Deck 5: Cell Membranes and Signalling

Question 1

Which phrase describes the selective permeability of a membrane?

A)the ability of a molecule to pass through a membrane
B)the ability of only certain molecules to pass across a membrane
C)the need for carrier proteins to transport certain molecules
D)the movement of a molecule from an area of greater concentration to an area of lesser concentration

Answer 1

B

Question 2

Unsaturated fatty acids cause a membrane to be fluid at lower temperatures. What is a reasonable explanation for this?

A)Unsaturated fatty acids permit more water into the interior of the membrane.
B)The double bonds form a kink in the fatty acid tail, forcing adjacent lipids to be spaced farther apart.
C)The double bonds in the unsaturated fatty acids block interaction among the hydrophilic head groups of the lipids.
D)Unsaturated fatty acids have a higher cholesterol content.

Answer 2

B

Question 3

What is the primary function of a cellular membrane?

A)recognizing other cells as being "like"
B)controlling the transport of substances into and out of cells
C)recognizing chemical signals from other cells
D)cell-cell binding

Answer 3

B

Question 4

How are the membranes of animal cells in winter able to remain fluid when the weather becomes extremely cold?

A)The percentage of both unsaturated phospholipids and cholesterol increases.
B)The percentage of saturated phospholipids in the membrane decreases.
C)The percentage of unsaturated phospholipids in the membrane decreases.
D)The percentage of cholesterol molecules in the membrane increases.

Question 5

Certain organisms such as the striped bass (Morone saxatilis) are able to migrate between the ocean and freshwater streams. Consider when the striped bass migrates into freshwater streams. Which of the following situations would be necessary to maintain life?

A)Water must be kept within the cells while ions are kept out.
B)The plasma membrane of the organism must change its glycolipid composition.
C)The plasma membrane of the organism must change its phospholipid composition.
D)Ions must be kept within the cells while water is kept out.

Question 6

Why do the cells die when the ambient temperature drops to freezing?

A)because of the increased cellular signalling inside the cell
B)because of the inhibition of cell division
C)because of the inhibition of molecule transport across the cell membrane
D)because of the increased metabolic reactions inside the cell

Question 7

In an aqueous environment, how are the phospholipids of a membrane arranged?

A)in a single layer
B)in a bilayer, with the fatty acid tails located at the surface
C)in a bilayer, but the phospholipids have no specific orientation
D)in a bilayer, with the polar heads of each layer located at the surface

Question 8

When referring to membrane glycolipids and glycoproteins, what does the prefix "glyco-" indicate?

A)polar carbohydrate groups that are attached to the molecules
B)nonpolar carbohydrate groups that are attached to the molecules
C)the molecules that are attached to the membrane by ionic bonds
D)the molecules that are attached to the membrane by covalent bonds

Question 9

Which type of lipid is most important in the structure of biological membranes?

A)wax
B)cholesterol
C)phospholipid
D)fat

Question 10

Suppose you are comparing the outside and inside halves of a cell membrane's phospholipid bilayer. Which of the following describes the composition of the lipids on the two surfaces?

A)symmetrical but not identical composition
B)asymmetrical composition
C)highly random and varied composition
D)identical composition

Question 11

What does the "mosaic" part of the fluid mosaic model refer to?

A)the membrane cholesterol
B)the membrane functions
C)the membrane proteins
D)the membrane phospholipids

Question 12

Which of the following strongly suggests that the membrane is exposed to low temperature?

A)Ions such as K⁺, Na⁺, and Ca⁺ begin to freely leak across the membrane.
B)Molecular motion may increase.
C)Molecular motion may decrease.
D)The membrane may become too fluid.

Question 13

One component of the cell membrane functions as a selective barrier, and one component has specific functions such as transport, recognizing other cells, and binding to other cells. Which pair of terms refers to these two components, respectively?

A)carbohydrate and nucleic acid
B)lipid and carbohydrate
C)protein and carbohydrate
D)lipid and protein

Question 14

In the fluid mosaic model of cell membranes, what does the "fluid" part of the model refer to?

A)the constant movement of the hydrophilic tails in the interior of the membrane
B)the phospholipid molecules, which freely move and exchange places with other lipids within the same half of the bilayer
C)the free movement of cholesterol molecules within the membrane
D)a thin layer of water found sandwiched between the two layers of phospholipids

Question 15

Cells must constantly bring in certain molecules and ions while keeping others out. What part of the cell accomplishes this function?

