Question 1

Refer to the figure below showing a substance diffusing into a cell over time.   Which statement provides an accurate description of this figure?

Accepted Answer

A)  The average rate of motion of particles is greater in panel A than in panel C. 
B)  In panel B, more particles move into the intracellular compartment than move into the extracellular compartment over the same time period. 
C)  Panel C shows the system at equilibrium, the state in which particles cease to move between the extracellular and intracellular compartments. 
D)  The rate of change in concentration of particles in the intracellular compartment gradually increases from panel A to panel B to panel C. 
E)  The rate of change in concentration of particles in the extracellular compartment remains constant from panel A to panel B to panel C. 
A)  The average rate of motion of particles is greater in panel A than in panel C. 
B)  In panel B, more particles move into the intracellular compartment than move into the extracellular compartment over the same time period. 
C)  Panel C shows the system at equilibrium, the state in which particles cease to move between the extracellular and intracellular compartments. 
D)  The rate of change in concentration of particles in the intracellular compartment gradually increases from panel A to panel B to panel C. 
E)  The rate of change in concentration of particles in the extracellular compartment remains constant from panel A to panel B to panel C.

Question 2

If a cell needs to acquire cholesterol, it is usually transported into the cell by

Accepted Answer

A)  endocytosis. 
B)  receptor-mediated endocytosis. 
C)  pinocytosis. 
D)  active transport. 
E)  phagocytosis. 
A)  endocytosis. 
B)  receptor-mediated endocytosis. 
C)  pinocytosis. 
D)  active transport. 
E)  phagocytosis.

Question 3

Refer to the table below.   The data in the table were collected during an analysis of neuronal cell membranes from fish of a single species transferred from a cold environment to a warm one.Which statement is consistent with these data and with what you know about membrane fluidity?

Accepted Answer

A)  More fluid membranes are formed at lower temperatures than at higher temperatures because of an increase in the ratio of saturated to unsaturated fatty acid chains in membrane phospholipids. 
B)  Exposure to higher temperatures results in a shift toward more unsaturated fatty acids in fish membrane phospholipids, which increases the membrane's fluidity. 
C)  Membranes are more fluid at higher than at lower temperatures, so to maintain a constant fluidity, fish undergo a shift toward increased saturated fatty acid compositions with increasing temperature. 
D)  Fish adjust the fluidity of their cell membranes at high temperatures by increasing the number of double bonds in the fatty acid chains that make up their membrane phospholipid molecules. 
E)  Addition of double bonds to fatty acid tails making up membrane phospholipids causes the membrane to become less fluid, so the ratio of saturated to unsaturated fatty acids increases in fish cell membranes as temperature increases. 
A)  More fluid membranes are formed at lower temperatures than at higher temperatures because of an increase in the ratio of saturated to unsaturated fatty acid chains in membrane phospholipids. 
B)  Exposure to higher temperatures results in a shift toward more unsaturated fatty acids in fish membrane phospholipids, which increases the membrane's fluidity. 
C)  Membranes are more fluid at higher than at lower temperatures, so to maintain a constant fluidity, fish undergo a shift toward increased saturated fatty acid compositions with increasing temperature. 
D)  Fish adjust the fluidity of their cell membranes at high temperatures by increasing the number of double bonds in the fatty acid chains that make up their membrane phospholipid molecules. 
E)  Addition of double bonds to fatty acid tails making up membrane phospholipids causes the membrane to become less fluid, so the ratio of saturated to unsaturated fatty acids increases in fish cell membranes as temperature increases.

Question 4

In some biological membranes the lipid bilayer contains phospholipids, each with a head and two fatty acid tails.Phospholipid molecules are typically arranged so that the

Accepted Answer

A)  fatty acid tails point toward each other. 
B)  fatty acids are oriented head-to-head. 
C)  fatty acids face the interior of the cell. 
D)  nonpolar tails extend into the cytoplasm. 
E)  nonpolar tails extend into the extracellular fluid. 
A)  fatty acid tails point toward each other. 
B)  fatty acids are oriented head-to-head. 
C)  fatty acids face the interior of the cell. 
D)  nonpolar tails extend into the cytoplasm. 
E)  nonpolar tails extend into the extracellular fluid.

