Feedback for Multiple Choice Quiz 22

  1. Some phospholipids contain positively charged groups, but not all. They all have hydrophilic heads and hydrophobic tails.

  2. For fatty acid micelles, the -COO- groups are the "hydrophilic heads"; the hydrocarbon chains are the "hydrophobic tails".

  3. The first three choices are commonly found in phospholipids.

  4. Although hydrophobic effects control the assembly of micelles and bilayers, they do not affect the melting properties. It is largely the van der Waals forces between the acyl chains that define the melting temperature.

  5. Cholesterol can be made by higher organisms; it spans half the thickness of the bilayer; lipid flip-flop in the bilayer hardly ever occurs; and plugging up cardiac arteries is hardly an "essential function".

  6. Unsaturated fatty acids have one or more double bonds.

  7. The CMC is the highest concentration of monomeric fatty acid that can exist in solution. The addition of any additional fatty acid above the CMC will enter micelles. Therefore, the more hydrophobic fatty acids will be less soluble in monomeric form, giving low CMC values.
  All of the correct answers have a green check mark.
  Incorrect answers have the "red-lit" button next to your choice.