Plants and photosynthesis

• What is the equation for photosynthesis ?

  Carbon dioxide + Water $\frac{sunlight}{chlorophyll}$> Glucose + Oxygen
• What are the products of photosynthesis used for?

  Growth, respiration and storage
• How do you test a leaf for starch?

  1. Boil the leaf in water
  2. Leave it in ethanol
  3. Dip the leaf
  4. Add iodine
• Why do you boil the leaf in a starch test?

  To kill it and stop reactions
• Why do you boil it in ethanol?

  To remove the chlorophyll
• Why do you dip the leaf in water?

  Soften the leaf
• Why do you add iodine?

  To test for starch
• What colour will the leaf turn if starch is present?

  Blue/black
• How do you work out the rate of photosynthesis?

  Count the number of bubbles released in a given time
• If you place a light close to the starch test, what will happen?

  More bubbles will be produced
• To show chlorophyll is needed for photosynthesis, what type of leaf do you use?

  A variegated leaf
• To show light is needed in photosynthesis, what do you do?

  Cover a section of the leaf with paper
• To show carbon dioxide is needed in photosynthesis, what do you do?

  Add sodium hydroxide to one section of leaves to remove the carbon dioxide, and the other section with water
• A leaf is when the site of photosynthesis is adapted for light absorption and gas exchange

  
• How are leaves adapted for light absorption?

  • Thin
  • Transparent cuticle
  • Lots of chloroplasts
• How are leaves adapted for gas exchange?

  • Stomata allow gases in and out of air spaces (CO2 and O2)
• What is the compensation point?

  Where the rate of respiration is equal to the rate of photosynthesis
• When there is a normal amount of carbon dioxide, photosynthesis = respiration
• When there is a low amount of carbon dioxide, photosynthesis > respiration
• When there is a high amount of carbon dioxide, there is only respiration
• What is a limiting factor?

  an environmental factor that limits the rate of photosynthesis due to that factor being present in too small an amount