A)the vesicles
B)the plasma membrane
C)the nucleus
D)the lysosomes

Question 16

What are the major structural components of a cell membrane?

A)glycolipids and cellulose
B)glycolipids and proteins
C)phospholipids and cellulose
D)phospholipids and proteins

Question 17

Of the molecules found in membranes, which demonstrate dual solubility characteristics?

A)proteins, ions, and glycolipids
B)proteins, phospholipids, and glycolipids
C)proteins, sterols, and ions
D)proteins, sterols, and phospholipids

Question 18

Suppose that Joe Scientist fuses a mouse cell and a human cell, and then treats the cell with specific antibodies covalently linked to fluorescent dyes (antibodies linked to mouse proteins are green; antibodies linked to human proteins are red). What will the cell look like immediately after labelling?

A)The red and green fluorescent labels will be uniformly distributed across the entire membrane of the cell.
B)The cell will be half red and half green.
C)The red and green labels will be distributed in the cell in intermingled patches.
D)The red and green labels will flash in the cell intermittently.

Question 19

Which of the following is a function of the sterols that are found in animal cell membranes?

A)They maintain membrane fluidity.
B)They facilitate ion transport.
C)They store cellular energy.
D)They increase the rate of diffusion.

Question 20

Suppose that Joe Scientist fuses a mouse cell and a human cell, and then treats the cell with specific antibodies covalently linked to fluorescent dyes (antibodies linked to mouse proteins are green; antibodies linked to human proteins are red). Forty minutes later, Joe Scientist looks at the fused cell. What will Joe Scientist observe?

A)The red and green labels will be distributed in intermingled patches.
B)The red and green fluorescent labels will be uniformly distributed across the entire membrane.
C)The red and green labels will flash intermittently.
D)The cell will be half red and half green.

Question 21

Which terms refer to the movement of water across a membrane from an area of lower solute concentration to a region of higher solute concentration?

A)both endocytosis and active transport
B)both diffusion and endocytosis
C)both active transport and osmosis
D)both diffusion and osmosis

Question 22

How do small polar and charged molecules typically cross the cell membrane?

A)by facilitated diffusion
B)by osmosis
C)by active transport
D)by filtration

Question 23

What are aquaporins?

A)spaces that transport water molecules
B)pores made of water molecules
C)protein channels for water transport
D)pores found only in bacterial cells

Question 24

Suppose a drop of food colouring is placed in a container of clear water. What happens to the coloured dye molecules?

A)They undergo osmosis at the top of the container.
B)They diffuse to the top of the container.
C)They undergo osmosis equally throughout the container.
D)They diffuse equally throughout the container.

Question 25

Why do transmembrane proteins have domains?

A)because they have to interact with both foreign DNA and the hydrophobic core
B)because they have to recognize cancer cells
C)because the cell needs them in order to reproduce
D)because they have to interact with both the aqueous environment and the hydrophobic core

Question 26

Suppose water moves across a membrane from an area of high water concentration to an area of low water concentration. What is this an example of?

A)both diffusion and osmosis
B)both osmosis and active transport
C)both diffusion and endocytosis
D)both endocytosis and active transport

Question 27

What is responsible for the selective permeability of a cell membrane?

A)the position of cholesterol in the membrane bilayer
B)the integral proteins of the membrane
C)the hydrophobic core formed by the phospholipid tails
D)the hydrophilic end facing the cell exterior

Question 28

Which of the following is absolutely necessary for diffusion to occur?

A)a phospholipid bilayer
B)a living cell
C)a selectively permeable membrane
D)a concentration gradient

Question 29

How are peripheral and transmembrane proteins different?

A)Transmembrane proteins are primarily nonpolar, while peripheral proteins are polar.
B)Transmembrane proteins are primarily nonpolar, while peripheral proteins are a mixture of polar and nonpolar amino acids.
C)Transmembrane proteins are primarily polar, while peripheral proteins are nonpolar.
D)Transmembrane proteins are a mixture of polar and nonpolar amino acids, while peripheral proteins are primarily nonpolar.

Question 30

What do we mean when we say that facilitated diffusion is specific?

A)A protein will transport specific molecules.
B)One specific integral protein per membrane is involved in facilitated diffusion.
C)Only specific hydrophobic molecules can be transported.
D)The energy molecule ATP is specifically required for transport.

