cells take up water and swell which forces them to open, in the dark they lose water and shrink which closes the stomata
• Cohesion and adhesion


  Allow water to move up the xylem without breaking apart, as water molecules stick together and to the xylem walls
• Levels of biological organisation

  • Cellular
  • Tissue
  • Organ
  • System
• Cellular level


  Most simple, with one or more cells working together, e.g. sponges
• Tissue level


  Two cell layers working together, e.g. jellyfish, corals
• Organ level


  Three cell layers working together, e.g. flatworms
• System level


  Different organs working together to perform major life functions, e.g. mammals
• Mammalian tissue types


  • Epithelial
  • Muscle
  • Connective
  • Nervous
• Tissues need a delivery system to be efficient, as cells in the middle of the tissue need to receive materials and remove waste
• Organ systems in animals do not operate in isolation, they rely on each other to function efficiently
• What does xylem transport in the plant?
• What process does water across a membrane?

  via osmosis
• What part of a plant undergoes photosynthesis?

  Leaves
• Xylem tissue is it living or non living?

  non-living
• What is the process of water loss called?

  transpiration
• Where does water leave from?

  stomata
• What 4 tissues are our body made from?

  nervous, connective, muscle and epidermal
• What do enzymes do in our digestive system?

  enzymes speed up the reaction of the digestion system