Question 1

Which statement is true?

Accepted Answer

A)  Animal cells in different tissues that are distant from one another can communicate through gap junctions. 
B)  Desmotubules are gap junctions found in the mammalian eye. 
C)  Plant cells are connected by channel structures known as connexons. 
D)  Gap junctions are membrane-lined channels between adjacent animal cells. 
E)  Plasmodesmata are membrane-lined channels between adjacent plant cells. 
A)  Animal cells in different tissues that are distant from one another can communicate through gap junctions. 
B)  Desmotubules are gap junctions found in the mammalian eye. 
C)  Plant cells are connected by channel structures known as connexons. 
D)  Gap junctions are membrane-lined channels between adjacent animal cells. 
E)  Plasmodesmata are membrane-lined channels between adjacent plant cells. E

Question 2

A transcription factor located in the cytoplasm of a eukaryotic cell

Accepted Answer

A)  is able to regulate gene expression. 
B)  acts as an enzyme. 
C)  is inactive until it is transported to the nucleus. 
D)  catalyzes biochemical responses. 
E)  promotes signal binding. 
A)  is able to regulate gene expression. 
B)  acts as an enzyme. 
C)  is inactive until it is transported to the nucleus. 
D)  catalyzes biochemical responses. 
E)  promotes signal binding. C

Question 3

Adrenocorticotropic hormone (ACTH) is a peptide consisting of 39 amino acids.When the arginine residue at position 8 in the peptide chain is replaced with cysteine, the peptide no longer activates signal transduction in cells containing ACTH receptors.Explain why a single change in amino acid identity in ACTH has this result.

Accepted Answer

The ACTH molecule must assume a particular three-dimensional shape to bind to the ACTH receptor and activate the receptor to change conformation to begin signal transduction along the signal pathway. The change in one amino acid at a critical place in the ACTH structure could result in an ACTH molecule that takes on a three-dimensional shape that no longer binds to and activates the receptor.

Question 4

Refer to the figure below.   The figure shows a signal transduction pathway involving two proteins found in the cytoplasm-JAK and STAT.Based on this figure, what are the roles of JAK and STAT in this pathway?

Accepted Answer

A)  JAK is a G protein and STAT is a transcription factor. 
B)  JAK is a transcription factor and STAT is a GTPase. 
C)  JAK is a protein kinase and STAT is a G protein. 
D)  JAK is a G protein and STAT is adenylyl cyclase. 
E)  JAK is a protein kinase and STAT is a transcription factor. 
A)  JAK is a G protein and STAT is a transcription factor. 
B)  JAK is a transcription factor and STAT is a GTPase. 
C)  JAK is a protein kinase and STAT is a G protein. 
D)  JAK is a G protein and STAT is adenylyl cyclase. 
E)  JAK is a protein kinase and STAT is a transcription factor.

Question 5

Refer to the table below.   Which molecules and ions are matched appropriately to the letters in the table?

Accepted Answer

A)  A = calcium ions; B = NO; C = cAMP; D = inositol trisphosphate 
B)  A = NO; B = inositol trisphosphate; C = cAMP; D = calcium ions 
C)  A = inositol trisphosphate; B = cAMP; C = calcium ions; D = NO 
D)  A = NO; B = cAMP; C = calcium ions; D = inositol trisphosphate 
E)  A = inositol trisphosphate; B = calcium ions; C = NO; D = cAMP 
A)  A = calcium ions; B = NO; C = cAMP; D = inositol trisphosphate 
B)  A = NO; B = inositol trisphosphate; C = cAMP; D = calcium ions 
C)  A = inositol trisphosphate; B = cAMP; C = calcium ions; D = NO 
D)  A = NO; B = cAMP; C = calcium ions; D = inositol trisphosphate 
E)  A = inositol trisphosphate; B = calcium ions; C = NO; D = cAMP

Question 6

The hydrolysis of phosphatidyl inositol-bisphosphate (PIP2) results in

Accepted Answer

A)  inositol trisphosphate and diacylglycerol. 
B)  inositol trisphosphate and cyclic AMP. 
C)  one second-messenger molecule. 
D)  G protein activation. 
E)  shutdown of a signal transduction pathway. 
A)  inositol trisphosphate and diacylglycerol. 
B)  inositol trisphosphate and cyclic AMP. 
C)  one second-messenger molecule. 
D)  G protein activation. 
E)  shutdown of a signal transduction pathway.

