Question 1

The formulation of a model for a structure or for a process serves which of the following purposes?

Accepted Answer

A)  It asks a scientific question. 
B)  It functions as a testable hypothesis. 
C)  It records observations. 
D)  It serves as a data point among results. 
E)  It can only be arrived at after years of experimentation. 
A)  It asks a scientific question. 
B)  It functions as a testable hypothesis. 
C)  It records observations. 
D)  It serves as a data point among results. 
E)  It can only be arrived at after years of experimentation.

Question 2

Human immunodeficiency virus (HIV) infects cells that have both CD4 and CCR5 cell surface molecules. The viral nucleic acid molecules are enclosed in a protein capsid, and the protein capsid is itself contained inside an envelope consisting of a lipid bilayer membrane and viral glycoproteins. One hypothesis for viral entry into cells is that binding of HIV membrane glycoproteins to CD4 and CCR5 initiates fusion of the HIV membrane with the plasma membrane, releasing the viral capsid into the cytoplasm. An alternative hypothesis is that HIV gains entry into the cell via receptor-mediated endocytosis, and membrane fusion occurs in the endocytotic vesicle. To test these alternative hypotheses for HIV entry, researchers labeled the lipids on the HIV membrane with a red fluorescent dye.
  
-What would be observed by live-cell fluorescence microscopy if HIV is endocytosed first, and then fuses with the endocytotic vesicle membrane?

Accepted Answer

A)  A spot of red fluorescence will remain on the infected cell's plasma membrane, marking the site of membrane fusion and HIV entry. 
B)  The red fluorescent dye-labeled lipids will diffuse in the endocytotic vesicle membrane and become difficult to detect. 
C)  A spot of red fluorescence will move into the infected cell's interior. 
D)  A spot of red fluorescence will remain outside the cell after delivering the viral capsid. 
E)  Fluorescence microscopy does not have enough resolution to visualize fluorescently labeled HIV virus particles. 
A)  A spot of red fluorescence will remain on the infected cell's plasma membrane, marking the site of membrane fusion and HIV entry. 
B)  The red fluorescent dye-labeled lipids will diffuse in the endocytotic vesicle membrane and become difficult to detect. 
C)  A spot of red fluorescence will move into the infected cell's interior. 
D)  A spot of red fluorescence will remain outside the cell after delivering the viral capsid. 
E)  Fluorescence microscopy does not have enough resolution to visualize fluorescently labeled HIV virus particles.

Question 3

Which of the following is true of the evolution of cell membranes?

Accepted Answer

A)  Cell membranes have stopped evolving now that they are fluid mosaics. 
B)  Cell membranes cannot evolve if the membrane proteins do not. 
C)  The evolution of cell membranes is driven by the evolution of glycoproteins and glycolipids. 
D)  All components of membranes evolve in response to natural selection. 
E)  An individual organism selects its preferred type of cell membrane for particular functions. 
A)  Cell membranes have stopped evolving now that they are fluid mosaics. 
B)  Cell membranes cannot evolve if the membrane proteins do not. 
C)  The evolution of cell membranes is driven by the evolution of glycoproteins and glycolipids. 
D)  All components of membranes evolve in response to natural selection. 
E)  An individual organism selects its preferred type of cell membrane for particular functions.

Question 4

In order for a protein to be an integral membrane protein it would have to be

Accepted Answer

A)  hydrophilic. 
B)  hydrophobic. 
C)  amphipathic, with at least one hydrophobic region. 
D)  completely covered with phospholipids. 
E)  exposed on only one surface of the membrane. 
A)  hydrophilic. 
B)  hydrophobic. 
C)  amphipathic, with at least one hydrophobic region. 
D)  completely covered with phospholipids. 
E)  exposed on only one surface of the membrane.

Question 5

Using live-cell fluorescence microscopy, researchers observed that a red fluorescent spot moved from the plasma membrane into the interior of target cells when red fluorescent dye-labeled HIV was added to the cells. What is the best conclusion from these observations?

Accepted Answer

A)  The hypothesis that HIV enters the cell via fusion with the target cell plasma membrane is proved. 
B)  The hypothesis that HIV enters the cell via fusion with the target cell plasma membrane is not supported. 
C)  The hypothesis that HIV enters the cell via endocytosis is proved. 
D)  The hypothesis that HIV enters the cell via endocytosis is not supported. 
E)  Neither hypothesis is supported by these results. 
A)  The hypothesis that HIV enters the cell via fusion with the target cell plasma membrane is proved. 
B)  The hypothesis that HIV enters the cell via fusion with the target cell plasma membrane is not supported. 
C)  The hypothesis that HIV enters the cell via endocytosis is proved. 
D)  The hypothesis that HIV enters the cell via endocytosis is not supported. 
E)  Neither hypothesis is supported by these results.

Question 6

In which of the following would there be the greatest need for osmoregulation?

Accepted Answer

A)  an animal connective tissue cell bathed in isotonic body fluid 
B)  cells of a tidepool animal such as an anemone 
C)  a red blood cell surrounded by plasma 
D)  a lymphocyte before it has been taken back into lymph fluid 
E)  a plant being grown hydroponically (in a watery mixture of designated nutrients) 
A)  an animal connective tissue cell bathed in isotonic body fluid 
B)  cells of a tidepool animal such as an anemone 
C)  a red blood cell surrounded by plasma 
D)  a lymphocyte before it has been taken back into lymph fluid 
E)  a plant being grown hydroponically (in a watery mixture of designated nutrients)

Question 7

Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?

