End of year

• Photosynthesis


  The production of chemical compounds by a reaction using light
• Photosynthesis


  Plants use sunlight to produce their own food
• Chloroplasts

  • Where photosynthesis takes place
  • Contain the green pigment chlorophyll
• Photosynthesis equation


  Carbon dioxide + Water -> Glucose + Oxygen
• Glucose produced in photosynthesis is a type of sugar and is the food for the plant
• Oxygen produced in photosynthesis is useful for both plants and animals in respiration
• Root hair cells do not contain chloroplasts and cannot do photosynthesis as they are underground and cannot absorb sunlight
• Plant cells within a leaf

  • Have lots of chloroplasts
  • Chloroplasts contain a green pigment called chlorophyll
  • Photosynthesis takes place in the chloroplasts
• Leaves of a plant

  Specially adapted for photosynthesis
• Most leaves have chlorophyll across the whole of the leaf, they are therefore green all over
• Variegated leaves


  Leaves that do not have chlorophyll in certain parts, have white areas
• Photosynthesis

  1. Carbon dioxide reacts with water

  2. Produces glucose plus oxygen
• Chlorophyll and sunlight

  Required for photosynthesis to take place
• Glucose


  Soluble, can dissolve easily, cannot be stored
• Starch

  Insoluble, cannot dissolve, can be stored
• Glucose molecule


  Single unit<|>Can be connected to form starch
• Variegated leaf


  Starch expected to be found in green parts, not white parts
• Investigating starch in variegated leaf

  1. Place leaf in boiling water

  2. Place leaf in ethanol to remove chlorophyll

  3. Add iodine to leaf
• Iodine turns black where starch is present, stays orange where no starch
• Green parts of leaf turn black, white parts turn orange with iodine
• Leaves


  • Come in all different shapes and sizes
  • Primary role is photosynthesis
  • Majority are green due to chlorophyll
• Cross-section of a leaf


  Top of leaf<|>Bottom of leaf
• Parts of a leaf

  • Waxy cuticle
  • Epidermal layer
  • Xylem
  • Phloem
  • Stomata
  • Guard cells
  • Spongy layer
  • Palisade layer
• Waxy cuticle


  Waxy coating on top of leaf
• Epidermal layer


  Covers top and bottom of leaf
• Xylem


  Tubes that carry water
• Phloem


  Tubes that carry food (glucose)
• Stomata


  Small holes in bottom of leaf
• Guard cells


  Cells that control opening and closing of stomata
• Spongy layer


  Layer with gaps between cells
• Palisade layer


  Layer of tightly packed rectangular cells
• Photosynthesis equation

  Carbon dioxide + Water → Glucose + Oxygen
• Sunlight and chlorophyll are needed for photosynthesis but are not reactants or products
• Epidermal layer


  Thin to allow sunlight through
• Xylem


  Carries water to leaf
• Phloem


  Carries glucose (food) produced in photosynthesis
• Stomata


  Allow gases (CO2, O2) to diffuse in and out
• Guard cells


  Control opening and closing of stomata
• Spongy layer


  Allows gas diffusion
• Palisade layer


  Where most photosynthesis takes place<|>Contains chloroplasts with chlorophyll