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Module 1A > 6 Cell Membrane Transport - Part 1 > Flashcards

6 Cell Membrane Transport - Part 1 Flashcards

1
Q

Which of the following is not a role of biological
membranes?
A. Like enzymes, it speeds up the transport of
large molecular weight solutes along the
semi- permeable membrane
B. It participates in the proper maintenance of
ionic charges within cells and their
surroundings
C. It prevents enzymes from acting in areas
where they may cause cell lysis and
degradation
D. It defines boundaries inside the cell itself

A

A. Like enzymes, it speeds up the transport of large
molecular weight solutes along the semi-permeable
membrane

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2
Q

Which cation is more abundant intracellularly
compared to the extracellular compartment?
A. Sodium
B. Magnesium
C. Calcium
D. Bicarbonate

A

B. Magnesium

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3
Q

What is the structure that most closely resembles a
membrane-bound vesicle?
A. Micelle
B. Soap bubble
C. Liposome
D. Phagosome

A

C. Liposome

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4
Q

In general, what is the relationship of temperature with
membrane fluidity?
A. As temperature increases, membrane fluidity
increases
B. As temperature increases, membrane fluidity
decreases
C. As temperature decreases, membrane fluidity
increases
D. There is generally no effect of temperature on
membrane fluidity because both are
independent of each other

A

A. As temperature increases, membrane fluidity
increases

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5
Q

In general, what is the relationship of cholesterol with
membrane fluidity?
A. Below melting temperature, membrane
fluidity increases with an increase in
cholesterol
B. Above melting temperature, an increase in
cholesterol limits fluidity
C. Both A and B are correct
D. Both A and B are incorrect

A

C. Both A and B are correct

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6
Q

Biological Membranes are said to be asymmetric
because of the unequal distribution of phospholipids in
the inner and outer leaflet of membranes. Which of the following
phospholipids is most commonly seen in the
inner leaflet of membranes?
A. Phosphatidylethanolamine
B. Phosphatidic acid
C. Phosphatidylcholine
D. Sphingomyelin

A

A. Phosphatidylethanolamine

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7
Q

Cellular degradation analysis shows a high
preponderance of the enzyme ATP synthase. This
most probably signifies:
A. An extensive plasma membrane network in
the cell
B. A large amount of glucose-6-phosphatases
C. A cell with plenty of mitochondria
D. A very active Golgi Complex

A

C. A cell with plenty of mitochondria

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8
Q

In the sodium-potassium ATPase pump,
phosphorylation of the Aspartic acid residue of the
alpha subunit protein results in:
A. The attachment of sodium ions to the alpha
subunit
B. An increase in the affinity of potassium ions to
the alpha subunit
C. The cleavage of aspartic acid from the
Na-K-ATPase transport protein

A

B. An increase in the affinity of potassium ions to the
alpha subunit

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9
Q

The drug digoxin, a digitalis derivative, inhibits the
sodium-potassium-ATPase pump in myocardial cells.
This results in:
A. An increased synthesis of ATP in the cell
B. An increase in the intracellular calcium ion
concentration
C. Depolarization of the cardiac cell
D. Vasodilation

A

B. An increase in the intracellular calcium ion
concentration

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10
Q

Which of the following is not a membrane lipid?
A. Cholesterol
B. Triacylglycerol
C. Phosphatidylcholine
D. Sphingomyelin

A

B. Triacylglycerol

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11
Q

Which of the following neurotransmitters activate
muscle fibers in the neuromuscular junction?
A. Acetylcholine
B. Nicotine
C. Dopamine
D. Serotonin

A

A. Acetylcholine

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12
Q

Which of the following has the highest membrane
permeability coefficient?
A. Water
B. Sodium
C. Glucose
D. Cortisol

A

B. Cortisol

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13
Q

Which of the following is equally distributed (same
concentration) between the inner and outer leaflet of
the lipid bilayer?
A. Phosphatidylcholine
B. Phosphatidylethanolamine
C. Sphingomyelin
D. None of the above

