Bioenergetics

• What type of reaction is photosynthesis?

  Photosynthesis is an endothermic reaction.
• What is the equation for photosynthesis?

  6CO₂ + 6H₂O ➡️ C₆H₁₂O₆ + 6O₂
• What are the limiting factors that affect the rate of photosynthesis?

  • Light intensity
  • CO₂ concentration
  • Temperature
  • Amount of chlorophyll
• How does the amount of chlorophyll affect photosynthesis?

  A lack of chlorophyll can reduce the rate of photosynthesis.
• What happens to the rate of photosynthesis when there is not enough light?

  Not enough light slows down the rate of photosynthesis.
• What is the relationship between light intensity and the rate of photosynthesis?

  As light intensity increases, the rate of photosynthesis increases up to a certain point.
• What happens to the rate of photosynthesis when CO₂ levels are insufficient?

  Not enough CO₂ slows down the rate of photosynthesis.
• What is the effect of temperature on the rate of photosynthesis?

  Temperature affects enzyme kinetics, which influences the rate of photosynthesis.
• At what temperature do enzymes needed for photosynthesis get damaged?

  About 45°C.
• What is the method to measure the effect of light intensity on the rate of photosynthesis using pondweed?

  1. Place a light source at a specific distance from pondweed.
  2. Allow pondweed to photosynthesize for a set time.
  3. Measure the length of the gas bubble in a capillary tube.
  4. Repeat with the light source at different distances.
• What is the independent variable in the pondweed experiment?

  The distance of light from pondweed (cm).
• What is the dependent variable in the pondweed experiment?

  The volume of oxygen produced.
• How can the effect of temperature be measured in the pondweed experiment?

  By placing the test tube of pondweed into a water bath at a set temperature.
• How can the effect of CO₂ be measured in the pondweed experiment?

  By dissolving a measured amount of sodium hydrogencarbonate in water.
• What does the inverse square law state regarding light intensity?

  Light intensity is inversely proportional to the square of the distance.
• What is the purpose of greenhouses in agriculture?

  Greenhouses help control environmental conditions for plant growth.
• How do greenhouses control temperature?

  They trap the sun's heat and may use heaters in winter.
• How do commercial farmers increase light intensity in greenhouses?

  By using artificial light after the sun goes down.
• How can CO₂ concentration be controlled in greenhouses?

  By using a CO₂ generator or a paraffin heater.
• What are the uses of glucose produced in photosynthesis?

  Glucose is used for respiration, stored as starch, converted to lipids, and used to produce cellulose and amino acids.
• What is respiration?

  Respiration is an exothermic reaction that occurs continuously in all living cells.
• What is the equation for aerobic respiration?

  glucose + oxygen ➡️ carbon dioxide + water + energy
• What happens during anaerobic respiration in muscles?

  It produces lactic acid when there is insufficient oxygen.
• What is the equation for anaerobic respiration in muscles?

  glucose ➡️ lactic acid
• What is fermentation in yeast?

  Fermentation is anaerobic respiration that produces ethanol and carbon dioxide.
• How does exercise affect respiration?

  Exercise increases respiration to supply more energy to muscles.
• What is oxygen debt?

  Oxygen debt is the extra oxygen needed to break down lactic acid after exercise.
• What happens to lactic acid after exercise?

  Lactic acid is transported to the liver to be converted back to glucose.
• What is metabolism?

  • The sum of all reactions in a cell or body.
  • Includes processes like:
  • Glucose to starch, glycogen, cellulose
  • Glycerol and fatty acids to lipids
  • Glucose and nitrate ions to amino acids
  • Respiration
  • Breakdown of excess amino acids to form urea