bionergectics

• Photosynthesis


  1. Takes place in the leaves

  2. Takes place in chloroplasts

  3. Chlorophyll absorbs light energy

  4. Converts carbon dioxide and water into glucose and oxygen
• Photosynthesis is an endothermic reaction, where energy is transferred from the environment to chloroplasts by light
• Carbon dioxide and water supply for photosynthesis

  1. Carbon dioxide diffuses into leaves through stomata

  2. Water is taken up from soil by roots and transported to leaves via xylem
• Products of photosynthesis

  • Glucose is the main product
  • Oxygen is also produced but not as important
• Uses of glucose produced by photosynthesis

  • Cellular respiration
  • Making cellulose
  • Making starch
  • Making amino acids
  • Making oils and fats
• Plant growth rate is often dependent on the rate of photosynthesis
• Factors affecting the rate of photosynthesis are light intensity, temperature, carbon dioxide concentration, and the amount of chlorophyll
• Factors affecting photosynthesis

  • Light intensity
  • Temperature
  • Concentration of carbon dioxide in the air
  • Amount of chlorophyll that the plants have
• Chlorophyll

  The pigment within chloroplasts that absorbs the light energy needed for photosynthesis
• Plants have less chlorophyll

  They won't be able to carry out as much photosynthesis
• Cellular respiration

  An exothermic reaction which transfers energy from glucose and is continuously occurring in living cells
• Factors that can reduce chlorophyll levels

  • Disease (e.g. tobacco mosaic virus)
  • Environmental stress
  • Lack of nutrients (e.g. water)
• Limiting factors for photosynthesis are normally light, carbon dioxide and temperature
• Cellular respiration

  Breaking apart glucose molecules to release the energy that's trapped inside
• Graphing limiting factors for photosynthesis

  1. Plot light intensity on x-axis

  2. Plot rate of photosynthesis on y-axis
• 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
• As light intensity increases

  Rate of photosynthesis increases
• The line flattens out when something else becomes the limiting factor, such as carbon dioxide concentrations or temperature
• Metabolism

  All the chemical processes that occur within a living organism in order to maintain life
• As carbon dioxide concentration increases

  Rate of photosynthesis increases
• 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
• As temperature increases

  Rate of photosynthesis increases initially, then starts to drop as enzymes denature
• Aerobic respiration

  Glucose + Oxygen -> Carbon dioxide + Water
• Anything beyond 45 degrees, the enzymes are fully denatured and the rate of reaction falls to zero
• Graphs can show multiple limiting factors, by comparing curves at different conditions
• The equation for aerobic respiration is the opposite of the equation for photosynthesis
• Farmers creating conditions to increase photosynthesis

  • Using greenhouses to trap heat and provide artificial light
  • Pumping in carbon dioxide
  • Using paraffin heaters for heat and CO2
  • Applying fertilizers for essential minerals
  • Using pesticides to control pests
• Anaerobic respiration

  • Respiration without oxygen, used when there is not enough oxygen to keep up with the demands of aerobic respiration
• Creating optimal conditions for photosynthesis can be costly for farmers, so they have to weigh the extra cost against the expected yield increase
• Anaerobic respiration

  Glucose -> Lactic acid
• Anaerobic respiration is less efficient because it involves incomplete breakdown of glucose and 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 and is used to make bread, beer, and wine
• 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
• Insufficient oxygen during intense exercise


  Cells use anaerobic respiration
• Anaerobic respiration


  Less efficient than aerobic respiration, produces lactic acid
• Lactic acid buildup during exercise

  Causes a burning sensation in muscles
• Removing lactic acid after exercise


  1. Lactic acid carried to liver

  2. Lactic acid reacts with oxygen

  3. Lactic acid converted back to glucose
• Oxygen debt


  Extra oxygen needed to remove lactic acid after exercise