Question 31

Which molecules will pass most easily through a cell membrane by diffusion?

A)large, hydrophilic molecules
B)large, polar molecules
C)small, hydrophobic molecules
D)ionic molecules

Question 32

What type of channel opens in response to changes in ionic charge across a membrane?

A)an electric-gated channel
B)a charge-gated channel
C)a ligand-gated channel
D)a voltage-gated channel

Question 33

An unknown cell contains cholesterol. What type of cell is it most likely to be?

A)a bacterial cell
B)a fungal cell
C)a plant cell
D)an animal cell

Question 34

Which of the following will diffuse most rapidly across membranes?

A)glucose
B)O₂
C)ions
D)macromolecules

Question 35

How do the various membranes of a cell differ?

A)Only certain membranes are constructed of a selectively permeable membrane.
B)Certain proteins are unique to each membrane.
C)Phospholipids are found only in certain membranes.
D)Only certain membranes are constructed from molecules with dual solubility.

Question 36

Which of the following do carrier proteins often transport?

A)proteins
B)steroid hormones
C)H₂O
D)glucose and amino acids

Question 37

Which statement applies to facilitated diffusion?

A)It requires ATP.
B)It can involve either carrier proteins or channel proteins.
C)It is nonspecific with respect to the nature of the molecules being transported.
D)It is not dependent on a concentration gradient.

Question 38

How are simple diffusion and facilitated diffusion similar to each other?

A)They both belong to active transport.
B)They both transport through the aid of a transport molecule.
C)They both require energy.
D)They both belong to passive transport.

Question 39

How are integral and peripheral proteins similar to each other?

A)They both interact with the hydrophobic core of the membrane.
B)They both function at the membrane.
C)They both consist of a mixture of polar and nonpolar amino acids.
D)They are both found on the membrane surface.

Question 40

How are simple diffusion and facilitated diffusion different?

A)Facilitated diffusion is passive transport, while simple diffusion is not.
B)Facilitated diffusion requires a transport protein, while simple diffusion does not.
C)Simple diffusion requires a transport protein, while facilitated diffusion does not.
D)Simple diffusion is passive transport, while facilitated diffusion is not.

Question 41

How are receptor-mediated endocytosis and pinocytosis similar to each other?

A)They both transport liquids into cells.
B)They both transport particles into cells.
C)They both transport particles out of cells.
D)They both transport liquids out of cells.

Question 42

How are exocytosis and endocytosis similar to each other?

A)They both transport large molecules.
B)They both transport materials into cells.
C)They both transport materials out of cells.
D)They both transport small molecules.

Question 43

How are facilitated diffusion and active transport different from each other?

A)Active transport requires a transport protein, while facilitated diffusion does not.
B)Facilitated diffusion requires a transport protein, while active transport does not.
C)Facilitated diffusion occurs against the gradient, while active transport does not.
D)Active transport occurs against the gradient, while facilitated diffusion does not.

Question 44

What two processes are involved when eukaryotic cells import and secrete large molecules?

A)exocytosis when importing and diffusion when secreting
B)exocytosis when importing and endocytosis when secreting
C)endocytosis when importing and exocytosis when secreting
D)diffusion when importing and exocytosis when secreting

Question 45

Which environment is ideal for plant cells, and which is best for animal cells?

A)isotonic for plant cells, and hypertonic for animal cells
B)isotonic for plant cells, and hypotonic for animal cells
C)hypotonic for plant cells, and isotonic for animal cells
D)hypotonic for plant cells, and hypertonic for animal cells

Question 46

How are exocytosis and endocytosis different?

A)Endocytosis transports small molecules into cells, and exocytosis transports large molecules out of cells.
B)Endocytosis transports large molecules into cells, and exocytosis transports large molecules out of cells.
C)Endocytosis transports small molecules out of cells, and exocytosis transports small molecules into cells.
D)Endocytosis transports large molecules into cells, and exocytosis transports small molecules out of cells.

Question 47

What does the cell wall do when a plant cell is placed in a hypotonic solution?

A)It prevents diffusion.
B)It prevents plasmolysis.
C)It prevents the cell from bursting.
D)It prevents active transport.

Question 48

Which process leads to a net movement of uncharged molecules from a low concentration to a higher concentration?

A)active transport
B)osmosis
C)facilitated diffusion
D)exocytosis

Question 49

Which of the following is responsible for maintaining the membrane potential?

