Deck 5: Transport Across the Plasma Membrane

Question 1

What types of cellular energy do cells use to move substances through the membrane uphill of their gradients?

A) thermal energy
B) kinetic energy of matter
C) chemical energy from ATP
D) gravitational energy

Answer 1

C

Question 2

Which word do physiologists use to describe the property of the membrane that means that some substances move through it easier than the others?

A) selectively soluble
B) selectively permeable
C) concentration graded
D) electrically graded

Answer 2

B

Question 3

Which type of membrane transport will still be possible when there is not enough oxygen available for producing adequate levels of ATP, such as during anaerobic exercise or in high altitudes ?

A) flow of ions through channels
B) transport of glucose by GLUT carriers
C) pumping Na⁺ and K⁺ by the Na⁺/K⁺ ATPase
D) All of the choices are correct.
E) both flow of ions through the channels and transport of glucose by GLUT carriers

Answer 3

E

Question 4

A concentration gradient can be described as

A) a difference in a substance's concentration in two different places in the cell
B) a difference in a substance's concentration on two sides of the membrane
C) Both statements describe concentration gradient.
D) None of the descriptions is correct.

Question 5

In passive transport modes such as simple or facilitated diffusion

A) substances move from lower to higher concentration
B) no cellular energy is used
C) cells end up building the gradient of transported substance
D) molecules tend to gather in one region of the cell

Question 6

What is chemical nature of membrane components that enable cells to move substances that cannot cross by the process of simple diffusion in and out of the cell?

A) phospholipids
B) carbohydrates
C) proteins
D) glycolipids

Question 7

Only excitable cells, such as neurons and muscle, maintain the concentration gradient of Na⁺ and K⁺ ions across their membranes.

Question 8

Substances moving through membranes in the process of diffusion

A) move according to their innate kinetic energy
B) move faster the smaller the concentration difference
C) end up on the wrong side of the membrane
D) move away from equilibrium concentration

Question 9

Every cell in multicellular organism maintains concentration gradients of ions across the plasma membrane.

Question 10

Which of these is an example of chemical gradient that exists in healthy living systems?

A) concentrations of Na⁺ inside the red blood cell and in the blood plasma
B) concentrations of K⁺ in blood and in cytoplasm of the muscle cell
C) concentrations of Ca²⁺ inside the sarcoplasmic reticulum and sarcoplasm of muscle cells between contractions
D) All of the choices are examples of chemical gradient.

Question 11

Cells that have reached equilibrium of all ion concentrations on both sides of the membrane are

A) in perfect health
B) dead
C) excited
D) polarized
E) energized

Question 12

A transport system that does not use any form of cellular energy is usually called

A) passive
B) active
C) efficacious
D) irreversible

Question 13

Simple diffusion relies on the

A) kinetic energy that all particles have
B) chemical energy of ATP bonds
C) energy of gradients of another molecule
D) energy of enzymatic reactions

Question 14

Membrane transport is classified as active when it

A) proceeds down the gradient
B) is reversible
C) requires input of energy
D) reaches equilibrium

Question 15

Selective permeability of the biological membrane means that

A) the membrane is made only of selected phospholipids
B) all molecules are able to pass through the membrane
C) no molecules can cross the membrane
D) various molecules pass through the membrane with various "easiness"

Question 16

Secondary active transport relies on the energy of

A) ATP hydrolysis
B) electrochemical gradients
C) magnetic pull between molecules
D) gravity

Question 17

Diffusion is a mode of membrane transport in which

A) substances move only against the gradient
B) substances move down concentration gradient
C) substances move toward higher concentration
D) substances move uphill along the gradient

Question 18

Without using cellular energy, molecules can move into and out of cells by

A) passing through channels
B) binding to a carrier protein
C) diffusing through the plasma membrane
D) All of the choices are correct.

Question 19

Which of the following transport proteins are integral membrane proteins?

A) ion channel
B) pump
C) symporter
D) antiporter
E) All of the choices are correct.

