Bioenergetics

• What is the process of photosynthesis?


  It is a chemical reaction that converts carbon dioxide and water into glucose and oxygen using light energy.
• Why is photosynthesis considered an endothermic reaction?


  Because it absorbs energy from light to power the reaction.
• Where does photosynthesis occur in plant cells?

  Inside chloroplasts.
• What are the word and balanced symbol equations for photosynthesis?

  • Word equation: carbon dioxide + water light glucose + oxygen
  • Balanced symbol equation: $6CO₂ +$$6H₂O \rightarrow C₆H₁₂O₆ +$$6O₂$
• What does the inverse square law describe?


  It describes how light intensity varies with distance from the source.
• How is light intensity related to distance according to the inverse square law?

  Light intensity is inversely proportional to the square of the distance from the source.
• If the light intensity is 1 unit at 25 cm, what is the light intensity at 0.25 m?

  16 arbitrary units.
• What is cellular respiration?

  It is a chemical reaction that releases energy from glucose in the mitochondria of cells.
• What are the two types of respiration?

  Aerobic (with oxygen) and anaerobic (without oxygen).
• What type of reaction is aerobic respiration?


  Exothermic.
• What are the word and balanced symbol equations for aerobic respiration?

  • Word equation: glucose + oxygen carbon dioxide + water + energy
  • Balanced symbol equation: $C₆H₁₂O₆ +$$6O₂ \rightarrow 6CO₂ +$$6H₂O +$$\text{energy}$
• What is the word equation for anaerobic respiration in animal cells?


  Glucose → lactic acid + energy.
• Why is anaerobic respiration less efficient than aerobic respiration?

  Because it involves the incomplete oxidation of glucose, releasing less energy.
• What is the word equation for anaerobic respiration in plant and yeast cells?

  Glucose → ethanol + carbon dioxide + energy.
• What are the uses of the products of anaerobic respiration in plants and yeast?


  They can be used for baking and producing alcohol.
• Where does anaerobic respiration occur in cells?


  In the cytoplasm.
• What happens to lactic acid after exercise?


  It must be converted to carbon dioxide and water and removed from the body.
• What is oxygen debt?


  It is the amount of oxygen required to remove lactic acid after exercise.
• What factors affect the rate of photosynthesis?

  • Water
  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• What are limiting factors in photosynthesis?


  They are factors that can limit the rate of the photosynthesis reaction if they are in short supply.
• How does increasing light intensity affect photosynthesis?


  It increases the rate of photosynthesis until another factor becomes limiting.
• What happens to the rate of photosynthesis when temperature increases?


  It increases until a chemical optimum temperature is reached, after which it decreases.
• What occurs below the optimum temperature for photosynthesis?


  The rate of photosynthesis increases due to increased kinetic energy of particles.
• What happens above the optimum temperature for photosynthesis?


  The rate of photosynthesis decreases due to the denaturing of enzymes.
• What happens to energy demand during exercise?


  There is an increased demand for energy, requiring increased cellular respiration.
• What is metabolism?


  It is the sum of all chemical reactions in a cell or body.
• What are some important factors contributing to an organism's metabolism?

  • Starch, glycogen, and cellulose production from glucose
  • Lipids synthesized from fatty acids and glycerol
  • Proteins produced from amino acids and glucose
  • Breakdown of proteins to form urea
• What are the uses of glucose produced by photosynthesis in plants?

  • Energy storage as insoluble starch
  • Production of cellulose for cell walls
  • Production of lipids and oils for storage
  • Production of amino acids for protein synthesis
  • Production of nucleic acids (DNA and RNA)
  • Production of vitamins and other molecules
• What are the benefits of greenhouse economies for plant growth?

  • Creates suitable conditions for growth
  • Provides artificial lighting in dark periods
  • Provides warmth and carbon dioxide from gas combustion
  • Increases crop yield despite higher costs
• How do you work out light intensity


  1/distance^2
• Photosynthesis practical

  1. 1.Set up a boiling tube containing 45 cm3 of sodium hydrogencarbonate solution (1%). Allow the tube to stand for a few minutes and shake to disperse any air bubbles that might form.
  2. Cut a piece of the pondweed, it should be 8 cm long.
  3. Use forceps to place the pondweed in the boiling tube carefully. Make sure not to damage pondweed
  4. Position the boiling tube so that the pondweed is 10 cm away from the light source. stand for five minutes. Count the number of bubbles emerging from the cut end of the stems in one minute. Repeat five times and record your results.
  5. Calculate the mean number of bubbles produced per minute. Repeat the experiment at different distances away from the light source.
• Anaerobic respiration vs aerobic respiration

  Anaerobic-

  releases less energy than aerobic

  Aerobic-

  Produces co2