A

D. None of the above

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14
Q

Why is it more common to see lateral flip flops in cell
membranes compared to transverse flip flops?
A. Lateral flip flops happen more spontaneously
compared to transverse flip flops
B. Transverse flip flops tend to cause cell death
C. Transverse flip flops are energy-requiring
changes
D. Lateral flip flops have to happen multiple
times first before a transverse flip flop occurs

A

B. Transverse flip flops tend to cause cell death

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15
Q

All of the following are amphipathic molecules,
EXCEPT:
A. Peripheral membrane proteins
B. Integral membrane proteins
C. Free cholesterol
D. Glycosphingolipids

A

A. Peripheral membrane proteins

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16
Q

Which of the following is a characteristic of a ligand-gated ion channel?
A. It functions by hydrolyzing ATP to transport ions against their gradient.
B. It remains permanently open once activated by a ligand.
C. It opens or closes in response to the binding of a specific molecule.
D. It allows the passage of nonpolar molecules across the membrane.

A

C. It opens or closes in response to the binding of a specific molecule.

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17
Q

What is the primary function of G-protein-coupled receptors (GPCRs)?
A. Directly phosphorylating target proteins in the cell.
B. Serving as ion channels for specific cations and anions.
C. Transmitting signals from extracellular ligands to intracellular G-proteins.
D. Degrading ligands after signal transduction.

A

C. Transmitting signals from extracellular ligands to intracellular G-proteins.

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18
Q

Which of the following does not participate in the signal transduction mechanism of receptor tyrosine kinases (RTKs)?
A. Autophosphorylation of the receptor.
B. Activation of downstream intracellular signaling proteins.
C. Direct binding to and activation of nuclear DNA.
D. Dimerization of the receptor upon ligand binding.

A

C. Direct binding to and activation of nuclear DNA.

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19
Q

In facilitated diffusion, which of the following is true?
A. Molecules move against their concentration gradient with the help of carrier proteins.
B. Energy in the form of ATP is required for the transport process.
C. The transport process is saturable, meaning it can reach a maximum rate.
D. It involves the direct interaction of small nonpolar molecules with the lipid bilayer.

A

C. The transport process is saturable, meaning it can reach a maximum rate.

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20
Q

Which of the following best describes the sodium-potassium pump (Na+/K+ ATPase)?
A. It transports three sodium ions into the cell and two potassium ions out of the cell.
B. It is a passive transport mechanism that does not require energy.
C. It plays a critical role in maintaining the cell’s membrane potential.
D. It allows for the passive diffusion of sodium and potassium ions across the membrane.

A

C. It plays a critical role in maintaining the cell’s membrane potential.

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21
Q

Which of the following statements about active transport is incorrect?
A. Active transport can move molecules from areas of low concentration to high concentration.
B. It requires energy, often in the form of ATP, to function.
C. It is always coupled with the transport of another molecule in the same direction.
D. It often involves carrier proteins that change shape during the transport process.

A

C. It is always coupled with the transport of another molecule in the same direction.

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22
Q

Which of the following types of transport does not require energy input?
A. Active transport
B. Facilitated diffusion
C. Primary active transport
D. Cotransport

A

B. Facilitated diffusion

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23
Q

What is the primary role of cholesterol in the plasma membrane?
A. Increasing membrane permeability to ions
B. Stabilizing membrane fluidity across temperature changes
C. Acting as a receptor for extracellular signals
D. Facilitating the transport of glucose into the cell

A

B. Stabilizing membrane fluidity across temperature changes

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24
Q

Which ion is most commonly pumped out of the cell by the Na+/K+ ATPase?
A. Potassium
B. Sodium
C. Calcium
D. Chloride

A

B. Sodium

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25
Q

What type of transport is involved in moving glucose into the cell using a concentration gradient of sodium?
A. Facilitated diffusion
B. Simple diffusion
C. Cotransport
D. Primary active transport

A

C. Cotransport

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26
Q

Which of the following is not a characteristic of passive transport?
A. Movement along a concentration gradient
B. No energy expenditure
C. Involvement of carrier proteins
D. Requires ATP

