2: nutrients and water

• To grow and survive, plants need water and nutrients.
• Plants produce their own carbon source (glucose) through photosynthesis
• Plants need carbon dioxide
• Label this

  A) coniferous

  B) deciduous

  
• Root hairs increase surface area for enhanced absorption of water and nutrients.
• After entering the root, water can move through the apoplast (between cells), or symplast (through the cells).
• When water reaches the endodermis, water is re-directed to move via the symplast to control water uptake.
• The Casparian strip is located within the endodermis and is used to regulate water movement.
• Water molecules inside the xylem tracheids and vessel elements adhere to each other and creates an internal column of water by hydrogen bonding to each other and the walls of the xylem vessels.
• Water can move 15 meters per hour in a large tree.
• Transpiration is the movement of water out of the leaf cells via stomata, creating a water deficit or negative water potential inside a leaf, pulling the water up the xylem from the roots. Transpirational pull is the main force moving water up the plant.
• Stomata open to take up carbon dioxide and release oxygen during photosynthesis.
• Stomata are found in the epidermal layer of leaf cells and are typically found on the underside of leaves to avoid exposure to direct cells.
• Guard cells of the stomata regulate the stomatal opening size. The larger the opening, the more water loss.
• Stomata typically open when

  • lots of water
  • lots of sunlight
  • high potassium levels within

  They will close in opposite conditions.
• The adaptations of xerophytes (plants that live in the desert) include:

  • reduced leaf size and fleshy leaves
  • drying down during dry seasons and growing in rainy conditions
  • closing the stomata during the day and opening them at night
  • deeper stomata within the epidermis
  • thick waxy cuticles to retain water
  • fewer stomata
• Phloem is used to transport sugar produced in the leaves to other parts of the plants.
• Sugar is loaded into the phloem cells by sugar transporters, creating a high osmotic pressure drawing in water from the xylem and causing a build up of turgour pressure to force sugar down the plant.
• Turgour pressure makes the sugar solution move via bulk flow to be unloaded at the cells that need it
• Label the steps of phloem sugar loading and unloading

  A) loading of sugar

  B) uptake of sugar

  C) unloading of sugar

  D) water recycled

  
• Maple syrup is xylem sap that drips out of drilled holes in maple trees due to positive pressure flow.
• Macronutrients of plants include nitrogen, potassium, and phosphorous. Micronutrients include iron, manganese, and boron.
• Ion channels facilitate the transport of nutrients into cells.