LipidsEdexcel International A Level Biology: Flashcards
What these 14 flashcards ask
- What is a triglyceride made of?
- What bond joins a fatty acid to glycerol?
- What type of reaction forms a triglyceride?
- How many water molecules are released when one triglyceride forms?
- What functional group do all fatty acids have at one end?
- How many –OH groups does glycerol have?
- What is a saturated fatty acid?
- What is an unsaturated fatty acid?
- What is the difference between monounsaturated and polyunsaturated?
- Why are unsaturated oils usually liquid at room temperature?
- Why are saturated fats often solid at room temperature?
- How does hydrolysis of a triglyceride differ from its synthesis?
- Which enzyme hydrolyses triglycerides?
- How many fewer hydrogen atoms does a fatty acid have for each C=C bond?
Exam questions on Lipids
- A food scientist compares butter with olive oil. Butter is solid at room temperature and olive oil is liquid. Both are made mostly of triglycerides.Olive oil contains a high proportion of unsaturated fatty acids. Explain why olive oil is liquid at room temperature whereas butter is solid.2 marks
- Stearic acid and oleic acid are two fatty acids found in animal fats. Both have 18 carbon atoms in each molecule. Stearic acid has no carbon–carbon double bonds. Oleic acid has one carbon–carbon double bond.The formula of stearic acid is C₁₈H₃₆O₂ and the formula of glycerol is C₃H₈O₃. Deduce the molecular formula of the triglyceride formed from one glycerol molecule and three stearic acid molecules. Show your working.2 marks
- Cheese made from cow's milk is rich in triglycerides. These are digested in the small intestine by the enzyme lipase. Stearic acid, C₁₈H₃₆O₂, is one of the fatty acids in the triglycerides and has no C=C double bonds.Oleic acid, another fatty acid in cheese, also has 18 carbon atoms but has one C=C double bond. Deduce the number of hydrogen atoms in a molecule of oleic acid and explain your answer.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).