B4 - Bioenergetics

• Endothermic reaction


  Takes energy in from the surroundings
• Photosynthesis


  Carbon dioxide + water -> oxygen + glucose

  6C02 6H20 6O2 C6H12O6
• Limiting factor of photosynthesis:

  Concentration of carbon dioxide


  As the concentration of carbon dioxide increases, the rate of photosynthesis also increases but then it levels off as there is not enough temperature or not enough light (limiting factors).
• Limiting factor of photosynthesis:

  Light intensity


  As the light intensity increases, the rate of photosynthesis also increases, but then it levels off as carbon dioxide and temperature are limiting factors.
• Limiting factor of photosynthesis:

  Temperature


  As the temperature increases, the rate of photosynthesis also increases but then at high temperature, the process stops as the enzymes denature.
• Inverse square law


  The intensity of light is inversely proportional to the square if the distance from the source.
• Uses of glucose from photosynthesis:

  Starch


  Glucose is turned into lipids (fats & oils) for storing in seeds. Seeds also store starch. e.g. sunflower seeds contain a lot of oil (margarine).
• Uses of glucose from photosynthesis:

  Cellulose


  For making cells walls especially in rapidly growing plants. Cell wall protection allows plant to grow tall, provide structure support.
• Uses of glucose from photosynthesis:

  Protein synthesis


  Glucose combines with nitrates (collected from the soil) to make amino acids which are then made into proteins. Protein is the building blocks of life itself. Enzymes are proteins; so are many structural parts of life and even organelles with cellulose are composed of protein.
• Uses of glucose from photosynthesis:

  Respiration


  Plants use some glucose they produce for respiration. It releases energy which allows them to converts the rest of the glucose into other useful substances. Can be used to build new cells and grow. To produce some of these, they need to gather a few minerals from the soil.
• Uses of glucose from photosynthesis:

  Storage


  Glucose which is soluble is converted into insoluble for storage. This starch can be stored in roots, leaves and stems ready for when photosynthesis isn't happening (night, winter). Potato and carrot store a lot of starch underground over winter so a new plant can grow from it the following spring.
• Uses of glucose from photosynthesis:

  Fruit

  Glucose, fructose turned into sucrose
• Aerobic respiration


  Oxygen + glucose -> carbon dioxide + water

  6O2 C6H12O6 6CO2 6H20
• Respiration


  A chemical reaction that releases energy from glucose using oxygen. Happens in the mitochondria of all cells.
• Breathing


  The mechanical part of the respiration process - it is how we get oxygen into and carbon dioxide out of the body.
• Uses of glucose in humans

  - Respiration

  - To make oils/fats

  - To make protein

  - Stored as glycogen
• Uses of energy from respiration

  - Growth

  - Maintaining optimum temperature

  - Muscle contraction (movement)

  - Active transport of glucose and amino acids from the small intestine
• Anaerobic respiration


  Glucose -> Lactic acid + energy

  C6H12O6 2C3H6O3 2ATP

  
  

  - Doesn't require oxygen

  - Releases less energy
• Fermentation


  A type of anaerobic process in plants and yeast that releases ethanol.
• Anaerobic respiration in yeast

  Glucose -> ethanol + carbon dioxide

  
  

  (Ethanol turned into gas when baked)
• During exercise

  - Heart rate increases

  - Breathing rate increases

  - Increased sweating

  - Breath volume increase

  - Hot / red in appearance
• Oxygen debt


  Amount of oxygen needed to breakdown/ remove lactic acid. Lactic acid the gets transported to the liver via the bloodstream.
• Metabolism


  Sum of all the chemical reaction in a cell or the body. Energy for all chemical reactions is provided by respiration.
• Factors affecting metabolism


  - Age (better when younger)

  - Gender (Men have naturally better metabolism)

  - Genetics (some may inherit a slower metabolism)
• Urea


  Excess amino acids go to the liver and turned into urea which is excreted via the urine.