Bioenergetics

• Photosynthesis


  The process by which plants make glucose from sunlight
• Photosynthesisword equation


  Carbon dioxide + water → glucose + oxygen
• Limiting factor


  An environmental condition (such as light intensity) which, in low levels, restricts any increase in the rate of photosynthesis
• Uses of glucose from photosynthesis

  • For respiration
  • Converted into starch for storage
  • To produce fat or oil for storage
  • To produce cellulose to strengthen cell walls
  • Combined with nitrates to form amino acids which produce proteins
• Types of respiration


  • Aerobic (with oxygen)
  • Anaerobic (without oxygen)
• Anaerobic respiration in animals

  Glucose → Lactic acid
• Anaerobic respiration in plants and yeast

  Glucose → Ethanol + Carbon dioxide
• Oxygen debt


  The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
• Metabolism


  The sum of all the reactions in a cell or the body, controlled by enzymes
• Metabolic reactions


  • Glucose to starch, glycogen and cellulose
  • Glycerol and fatty acids to lipids
  • Glucose and nitrate to amino acids and proteins
  • Respiration reactions
  • Urea forming from protein breakdown
• Chlorophyll


  Pigment within chloroplasts that absorbs the light energy needed for photosynthesis
• Different plants will naturally have different amounts of chlorophyll
• Factors that damage chloroplasts and reduce chlorophyll production include disease, environmental stress, and lack of nutrients
• Limiting factors for photosynthesis

  • Light
  • Carbon dioxide
  • Temperature
  • Amount of chlorophyll
• Graphing factors affecting photosynthesis using light

  1. Plot light intensity on x-axis

  2. Plot rate of photosynthesis on y-axis

  3. As light intensity increases, rate of photosynthesis increases

  4. Rate plateaus when something else becomes limiting factor (carbon dioxide or temperature)
• Graphing carbon dioxide effect on photosynthesis

  1. Rate of photosynthesis increases with carbon dioxide concentration

  2. Plateaus when something else becomes limiting factor
• Graphing temperature effect on photosynthesis

  1. Rate increases initially as enzymes work faster

  2. Rate starts to drop as enzymes denature at higher temperatures

  3. Rate falls to zero by around 45 degrees
• How farmers can create optimal conditions for photosynthesis

  • Use greenhouses to trap heat and provide artificial light
  • Pump in carbon dioxide
  • Use fertilizers for essential minerals
  • Use pesticides to control pests and pathogens
• Creating optimal conditions for photosynthesis can be costly for farmers
• Cellular respiration


  Breaking apart glucose molecules to release the energy that's trapped inside
• Examples of how organisms use their energy

  • Building up larger molecules from smaller ones (e.g. combining amino acids to form proteins)
  • Muscular contraction for movement
  • Maintaining body temperature
• Energy is needed for loads of reactions in our cells, most of which are catalyzed by enzymes
• Metabolism


  All the chemical processes that occur within a living organism in order to maintain life
• Aerobic respiration


  • More common type
  • Takes place whenever there's enough oxygen
  • Most efficient way to transfer energy from glucose
  • Takes place continuously in both plants and animals
  • Takes place within mitochondria
• The equation for aerobic respiration is the opposite of the equation for photosynthesis
• Anaerobic respiration


  • Respiration without oxygen
  • Used when not enough oxygen to keep up with demands of aerobic respiration
  • Incomplete breakdown of glucose molecule
  • Leads to lactic acid buildup
• Anaerobic respiration in plants and yeast

  • Glucose is converted to ethanol and carbon dioxide instead of lactic acid
  • In yeast, this process is called fermentation
  • Used to make bread, beer, and wine
• Pondweed required practical
• Light intensity is inversely proportional to the square of the distance (inverse square law)
• Plants that have less chlorophyll won't be able to carry out as much photosynthesis
• Photosynthesis is an endothermic reaction as energy is transferred from the environment to the chloroplasts by light
• Glucose 


  C6H12O6
• Respiration


  An exothermic reaction, which transfers energy from glucose, and is continuously occurring in living cells
• Aerobic respiration- word equation

  Glucose + Oxygen → Carbon dioxide + Water
• Exercise


  Causes the body to carry out more cellular respiration
• Cellular respiration during exercise

  1. Muscles require more energy

  2. Muscles require more oxygen

  3. Breathing rate and volume increase

  4. Heart rate increases
• If there's insufficient oxygen during intense exercise the body uses anaerobic respiration
• Removing lactic acid after exercise

  1. Lactic acid carried to liver

  2. Lactic acid reacts with oxygen

  3. Lactic acid converted back to glucose
• Breathing rate is measured by counting chest rises and falls per minute
• Heart rate is measured by feeling the pulse in the wrist or neck