A

D. Requires ATP

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27
Q

Which molecule can pass through the lipid bilayer without the need for a transport protein?
A. Glucose
B. Sodium ion
C. Oxygen
D. Protein

A

C. Oxygen

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28
Q

Which of the following best describes the fluid mosaic model of the plasma membrane?
A. A rigid structure with fixed components
B. A solid barrier impermeable to all molecules
C. A dynamic structure with proteins and lipids that move laterally
D. A double-layered membrane with immobile proteins

A

C. A dynamic structure with proteins and lipids that move laterally

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29
Q

What is the function of clathrin in vesicular transport?
A. To hydrolyze ATP for vesicle movement
B. To stabilize the plasma membrane
C. To coat vesicles during endocytosis
D. To act as a ligand for membrane receptors

A

C. To coat vesicles during endocytosis

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30
Q

In receptor-mediated endocytosis, which component binds to the ligand?
A. Clathrin
B. Adaptin
C. Dynamin
D. Receptor protein

A

D. Receptor protein

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31
Q

Which of the following is most directly responsible for the resting membrane potential of a cell?
A. The Na+/K+ ATPase pump
B. Ion channels in the membrane
C. The concentration of glucose in the blood
D. The synthesis of proteins

A

A. The Na+/K+ ATPase pump

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32
Q

What happens when a ligand binds to a G-protein-coupled receptor?
A. The receptor becomes phosphorylated
B. The receptor activates a G-protein
C. The receptor directly opens an ion channel
D. The receptor is endocytosed

A

B. The receptor activates a G-protein

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33
Q

Which of the following ions is typically found in higher concentration inside the cell compared to the outside?
A. Sodium
B. Potassium
C. Chloride
D. Calcium

A

B. Potassium

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34
Q

What is the role of aquaporins in the plasma membrane?
A. Transporting ions
B. Facilitating the diffusion of water
C. Acting as receptors for hormones
D. Transporting glucose

A

B. Facilitating the diffusion of water

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35
Q

Which component of the plasma membrane is primarily responsible for cell-cell recognition?
A. Phospholipids
B. Cholesterol
C. Glycoproteins
D. Integral proteins

A

C. Glycoproteins

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36
Q

Which of the following is true about ion channels?
A. They require ATP to function.
B. They are always open.
C. They are selective for specific ions.
D. They transport ions against their concentration gradient.

A

C. They are selective for specific ions.

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37
Q

Which of the following is not a characteristic of facilitated diffusion?
A. It is a passive process.
B. It involves carrier proteins.
C. It can move substances against their concentration gradient.
D. It does not require energy.

A

C. It can move substances against their concentration gradient.

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38
Q

Which of the following is true about the sodium-potassium pump?
A. It pumps sodium into the cell and potassium out.
B. It requires ATP to function.
C. It is a type of facilitated diffusion.
D. It only operates in nerve cells.

A

B. It requires ATP to function.

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39
Q

What is the function of the endoplasmic reticulum in membrane transport?
A. Synthesizing proteins for secretion
B. Synthesizing ATP for active transport
C. Facilitating the passage of ions across the membrane
D. Degrading misfolded proteins

A

A. Synthesizing proteins for secretion

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40
Q

Which of the following is a second messenger often involved in G-protein-coupled receptor signaling?
A. cAMP
B. ATP
C. Na+
D. Glucose

A

A. cAMP

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41
Q

Which of the following statements is true regarding osmosis?
A. Water moves from an area of low solute concentration to high solute concentration.
B. Water moves from an area of high solute concentration to low solute concentration.
C. Osmosis requires energy in the form of ATP.
D. Osmosis involves the active transport of water molecules.

A

A. Water moves from an area of low solute concentration to high solute concentration.

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42
Q

What role does phosphatidylserine play in the plasma membrane?
A. It is involved in cell signaling.
B. It is responsible for cell-cell adhesion.
C. It triggers apoptosis when found on the outer leaflet.
D. It acts as a receptor for neurotransmitters.

