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• Cardiovascular disease

  A disease that is in your heart or blood vessels
• Coronary heart disease


  When the coronary arteries get blocked by fatty material
• Stents


  Tubes inserted into your arteries to help keep it open and allow more blood to flow through, reducing risks
• Plant Cells Are Organised Into Tissues And Organs
• Plant organs work together to make organs
• Plant organs are made of tissues
• Plant organs perform the various tasks that a plant needs to carry out to survive and grow
• Examples of plant organs

  • Roots
  • Stems
  • Leaves
• Epidermis covers the whole plant
• Palisade


  The part of the leaf where most photosynthesis happens
• Spongy mesophyll


  This is also in the leaf, and contains big air spaces to allow gases to shift in and out of cells
• Xylem and phloem


  They transport things like water, mineral ions and food around the plant (through the roots, stems and leaves)
• Meristem


  This is found at the growing tips of shoots and roots and is able to differentiate (change) into lots of different types of plant cell, allowing the plant to grow
• The Leaf is an Organ Made Up of Several Types of Tissue
• Tissues found in leaves


  • Epidermal
  • Mesophyll
  • Xylem
  • Phloem
• Leaves contain a waxy cuticle
• Starch


  Turns iodine from orange to black
• Protein


  Turns Biuret's reagent from blue to purple
• Sugars


  Turn Benedict's solution from blue to orange
• Lipids (fats)


  Turn cold ethanol cloudy
• The Leaf is an Organ Made Up of Several Types of Tissue
• Epidermal tissues


  • Covered with films, helps reduce water loss by transpiration
• Upper side of leaf


  • Transparent so light can pass through to the palisade layer
• Palisade layer


  • Has lots of chloroplasts where photosynthesis takes place, near the top of the leaf to get the most light
• Xylem and phloem


  • Form a network of vascular bundles, deliver water and nutrients, take away glucose produced by photosynthesis, help support the structure
• Leaf surfaces


  • Adapted for efficient gas exchange - epidermis has stomata that let CO2 diffuse directly into the leaf, opening and closing of stomata controlled by guard cells in response to environmental conditions, air spaces in spongy mesophyll tissue increase rate of gas diffusion