Question 1

You are the biologist on an interstellar spacecraft and discover a life form.It appears similar to life forms on Earth.You extract a number of molecules from the organism and characterize them.From the described properties,what kind of molecules are they likely to be and where are they likely to be found?
A.an amphipathic molecule that has two long hydrocarbon chains and a polar oligosaccharide head group.
B.another amphipathic molecule with two hydrocarbon chains and a phosphate-containing head group.
C.a polymer made of amino acids with hydrophobic amino acids on its outer surface in the middle of the molecule and hydrophilic amino acids on its outer surface on each end of the molecule.

Accepted Answer

The answer of You are the biologist on an interstellar...

Question 2

Which of the following is a function of membranes?

Accepted Answer

A) compartmentalization 
B) selectively permeable barrier 
C) mediates intercellular interactions 
D) helps cells respond to external stimuli 
E) All of these are correct.

Question 3

What causes the membrane potential to return to the normal negative value after an action potential has occurred?

Accepted Answer

A) opening of a voltage-gated K+ channel 
B) opening of a voltage-gated Na+ channel 
C) closing of a voltage-gated K+ channel 
D) opening of a ligand-gated Na+ channel 
E) opening of a voltage-gated K+ facilitated transporter

Question 4

Synaptic malfunction or dysfunction may cause which of the following diseases?

Accepted Answer

A) myasthenia gravis 
B) Parkinson's disease 
C) schizophrenia 
D) depression 
E) All of these are correct.

Question 5

How might a lack of Cl- transport cause the respiratory tract symptoms of cystic fibrosis (CF),specifically the thickened mucus?

Accepted Answer

The answer of How might a lack of Cl- transport...

Question 6

What is caused by the inability of Na+ ion channels to open for several milliseconds after their inactivation?

Accepted Answer

A) hyperpolarization 
B) depolarization 
C) termination 
D) a refractory period 
E) an action potential

Question 7

What word below characterizes the amino acids that are found in an $\alpha$-helical segment that spans a membrane?

Accepted Answer

A) exclusively circular 
B) predominantly hydrophilic 
C) predominantly hydrophobic 
D) predominantly antiparallel 
E) totally parallel

Question 8

What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer?

Accepted Answer

A) integral protein 
B) lipid-anchored protein 
C) peripheral proteins 
D) transmembrane protein 
E) both integral protein and transmembrane protein

Question 9

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

Accepted Answer

The answer of What complications in the story of the...

Question 10

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Accepted Answer

A) via a direct connection 
B) via a spark 
C) via a neurotransmitter 
D) via Na+ ions 
E) via plasmodesmata

Question 11

Why are the proteins being separated on an SDS polyacrylamide gel attracted equally to the positive electrode?

Accepted Answer

A) They carry a relatively uniform positive charge distribution 
B) They carry a relatively uniform negative charge distribution. 
C) They are all the same molecular weight. 
D) They are all the same size. 
E) They all have the same degree of hydrophobicity.

Question 12

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Accepted Answer

A) Play a role in establishing and maintaining membrane lipid asymmetry 
B) Interacts with neighboring epithelial cells,or the basal membrane 
C) Blocks post-synaptic membrane 
D) Transport proteins 
E) All of the above

Question 13

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

Accepted Answer

A) cell movement 
B) cell division 
C) formation of intercellular junctions 
D) endocytosis 
E) All of these are correct.

Question 14

A channel that opens in response to the binding of a specific molecule,which is usually not the solute that passes through the channel is called a ________.

Accepted Answer

A) voltage-gated channel 
B) charge-gated channel 
C) ligand-gated channel 
D) positive-gated channel 
E) electric-gated channel

Question 15

Why are integral membrane proteins difficult to study?

Accepted Answer

A) They are difficult to isolate in soluble form due to their hydrophobic transmembrane domains. 
B) They are difficult to isolate in soluble form due to their hydrophilic transmembrane domains. 
C) They are so small. 
D) They are so large. 
E) None of these are correct.

Question 16

Glycolipids have been shown to play roles in certain disease states in humans and other mammals.Which of the situations below illustrate the ways in which this can happen?