Accepted Answer

A)  transmembrane proteins 
B)  integral proteins 
C)  peripheral proteins 
D)  integrins 
E)  glycoproteins 
A)  transmembrane proteins 
B)  integral proteins 
C)  peripheral proteins 
D)  integrins 
E)  glycoproteins

Question 8

When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?

Accepted Answer

A)  The cell will burst. 
B)  The cell membrane will lyse. 
C)  Plasmolysis will shrink the interior. 
D)  The cell will become flaccid. 
E)  The cell will become turgid. 
A)  The cell will burst. 
B)  The cell membrane will lyse. 
C)  Plasmolysis will shrink the interior. 
D)  The cell will become flaccid. 
E)  The cell will become turgid.

Question 9

Which of the following processes includes all others?

Accepted Answer

A)  osmosis 
B)  diffusion of a solute across a membrane 
C)  facilitated diffusion 
D)  passive transport 
E)  transport of an ion down its electrochemical gradient 
A)  osmosis 
B)  diffusion of a solute across a membrane 
C)  facilitated diffusion 
D)  passive transport 
E)  transport of an ion down its electrochemical gradient

Question 10

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water-equal to the volume of blood lost-is transferred directly into one of his veins. What will be the most probable result of this transfusion?

Accepted Answer

A)  It will have no unfavorable effect as long as the water is free of viruses and bacteria. 
B)  The patient's red blood cells will shrivel up because the blood fluid has become hypotonic compared to the cells. 
C)  The patient's red blood cells will swell because the blood fluid has become hypotonic compared to the cells. 
D)  The patient's red blood cells will shrivel up because the blood fluid has become hypertonic compared to the cells. 
E)  The patient's red blood cells will burst because the blood fluid has become hypertonic compared to the cells. 
A)  It will have no unfavorable effect as long as the water is free of viruses and bacteria. 
B)  The patient's red blood cells will shrivel up because the blood fluid has become hypotonic compared to the cells. 
C)  The patient's red blood cells will swell because the blood fluid has become hypotonic compared to the cells. 
D)  The patient's red blood cells will shrivel up because the blood fluid has become hypertonic compared to the cells. 
E)  The patient's red blood cells will burst because the blood fluid has become hypertonic compared to the cells.

Question 11

Which of the following membrane activities require energy from ATP hydrolysis?

Accepted Answer

A)  facilitated diffusion of chloride ions across the membrane through a chloride channel 
B)  movement of water into a cell 
C)  Na⁺ ions moving out of a mammalian cell bathed in physiological saline 
D)  movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell 
E)  movement of carbon dioxide out of a paramecium 
A)  facilitated diffusion of chloride ions across the membrane through a chloride channel 
B)  movement of water into a cell 
C)  Na⁺ ions moving out of a mammalian cell bathed in physiological saline 
D)  movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell 
E)  movement of carbon dioxide out of a paramecium

Question 12

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 line in the graph represents the bag with the highest initial concentration of sucrose?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 13

For the following questions, match the labeled component of the cell membrane in the figure with its description.
  
-Which component is the fiber of the extracellular matrix?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 14

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 line or lines in the graph represent(s)bags that contain a solution that is hypertonic at 50 minutes?

Accepted Answer

A)  A and B 
B)  B 
C)  C 
D)  D 
E)  D and E 
A)  A and B 
B)  B 
C)  C 
D)  D 
E)  D and E

Question 15

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?

Accepted Answer

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 cotransport of glucose and hydrogen 
E)  by using active transport 
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 cotransport of glucose and hydrogen 
E)  by using active transport

Question 16

White blood cells engulf bacteria through what process?

Accepted Answer

A)  exocytosis 
B)  phagocytosis 
C)  pinocytosis 
D)  osmosis 
E)  receptor-mediated exocytosis 
A)  exocytosis 
B)  phagocytosis 
C)  pinocytosis 
D)  osmosis 
E)  receptor-mediated exocytosis

Question 17

Singer and Nicolson's fluid mosaic model of the membrane proposed that

Accepted Answer

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. 
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.

Question 18

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?

Accepted Answer

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. 
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.

Question 19

The cell membranes of Antarctic ice fish might have which of the following adaptations?

Accepted Answer

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 
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

Question 20

Nitrous oxide gas molecules diffusing across a cell's plasma membrane is an example of

Accepted Answer

A)  diffusion across the lipid bilayer. 
B)  facilitated diffusion. 
C)  active transport. 
D)  osmosis. 
E)  cotransport. 
A)  diffusion across the lipid bilayer. 
B)  facilitated diffusion. 
C)  active transport. 
D)  osmosis. 
E)  cotransport.

Exam 7: Membrane Structure and Function

The formulation of a model for a structure or for a process serves which of the following purposes?

Which of the following is true of the evolution of cell membranes?

In order for a protein to be an integral membrane protein it would have to be

Using live-cell fluorescence microscopy, researchers observed that a red fluorescent spot moved from the plasma membrane into the interior of target cells when red fluorescent dye-labeled HIV was added to the cells. What is the best conclusion from these observations?

In which of the following would there be the greatest need for osmoregulation?

Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?

When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?

Which of the following processes includes all others?

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water-equal to the volume of blood lost-is transferred directly into one of his veins. What will be the most probable result of this transfusion?

Which of the following membrane activities require energy from ATP hydrolysis?

For the following questions, match the labeled component of the cell membrane in the figure with its description. -Which component is the fiber of the extracellular matrix?

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?

White blood cells engulf bacteria through what process?

Singer and Nicolson's fluid mosaic model of the membrane proposed that

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?

The cell membranes of Antarctic ice fish might have which of the following adaptations?

Nitrous oxide gas molecules diffusing across a cell's plasma membrane is an example of

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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