Question 1

The presence of cholesterol in the plasma membranes of some animals

Accepted Answer

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. 
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.

Question 2

Figure 5.4
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 3

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?

Accepted Answer

A)  Proton pumps must have evolved before any living organisms were present on Earth. 
B)  Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life. 
C)  The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism. 
D)  Cells of each domain evolved proton pumps independently when oceans became more acidic. 
E)  Proton pumps are necessary to all cell membranes. 
A)  Proton pumps must have evolved before any living organisms were present on Earth. 
B)  Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life. 
C)  The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism. 
D)  Cells of each domain evolved proton pumps independently when oceans became more acidic. 
E)  Proton pumps are necessary to all cell membranes.

Question 4

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

Accepted Answer

A)  to facilitate diffusion of molecules down their concentration gradients. 
B)  to actively transport molecules against their concentration gradients. 
C)  to maintain the integrity of a fluid mosaic membrane. 
D)  to maintain membrane fluidity at low temperatures. 
E)  to mediate cell-to-cell recognition. 
A)  to facilitate diffusion of molecules down their concentration gradients. 
B)  to actively transport molecules against their concentration gradients. 
C)  to maintain the integrity of a fluid mosaic membrane. 
D)  to maintain membrane fluidity at low temperatures. 
E)  to mediate cell-to-cell recognition.

Question 5

Use this description to answer the following question.
A major group of G-protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
-Which of the following factors would tend to increase membrane fluidity?

Accepted Answer

A)  a greater proportion of unsaturated phospholipids 
B)  a greater proportion of saturated phospholipids 
C)  a lower temperature 
D)  a relatively high protein content in the membrane 
E)  a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses 
A)  a greater proportion of unsaturated phospholipids 
B)  a greater proportion of saturated phospholipids 
C)  a lower temperature 
D)  a relatively high protein content in the membrane 
E)  a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses

Question 6

Ions diffuse across membranes through specific ion channels

Accepted Answer

A)  down their chemical gradients. 
B)  down their concentration gradients. 
C)  down the electrical gradients. 
D)  down their electrochemical gradients. 
E)  down the osmotic potential gradients. 
A)  down their chemical gradients. 
B)  down their concentration gradients. 
C)  down the electrical gradients. 
D)  down their electrochemical gradients. 
E)  down the osmotic potential gradients.

Question 7

Figure 5.1
For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description.
-Which component is a microfilament of the cytoskeleton?

Accepted Answer

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

Question 8

Which of the following is the greatest advantage of having multiple steps in a transduction pathway?

Accepted Answer

A)  Many of the steps can be used in multiple pathways. 
B)  Having multiple steps in a pathway requires the least amount of ATP. 
C)  Having multiple steps provides for greater possible amplification of a signal. 
D)  Each individual step can remove excess phosphate groups from the cytoplasm. 
E)  Each step can be activated by several G proteins simultaneously. 
A)  Many of the steps can be used in multiple pathways. 
B)  Having multiple steps in a pathway requires the least amount of ATP. 
C)  Having multiple steps provides for greater possible amplification of a signal. 
D)  Each individual step can remove excess phosphate groups from the cytoplasm. 
E)  Each step can be activated by several G proteins simultaneously.

Question 9

Use this description to answer the following question.
A major group of G-protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
-Which of the following processes includes all the 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

Use this description to answer the following question.
A major group of G-protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
-If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

Accepted Answer

A)  It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
B)  It could activate only the epinephrine system. 
C)  It would be able to carry out reception and transduction but would not be able to respond to a signal. 
D)  It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
E)  It would employ a transduction pathway directly from an external messenger. 
A)  It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
B)  It could activate only the epinephrine system. 
C)  It would be able to carry out reception and transduction but would not be able to respond to a signal. 
D)  It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
E)  It would employ a transduction pathway directly from an external messenger.

Question 11

The sodium-potassium pump is called an electrogenic pump because it

Accepted Answer

A)  pumps equal quantities of Na+ and K+ across the membrane. 
B)  pumps hydrogen ions out of the cell. 
C)  contributes to the membrane potential. 
D)  ionizes sodium and potassium atoms. 
E)  is used to drive the transport of other molecules against a concentration gradient. 
A)  pumps equal quantities of Na+ and K+ across the membrane. 
B)  pumps hydrogen ions out of the cell. 
C)  contributes to the membrane potential. 
D)  ionizes sodium and potassium atoms. 
E)  is used to drive the transport of other molecules against a concentration gradient.

