Bioenergetics GCSE

• Cellular respiration


  Process that releases energy by breaking down glucose and other food molecules
• Exothermic reaction


  A reaction that releases energy to its surroundings, usually in the form of heat
• Aerobic respiration


  Cell respiration which happens in the presence of oxygen in the mitochondria of the cell
• Word equation for aerobic respiration

  Glucose + oxygen -> carbon dioxide + water (+energy)
• Balanced chemical equation for aerobic respiration

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• Anaerobic respiration


  Cell respiration which happens in the absence of oxygen
• Word equation for anaerobic respiration

  Glucose -> lactic acid (+energy)
• Lactic acid


  A toxic waste product that is produced during anaerobic respiration in humans and can cause muscle fatigue
• Incomplete oxidation


  Occurs during anaerobic respiration causing a build up of lactic acid in the muscles
• Fermentation

  Anaerobic respiration in plant and yeast cells which produces ethanol and carbon dioxide
• Word equation for fermentation

  Glucose -> carbon dioxide + ethanol (+energy)
• Uses of fermentation

  The manufacture of bread and alcoholic drinks
• Liver


  Receives blood from the muscles with lactic acid and converts the lactic acid back into glucose
• Oxygen debt


  The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid
• Effect of exercise

  Increased heart rate, breathing rate and breath volume to supply the muscles with more oxygen
• Organisms need energy for

  Movement, keeping warm and chemical reactions to make larger molecules
• Glucose (C6H12O6)


  The main reactant of respiration that is obtained from the digestion of carbohydrates
• Oxygen (O2)


  A molecule that is essential for the complete oxidation of glucose in aerobic respiration
• Carbon dioxide (CO2)


  A waste product of respiration that is removed from cells and the body via gas exchange
• Water (H2O)


  A byproduct of respiration that is either used or removed from the body typically during exhalation or urination
• Metabolism


  The sum of all the reactions in a cell or the body
• Metabolism includes

  The synthesis of new molecules, the breakdown of existing molecules and the process of respiration
• Energy transferred by cellular respiration


  Is used by organisms for the continual enzyme-controlled processes of metabolism
• Enzymes and metabolism

  Enzymes regulate most cellular reactions and are essential for the synthesis and breakdown of molecules
• Conversion of glucose to complex carbohydrates

  Glucose can be converted into starch, glycogen and cellulose
• Formation of lipid molecules

  One molecule of glycerol joins with three fatty acids
• Amino acid production

  Glucose and nitrate ions form amino acids which are used to make proteins
• Protein synthesis

  Amino acids join together in specific arrangements to form proteins
• Urea excretion

  Excess proteins are broken down to form urea for excretion
• Digestion


  Requires energy from respiration to break down large insoluble molecules into smaller soluble molecules
• Carbohydrates


  Provide energy for chemical reactions and can break down into sugars
• Proteins

  The building blocks of cells and tissues that can break down into amino acids
• Lipids


  An energy store of fats and oils that can break down into glycerol and fatty acids
• Photosynthesis


  A process where plants and algae synthesise glucose from carbon dioxide and water, using light energy from the sun
• Photosynthesis word equation

  Carbon dioxide + water (+light energy) -> glucose + oxygen
• Balanced equation for photosynthesis

  6CO2 + 6H2O -> C6H12O6 + 6O2
• Glucose (C6H12O6)


  The main chemical product of photosynthesis that has many different uses in a plant, including respiration
• Oxygen (O2)


  A waste product of photosynthesis that leaves the plant through the stomata of the leaves or can be used for respiration
• Carbon dioxide (CO2)


  A reactant needed for photosynthesis to synthesise glucose, this gas enters the plant via gas exchange through the stomata of the leaves
• Water (H2O)


  A reactant needed for photosynthesis to take place, water is absorbed by the roots and is transported by the xylem to reach the leaves where photosynthesis occurs