plant structure

• xylem: transports water and mineral ions from the roots to the leaves

  • made of dead cells
  • cell wall made of lignin
  • no cytoplasm
  • thick cell wall
  • flow is upward (oneway)
  • no end wall between cells
• phloem: transports sucrose and amino acids (translocation) from the leaves and other parts of the plant

  • cell wall made of cellulose
  • permeable cell wall
  • transports food
  • thin cell wall
  • flow is up and down
  • living cells
  • contains cytoplasm
• Plant minerals:

  • nitrogen - nitrates used to make protein for new cell growth, poor growth, slowly photosynthesis and yellow leaves
  • phosphorus - phosphates used for energy transfer, reproduction, nutrient movement, photosynthesis, poor root growth, purple leaves, small acid tasting fruit
  • potassium - potassium compounds needed in cytoplasm so reactions like respiration and photosynthesis can occur, yellow leaves, slower photosynthesis, poor growth
• Stomata: controls gas exchange in leaf, each stoma can be open or closed depending on how turgid it's guard cells are

  • it can open and close to control gas exchange and regulate transpiration
  • stomata closes at night when no photosynthesis occurs so no carbon dioxide is needed

  
• • cuticle - waxy, waterproof layer which reduces water loss, transparent allowing light to enter
  • palisade layer - packed with chloroplasts
  • vein - contains xylem and phloem
  • guard cells - open and close the stomata , allowing carbon dioxide to enter or preventing water loss

  
• Leaf needs:

  • a way to transport water to leaf and glucose to other parts
  • a way to exchange carbon dioxide and oxygen
  • ability to absorb light energy efficiently
  • it has a large surface area for maximum light absorption
  • thin - short distance for carbon dioxide to diffuse into leaf cells
  • cuticle - waxy waterproof laer reduces water loss and transparent to allow light through
• light absorption:

  Light absorption happens in the palisade mesophyll tissue of the leaf. Palisade cells are column-shaped and packed with many chloroplasts. They are arranged closely together so that a lot of light energy can be absorbed.

  
• Vascular bundles: xylem and phloem are found in groups called vascular bundles, position of bundles varies in different parts of plant, In a leaf, phloem found closer to the lower surface

  • root - Xylem vessels tough and strong, vascular bundles in center of root to resist forces that could pull the plant out of ground.
  • stem - has to resist compression and bending forces caused by plant’s weight and wind, vascular bundles arranged near edge of stem, with phloem on outside and xylem on inside.