THE CELL
TRANSPORT INTO AND OUT OF THE CELL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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It is easier for small molecules to diffuse across the cell membrane
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It is easier for large molecules to diffuse across the cell membrane
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Particle size is not important
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Particle size is not as important as shape when moving across the membrane
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Detailed explanation-1: -Larger molecules diffuse through a cell membrane at a slower rate than do smaller ones.
Detailed explanation-2: -The rate of diffusion is inversely proportional to the size of the molecules. This means that the smaller is the size of the molecule, the higher is the rate of diffusion.
Detailed explanation-3: -Protein channels formed by integral proteins allow ions to diffuse across the membrane. Different cells have different permeabilities to these ions. The diameter of the channel and the polar groups on the protein subunits forming channel walls determine the permeability of the channels by various ions and molecules.
Detailed explanation-4: -Smaller molecules tend to diffuse faster than larger molecules. Molecules diffuse faster in a fluid with a lower viscosity, like water, than in a fluid with a higher viscosity, like syrup.
Detailed explanation-5: -Size and polarity affect the permeability of molecules through the phospholipid bilayer. The lipid bilayer has a largely non-polar interior, therefore, non-polar molecules are more permeable than polar molecules. The smaller the molecule, the easier it can cross the membrane.