B4- Bioenergetics

• What is the overall equation for photosynthesis?


  6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• What are the factors limiting photosynthesis?


  • Right daylight intensity
  • Mineral deficient soil
  • Not enough chlorophyll
  • Warm and bright (no CO₂)
  • Winter (low beamed)
• What factors affect the rate of photosynthesis?


  • Chlorophyll concentration
  • Temperature
  • Light intensity
  • Carbon dioxide concentration
• Where does photosynthesis take place?


  In chloroplasts, found in plants and algae
• What is chlorophyll and its role in photosynthesis?


  Chlorophyll is a chemical found in chloroplasts that traps sunlight
• What type of reaction is photosynthesis?


  It is an endothermic reaction that requires energy (sunlight)
• What are the optimum conditions for photosynthesis?


  • High chlorophyll concentration
  • High temperature (up to 45°C or enzymes will denature)
  • High light intensity (up to a certain point)
  • High carbon dioxide concentration (up to a certain point)
• Why is understanding water limiting factors important for plant production in greenhouses?


  Farmers must evaluate the balance between the costs of lighting and heating, and the rate of photosynthesis
• What are the products of photosynthesis?


  Oxygen and glucose
• How can glucose produced in photosynthesis be utilized by plants?


  • Converted into proteins (for cell growth and repair)
  • Converted into cellulose (to strengthen cell walls)
  • Stored as starch (insoluble, stored in seeds)
  • Converted into fats and oils (stored in seeds)
• What is the purpose of testing the rate of photosynthesis using an aquatic plant like pondweed?


  To investigate the effect of light intensity on the rate of photosynthesis
• What are the variables in the experiment to test the rate of photosynthesis?


  • Independent variable: Light intensity
  • Dependent variable: Number of bubbles produced
• What is aerobic respiration?


  Aerobic respiration is the process of breaking down glucose with oxygen
• What is anaerobic respiration and how does it differ from aerobic respiration?


  Anaerobic respiration occurs without oxygen and releases much less energy than aerobic respiration
• What is the product of anaerobic respiration in yeast cells?


  Glucose is converted into ethanol and carbon dioxide
• What happens during anaerobic respiration in animals?


  Glucose is converted into lactic acid when not enough oxygen reaches the muscles
• What is oxygen debt?

  Oxygen debt is the extra oxygen needed after exercise to break down lactic acid
• What physiological changes occur during exercise to meet increased energy demands?


  • Increase in breathing rate (increases gas exchange)
  • Increase in breath volume (more oxygen taken in)
  • Increase in heart rate (delivers more blood containing glucose and oxygen to muscles)
  • Dilation of blood vessels (ensures more blood reaches the muscles)
• What can cause muscle pain and fatigue during exercise?

  Build-up of lactic acid can cause muscle pain and fatigue
• What is photosynthesis?

  The process by which plants make glucose
• What type of reaction is photosynthesis?

  It is an endothermic reaction
• What is the equation for photosynthesis?

  Carbon dioxide + water → glucose + oxygen

  
• What is the chemical symbol for carbon dioxide?

  CO​2
• What is the chemical symbol for water?

  H​2​O
• What is the chemical symbol for oxygen?

  O​2
• What is the chemical formula for glucose?

  C​6​H​12​O​6
• What factors affect the rate of photosynthesis?

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll

  
• How does temperature affect the rate of photosynthesis?

  It increases until enzymes denature
• How does light intensity affect the rate of photosynthesis?

  Higher light intensity increases the rate
• How does carbon dioxide concentration affect photosynthesis?

  Higher concentration increases the rate

  
• What role does chlorophyll play in photosynthesis?

  It converts light energy to food
• How can the rate of photosynthesis be measured experimentally?

  By measuring oxygen production in plants
• Describe the experimental setup to measure photosynthesis rate.

  • Pondweed in a test tube with water
  • Sealed with a bung
  • Capillary tube attached to a syringe
  • Lamp at a measured distance
  • Measure oxygen bubble movement
• What is a limiting factor in photosynthesis?

  An environmental condition restricting the rate
• How can a graph show limiting factors in photosynthesis?

  By leveling off at certain factor levels
• What does it mean if a graph has two lines representing limiting factors?

  Two experiments with different conditions
• How is light intensity measured in experiments?

  In lux
• What is the inverse square law in relation to light intensity?

  Light intensity is inversely proportional to distance squared
• If a lamp is 2 meters away, what is the light intensity?

  It is a quarter of its original value
• What are the uses of glucose from photosynthesis?

  1. For respiration
  2. Converted to insoluble starch for storage
  3. To produce fat or oil for storage
  4. To produce cellulose for cell walls
  5. Combined with nitrates to form amino acids