Multiple Choice
In the context of principles of transmembrane transport, which statement correctly contrasts facilitated diffusion with active transport?
23
views
9. Transport Across Membranes
Principles of Transmembrane Transport
Multiple Choice
In the context of principles of transmembrane transport, what does it mean that the cell membrane is selectively permeable?
A
It allows all molecules to diffuse freely across the lipid bilayer at the same rate.
B
It permits passage only of molecules moving against their concentration gradient.
C
It prevents all ions and polar molecules from crossing under any conditions, regardless of transport proteins.
D
It allows some substances to cross more easily than others based on properties such as size, charge, and polarity, often requiring specific transport proteins.
Verified step by step guidance1
Understand that selective permeability refers to the cell membrane's ability to regulate which substances can pass through it and at what rate.
Recognize that the lipid bilayer itself is hydrophobic, so small nonpolar molecules can diffuse more easily, while ions and polar molecules cannot cross freely.
Know that specific transport proteins embedded in the membrane facilitate the movement of certain molecules, especially those that are charged or large, allowing controlled passage.
Realize that selective permeability means the membrane does not allow all molecules to diffuse freely or indiscriminately; instead, it discriminates based on molecular properties like size, charge, and polarity.
Conclude that this selective control is essential for maintaining cellular homeostasis by regulating the internal environment of the cell.
Related Videos
Related Practice
