Bioenergetics

• What is photosynthesis?


  Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen.
• What type of reaction is photosynthesis?

  Endothermic.
• Why is photosynthesis an endothermic reaction?

  Energy is absorbed from the surroundings during photosynthesis.
• Where does photosynthesis take place in plants?

  The leaves.
• What is the green chemical which leaves contain?

  Chlorophyll.
• Chlorophyll can absorb light energy.
• What is the word equation for photosynthesis?

  Carbon dioxide + water -Light/chlorophyll glucose + oxygen.
• What is the chemical equation for photosynthesis?

  6CO2 + 6H2O -> C6H12O6 + 6O2
• what do plants need in order to carry out photosynthesis?

  Light.
• what happens to the rate of photosynthesis as we increase the light intensity?

  It increases.
• Why does the rate of photosynthesis increase along with light intensity?

  Because the plant now has more light energy to carry out photosynthesis therefore the reaction speeds up.
• Why is light intensity considered a limiting factor in photosynthesis?

  Because it means that photosynthesis was not as fast as it could have been because there was not enough light.
• What else can be limiting factors of photosynthesis?

  1. Light.
  2. co2
  3. Amount of chlorophyll.
  4. Temperature.
• Uses of glucose in photosynthesis.

  1. To release energy in respiration.
  2. Produce starch which can be converted back to glucose at night.
  3. Converted to fats and oils as another storage of energy.
  4. Produce amino acids to synthesise proteins.
• What do plants need to do to make amino acids from glucose?


  Absorb nitrate ions from the soil.
• When the concentration of carbon dioxide is increased, the rate of photosynthesis increases.
• What happens if we increase the temperature too much during photosynthesis?

  Enzymes in the leaf will start to denature causing the rate of photosynthesis to fall.
• Why do farmers use greenhouses?

  To increase the yield of crops they produce.
• What do farmers add to their greenhouses?

  1. Light.
  2. Heat.
  3. Extra co2.
• Greenhouses are very expensive so some gardeners use oil burners as they release both heat and co2 at the same time.
• What do we need energy for?

  1. Movement.
  2. Keep warm.
  3. Chemical reactions to build larger molecules..
• What is the energy we need supplied from?

  Cellular respiration.
• What type of reaction is respiration?

  Exothermic.
• Why is respiration an exothermic reaction?

  Because it releases energy.
• What is the word equation for aerobic respiration?


  Glucose + Oxygen -> Carbon Dioxide + Water + Energy
• Aerobic respiration releases a great deal of energy.
• Why does aerobic respiration release a great deal of energy?

  Because the glucose molecule has been fully oxidised.
• What is the chemical equation for respiration?


  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• Aerobic respiration happens in the presence of oxygen.
• Anaerobic respiration occurs in the absence of oxygen.
• What is the word equation for anaerobic respiration?

  glucose -> lactic acid + energy.
• Anaerobic respiration releases much less energy than aerobic respiration.
• Why does anaerobic respiration release less energy than aerobic respiration?

  Because the oxidation of glucose is incomplete.
• What is the word equation for anaerobic respiration in plants?

  Glucose → Ethanol + Carbon Dioxide + Energy
• What is anaerobic respiration in yeast called?

  Fermentation.
• What do we use fermentation for?

  To make alcholic drinks such as beer.
• Uses of yeast.

  1. To make bread.
• During exercise the body needs a great deal of energy for muscle contraction.
• What happens during exercise to provide extra oxygen?

  Breathing rate and volume increase.
• Why does the heart rate increase during exercise?

  To pump more oxygenated blood around the body.