Back to quiz

6. What does an ion diffuse down?

  • Electrochemical gradient
  • Concentration gradient

7. What gives the cell membrane strength?

  • Cholesterol
  • Connection to the cytoskeleton or fibres of the extracellular matrix
  • The presence of proteins in the bilayer

8. What are integral proteins?

  • Proteins that penetrate the hydrophobic interior of the lipid bilayer
  • Proteins that are not embedded in the lipid bilayer, and are loosely bound to the surface of the membrane

9. What are channel proteins that transport ions called?

  • Channel proteins
  • Ion channels
  • Carrier proteins

10. How do cells recognise other cells?

  • By binding to molecules on the extracellular surface of the plasma membrane
  • By the secretion and absorption of chemical communicants

11. What determines the temperature at which a cell membrane will solidify?

  • The number of saturated and unsaturated fatty acids in its phospholipid bilayer
  • The number of proteins studded throughout the phospholipid bilayer
  • The amount of cholesterol in the phospholipid bilayer

12. What are peripheral proteins?

  • Proteins that are not embedded in the lipid bilayer, and are loosely bound to the surface of the membrane
  • Proteins that penetrate the hydrophobic interior of the lipid bilayer

13. Can polar or non-polar molecules easily pass through the plasma membrane?

  • Non-polar
  • Polar

14. What role does cholesterol have in a cell membrane?

  • It resists changes in membrane fluidity
  • It provides a path for ions to travel across

15. What did Singer & Nicolson's theory state?

  • That the cell membrane is studded with proteins, with hydrophilic areas protruding
  • That the cell membrane is coated on both sides with hydrophilic proteins, like a sandwich

16. What is membrane potential?

  • The difference in voltage across a cell membrane
  • The difference in current across a cell membrane

17. Can proteins and lipids shift laterally across a cell membrane?

  • Yes
  • No

18. Describe the hydrophobic part of an integral protein

  • One or more stretches of nonpolar amino acids that are usually coiled into α helices
  • One or more stretches of polar amino acids that are usually coiled into α helices

19. What is an amphipathic molecule?

  • One that has both hydrophilic and hydrophobic regions
  • One that does not react immediately to stimuli
  • One with a changeable structure

20. What are carrier proteins?

  • Proteins that alter their shapes in order to transport molecules across the cell membrane
  • Proteins that allow molecules to pass freely through them and across the cell membrane