Question 20

Diffusion is a mode of cellular transport across the membrane in which

A) a cell hydrolyzes ATP to power the transport
B) a cell uses water to drive the transport
C) proceeds only if the is sufficient availability of ATP in the cell
D) particles move randomly because of their intrinsic kinetic energy

Question 21

The rate of simple diffusion of CO₂ through the cell membranes of lung cells in a crowded room (higher concentration of CO₂ in the air), in comparison to outdoors, is

A) faster
B) slower
C) the same

Question 22

Fatty acids' transport from blood to the cells, that proceeds by simple diffusion due to their hydrophobic nature proceeds at a greater rate when

A) there is a steeper concentration gradient between blood and the cell
B) molecular mass of a fatty acid is higher
C) when the cells have smaller surface area
D) when the core body temperature is below normal

Question 23

If the solute concentration is greater inside the cell than outside the cell, water will move by osmosis

A) into the cell
B) out of the cell
C) in equal amount into and out of the cell
D) toward lower concentration of solute

Question 24

When a poisonous carbon monoxide gas (CO) crosses the membranes of cells lining the lungs to get to blood in the process of simple diffusion, the rate of transport is dependent on

A) temperature
B) surface area of the lungs
C) distance between lung space and blood vessels
D) All of the choices are correct.

Question 25

Osmosis is a process when

A) solutes move through a selectively permeable membrane
B) solutes move against the gradient
C) solvent moves to the area of higher concentration of solutes
D) solvent moves to the lower concentration of solutes

Question 26

Which of the following conditions DO NOT affect the rate of diffusion of a chemical across a plasma membrane?

A) concentration gradient of the chemical across the membrane
B) mass of the diffusing chemical
C) distance that the chemical has to cross
D) amount of ATP available
E) temperature

Question 27

A steroid hormone cortisol is a very hydrophobic substance that enters the cell by the process of simple diffusion. What conditions increase to the speed of transport of cortisol into the cells?

A) lower temperature
B) higher temperature
C) lower membrane fluidity
D) more proteins in the membrane

Question 28

Which sentence best describes simple diffusion?

A) transport capacity by simple diffusion can max out when all transport proteins are occupied
B) transport by simple diffusion relies on the energy derived from ATP hydrolysis
C) transport by simple diffusion is unregulated, and proceeds until there is no concentrations gradient
D) transport by simple diffusion is always proceeding in one direction, no matter what the gradient

Question 29

The process of osmosis

A) does not use ATP
B) uses energy from ATP to move water against the gradient
C) pumps water towards the lower concentration of solute
D) removes water away from the higher concentration of solute

Question 30

Higher concentration of polyunsaturated fatty acids, such as omega-3, that increases membrane fluidity and the number of gaps in the phospholipid bilayer

A) increase the rate of simple diffusion
B) decrease the rate of simple diffusion
C) do not affect the rate of simple diffusion
D) stop simple diffusion

Question 31

Which of the following is typical of carrier mediated facilitated diffusion?

A) it couples the movement of one molecule against the concentration gradient to the movement of another molecule down the gradient
B) it uses permanent pores in the membrane to move molecules in and out of the cells
C) it accelerates a process that is already energetically favorable
D) it uses intrinsic ATPase activity of carrier proteins to bring needed substance into the cell

Question 32

Respiratory gases, such as O₂ and CO₂, move through the cell membranes by

A) simple diffusion
B) carrier mediated facilitated diffusion
C) channel mediated facilitated diffusion
D) gas pumps

Question 33

Higher membrane fluidity and increased number of gaps in the phospholipid bilayer

A) increases transport of glucose into neurons
B) decreases transport of glucose into neurons
C) will not change transport of glucose into neurons
D) increases expression of channels in neurons

Question 34

What is the name of the membrane transport protein responsible for water movement across the membranes of the cells?

A) aquaporin
B) Na⁺/water symporter
C) Na⁺/water antiporter
D) water pump

Question 35

What is the measure of a solution's ability to change the volume of cells by altering their water content?

A) osmolarity
B) tonicity
C) normality
D) molarity

Question 36

Which of the following molecules has the highest rate of simple diffusion across the phospholipid bilayer?

A) laughing gas (N₂O)
B) glucose
C) K⁺
D) lysine

Question 37

Carbon dioxide is a product of cellular metabolism and has to be removed from cells. It leaves the cells by

A) receptor mediated endocytosis
B) simple diffusion
C) carrier mediated facilitated diffusion
D) carbon monoxide pump

Question 38

Higher number of gaps between fatty acid tails in phospholipid bilayers will ______ the rate of simple diffusion.