Accepted Answer

A) failure to add a sugar to the glycolipid. 
B) inhibition of glycolipid synthesis. 
C) they are the site at which bacterial toxins like those that cause botulism and cholera first bind cells. 
D) they are the site at which the influenza virus first binds a cell. 
E) All of these are correct.

Question 17

A new,promising drug in the treatment of cystic fibrosis (CF)and the improvement in the quality of life in CF patients is Bronchitol.What is Bronchitol's overall effect on the patient that allows it to improve their situation? What sugar is a major constituent of Bronchitol? How does Bronchitol cause water to move into the extracellular fluid of the airways after being inhaled? What other kinds of compounds might be used in CF treatment in the future?

Accepted Answer

The answer of A new,promising drug in the treatment of...

Question 18

An important aspect of transport by facilitated transporters and pumps is ________.

Accepted Answer

A) conformational shifts 
B) rigidity 
C) softness 
D) $\alpha$-helix 
E) $\beta$-pleated sheet

Question 19

People with the most severe cases of CF transport no chloride ions,while people with less severe cases transport some Cl- ions.What is a possible explanation of this?

Accepted Answer

The answer of People with the most severe cases of...

Question 20

Cocaine acts by _________.

Accepted Answer

A) enhancing the degradation of acetylcholine. 
B) depressing the degradation of acetylcholine 
C) interfering with dopamine reuptake from the synaptic cleft 
D) enhancing dopamine reuptake from the synaptic cleft 
E) destroying dopamine in the synapse

Exam 4: The Structure and Function of the Plasma Membrane

Which of the following is a function of membranes?

What causes the membrane potential to return to the normal negative value after an action potential has occurred?

Synaptic malfunction or dysfunction may cause which of the following diseases?

How might a lack of Cl- transport cause the respiratory tract symptoms of cystic fibrosis (CF),specifically the thickened mucus?

What is caused by the inability of Na+ ion channels to open for several milliseconds after their inactivation?

What word below characterizes the amino acids that are found in an $\alpha$ -helical segment that spans a membrane?

What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer?

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Why are the proteins being separated on an SDS polyacrylamide gel attracted equally to the positive electrode?

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

A channel that opens in response to the binding of a specific molecule,which is usually not the solute that passes through the channel is called a ________.

Why are integral membrane proteins difficult to study?

Glycolipids have been shown to play roles in certain disease states in humans and other mammals.Which of the situations below illustrate the ways in which this can happen?

An important aspect of transport by facilitated transporters and pumps is ________.

People with the most severe cases of CF transport no chloride ions,while people with less severe cases transport some Cl- ions.What is a possible explanation of this?

Cocaine acts by _________.

Exam 4: The Structure and Function of the Plasma Membrane

Which of the following is a function of membranes?

What causes the membrane potential to return to the normal negative value after an action potential has occurred?

Synaptic malfunction or dysfunction may cause which of the following diseases?

How might a lack of Cl- transport cause the respiratory tract symptoms of cystic fibrosis (CF),specifically the thickened mucus?

What is caused by the inability of Na+ ion channels to open for several milliseconds after their inactivation?

What word below characterizes the amino acids that are found in an α\alphaα -helical segment that spans a membrane?

What kind of membrane protein penetrates into the hydrophobic part of the lipid bilayer?

What complications in the story of the CFTR and its relationship to CF have been introduced by subsequent studies?

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Why are the proteins being separated on an SDS polyacrylamide gel attracted equally to the positive electrode?

Enzymes that move certain phospholipids between leaflets have also which of the following properties?

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid,nonfluid structures?

A channel that opens in response to the binding of a specific molecule,which is usually not the solute that passes through the channel is called a ________.

Why are integral membrane proteins difficult to study?

Glycolipids have been shown to play roles in certain disease states in humans and other mammals.Which of the situations below illustrate the ways in which this can happen?

An important aspect of transport by facilitated transporters and pumps is ________.

People with the most severe cases of CF transport no chloride ions,while people with less severe cases transport some Cl- ions.What is a possible explanation of this?

Cocaine acts by _________.

What word below characterizes the amino acids that are found in an $\alpha$ -helical segment that spans a membrane?