Question 7

Refer to the table below.   The table summarizes results of experiments using a group of normal cells and three other groups of the same type of cells, each carrying a different mutation in a membrane receptor protein.The receptor is part of a signal transduction pathway that is stimulated by glucose-6-phosphate.Cells were tested for their ability to respond, via the signal transduction pathway, to a variety of ligand molecule, as shown in the table.Based on these data, which statement about these three mutations is plausible?

Accepted Answer

A)  Mutations 1, 2, and 3 each broaden the specificity of ligand binding in different ways. 
B)  Mutations 1 and 3 broaden the specificity of ligand binding, while mutation 2 eliminates ligand binding. 
C)  Mutation 1 broadens the specificity of ligand binding, while mutations 2 and 3 eliminate ligand binding. 
D)  Mutation 3 has no effect on ligand binding, while mutations 1 and 2 have dramatic effects on ligand binding. 
E)  Mutations 1 and 3 have no effect on ligand binding, while mutation 2 has a dramatic effect on ligand binding. 
A)  Mutations 1, 2, and 3 each broaden the specificity of ligand binding in different ways. 
B)  Mutations 1 and 3 broaden the specificity of ligand binding, while mutation 2 eliminates ligand binding. 
C)  Mutation 1 broadens the specificity of ligand binding, while mutations 2 and 3 eliminate ligand binding. 
D)  Mutation 3 has no effect on ligand binding, while mutations 1 and 2 have dramatic effects on ligand binding. 
E)  Mutations 1 and 3 have no effect on ligand binding, while mutation 2 has a dramatic effect on ligand binding.

Question 8

In which aspect are gap junctions and plasmodesmata least similar to each other?

Accepted Answer

A)  Composition 
B)  Location 
C)  Internal diameter 
D)  Role 
E)  Shape 
A)  Composition 
B)  Location 
C)  Internal diameter 
D)  Role 
E)  Shape

Question 9

Which structure makes up part of a plasmodesma?

Accepted Answer

A)  A gap junction 
B)  A connexon 
C)  A desmotubule 
D)  A movement protein 
E)  An integral membrane protein 
A)  A gap junction 
B)  A connexon 
C)  A desmotubule 
D)  A movement protein 
E)  An integral membrane protein

Question 10

Neighboring animal cells can communicate directly through specialized cell connections called

Accepted Answer

A)  signal transduction pathways. 
B)  receptor proteins. 
C)  desmosomes. 
D)  ion channels. 
E)  gap junctions. 
A)  signal transduction pathways. 
B)  receptor proteins. 
C)  desmosomes. 
D)  ion channels. 
E)  gap junctions.

Question 11

Signals that travel to distant cells through the circulatory system are

Accepted Answer

A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  juxtacrine signals. 
E)  hormones. 
A)  paracrine signals. 
B)  parasitic signals. 
C)  autocrine signals. 
D)  juxtacrine signals. 
E)  hormones.

Question 12

Refer to the figure below, which represents structures connecting adjacent cells in multicellular organisms.   The structures shown are found in (plants/animals) _______.

Accepted Answer

The answer of Refer to the figure below, which represents...

Question 13

Which was probably not a step in the evolution from single-celled to multicellular organisms?

