biology-Bioenergetics

• 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
• 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
• Plant growth rate is often dependent on the rate of photosynthesis
• Factors affecting photosynthesis


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


  They won't be able to carry out as much photosynthesis
• The level of chlorophyll within an individual plant can vary due to disease, environmental stress or lack of nutrients like water
• The limiting factors for photosynthesis are normally light, carbon dioxide and temperature
• Relationship between light intensity and rate of photosynthesis

  1. As light intensity increases, the rate of photosynthesis increases

  2. The rate plateaus when something else becomes the limiting factor, such as carbon dioxide concentrations or temperature
• Relationship between temperature and rate of photosynthesis

  1. As temperature increases, the rate of photosynthesis increases initially

  2. The rate starts to drop again as the enzymes involved begin to denature, and falls to zero by around 45 degrees
• Techniques used by farmers


  • Placing crops in greenhouses to trap heat and increase temperature
  • Providing artificial light so photosynthesis can continue day and night
  • Pumping carbon dioxide into greenhouses
  • Using paraffin heaters that release heat and carbon dioxide
  • Using fertilizers to ensure plants have enough essential minerals
  • Using pesticides to kill unwanted bugs
• Artificially creating optimal conditions for photosynthesis can be costly for farmers
• Cellular respiration


  An exothermic reaction which transfers energy from glucose and is continuously occurring in living cells
• Cellular respiration


  Breaking apart glucose molecules to release the energy that's trapped inside
• 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
• Aerobic respiration


  Glucose + Oxygen -> Carbon dioxide + Water
• The equation for aerobic respiration is the opposite of the equation for photosynthesis
• Anaerobic respiration


  Glucose -> Lactic acid
• Anaerobic respiration is less efficient because it involves incomplete breakdown of glucose and leads to lactic acid buildup
• 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
• Measuring effects of exercise

  1. Measure breathing rate

  2. Measure heart rate
• 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