Question 5

Which statement about channel proteins is true?

Accepted Answer

A)  They have a central pore of nonpolar amino acids. 
B)  They are integral membrane proteins. 
C)  They aid in active transport across a membrane. 
D)  They allow any substance to diffuse through a membrane. 
E)  They are anchored in a membrane by an outer coating of polar amino acids. 
A)  They have a central pore of nonpolar amino acids. 
B)  They are integral membrane proteins. 
C)  They aid in active transport across a membrane. 
D)  They allow any substance to diffuse through a membrane. 
E)  They are anchored in a membrane by an outer coating of polar amino acids.

Question 6

Biological membranes are composed of a continuous lipid bilayer in which proteins are embedded.This general design is known as the _______ model.

Accepted Answer

The answer of Biological membranes are composed of a continuous...

Question 7

Because some of the lipids composing biological membranes contain a phosphate group in their hydrophilic heads, they are called _______.

Accepted Answer

The answer of Because some of the lipids composing biological...

Question 8

Depending on an animal cell's job, it might require a certain kind of junction to ensure proper function.If tight junctions were replaced by desmosomes in cells lining the bladder, what might be the result?

Accepted Answer

A)  Bladder cell contents would move through the extracellular matrix. 
B)  Migration of proteins in the bladder cell membranes would be restricted. 
C)  Intercellular spaces between the bladder cells would be sealed off. 
D)  The number of gap junctions in the bladder cells would increase. 
E)  Fewer integrins would be needed to anchor the bladder cells. 
A)  Bladder cell contents would move through the extracellular matrix. 
B)  Migration of proteins in the bladder cell membranes would be restricted. 
C)  Intercellular spaces between the bladder cells would be sealed off. 
D)  The number of gap junctions in the bladder cells would increase. 
E)  Fewer integrins would be needed to anchor the bladder cells.

Question 9

In passive transport, molecules move

Accepted Answer

A)  against their concentration gradient. 
B)  more slowly than in active transport. 
C)  toward a region of higher concentration. 
D)  so as to reduce differences in concentration across a membrane. 
E)  until a state of equilibrium is reached and movement stops. 
A)  against their concentration gradient. 
B)  more slowly than in active transport. 
C)  toward a region of higher concentration. 
D)  so as to reduce differences in concentration across a membrane. 
E)  until a state of equilibrium is reached and movement stops.

Question 10

The process of _______ involves coated pits, clathrin, and coated vesicles.

Accepted Answer

receptor-m

Question 11

Refer to the figures below.   Figure A shows a cross section through normal human skin.Figure B shows a cross section through skin of an individual with a disorder that disrupts linkages between proteins in desmosomes.This disorder causes severe blistering of the skin.What does this disorder indicate about the role of cell junctions in human skin?

Accepted Answer

A)  Desmosomes regulate skin cell development. 
B)  Desmosomes maintain the continuity of skin tissue. 
C)  Desmosomes increase the migration of cells within skin tissue. 
D)  Desmosomes maintain internal structures within skin cells. 
E)  Desmosomes increase access of skin cells to extracellular fluids. 
A)  Desmosomes regulate skin cell development. 
B)  Desmosomes maintain the continuity of skin tissue. 
C)  Desmosomes increase the migration of cells within skin tissue. 
D)  Desmosomes maintain internal structures within skin cells. 
E)  Desmosomes increase access of skin cells to extracellular fluids.

Question 12

Refer to the figure below.   A channel protein is represented by the letter _______.

Accepted Answer

The answer of Refer to the figure below.  ...

Question 13

If cells that normally contain aquaporins undergo a mutation that destroys aquaporin function, which outcome can be expected?