A) increase
B) decrease
C) will not change

Question 39

During pneumonia a layer of fluid accumulates in the alveoli adding a layer to the distance O₂ has to cross on its way to red blood cells and hemoglobin. The rate of O₂ diffusion in pneumonia will be

A) higher
B) lower
C) not changed
D) faster

Question 40

Nonpolar hydrophobic molecules such as steroids move across cell membranes by

A) primary active transport
B) secondary active transport
C) simple diffusion
D) carrier mediated facilitated diffusion

Question 41

What is the name of the membrane transport proteins which primary function is to create and maintain a chemical gradient across the cell membrane's

A) pumps
B) ion channels
C) symporters
D) secondary proteins

Question 42

GLUT, the glucose transporter protein is a

A) channel
B) pump
C) carrier
D) symporter

Question 43

Osmosis is a process when

A) only solutes move
B) only solvents move
C) solutes move against concentration gradient
D) solutes move with natural kinetic energy

Question 44

Carrier proteins such as the glucose transporter GLUT

A) can be open to both sides of the membrane at the same time
B) undergo significant conformational change during transport
C) provide high resistance passage for the substance to cross
D) always transport in the same direction

Question 45

Flow of ions through the small pores in the cell membrane called ion channels is an example of what mode of transport?

A) simple diffusion
B) facilitated diffusion
C) primary active transport
D) secondary active transport

Question 46

Which membrane transporters are small, highly selective pores in the cell membrane?

A) pumps
B) ion channels
C) carriers
D) symporters

Question 47

What is a property of carrier mediated facilitated diffusion that distinguishes it from simple diffusion?

A) saturation of transport
B) direction of molecule movement
C) use of energy from ATP
D) reversibility

Question 48

GLUT4, the insulin regulated glucose carrier is expressed in

A) every cell
B) adipocytes
C) gametes only
D) neurons only

Question 49

Which insulin transport protein (GLUT) is found in most tissues in the body and is expressed regardless of insulin presence or absence in the blood?

A) GLUT1
B) GLUT2
C) GLUT3
D) GLUT4

Question 50

Carrier proteins on the cell membrane can never be saturated

Question 51

Movement of ions through open ion channels

A) requires ATP hydrolysis to power the transport
B) proceeds down the concentration gradient for the ion
C) is faster the more gaps the phospholipid bilayer has
D) is always connected to movement of another ion in opposite direction

Question 52

Gradients of Na⁺ and K⁺ created by sodium-potassium pump

A) are critical for the ability of some cells to generate electrical signals
B) can be used by secondary active transporters to move other molecules
C) are critical for maintaining normal cell volume
D) All of the choices depend on ion gradients.

Question 53

Carrier mediated facilitated diffusion

A) stops when the transported substance reaches equilibrium concentration
B) proceeds until all of the substance is transported to the other side
C) depends on physical gaps of the phospholipid bilayer
D) is never reversible

Question 54

Tonicity of a solution is proportional to the

A) concentration of solute particles that cannot cross the membrane
B) amount of water in the cell
C) temperature of the solution
D) size of the solute molecules that cross the membrane

Question 55

When glucose is transported by GLUT in and out of liver cells

A) it travels against the glucose concentration gradient
B) it travels down the glucose concentration gradient
C) it always goes in
D) it always exits the cell

Question 56

A function of Na⁺/K⁺ ATPase is to

A) maintain high extracellular concentration of K⁺
B) maintain low intracellular concentration of Na⁺
C) remove K⁺ from cytosol
D) bring the Na⁺ into the cell

Question 57

In the human body, intracellular Na⁺ concentration is lower than extracellular Na⁺ concentration. If the gate of a sodium channel opens, which way will Na⁺ flow?

A) into the cell because of the gradient
B) out of the cell against the gradient
C) Na⁺ won't flow unless there is ATP round
D) it depends what type of Na⁺ channels open

Question 58

Which of the following statements is correct concerning facilitated diffusion?

A) it requires an input of energy
B) it allows diffusion to proceed against a gradient
C) occurs via a carrier protein
D) All of the choices are correct.

Question 59

Ion pumps such as the sodium-potassium pump that are powered by ATP hydrolysis

A) transport ions or small molecules down a concentration/electric-potential gradient
B) produce an equilibrium distribution of the transported ion across the membrane
C) transport ions or small molecules against a concentration/electric-potential gradient
D) can readily derive energy from other nucleoside triphosphates such as GTP

Question 60

A gradient of Na⁺ created by Na⁺/K⁺ ATPase across a cell membrane can be used as a driving force to

A) move substances by secondary active transporters
B) move substances like glucose into the cells
C) move substances like Ca²⁺ out of cells
D) All of the choices are correct.