A

C. It triggers apoptosis when found on the outer leaflet.

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43
Q

Which of the following is not involved in the transport of molecules across cell membranes?
A. Ion channels
B. Carrier proteins
C. Ribosomes
D. ATP-powered pumps

A

C. Ribosomes

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44
Q

Which type of molecule typically requires a transport protein to cross the cell membrane?
A. Small nonpolar molecules
B. Large polar molecules
C. Gases like O2 and CO2
D. Lipid-soluble vitamins

A

B. Large polar molecules

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45
Q

What happens when an action potential reaches the axon terminal of a neuron?
A. The membrane potential becomes negative.
B. Voltage-gated calcium channels open.
C. Sodium ions are released into the synaptic cleft.
D. The neuron becomes hyperpolarized.

A

B. Voltage-gated calcium channels open.

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46
Q

Which of the following statements is true about membrane proteins?
A. All membrane proteins are enzymes.
B. They can function as receptors, channels, and transporters.
C. They are always located on the outer surface of the membrane.
D. They cannot move within the membrane.

A

B. They can function as receptors, channels, and transporters.

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47
Q

Which lipid is found in greater concentration in the outer leaflet of the plasma membrane?
A. Phosphatidylinositol
B. Phosphatidylethanolamine
C. Phosphatidylcholine
D. Cardiolipin

A

C. Phosphatidylcholine

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48
Q

Which process is used by cells to take in large molecules or particles?
A. Exocytosis
B. Endocytosis
C. Diffusion
D. Filtration

A

B. Endocytosis

49
Q

Which of the following is not a role of phospholipids in the plasma membrane?
A. Providing fluidity to the membrane
B. Serving as receptors for signaling molecules
C. Forming the basic structure of the membrane
D. Contributing to membrane asymmetry

A

B. Serving as receptors for signaling molecules

50
Q

Which of the following is true about receptor tyrosine kinases (RTKs)?
A. They are involved in G-protein signaling.
B. They dimerize and autophosphorylate upon ligand binding.
C. They directly transport ions across the membrane.
D. They are exclusively found in the nuclear membrane.

A

B. They dimerize and autophosphorylate upon ligand binding.

51
Q

Which type of transport allows glucose to enter cells against its concentration gradient?
A. Simple diffusion
B. Facilitated diffusion
C. Primary active transport
D. Cotransport

A

D. Cotransport

52
Q

Which of the following statements is true about the lipid bilayer?
A. It is impermeable to all molecules.
B. It allows free passage of large, charged molecules.
C. It is composed primarily of phospholipids and proteins.
D. It is symmetric in its lipid composition.

A

C. It is composed primarily of phospholipids and proteins.

53
Q

Which of the following components is not part of the extracellular matrix?
A. Collagen
B. Elastin
C. Phospholipids
D. Proteoglycans

A

C. Phospholipids

54
Q

Which type of receptor directly alters ion flow across the membrane when activated?
A. G-protein-coupled receptor
B. Ionotropic receptor
C. Nuclear receptor
D. Enzyme-linked receptor

A

B. Ionotropic receptor

55
Q

Which of the following describes the role of ATP in active transport?
A. ATP acts as a signal molecule.
B. ATP is hydrolyzed to provide energy for transport.
C. ATP binds to the transported molecules.
D. ATP is not involved in active transport.

A

B. ATP is hydrolyzed to provide energy for transport.

56
Q

Which type of cellular junction prevents the passage of molecules between cells in an epithelial layer?
A. Tight junctions
B. Gap junctions
C. Desmosomes
D. Adherens junctions

A

A. Tight junctions

57
Q

What is the primary function of ion channels?
A. Transporting large molecules
B. Facilitating the movement of ions across the membrane
C. Synthesizing ATP
D. Binding to hormones

A

B. Facilitating the movement of ions across the membrane

58
Q

What triggers the release of neurotransmitters into the synaptic cleft?
A. Opening of potassium channels
B. Opening of voltage-gated calcium channels
C. Closing of sodium channels
D. Activation of receptor tyrosine kinases

A

B. Opening of voltage-gated calcium channels

59
Q

Which of the following is true about phospholipid bilayers?
A. They are rigid and inflexible.
B. They are impermeable to all ions.
C. They can self-assemble in aqueous environments.
D. They require energy to maintain their structure.