Accepted Answer

A)  The specialization of cells within a cluster of cells 
B)  The collecting of several cells into a cluster 
C)  The organization of specialized cells into groups 
D)  The rise of intercellular communication within a cluster of cells 
E)  The rise of intracellular signal transduction pathways 
A)  The specialization of cells within a cluster of cells 
B)  The collecting of several cells into a cluster 
C)  The organization of specialized cells into groups 
D)  The rise of intercellular communication within a cluster of cells 
E)  The rise of intracellular signal transduction pathways

Question 14

Refer to the table below.   Listed in the first row of the table is the dissociation constant for a ligand and its receptor.Listed below this are the dissociation constants for the same ligand and four different mutants of the same receptor.Which sequence displays the range of affinities of the receptor for the ligand in order, from lowest to highest affinity?

Accepted Answer

A)  Mutant 1, mutant 4, mutant 2, normal, mutant 3 
B)  Mutant 3, mutant 1, normal, mutant 2, mutant 4 
C)  Mutant 1, mutant 3, mutant 1, normal, mutant 4 
D)  Mutant 4, mutant 2, mutant 1, normal, mutant 3 
E)  Mutant 3, normal, mutant 2, mutant 4, mutant 1 
A)  Mutant 1, mutant 4, mutant 2, normal, mutant 3 
B)  Mutant 3, mutant 1, normal, mutant 2, mutant 4 
C)  Mutant 1, mutant 3, mutant 1, normal, mutant 4 
D)  Mutant 4, mutant 2, mutant 1, normal, mutant 3 
E)  Mutant 3, normal, mutant 2, mutant 4, mutant 1

Question 15

PIP2 is a phospholipid in cell membranes that produces two lipid-derived _______ when hydrolyzed by phospholipase C.

Accepted Answer

A)  receptors 
B)  kinase receptors 
C)  enzymes 
D)  second messengers 
E)  targets 
A)  receptors 
B)  kinase receptors 
C)  enzymes 
D)  second messengers 
E)  targets

Question 16

Which statement about the IP3-DAG pathway is false?

Accepted Answer

A)  Diacylglycerol can act as a second messenger. 
B)  Inositol trisphosphate can act as a second messenger. 
C)  Protein kinase C can phosphorylate a wide variety of proteins. 
D)  Inositol trisphosphate remains bound to the membrane after phospholipase C catalyzes its formation. 
E)  Inositol trisphosphate can open ion channels in the membranes of smooth endoplasmic reticulum, releasing calcium into the cytoplasm. 
A)  Diacylglycerol can act as a second messenger. 
B)  Inositol trisphosphate can act as a second messenger. 
C)  Protein kinase C can phosphorylate a wide variety of proteins. 
D)  Inositol trisphosphate remains bound to the membrane after phospholipase C catalyzes its formation. 
E)  Inositol trisphosphate can open ion channels in the membranes of smooth endoplasmic reticulum, releasing calcium into the cytoplasm.

Question 17

Which sequence lists the various mechanisms cells use to respond to signals in order, from shortest to longest response time?

Accepted Answer

A)  Ion channel opening, enzyme activation/deactivation, differential gene expression 
B)  Enzyme activation/deactivation, differential gene expression, ion channel opening 
C)  Differential gene expression, enzyme activation/deactivation, ion channel opening 
D)  Ion channel opening, differential gene expression, enzyme activation/deactivation 
E)  Enzyme activation/deactivation, ion channel opening, differential gene expression 
A)  Ion channel opening, enzyme activation/deactivation, differential gene expression 
B)  Enzyme activation/deactivation, differential gene expression, ion channel opening 
C)  Differential gene expression, enzyme activation/deactivation, ion channel opening 
D)  Ion channel opening, differential gene expression, enzyme activation/deactivation 
E)  Enzyme activation/deactivation, ion channel opening, differential gene expression

Question 18

A signal transduction pathway includes the steps listed below. 
1.An inactive signal transduction molecule is activated.
2.A transcription factor enters the nucleus.
3.A gene is expressed.
4.A ligand binds to a protein.
5.A protein undergoes a conformational change.
6.An active signal transduction molecule binds a transcription factor.
Which represents the correct order of these steps?"

