Biology (Raven), 10th Edition

Chapter 5: Membranes

Pre-Test

1
The primary constituents of biological membranes are
A)Triglyceride bilayers.
B)Saccharides.
C)Phospholipid bilayers.
D)Glycoproteins.
E)Peptidoglycans.
2
Which of the following statements accurately describes the nature of the cell membrane?
A)The molecules are covalently linked forming a solid structure.
B)The molecules form a single layer with polar regions facing towards the interior part of the cell and the hydrophilic regions facing the exterior.
C)Ionically bonded sugars form a double layer that is semi-permeable.
D)The molecules form a double layer with polar regions facing the interior and the exterior of the cell while the hydrophobic regions orient towards each other.
E)A single layer of molecules is oriented with polar regions oriented toward the interior and exterior of the cell.
3
Why are cell membranes said to be fluid?
A)The covalently bound molecules exist as a liquid at biological temperatures.
B)The lipid bilayers are not bonded to one another, allowing movement like a fluid.
C)The molecules allow fluids to pass readily across the membrane.
D)The membrane exists as a fatty acid layer which is stabilized by hydrophobic interactions with water.
E)Proteins embedded within the membrane force the structure to expand and contract giving it fluid qualities.
4
The name given to the accepted description of the cell membrane is the
A)"soap bubble" model
B)"lipid fluid" model
C)"membrane cross-linkage" model
D)"protein interchange" model
E)"fluid mosaic" model
5
Substance A is allowed to readily travel across the cell membrane following the concentration gradients. This is called
A)Diffusion.
B)Facilitated diffusion.
C)Osmosis.
D)Bulk transport.
E)Active transport.
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