A

C. They can self-assemble in aqueous environments.

60
Q

Which molecule is directly responsible for muscle contraction?
A. Acetylcholine
B. ATP
C. Calcium
D. Sodium

A

C. Calcium

61
Q

What role does the Golgi apparatus play in membrane trafficking?
A. Synthesizing membrane lipids
B. Sorting and packaging proteins for transport
C. Degrading misfolded proteins
D. Generating ATP for active transport

A

B. Sorting and packaging proteins for transport

62
Q

Which of the following is true about transmembrane proteins?
A. They are peripheral proteins that do not span the membrane.
B. They are anchored only to the inner leaflet of the membrane.
C. They span the lipid bilayer and may function as channels or receptors.
D. They are composed only of hydrophobic amino acids.

A

C. They span the lipid bilayer and may function as channels or receptors.

63
Q

Which of the following best describes the role of membrane carbohydrates?
A. Providing energy for active transport
B. Facilitating membrane fluidity
C. Mediating cell-cell recognition and adhesion
D. Forming the hydrophobic core of the lipid bilayer

A

C. Mediating cell-cell recognition and adhesion

64
Q

Which type of ion channel opens in response to changes in membrane potential?
A. Ligand-gated ion channel
B. Voltage-gated ion channel
C. Mechanosensitive ion channel
D. Leak ion channel

A

B. Voltage-gated ion channel

65
Q

Which of the following molecules cannot diffuse directly through the lipid bilayer?
A. Oxygen
B. Carbon dioxide
C. Glucose
D. Nitrogen

A

C. Glucose

66
Q

Which of the following is true about the phospholipid bilayer of the cell membrane?
A. The hydrophobic tails face the aqueous environment.
B. The hydrophilic heads face the aqueous environment.
C. It is composed only of phospholipids and proteins.
D. The hydrophilic heads face inward towards each other.

A

B. The hydrophilic heads face the aqueous environment.

67
Q

What is the function of gap junctions in animal cells?
A. Preventing the passage of molecules between cells
B. Allowing direct communication between adjacent cells
C. Anchoring cells to the extracellular matrix
D. Providing structural support to the plasma membrane

A

B. Allowing direct communication between adjacent cells

68
Q

Which of the following is a function of membrane-bound enzymes?
A. Synthesizing ATP from ADP and Pi
B. Transporting ions across the membrane
C. Catalyzing chemical reactions at the membrane surface
D. Binding to extracellular ligands

A

C. Catalyzing chemical reactions at the membrane surface

69
Q

Which ion is most likely to be involved in generating an action potential in neurons?
A. Chloride
B. Sodium
C. Magnesium
D. Phosphate

A

B. Sodium

70
Q

Which of the following is involved in vesicle fusion during exocytosis?
A. Clathrin
B. SNARE proteins
C. Ribosomes
D. DNA

A

B. SNARE proteins

71
Q

Which of the following best describes facilitated diffusion?
A. The passive movement of molecules down their concentration gradient with the aid of a transport protein.
B. The active movement of molecules against their concentration gradient with the aid of ATP.
C. The passive movement of molecules through the lipid bilayer without any protein involvement.
D. The active movement of ions across the membrane coupled with the transport of another molecule.

A

A. The passive movement of molecules down their concentration gradient with the aid of a transport protein.

72
Q

What is the primary function of ionotropic receptors?
A. They directly alter gene expression.
B. They directly change ion flow across the membrane.
C. They are involved in endocytosis.
D. They catalyze the conversion of ATP to cAMP.

A

B. They directly change ion flow across the membrane.

73
Q

Which of the following is a characteristic of a carrier protein?
A. It forms a continuous pore through the membrane.
B. It binds to a specific molecule and undergoes a conformational change.
C. It requires ATP to function.
D. It is always open and non-selective.