Accepted Answer

A)  5, 4, 3, 1, 6, 2 
B)  4, 5, 1, 6, 2, 3 
C)  1, 5, 4, 2, 6, 3 
D)  5, 4, 1, 6, 3, 2 
E)  4, 1, 5, 6, 2, 3 
A)  5, 4, 3, 1, 6, 2 
B)  4, 5, 1, 6, 2, 3 
C)  1, 5, 4, 2, 6, 3 
D)  5, 4, 1, 6, 3, 2 
E)  4, 1, 5, 6, 2, 3

Question 19

The G protein-mediated cascade stimulated by epinephrine within a liver cell results in the phosphorylation of two key enzymes.The eventual results of this phosphorylation are the _______ of glycogen synthase and the _______ of glycogen phosphorylase, leading to the release of glucose.

Accepted Answer

A)  inhibition; activation 
B)  activation; inhibition 
C)  inhibition; degradation 
D)  activation; activation 
E)  inhibition; inhibition 
A)  inhibition; activation 
B)  activation; inhibition 
C)  inhibition; degradation 
D)  activation; activation 
E)  inhibition; inhibition

Question 20

Explain how observations about various algal species support the current scientific thinking about how multicellularity arose.

Accepted Answer

Scientists have observed several species

Exam 7: Cell Communication and Multicellularity

Which statement is true?

A transcription factor located in the cytoplasm of a eukaryotic cell

Refer to the figure below. The figure shows a signal transduction pathway involving two proteins found in the cytoplasm-JAK and STAT.Based on this figure, what are the roles of JAK and STAT in this pathway?

Refer to the table below. Which molecules and ions are matched appropriately to the letters in the table?

The hydrolysis of phosphatidyl inositol-bisphosphate (PIP2) results in

In which aspect are gap junctions and plasmodesmata least similar to each other?

Which structure makes up part of a plasmodesma?

Neighboring animal cells can communicate directly through specialized cell connections called

Signals that travel to distant cells through the circulatory system are

Refer to the figure below, which represents structures connecting adjacent cells in multicellular organisms. The structures shown are found in (plants/animals) _______.

Which was probably not a step in the evolution from single-celled to multicellular organisms?

PIP2 is a phospholipid in cell membranes that produces two lipid-derived _______ when hydrolyzed by phospholipase C.

Which statement about the IP3-DAG pathway is false?

Which sequence lists the various mechanisms cells use to respond to signals in order, from shortest to longest response time?

The G protein-mediated cascade stimulated by epinephrine within a liver cell results in the phosphorylation of two key enzymes.The eventual results of this phosphorylation are the _______ of glycogen synthase and the _______ of glycogen phosphorylase, leading to the release of glucose.

Explain how observations about various algal species support the current scientific thinking about how multicellularity arose.

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 Membranes

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

Protostome Animals

Deuterostome Animals

The Plant Body

Transport in Plants

Plant Nutrition

Regulation of Plant Growth

Reproduction in Flowering Plants

Plant Responses to Environmental Challenges

Physiology, Homeostasis, and Temperature Regulation

Animal Hormones

Immunology: Animal Defense Systems

Animal Reproduction

Animal Development

Neurons, Glia, and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Functions

Musculoskeletal Systems

Gas Exchange

Circulatory Systems

Nutrition, Digestion, and Absorption

Salt and Water Balance and Nitrogen Excretion

Animal Behavior

The Physical Environment and Biogeography of Life

Populations

Species Interactions

Communities

Ecosystems

A Changing Biosphere

Filters

The hydrolysis of phosphatidyl inositol-bisphosphate (PIP₂) results in

PIP₂ is a phospholipid in cell membranes that produces two lipid-derived _______ when hydrolyzed by phospholipase C.

Which statement about the IP₃-DAG pathway is false?

The G protein-mediated cascade stimulated by epinephrine within a liver cell results in the phosphorylation of two key enzymes.The eventual results of this phosphorylation are the _ of glycogen synthase and the _ of glycogen phosphorylase, leading to the release of glucose.