Question 61

Symporters

A) are a form of facilitated diffusion
B) transport two molecules in the SAME direction
C) transport two molecules in OPPOSITE directions
D) None of the choices is correct.

Question 62

If the sodium glucose symporter in the intestinal epithelium was defective as happens in the GGMS (glucose galactose malabsorption syndrome), blood glucose levels after the meal would be

A) higher than in a healthy person
B) lower than in a healthy person
C) "sky high" indicating diabetes mellitus
D) fluctuating widely

Question 63

Tight junctions in epithelial cells

A) are located at the center of gap junctions
B) permit lipid diffusion between two adjacent cells
C) make easier the passage of substances between cells in the epithelium
D) separate the basolateral and apical surfaces of epithelial cells

Question 64

Which of the following statements concerning receptor-mediated endocytosis is FALSE?

A) it is a form of specific transport
B) it is a process by which cells internalize molecules
C) it occurs via clathrin coated pits
D) it is a form of passive transport

Question 65

Receptor mediated endocytosis is used to

A) transport glucose into the cell
B) remove calcium from the cell
C) create ion gradients across the membrane
D) bring particles such as LDL to the endosomes

Question 66

Which transporter, on the apical side of intestinal epithelium, is responsible for absorbing glucose from the bagel you ate for breakfast into the intestinal epithelial cells?

A) GLUT carrier protein
B) sodium glucose symporter
C) glucose pump
D) sodium channel

Question 67

What is the source of energy used for transport of Na⁺ ions out of the cell and K⁺ ions into the cell by the sodium/potassium pump?

A) ATP hydrolysis
B) gradient of Na⁺
C) no energy is needed, it's simple diffusion
D) electrical gradient of Na⁺ and K⁺

Question 68

The process of vesicle docking and fusion depends on

A) pairing of the SNAREs on the vesicle and destination membrane
B) presence of appropriate coat proteins on both vesicle and destination membrane
C) Both of the choices are correct.
D) None of the choices is correct.

Question 69

The process that uses vesicles to secrete materials into the extracellular fluid is called

A) exocytosis
B) expansion
C) endocytosis
D) endotoxicosis

Question 70

The Na⁺/glucose symporter in the apical membrane of the intestinal epithelial cells

A) uses a glucose gradient to bring Na⁺ in
B) uses a combination of Na⁺/ K⁺ to bring glucose in
C) uses a 2Na⁺/3K⁺ ATPase in the basolateral membrane to bring glucose in
D) uses a Na⁺ gradient to bring glucose in

Question 71

Choose the answer that best describes the movement of molecules by symporters and antiporters.

A) In both symporters and antiporters one molecule is moving down the gradient and the other molecule is moving against the gradient.
B) In symporters, both molecules move in the same direction and against their gradient.
C) In antiporters the molecules move in the opposite direction and both move down their gradient.
D) Symporters move two molecules in opposite directions and antiporters move two molecules in the same direction.

Question 72

Once imported to the cell in the process of receptor mediated endocytosis, LDL molecules are

A) recycled to the cell surface
B) degraded in lysosomes
C) sorted in trans-Golgi
D) sorted in ER

Question 73

Glucose that got absorbed into intestinal epithelial cells exits from intestinal epithelial cells to blood via

A) passive diffusion
B) glucose pump
C) GLUT transporter
D) sodium glucose symporter

Question 74

When low density lipoproteins (LDL) are brought into the cell in the process of receptor mediated endocytosis

A) LDL receptors are degraded in lysosomes
B) LDL receptors are recycled to the cell membrane
C) LDL particles are recycled to the cell membrane
D) LDL particles are excluded from the endocytic vesicles

Question 75

The process of internalization of extracellular molecules into vesicles is called

A) exocytosis
B) expansion
C) endocytosis
D) endotoxicosis

Question 76

Why is the magnitude of Na⁺ electrochemical gradient created by the Na⁺/K⁺ pump larger than the magnitude of K⁺ electrochemical gradient?

A) because K⁺ chemical and electrical gradients occur in the same direction whereas Na⁺ electrical and chemical gradients occur in opposite directions
B) because Na⁺ chemical and electrical gradients occur in the same direction whereas K+ electrical and chemical gradients occur in opposite directions
C) because Na⁺ is a bigger ion than potassium
D) because Na⁺ gradient is directed toward the inside of the cell