Biological molecules

• What are the four main carbon-based molecules common to all life?

  carbohydrates, lipids, proteins, nucleic acids
• Which biological molecules form the major parts of plasma membranes?

  lipids
• Which biological molecules are involved in making proteins?

  nucleic acids
• Which two biological molecules are the main respiratory substrates?

  carbohydrates and lipids
• What are the units of a polymer called?

  monomers
• What is the name of the reaction that builds polymers?

  condensation reaction
• What is the name of the reaction that breaks down polymers?

  hydrolysis reaction
• What are the monomers of the disaccharide sucrose?

  glucose and fructose
• What type of bond forms between two monosaccharides?

  glycosidic bond
• Which chemical is used in the biochemical test for reducing and non-reducing sugars?

  Benedict's reagent
• Which isomer of glucose makes up glycogen?

  Alpha glucose
• What are the two groups of lipids?

  triglycerides and phospholipids
• Which bonds form between glycerol and fatty acids?

  ester bonds
• What is the test for lipids?

  emulsion test
• Which molecules are triglycerides made of?

  glycerol and three fatty acids
• Which type of lipid is common in plasma membranes?

  phospholipids
• Which three elements are common to biological molecules?

  Carbon, hydrogen, and oxygen
• What makes a lipid unsaturated?

  carbon–carbon double bonds
• Which chemical is used in the biochemical test for starch?

  iodine/potassium iodide
• Large molecules often contain carbon. Why?

  Carbon atoms readily link to one another to form a chain
• Why does Benedict's reagent turn red when heated with a reducing sugar?


  Sugar donates electrons that reduce blue copper (II) sulphate to orange copper (I) oxide
• Why do organisms that move use lipids rather than carbohydrates?

  Lipids provide more than twice as much energy as carbohydrate when they are oxidised. If fat is stored, the same amount of energy can be provided for less than half the mass. It is therefore a lighter storage product - a major advantage if the organism is motile