A

B. It binds to a specific molecule and undergoes a conformational change.

74
Q

Which process involves the engulfing of large particles by the cell membrane?
A. Pinocytosis
B. Phagocytosis
C. Exocytosis
D. Transcytosis

A

B. Phagocytosis

75
Q

What type of molecule is most likely to pass through the cell membrane without assistance?
A. A small, nonpolar molecule
B. A large, polar molecule
C. An ion
D. A protein

A

A. A small, nonpolar molecule

76
Q

Which of the following best describes the function of the Na+/K+ ATPase?
A. It maintains the membrane potential by exchanging three sodium ions for two potassium ions.
B. It facilitates passive diffusion of sodium and potassium ions.
C. It transports glucose into the cell.
D. It synthesizes ATP using the energy of ion gradients.

A

A. It maintains the membrane potential by exchanging three sodium ions for two potassium ions.

77
Q

What is the main role of caveolae in the plasma membrane?
A. They serve as sites for clathrin-mediated endocytosis.
B. They are involved in signal transduction and endocytosis.
C. They anchor cytoskeletal elements to the membrane.
D. They facilitate the movement of large molecules across the membrane.

A

B. They are involved in signal transduction and endocytosis.

78
Q

What triggers the opening of ligand-gated ion channels?
A. A change in membrane potential
B. The binding of a specific ligand
C. Mechanical stress on the membrane
D. The phosphorylation of the channel

A

B. The binding of a specific ligand

79
Q

Which of the following best describes the function of membrane rafts?
A. They increase the fluidity of the membrane.
B. They are involved in cell signaling and protein sorting.
C. They prevent the movement of proteins within the membrane.
D. They serve as barriers to the passage of ions.

A

B. They are involved in cell signaling and protein sorting.

80
Q

Which of the following processes requires energy in the form of ATP?
A. Facilitated diffusion
B. Osmosis
C. Active transport
D. Simple diffusion

A

C. Active transport

81
Q

What is the main function of the extracellular matrix (ECM)?
A. To regulate ion transport across the membrane
B. To provide structural support and regulate cell behavior
C. To facilitate intracellular signaling
D. To transport oxygen and nutrients to cells

A

B. To provide structural support and regulate cell behavior

82
Q

Which of the following proteins is involved in the formation of tight junctions?
A. Integrins
B. Claudins
C. Cadherins
D. Collagen

A

B. Claudins

83
Q

Which type of transport involves the movement of two substances in the same direction across the membrane?
A. Antiport
B. Symport
C. Uniport
D. Facilitated diffusion

A

B. Symport

84
Q

What role do integrins play in the plasma membrane?
A. They facilitate ion transport across the membrane.
B. They mediate cell adhesion to the extracellular matrix.
C. They act as receptors for steroid hormones.
D. They pump protons into lysosomes.

A

B. They mediate cell adhesion to the extracellular matrix.

85
Q

Which type of receptor typically activates intracellular signaling cascades involving second messengers?
A. Ionotropic receptor
B. G-protein-coupled receptor (GPCR)
C. Nuclear receptor
D. Enzyme-linked receptor

A

B. G-protein-coupled receptor (GPCR)

86
Q

Which of the following is true about membrane potential?
A. It is the same across all cell types.
B. It is established by the movement of water across the membrane.
C. It is primarily maintained by ion gradients across the membrane.
D. It is independent of ion channels.

A

C. It is primarily maintained by ion gradients across the membrane.

87
Q

What is the role of dynamin in endocytosis?
A. To stabilize the clathrin-coated vesicle
B. To hydrolyze ATP for vesicle formation
C. To pinch off the vesicle from the plasma membrane
D. To transport the vesicle to the lysosome

A

C. To pinch off the vesicle from the plasma membrane

88
Q

Which of the following molecules is typically involved in the formation of gap junctions?
A. Connexins
B. Cadherins
C. Selectins
D. Actin

A

A. Connexins

89
Q

Which of the following is true about lipid-anchored proteins?
A. They span the entire lipid bilayer.
B. They are covalently attached to a lipid molecule within the membrane.
C. They freely move within the membrane.
D. They are found only on the cytoplasmic side of the membrane.

