SL Content Statements

• B1.1.8

  Hydrophobic properties of lipids

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  Lipids are substances in living organisms that dissolve in non-polar solvents but are only sparingly soluble in aqueous solvents. Lipids include fats, oils, waxes and steroids.

• B1.1.9

  Formation of triglycerides and phospholipids by condensation reactions

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  One glycerol molecule can link three fatty acid molecules or two fatty acid molecules and one phosphate group.

• B1.1.10

  Difference between saturated, monounsaturated and polyunsaturated fatty acids

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  Include the number of double carbon (C=C) bonds and how this affects melting point. Relate this to the prevalence of different types of fatty acids in oils and fats used for energy storage in plants and endotherms respectively.

• B1.1.11

  Triglycerides in adipose tissues for energy storage and thermal insulation

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  Students should understand that the properties of triglycerides make them suited to long-term energy storage functions. Students should be able to relate the use of triglycerides as thermal insulators to body temperature and habitat.

• B1.1.12

  Formation of phospholipid bilayers as a consequence of the hydrophobic and hydrophilic regions

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  Students should use and understand the term “amphipathic”.

• B1.1.13

  Ability of non-polar steroids to pass through the phospholipid bilayer

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  Include oestradiol and testosterone as examples. Students should be able to identify compounds as steroids from molecular diagrams.