Biology AOS2 Unit 1 - Chp 5

• Levels of Structural Organization


  1. Cells

  2. Tissue

  3. Organ

  4. System

  5. Organism
• Tissue Types


  epithelial, connective, muscle, nervous
• Muscle tissues


  striated, cardiac, smooth
• Nervous tissues


  bipolar interneuron, unipolar sensory neuron, multipolar motor neuron
• Epithelial tissues


  form a protective covering for all of the internal and external surfaces of the body
• Connective tissues


  support and connect organs and other body tissues; cartilage, dermis, ligaments, tendons.
• Organs


  When two or more types of tissue work together to perform one or more specific functions.
• Systems


  groups of organs working together to perform complex functions
• Major systems in the body

  respiratory, immune, nervous, circulatory, lymphatic systems
• dicots


  Flowering plant whose embryos have 2 cotyledons.
• Phloem


  Living vascular tissue that carries sugar and organic substances throughout a plant
• What is xylem?


  Vascular tissue in plants
• What does xylem do?

  Carries water and nutrients upward in plants
• Vascular cylinder


  central region of a root that includes the vascular tissue-xylem and phloem
• Stile is....


  another word for the vascular cylinder
• Cell walls of xylem is...


  the cell walls are thick with lignin, which is deposited whilst the cell is alive. Lignin strengthens the cell wall but ultimately kills the contents of the cell.
• Vascular bundles


  plant stem structure that contains xylem and phloem tissue
• Vascular bundles in the dicot stem


  in the stem of a dicot, xylem and phloem are arranged in vascular bundles situated in a circle around the cambium layer.
• Cambium layer


  a layer of dividing cells between the phloem and xylem responsible for lateral (sideways) growth
• Sclerenchyma


  thick, fibrous cells, there to give the plant support.
• Vascular tissues in the dicot leaf


  Xylem and phloem are also found in vascular bundles in the leaf. Water and nutrients also move from one mesophyll cell to another.
• Mesophyll


  the photosynthetic cells in a leaf
• 2 main kinds of mesophyll

  palisade, spongy
• palisade mesophyll


  photosynthetic tissue below the epidermis in a leaf- where most of the photosynthesis occurs - contains chloroplasts
• spongy mesophyll


  Loose tissue beneath the palisade layer of a leaf - allows interchange of gases needed for photosynthesis
• The transpiration stream


  Movement of water up through the xylem from the roots to the leaves, driven by four main forces
• 4 main forces of the transpiration stream

  osmosis in the roots, adhesion between water and the xylem walls, transpiration that creates negative pressure, and cohesion between water molecules.
• Adhesion


  force of attraction between different kinds of molecules
• adhesion in vascular system


  water is attracted to other molecules as it moves across surfaces, and in a plant water moves by adhesion up the xylem and through cellulose cell walls, sticking to the organic tissues of plants.
• cohesion


  Attraction between molecules of the same substance
• cohesion in vascular system

  water molecules are attracted to each other (because they are polar). So, if water is being pulled up the xylem, other water will follow because its attracted to the water that's been pulled up ahead of it.
• What are stomata?


  Stomata are tiny pores in the epidermis of leaves.
• What is the function of stomata?


  Stomata allow carbon dioxide into the leaf for photosynthesis and allow oxygen to diffuse out.
• How does water vapor leave the leaves?

  Water vapor leaves the leaves through the stomata, which can open and close.
• What is transpiration?


  The process by which water is lost from the stomata of leaves.
• How does transpiration affect the xylem vessels?


  Transpiration creates a negative pressure at the top of the xylem vessel, drawing water up the vessel to replace the water being lost by transpiration.
• Guard cells


  control the opening and closing of a stoma
• How do guard cells open and close?


  When the guard cell contains fluid under high pressure, it becomes turgid and the central space opens up. When the guard cell loses fluid, it becomes flaccid and the space closes.
• Translocation of sugars in plants


  The sugars produced in the sources, such as leaves, must be delivered to growing parts of the plant. These sugars are transported through the plant via the phloem in a process called translocation.
• Where is sugar produced in plants?

  Sugar is produced by photosynthesis in the mesophyll cells of leaves.