A

B. They are covalently attached to a lipid molecule within the membrane.

90
Q

What is the function of the sodium-glucose cotransporter (SGLT)?
A. It transports glucose into cells independently of sodium.
B. It uses the sodium gradient to drive glucose uptake into cells.
C. It pumps sodium out of the cell in exchange for glucose.
D. It transports glucose out of the cell against its concentration gradient.

A

B. It uses the sodium gradient to drive glucose uptake into cells.

91
Q

Which of the following is a function of phosphatidylinositol (PI) in the plasma membrane?
A. It serves as a precursor for second messengers.
B. It stabilizes membrane fluidity.
C. It forms the core structure of lipid rafts.
D. It acts as a primary ion channel in the membrane.

A

A. It serves as a precursor for second messengers.

92
Q

What is the role of SNARE proteins in vesicular transport?
A. They coat vesicles during endocytosis.
B. They facilitate the fusion of vesicles with target membranes.
C. They bind ligands for receptor-mediated endocytosis.
D. They transport vesicles along microtubules.

A

B. They facilitate the fusion of vesicles with target membranes.

93
Q

Which of the following processes is involved in the degradation of membrane proteins?
A. Phagocytosis
B. Ubiquitination and proteasomal degradation
C. Exocytosis
D. Endocytosis followed by lysosomal degradation

A

D. Endocytosis followed by lysosomal degradation

94
Q

What is the primary function of desmosomes?
A. To allow the passage of ions between cells
B. To anchor intermediate filaments to the plasma membrane
C. To prevent the movement of molecules between cells
D. To facilitate cell-cell communication

A

B. To anchor intermediate filaments to the plasma membrane

95
Q

Which of the following ions is most closely associated with the depolarization phase of an action potential?
A. Sodium (Na+)
B. Potassium (K+)
C. Chloride (Cl-)
D. Calcium (Ca2+)

A

A. Sodium (Na+)

96
Q

Which of the following is not a function of the plasma membrane?
A. Protecting the cell from its external environment
B. Regulating the passage of substances into and out of the cell
C. Storing genetic information
D. Facilitating cell signaling

A

C. Storing genetic information

97
Q

What type of transport is primarily involved in maintaining the resting membrane potential?
A. Simple diffusion
B. Secondary active transport
C. Facilitated diffusion
D. Primary active transport

A

D. Primary active transport

98
Q

Which of the following best describes an electrochemical gradient?
A. A difference in ion concentration across a membrane
B. A combination of a chemical gradient and an electrical gradient
C. The movement of molecules against their concentration gradient
D. A measure of the membrane’s permeability to ions

A

B. A combination of a chemical gradient and an electrical gradient

99
Q

What is the primary role of glycoproteins in the plasma membrane?
A. Structural support
B. Ion transport
C. Cell recognition and signaling
D. Membrane fluidity regulation

A

C. Cell recognition and signaling

100
Q

Which type of cellular junction is primarily involved in anchoring cells to one another?
A. Tight junctions
B. Gap junctions
C. Desmosomes
D. Hemidesmosomes

A

C. Desmosomes

101
Q

Which type of membrane protein is involved in cell-cell adhesion?
A. Transporters
B. Enzymes
C. Cadherins
D. Ion channels

A

C. Cadherins

102
Q

What is the primary function of the Na+/K+ ATPase pump?
A. To move sodium into the cell and potassium out
B. To maintain the concentration gradients of Na+ and K+ across the membrane
C. To facilitate the diffusion of water across the membrane
D. To generate ATP

A

B. To maintain the concentration gradients of Na+ and K+ across the membrane

103
Q

What happens when a ligand binds to an enzyme-linked receptor?
A. The receptor opens an ion channel
B. The receptor dimerizes and activates its enzymatic function
C. The receptor is internalized by endocytosis
D. The receptor changes its conformation but remains inactive

A

B. The receptor dimerizes and activates its enzymatic function

104
Q

Which of the following is a common characteristic of ion channels?
A. They require ATP to function
B. They are specific for certain ions
C. They are always open
D. They can only transport ions out of the cell

