The function of the cell plasma membrane

The function of the cell plasma membrane
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C. Glandular epithelium
D. Muscle tissue
Answer is A: Epithelial tissue has one surface “open” to the exterior or to the con-
tents of the tube.
91. Which of the following is true for connective tissue?
A. It consists of cells, a basement membrane and intercellular matrix.
B. Its cells are closely packed and held together by protein fibres.
C. It has a high rate of cell division and no blood supply.
D. It is made of cells, protein fibres and ground substance.
Answer is D: Connective tissue includes fibres and cells which are not closely
packed.
92. The cell membrane’s resting potential (about −70 mV inside with respect to the
outside) is due mainly to which of the following mechanisms?
A. The sodium-potassium pump
B. The diffusion of cations and anions through the membrane along their con-
centration gradients
C. The diffusion of sodium and potassium across the cell membrane
D. The presence inside the cell of anions too large to passively cross the cell
membrane
Answer is A: The ATPase pump shifts 3 Na out of the cell and 2 K into the cell.
This disparity in positive charge is the major influence on the resting potential.
93. Which of the following cells are uninucleate (have a single nucleus)?
A. Red blood cells
B. Epithelial cells
C. Skeletal muscle cells
D. Osteoclasts
Answer is B: Red blood cells have no nucleus, while osteoclasts and skeletal muscle
cells are multinucleate.
94. What is the function of the cell plasma membrane?
A. It maintains an intracellular environment that is hypotonic compared to the
extracellular fluid.
B. It protects the cell from dehydration by limiting water flow from the cell.
C. It regulates the passage of molecules and ions into an out of the cell.
D. It provides the supportive medium for membrane proteins.
Answer is C: The plasma membrane is made of lipid and separates the aqueous
intracellular fluid from the aqueous extracellular fluid. Substances cannot enter or
leave the cell unless they are lipid soluble or by endo-/exocytosis or have a mem-
brane protein pore or transport mechanism that can move them through the
membran