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LipidsAQA A-Level Biology: Mind map

What this mind map covers

  • Triglyceride
  • Fatty acids
  • Phospholipid
  • Properties
  • Emulsion test

Exam questions on Lipids

  1. Fatty acids have the general formula R–COOH, where R is a hydrocarbon chain. Palmitic acid is CH₃(CH₂)₁₄COOH. Oleic acid is CH₃(CH₂)₇CH=CH(CH₂)₇COOH.
    Explain why oleic acid is described as an unsaturated fatty acid.2 marks
  2. A triglyceride is made from one molecule of glycerol and three molecules of palmitic acid. To the nearest whole number the relative formula masses are: glycerol 92, palmitic acid 256 and water 18.
    Describe how the emulsion test could be used to show that a sample contains a triglyceride.2 marks
  3. Phospholipids and triglycerides both contain fatty acids joined to glycerol. In a phospholipid one fatty acid is replaced by a phosphate-containing group. Phospholipids form the cell surface membrane, whereas triglycerides are stored in fat cells.
    Describe how the structure of a phospholipid differs from the structure of a triglyceride.3 marks
See the full worksheet

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).