A

B. They are specific for certain ions

105
Q

Which type of transport involves the movement of water across a semipermeable membrane?
A. Diffusion
B. Osmosis
C. Active transport
D. Endocytosis

A

B. Osmosis

106
Q

Which molecule typically triggers the opening of ligand-gated ion channels?
A. Calcium ions
B. Neurotransmitters
C. Glucose
D. ATP

A

B. Neurotransmitters

107
Q

What is the role of peripheral membrane proteins?
A. To act as ion channels
B. To span the lipid bilayer
C. To attach to the membrane temporarily for signaling or structural purposes
D. To pump ions across the membrane

A

C. To attach to the membrane temporarily for signaling or structural purposes

108
Q

Which of the following best describes the role of phosphatidylinositol in the plasma membrane?
A. Structural support
B. Cell-cell adhesion
C. Signal transduction
D. Maintaining membrane fluidity

A

C. Signal transduction

109
Q

Which of the following processes is responsible for the uptake of solid particles into the cell?
A. Pinocytosis
B. Phagocytosis
C. Exocytosis
D. Simple diffusion

A

B. Phagocytosis

110
Q

Which molecule serves as the energy currency of the cell, often used to power active transport?
A. Glucose
B. ATP
C. GTP
D. ADP

A

B. ATP

111
Q

What is the function of connexins in the plasma membrane?
A. To bind to ligands for signal transduction
B. To form channels that allow direct communication between adjacent cells
C. To act as receptors for neurotransmitters
D. To stabilize the membrane structure

A

B. To form channels that allow direct communication between adjacent cells

112
Q

Which process describes the movement of molecules from an area of high concentration to an area of low concentration?
A. Active transport
B. Facilitated diffusion
C. Osmosis
D. Diffusion

A

D. Diffusion

113
Q

Which of the following is true about exocytosis?
A. It is a form of passive transport.
B. It involves the release of substances from the cell via vesicles.
C. It requires the cell to engulf large particles.
D. It occurs only in prokaryotic cells.

A

B. It involves the release of substances from the cell via vesicles.

114
Q

Which type of membrane receptor is most directly associated with the activation of intracellular signaling cascades?
A. G-protein-coupled receptors
B. Ion channels
C. Nuclear receptors
D. Structural proteins

A

A. G-protein-coupled receptors

115
Q

Which of the following is true about passive transport?
A. It requires energy input from ATP.
B. It can only occur in the presence of transport proteins.
C. It moves substances against their concentration gradient.
D. It moves substances down their concentration gradient.

A

D. It moves substances down their concentration gradient.

116
Q

Which of the following best describes the role of calcium ions in cellular signaling?
A. Calcium ions act as a primary messenger that binds to receptors on the cell surface.
B. Calcium ions enter the cell through ligand-gated channels and activate intracellular enzymes.
C. Calcium ions are stored in the Golgi apparatus and released into the cytoplasm during signaling.
D. Calcium ions directly bind to DNA to regulate gene expression.

A

B. Calcium ions enter the cell through ligand-gated channels and activate intracellular enzymes.

117
Q

Which type of protein spans the entire plasma membrane and is involved in transporting molecules across the membrane?
A. Peripheral proteins
B. Integral proteins
C. G-proteins
D. Structural proteins

A

B. Integral proteins

118
Q

What is the primary function of receptor tyrosine kinases (RTKs)?
A. To transport ions across the membrane
B. To phosphorylate specific target proteins after ligand binding
C. To act as channels for water and small solutes
D. To facilitate vesicular transport

A

B. To phosphorylate specific target proteins after ligand binding

119
Q

Which of the following best describes the process of pinocytosis?
A. The cell engulfs large particles or entire cells.
B. The cell takes in liquid and small solutes by forming vesicles.
C. The cell releases substances into the extracellular space.
D. The cell transports ions through ion channels.

A

B. The cell takes in liquid and small solutes by forming vesicles.

Module 1A (5 decks)

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