LipidsAQA A-Level Biology: Flashcards

What these 14 flashcards ask

Name two groups of lipid.
What is a triglyceride made from?
What type of reaction forms a triglyceride?
What bond forms between glycerol and a fatty acid?
How many water molecules are released when a triglyceride forms?
What is a saturated fatty acid?
What is an unsaturated fatty acid?
How does a phospholipid differ from a triglyceride?
Which part of a phospholipid is hydrophilic?
Which part of a phospholipid is hydrophobic?
Why do phospholipids form a bilayer in water?
Why is a triglyceride a good energy store?
How do you carry out the emulsion test?
Why do triglycerides not affect the water potential of a cell?

Exam questions on Lipids

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
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
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

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).