MCQ: the plasma membrane

16. Which statement accurately describes the fluid mosaic model of the plasma membrane?
a) The model proposes that the membrane is rigid and fixed in composition.
b) The model suggests that protein is embedded in a sea of lipids
c) The model emphasizes the dynamic and fluid nature of the membrane’s structure.
d) The model suggests that carbohydrates are the primary building blocks of the membrane.

17. What is the primary function of glycoproteins and glycolipids in the plasma membrane?
a) Providing mechanical strength to the membrane.
b) Facilitating active transport of ions.
c) Mediating cell-cell communication and recognition.
d) Assisting in the breakdown of lipids.

18. Which lipid component is responsible for maintaining the rigidity and fluidity of the plasma membrane?
a) Glycerol
b) Sterols
c) Fatty acids
d) Phosphate groups

19. Which lipid type is found exclusively in the outer leaflet of the plasma membrane?
a) Phospholipids
b) Glycolipids
c) Sterols
d) Sphingolipids

20. How are lipid rafts significant in the plasma membrane’s function?
a) They prevent lateral diffusion of lipids.
b) They primely mediate endocytosis and exocytosis.
c) They act as barriers to protect the cell from external factors.
d) They play roles in signal transduction and cholesterol transport.

21. What role do transmembrane proteins play in the plasma membrane?
a) They provide mechanical strength to the membrane.
b) They mediate cell-cell adhesion events.
c) They facilitate the movement of molecules across the membrane.
d) They act as enzymes for lipid synthesis

22. Which protein structure is common among many transmembrane proteins?
a) Alpha-helix
b) Beta-sheet
c) Coiled-coil
d) Random coil

23. The fluidity of the plasma membrane is influenced by:
a) Nucleic acid concentration
b) Carbohydrate composition
c) Lipid composition and temperature
d) Sterol concentration only

24. Which structure is responsible for preventing freezing of the plasma membrane at lower temperatures?
a) Glycolipids
b) Sterols
c) Sphingolipids
d) Glycerol

25. What is the primary function of the cell coat and glycocalyx on cell surfaces?
a) Maintaining rigid structure
b) Assisting in lipid synthesis
c) Mediating specific cell-cell adhesion events
d) Facilitating ion transport

26. The main function of cholesterol in the plasma membrane is to:
a) Maintain the rigid structure of the membrane.
b) Facilitate endocytosis.
c) Catalyze lipid synthesis.
d) Influence fluidity at different temperatures.