Accepted Answer

A)  The cells will experience uncontrollable water loss. 
B)  The cells will experience uncontrollable sodium and potassium ion uptake. 
C)  The cells will lose the ability to take up or release sodium and potassium ions. 
D)  The cells' membranes will become impermeable to water. 
E)  The cells will have no means for any polar compounds to diffuse across their membranes. 
A)  The cells will experience uncontrollable water loss. 
B)  The cells will experience uncontrollable sodium and potassium ion uptake. 
C)  The cells will lose the ability to take up or release sodium and potassium ions. 
D)  The cells' membranes will become impermeable to water. 
E)  The cells will have no means for any polar compounds to diffuse across their membranes.

Question 14

A group of transmembrane proteins involved in maintaining animal cell structure via their interactions with the cytoskeleton are known as

Accepted Answer

A)  integrins. 
B)  desmosomes. 
C)  seal tissues. 
D)  connexins. 
E)  keratins. 
A)  integrins. 
B)  desmosomes. 
C)  seal tissues. 
D)  connexins. 
E)  keratins.

Question 15

The sodium‒potassium pump found in animal cells is a(n)

Accepted Answer

A)  uniporter. 
B)  carrier protein. 
C)  symporter. 
D)  peripheral membrane protein. 
E)  antiporter. 
A)  uniporter. 
B)  carrier protein. 
C)  symporter. 
D)  peripheral membrane protein. 
E)  antiporter.

Question 16

Osmosis moves water across membranes from a _______ to a(n) _______.

Accepted Answer

A)  high concentration of dissolved material; low concentration of dissolved material 
B)  low concentration of dissolved material; high concentration of dissolved material 
C)  hypertonic solution; hypotonic solution 
D)  hypertonic solution; isotonic solution 
E)  low concentration of water; high concentration of water 
A)  high concentration of dissolved material; low concentration of dissolved material 
B)  low concentration of dissolved material; high concentration of dissolved material 
C)  hypertonic solution; hypotonic solution 
D)  hypertonic solution; isotonic solution 
E)  low concentration of water; high concentration of water

Question 17

A molecule is present at two different concentrations on either side of a membrane.The molecule will have the greatest diffusion rate if the concentration is _______ F1F1F1S1F1F1F10M on one side and _______ F1F1F1S1F1F1F10M on the other.

Accepted Answer

A)  10; 20 
B)  20; 30 
C)  50; 60 
D)  30; 30 
E)  15; 50 
A)  10; 20 
B)  20; 30 
C)  50; 60 
D)  30; 30 
E)  15; 50

Question 18

If a cell has an increased need for a particular molecule already present in a higher concentration within the cell than in the extracellular fluid, the cell might use active transport, which usually moves molecules

Accepted Answer

A)  in the same direction as diffusion moves them. 
B)  in a direction opposite to the one in which diffusion moves them. 
C)  in a direction that tends to bring about equilibrium. 
D)  toward higher pH. 
E)  from inside to outside the cell. 
A)  in the same direction as diffusion moves them. 
B)  in a direction opposite to the one in which diffusion moves them. 
C)  in a direction that tends to bring about equilibrium. 
D)  toward higher pH. 
E)  from inside to outside the cell.

Question 19

A transmembrane protein may contain one or more hydrophilic side chains.If these were removed, the rest of the protein molecule would

Accepted Answer

A)  remain anchored to the cytoskeleton. 
B)  extend into the cytoplasm. 
C)  protrude into the extracellular space. 
D)  remain inside the membrane. 
E)  become a peripheral protein. 
A)  remain anchored to the cytoskeleton. 
B)  extend into the cytoplasm. 
C)  protrude into the extracellular space. 
D)  remain inside the membrane. 
E)  become a peripheral protein.

Question 20

Refer to the figure below showing the process of receptor-mediated endocytosis.   Which statement regarding this process is false?

