Campbell Biology Chapter 7 Test Preparation Exam 2024 100% Verified!!
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Course
Campbell Biology
Institution
Campbell Biology
In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane?
A) They are synthesized on ribosomes on the plasma membrane.
B) They are synthesized by ribosomes in the rough ER, and ar...
Campbell Biology Chapter 7 Test
Preparation Exam 2024 100% Verified!!
In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma
membrane. How do the viral glycoproteins get to the plasma membrane?
A) They are synthesized on ribosomes on the plasma membrane.
B) They are synthesized by ribosomes in the rough ER, and arrive at the plasma membrane in the
membrane of secretory vesicles.
C) They are synthesized on free cytoplasmic ribosomes, and then inserted into the plasma
membrane.
D) They are synthesized by ribosomes in the rough ER, secreted from the cell, and inserted into the
plasma membrane from the outside.
E) They are synthesized by ribosomes on the HIV viral membrane, which fuses with the plasma
membrane from inside the cell. - ANSWER B) They are synthesized by ribosomes in the rough ER,
and arrive at the plasma membrane in the membrane of secretory vesicles.
Familial hypercholesterolemia is characterized by which of the following?
A) defective LDL receptors on the cell membranes
B) poor attachment of the cholesterol to the extracellular matrix of cells
C) a poorly formed lipid bilayer that cannot incorporate cholesterol into cell membranes
D) inhibition of the cholesterol active transport system in red blood cells
E) a general lack of glycolipids in the blood cell membranes - ANSWER A) defective LDL receptors on
the cell membranes
Cell membranes are asymmetrical. Which of the following is the most likely explanation?
A) The cell membrane forms a border between one cell and another in tightly packed tissues such as
epithelium.
B) Cell membranes communicate signals from one organism to another.
C) The two sides of a cell membrane face different environments and carry out different functions.
D) The "innerness" and "outerness" of membrane surfaces are predetermined by genes.
E) Proteins can only be associated with the cell membranes on the cytoplasmic side. - ANSWER C)
The two sides of a cell membrane face different environments and carry out different functions.
,Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose,
were filled with various concentrations of sucrose and then placed in separate beakers containing an
initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed
(weighed) and the percent change in mass of each bag was graphed.
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any
membrane more fluid at lower temperatures?
A) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
B) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in
membranes.
C) Unsaturated fatty acids are more polar than saturated fatty acids.
D) The double bonds block interaction among the hydrophilic head groups of the lipids.
E) The double bonds result in shorter fatty acid tails and thinner membranes. - ANSWER A) The
double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
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 - ANSWER E) E. Gorter and F. Grendel
The cell membranes of Antarctic ice fish might have which of the following adaptations?
A) very long chain fatty acids
B) branched isoprenoid lipids
C) a high percentage of polyunsaturated fatty acids
D) a higher percentage of trans-fatty acids
E) no cholesterol - ANSWER C) a high percentage of polyunsaturated fatty acids
The phosphate transport system in bacteria imports phosphate into the cell even when the
concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate
concentration. Phosphate import depends on a pH gradient across the membrane-more acidic
outside the cell than inside the cell. Phosphate transport is an example of
A) passive diffusion.
, B) facilitated diffusion.
C) active transport.
D) osmosis.
E) cotransport. - ANSWER E) cotransport.
Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at
the beginning of the experiment?
A) A
B) B
C) C
D) D
E) E - ANSWER C) C
If HIV first enters the cell in an endocytotic vesicle, instead of directly fusing with the plasma
membrane, then
A) HIV infection should be hindered by microtubule polymerization inhibitors such as nocodazole.
B) HIV infection should be more efficient at lower temperatures.
C) intact cortical actin microfilaments should interfere with HIV infection.
D) cells lacking integrins should be resistant to HIV infection.
E) addition of ligands for other cell-surface receptors to stimulate their endocytosis should increase
the efficiency of HIV infection. - ANSWER A) HIV infection should be hindered by microtubule
polymerization inhibitors such as nocodazole.
Singer and Nicolson's fluid mosaic model of the membrane proposed that
A) membranes are a phospholipid bilayer.
B) membranes are a phospholipid bilayer between two layers of hydrophilic proteins.
C) membranes are a single layer of phospholipids and proteins.
D) membranes consist of protein molecules embedded in a fluid bilayer of phospholipids.
E) membranes consist of a mosaic of polysaccharides and proteins. - ANSWER D) membranes consist
of protein molecules embedded in a fluid bilayer of phospholipids.
Which component is the fiber of the extracellular matrix?
A) A
B) B
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