24. What is the characteristic of the cell membrane consisting of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins that creates a hydrophobic region between two layers of lipids?
Answer: C
Selectively permeable
The cell membrane is characterized as selectively permeable due to its bilayer structure of phospholipids that includes proteins, cholesterol, and glycoproteins, which allows it to regulate the passage of substances in and out of the cell while maintaining a hydrophobic region between the lipid layers.
A) Impermeable
This option is incorrect because an impermeable membrane would not allow any substances to pass through. The cell membrane, however, permits certain molecules to enter or exit, indicating that it is not completely impermeable.
B) Permeable
While this option suggests that the membrane allows substances to pass freely, it fails to capture the selective nature of the cell membrane. Being permeable without any restrictions does not accurately describe the function of the cell membrane.
C) Selectively permeable
This option accurately describes the cell membrane's ability to control the entry and exit of various substances. The presence of a hydrophobic region and the arrangement of proteins and lipids facilitate this selective transport, making it the correct answer.
D) Selectively impermeable
This choice is misleading as it suggests that the membrane selectively prevents all substances from passing through, which is not the case. The cell membrane allows specific molecules to enter or exit while blocking others, thus it cannot be classified as selectively impermeable.
Conclusion
The correct answer, selectively permeable, reflects the cell membrane's essential function of regulating the movement of substances, a critical aspect of cellular homeostasis. Other options fail to accurately represent the membrane's characteristics, as they either imply complete blockage or unrestricted passage, which do not align with the membrane's selective nature.