Accepted Answer

A)  Receptor-mediated endocytosis involves receptor proteins located on the cell's surface. 
B)  Coated pits are lined on their cytoplasmic surface by clathrin. 
C)  Receptor-mediated endocytosis is important in cellular uptake of cholesterol. 
D)  Coated vesicles eventually become part of the endoplasmic reticulum. 
E)  Coated vesicles contain materials that were previously extracellular. 
A)  Receptor-mediated endocytosis involves receptor proteins located on the cell's surface. 
B)  Coated pits are lined on their cytoplasmic surface by clathrin. 
C)  Receptor-mediated endocytosis is important in cellular uptake of cholesterol. 
D)  Coated vesicles eventually become part of the endoplasmic reticulum. 
E)  Coated vesicles contain materials that were previously extracellular.

Exam 6: Cell Membranes

Refer to the figure below showing a substance diffusing into a cell over time. Which statement provides an accurate description of this figure?

If a cell needs to acquire cholesterol, it is usually transported into the cell by

Refer to the table below. The data in the table were collected during an analysis of neuronal cell membranes from fish of a single species transferred from a cold environment to a warm one.Which statement is consistent with these data and with what you know about membrane fluidity?

In some biological membranes the lipid bilayer contains phospholipids, each with a head and two fatty acid tails.Phospholipid molecules are typically arranged so that the

Which statement about channel proteins is true?

Biological membranes are composed of a continuous lipid bilayer in which proteins are embedded.This general design is known as the _______ model.

Because some of the lipids composing biological membranes contain a phosphate group in their hydrophilic heads, they are called _______.

Depending on an animal cell's job, it might require a certain kind of junction to ensure proper function.If tight junctions were replaced by desmosomes in cells lining the bladder, what might be the result?

In passive transport, molecules move

The process of _______ involves coated pits, clathrin, and coated vesicles.

Refer to the figure below. A channel protein is represented by the letter _______.

If cells that normally contain aquaporins undergo a mutation that destroys aquaporin function, which outcome can be expected?

A group of transmembrane proteins involved in maintaining animal cell structure via their interactions with the cytoskeleton are known as

The sodium‒potassium pump found in animal cells is a(n)

Osmosis moves water across membranes from a _______ to a(n) _______.

A molecule is present at two different concentrations on either side of a membrane.The molecule will have the greatest diffusion rate if the concentration is _______ M on one side and _______ M on the other.

If a cell has an increased need for a particular molecule already present in a higher concentration within the cell than in the extracellular fluid, the cell might use active transport, which usually moves molecules

A transmembrane protein may contain one or more hydrophilic side chains.If these were removed, the rest of the protein molecule would

Refer to the figure below showing the process of receptor-mediated endocytosis. Which statement regarding this process is false?

Studying Life

Small Molecules and the Chemistry of Life

Proteins, Carbohydrates, and Lipids

Nucleic Acids and the Origin of Life

Cells: the Working Units of Life

Cell Communication and Multicellularity

Energy, Enzymes, and Metabolism

Pathways That Harvest Chemical Energy

Photosynthesis: Energy From Sunlight

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

Dna and Its Role in Heredity

From Dna to Protein: Gene Expression

Gene Mutation and Molecular Medicine

Regulation of Gene Expression

Genomes

Recombinant Dna and Biotechnology

Mechanisms of Evolution

Reconstructing and Using Phylogenies

Speciation

Evolution of Genes and Genomes

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

Plants Without Seeds: From Water to Land

The Evolution of Seed Plants

The Evolution and Diversity of Fungi

Animal Origins and the Evolution of Body Plans

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The Plant Body

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Reproduction in Flowering Plants

Plant Responses to Environmental Challenges

Physiology, Homeostasis, and Temperature Regulation

Animal Hormones

Immunology: Animal Defense Systems

Animal Reproduction

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Neurons, Glia, and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Functions

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Salt and Water Balance and Nitrogen Excretion

Animal Behavior

The Physical Environment and Biogeography of Life

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Filters

Osmosis moves water across membranes from a _ to a(n) _.

A molecule is present at two different concentrations on either side of a membrane.The molecule will have the greatest diffusion rate if the concentration is _ M on one side and _ M on the other.