photosynthesis

• what is photsynthesis?

  when plants use carbon dioxide and water to make glucose and oxygen
• where does photosynthesis take place?


  within the chloroplasts in leaf palisade cells

  • needs light energy to happen
• whats the symbol equation for photosynthesis?

  6CO2 + 6H2O + light energy -> C6H12O6 + 6O2
• whats the word equation for photosynthesis?


  carbon dioxide + water -> glucose + oxygen
• is photosynthesis endothermic or exothermic?


  endothermic because energy is transferred from the environment to chloroplasts by light
• how can you show that a plant gives off oxygen during photosynthesis?


  • using a water plant
  • collect gas bubbles produced during photosynthesis
  • the gas will relight a glowing splint as it contains oxygen
• what is the point of the photosynthesis practical?


  to find out what happens to the rate of photosynthesis when we change the light intensity
• what are the results after the photosynthesis practical?


  the closer the lamp, the quicker the bubbles are produced

  • so higher rate of photosynthesis
• give examples of leaf adaptations which maximise the rate of photosynthesis


  • borad leaves - maximises surface area
  • thin leaves - short diffusion distance
  • chlorophyll present- traps light energy
  • guard cells - controls 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?


  increases the rate of temperature increases the rate of photosynthesis
• how does light intensity affect the rate of photosynthesis?


  increasing the light intensity increases the rate of photosynthesis
• how does carbon dioxide concentration affect the rate of photosynthesis?


  increasing the carbon dioxide increases the rate of photosynthesis as carbon dioxide 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 chlorophyll is required to absorb light energy
• what is a limiting factor?


  an environmental factor which can restrict the rate if photosynthesis like light intensity
• explain how you can calculate the rate of photosynthesis by measuring oxygen production.


  • set up bubble potometer apparatus
  • pondweed in a sealed tube of water, attached to a capillary tube and a gas syringe
  • oxygen gas produced causes the bubble in the capillary tube to move
  • the distance moved by the bubble is used to calculate the volume of oxygen produced
• why could the results of calculating the rate of photosynthesis by measuring oxygen production may be inaccurate?


  • difficult to count very small bubbles
  • each bubble counts as '1' no matter how big it is
• why should you leave the plant for a few minutes before starting to count bubbles?

  • it takes time for the plant to adjust to the light/ temperarture
  • photosynthesis to reach the correct rate
• heat from a lamp is a source of error, how could you avoid this?


  place a glass screen infront of the beaker so that light gets through but heat doesn't
• how can farmers use their knowledge of limiting factors to increase their profits?


  they can control..

  • temperature
  • light intensity
  • carbon dioxide concentration

  to achieve the fastest possible rate of photosunthesis leading to a greater yield