Question 12

Figure 5.1
For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description.
-Which component is cholesterol?

Accepted Answer

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

Question 13

In which of the following ways do plant hormones differ from hormones in animals?

Accepted Answer

A)  Plant hormones interact primarily with intracellular receptors. 
B)  Plant hormones may travel in air or through vascular systems. 
C)  Animal hormones are found in much greater concentration. 
D)  Plant hormones are synthesized from two or more distinct molecules. 
E)  Animal hormones are primarily for mating and embryonic development. 
A)  Plant hormones interact primarily with intracellular receptors. 
B)  Plant hormones may travel in air or through vascular systems. 
C)  Animal hormones are found in much greater concentration. 
D)  Plant hormones are synthesized from two or more distinct molecules. 
E)  Animal hormones are primarily for mating and embryonic development.

Question 14

Cell membranes are asymmetrical. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

Accepted Answer

A)  Because the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical 
B)  Because cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. 
C)  The two sides of a cell membrane face different environments and carry out different functions. 
D)  The chemical constitution of the inner and outer layer of the cell membrane is predetermined by genes. 
E)  Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature. 
A)  Because the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical 
B)  Because cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. 
C)  The two sides of a cell membrane face different environments and carry out different functions. 
D)  The chemical constitution of the inner and outer layer of the cell membrane is predetermined by genes. 
E)  Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature.

Question 15

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?

Accepted Answer

A)  Water will leave the cells, causing them to shrivel and collapse. 
B)  NaCl will be exported from the red blood cells by facilitated diffusion. 
C)  The blood cells will take up water, swell, and eventually burst. 
D)  NaCl will passively diffuse into the red blood cells. 
E)  The blood cells will expend ATP for active transport of NaCl into the cytoplasm. 
A)  Water will leave the cells, causing them to shrivel and collapse. 
B)  NaCl will be exported from the red blood cells by facilitated diffusion. 
C)  The blood cells will take up water, swell, and eventually burst. 
D)  NaCl will passively diffuse into the red blood cells. 
E)  The blood cells will expend ATP for active transport of NaCl into the cytoplasm.

Question 16

The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell 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.

Question 17

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

Accepted Answer

A)  peripheral proteins. 
B)  phospholipids. 
C)  carbohydrates. 
D)  integral proteins. 
E)  cholesterol molecules. 
A)  peripheral proteins. 
B)  phospholipids. 
C)  carbohydrates. 
D)  integral proteins. 
E)  cholesterol molecules.

Question 18

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

Accepted Answer

A)  receptor 
B)  relay molecule 
C)  transducer 
D)  signal molecule 
E)  endocrine molecule 
A)  receptor 
B)  relay molecule 
C)  transducer 
D)  signal molecule 
E)  endocrine molecule

Question 19

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?

Accepted Answer

A)  simple diffusion 
B)  phagocytosis 
C)  active transport pumps 
D)  exocytosis 
E)  facilitated diffusion 
A)  simple diffusion 
B)  phagocytosis 
C)  active transport pumps 
D)  exocytosis 
E)  facilitated diffusion

Question 20

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in

Accepted Answer

A)  peroxisomes. 
B)  lysosomes. 
C)  Golgi vesicles. 
D)  vacuoles. 
E)  secretory vesicles. 
A)  peroxisomes. 
B)  lysosomes. 
C)  Golgi vesicles. 
D)  vacuoles. 
E)  secretory vesicles.

Exam 5: Membrane Transport and Cell Signaling

The presence of cholesterol in the plasma membranes of some animals

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

Ions diffuse across membranes through specific ion channels

Figure 5.1 For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description. -Which component is a microfilament of the cytoskeleton?

Which of the following is the greatest advantage of having multiple steps in a transduction pathway?

The sodium-potassium pump is called an electrogenic pump because it

Figure 5.1 For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description. -Which component is cholesterol?

In which of the following ways do plant hormones differ from hormones in animals?

Cell membranes are asymmetrical. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?

The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of

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

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development, Stem Cells, and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition, Nutrition, and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons, Synapses, and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Species Interactions

Ecosystems and Energy

Global Ecology and Conservation Biology

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