Photosynthesis

Cards (16)

  • What is photosynthesis
    The process by which plants synthesise glucose using light energy from the sun. Light energy is converted into chemical energy
  • Where does photosynthesis take place
    Within chloroplasts in leaf palisade cells. They contain chlorophyll a pigment which absorbs light energy
  • Word equation for photosynthesis
    carbon dioxide +water -> glucose +oxygen
  • Symbol equation for photosynthesis
    6CO2 + 6H2O -> C6H12O6 + 6CO2
  • Is photosynthesis an endothermic or exothermic reaction and why
    Endothermic- energy is transferred from the environment to chloroplasts by light
  • How can you show that a plant give of oxygen during photosynthesis
    Using a water plant ,collect gas bubble produced photosynthesis. The gas will relict a glowing splint as it contains oxygen
  • Give examples of leaf adaptations which maximise the rate of photosynthesis
    • Broad leaves-maximise surface area
    • thin leaves -short diffusion distance
    • chlorophyll present -trap light energy
    • veins- transport water to leaves viz xylem, remove photosynthesis products via phloem
    • air spaces -allow CO2 to enter and O2 to leave
    • guard cells control opening of stomata for gaseous exchange and prevent water loss
  • What are the four main factors that affect the rate of photosynthesis
    • Temperature
    • light intensity
    • carbon dioxide concentration
    • amount of chlorophyll
  • How does temperature affect the rate of photosynthesis
    Increasing the temperature increases the rate of photosynthesis as the kinetic energy of particles is increased. The rate decreases past a certain temperature as enzymes become denatured
  • How does light intensity affect the rate of photosynthesis
    Increasing light intensity increases the rate of photosynthesis until another factor becomes limiting
  • How does carbon dioxide concentration affect the rate of photosynthesis
    Increasing the carbon dioxide concentration increases the rate of photosynthesis (until another factor becomes limiting) as CO2 is required to make glucose
  • How does the amount of chlorophyll affect the rate of photosynthesis
    Decreasing the amount of chlorophyll decreases the rate of photosynthesis as chlorophyl is required to absorb light energy
  • What is a limiting factor
    An environmental factor which can restrict the rate of photosynthesis
  • How can farmers use their knowledge of limiting factors to increase their profits
    They can control temperature, light intensity and CO2 concentration to achieve the fastest possible rate of photosynthesis leading to a greater yield
  • State the law which describes the relationship between the distance of a light source from a plant and light intensity
    Inverse square law - light intensity OC 1 / distance2
  • State 5 uses of the glucose produced during photosynthesis
    • Respiration
    • starch for storage
    • cellulose for strength
    • amino acid and protein synthesis (combined with nitrates)
    • lipids for energy storage in seeds