Chapter 1 Test Biology

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Biology, 8e (Campbell)
Chapter 7

Membrane Structure and Function

Multiple-Choice Questions

1) Who was/were the first to propose that cell membranes are phospholipid bilayers? A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

2) Who proposed that membranes are a phospholipid bilayer between two layers of hydrophilic proteins? A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

3) Who proposed that the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids? A) H. Davson and J. Danielli
B) I. Langmuir
C) C. Overton
D) S. Singer and G. Nicolson
E) E. Gorter and F. Grendel

4) Which of the following types of molecules are the major structural components of the cell membrane? A) phospholipids and cellulose
B) nucleic acids and proteins
C) phospholipids and proteins
D) proteins and cellulose
E) glycoproteins and cholesterol

For the following questions, match the labeled component of the cell membrane (Figure 7.1) with its description.

Figure 7.1

5) peripheral protein

6) cholesterol

7) fiber of the extracellular matrix

8) microfilament of the cytoskeleton

9) glycolipid

10) When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that A) the integral membrane proteins are not strong enough to hold the bilayer together. B) water that is present in the middle of the bilayer freezes and is easily fractured. C) hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing. D) the carbon-carbon bonds of the phospholipid tails are easily broken. E) the hydrophobic interactions that hold the membrane together are weakest at this point.

11) The presence of cholesterol in the plasma membranes of some animals A) enables the membrane to stay fluid more easily when cell temperature drops. B) enables the animal to remove hydrogen atoms from saturated phospholipids. C) enables the animal to add hydrogen atoms to unsaturated phospholipids. D) makes the membrane less flexible, allowing it to sustain greater pressure from within the cell. E) makes the animal more susceptible to circulatory disorders.

12) According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? A) They can move laterally along the plane of the membrane. B) They frequently flip-flop from one side of the membrane to the other. C) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. D) They are free to depart from the membrane and dissolve in the surrounding solution. E) They have hydrophilic tails in the interior of the membrane.

13) Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold? A) by increasing the percentage of unsaturated phospholipids in the membrane B) by increasing the percentage of cholesterol molecules in the membrane C) by decreasing the number of hydrophobic proteins in the membrane D) by co-transport of glucose and hydrogen

E) by using active transport

14) In order for a protein to be an integral membrane protein it would have to be which of the following? A) hydrophilic
B) hydrophobic
C) amphipathic
D) completely covered with phospholipids
E) exposed on only one surface of the membrane

15) When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are A) peripheral proteins.

B) phospholipids.
C) carbohydrates.
D) integral proteins.
E) cholesterol...
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