GCSE biology Photosynthesis

• Why do plants need photosynthesis?

  To make their own food
• What is the word equation for photosynthesis?


  Carbon dioxide + water = glucose + oxygen
• What is the balanced symbol equation for photosynthesis?

  6CO2 + 6H2O = C6H12O6 + 6O2
• Factors that effect the rate of photosynthesis

  Temperature, carbon dioxide concentration, light intensity, amount of chlorophyll
• How does temperature effect the rate of photosynthesis?

  Temperature increases the rate but if it gets too high enzymes denature
• How does the carbon dioxide concentration effect the rate of photosynthesis?

  The rate increases until the concentration becomes very high and then it doesnt increase further
• What is a limiting factor?


  A factor that stops the rate of photosynthesis from increasing
• When do enzymes become denatured?

  At high temperatures
• Stages in starch test experiment

  Wash leaf, boil it in water, cover with iodine solution, boil leaf in ethanol
• What colour does the leaf turn if starch is present?

  Blue/black
• What colour would the leaf turn if starch wasn't present?

  Orange/brown
• What is an independent variable?


  the variable that is changed
• What is a dependent variable?


  variable that is measured
• How does light intensity affect the rate of photosynthesis?

  the more intense the light is, the oxygen rate increases and more photosynthesis takes place
• How does the amount of chlorophyll effect the rate of photosynthesis?


  the higher the amount of chlorophyll, the more the plant will be able to take in light energy for photsynthesis
• How do plants make glucose?

  Plants use the energy of the sun to change water and carbon dioxide into a sugar called glucose.
• What do plants use glucose for?

  Glucose is used by plants for energy and to make other substances like cellulose and starch.
• What is the economic significance of photosynthesis?

  It ensures that all living species have access to oxygen in the atmosphere. It keeps the ecosystem's oxygen and carbon dioxide levels in check. Plants are the source of fossil fuels.
• How do plants purify the air?

  By taking in carbon dioxide and giving off oxygen