Multiple Choice
Which description best explains how phospholipids are arranged in the cell membrane lipid bilayer?
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8. Membrane Structure
The Lipid Bilayer
Multiple Choice
In the context of the lipid bilayer, which factor most directly influences a molecule’s ability to passively diffuse across a cell membrane?
A
The nucleotide sequence of nearby membrane-associated DNA
B
The rate of transcription of cytosolic enzymes
C
The molecule’s polarity/charge (lipid solubility)
D
The number of ribosomes attached to the membrane surface
Verified step by step guidance1
Understand that passive diffusion across the lipid bilayer depends on the molecule's ability to interact with the hydrophobic core of the membrane.
Recall that the lipid bilayer is composed mainly of hydrophobic fatty acid tails, which create a nonpolar environment inside the membrane.
Recognize that molecules that are nonpolar or lipid-soluble can dissolve in the hydrophobic core and pass through more easily, while polar or charged molecules have difficulty crossing without assistance.
Eliminate options unrelated to membrane permeability, such as nucleotide sequences, transcription rates, or ribosome numbers, since these do not directly affect passive diffusion.
Conclude that the molecule's polarity or charge (which affects lipid solubility) is the key factor influencing its ability to passively diffuse across the cell membrane.
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