A)the Na⁺/K⁺ pump
B)the diffusion gradient
C)the Ca²⁺ pump
D)the H⁺ pump

Question 50

What should the tonicity of the distilled water be compared to body cells?

A)It should be isotonic to the cells.
B)It should be hypotonic to the cells.
C)It should be protonic to the cells.
D)It should be hypertonic to the cells.

Question 51

Which pair of activities are carrier molecules involved in?

A)passive transport and osmosis
B)active and passive transport
C)active transport and osmosis
D)osmosis and diffusion

Question 52

When do cells undergo exocytosis?

A)when secreting protein and wastes from the cell
B)when replicating
C)when ingesting nutrients
D)when pumping protons down a concentration gradient

Question 53

Which of the following is created as ions diffuse across membranes?

A)an electrical gradient
B)an electrochemical gradient
C)a chemical gradient
D)a biochemical gradient

Question 54

Which term refers to the movement of a substance from an area of low concentration to an area of high concentration using energy obtained from ATP?

A)passive transport
B)facilitated transport
C)active transport
D)osmosis

Question 55

How does the concentration inside of a cell compare to an isotonic solution outside of the cell?

A)The concentration is less than that of the outside solution.
B)The concentration is equal to that of the outside solution.
C)The concentration is much greater than that of the outside solution.
D)The concentration is slightly greater than that of the outside solution.

Question 56

Which of the following molecules could be secreted from a eukaryotic cell?

A)ions
B)metals
C)water
D)carbohydrates

Question 57

Which term refers to the voltage across a membrane?

A)membrane electrochemical gradient
B)membrane potential
C)membrane chemical gradient
D)membrane turgor pressure

Question 58

How do the charges inside and outside of the cell compare?

A)There is negative charge inside and positive charge outside of the cell.
B)There is positive charge inside and positive charge outside of the cell.
C)There is positive charge inside and negative charge outside of the cell.
D)There is negative charge inside and negative charge outside of the cell.

Question 59

Which statement applies to both simple diffusion and active transport?

A)Transport proteins are not specific for the molecules being transported.
B)A concentration gradient is not present.
C)A concentration gradient is present.
D)Transport proteins are specific for the molecules being transported.

Question 60

Suppose an animal cell was placed in a beaker of solution. The cell immediately began to swell and ultimately burst. Why did this happen?

A)because the cell's cytoplasm was hypotonic to the solution, which was isotonic
B)because the cell's cytoplasm was hypertonic to the solution, which was hypotonic
C)because the cell's cytoplasm was hypertonic to the solution, which was isotonic
D)because the cell's cytoplasm was hypotonic to the solution, which was hypertonic

Question 61

Match each mechanism of cellular transport with its correct definition.
a.movement of a molecule from an area of high concentration to an area of lower concentration
b.cells internalize molecules into a cell by the inward budding of vesicles possessing receptors specific to the molecule being transported
c.movement of water from a hypotonic solution into a hypertonic solution across a selectively permeable membrane
d.large particles are enveloped by the cell membrane and internalized
e.a process in which liquid droplets are ingested by living cells
f.diffusion of molecules across the plasma membrane with the assistance of transport proteins
diffusion

Question 62

Identify the structures indicated in this drawing of a typical plasma membrane.
microfilament

Question 63

Match each mechanism of cellular transport with its correct definition.
a.movement of a molecule from an area of high concentration to an area of lower concentration
b.cells internalize molecules into a cell by the inward budding of vesicles possessing receptors specific to the molecule being transported
c.movement of water from a hypotonic solution into a hypertonic solution across a selectively permeable membrane
d.large particles are enveloped by the cell membrane and internalized
e.a process in which liquid droplets are ingested by living cells
f.diffusion of molecules across the plasma membrane with the assistance of transport proteins
receptor-mediated endocytosis

Question 64

Physiological saline is 0.9% NaCl. Red blood cells placed in such a solution will NOT gain or lose water; therefore, one could state that the fluid in red blood cells is hypertonic.

Question 65

A solution of 65% water, 35% solute is more concentrated with respect to solute than a solution of 70% water, 30% solute.

Question 66

Identify the structures indicated in this drawing of a typical plasma membrane.
carbohydrate groups

Question 67

Water is a strongly polar molecule, so how does it cross the plasma membrane?

Question 68

How are receptor-mediated endocytosis and pinocytosis different?

A)Receptor-mediated endocytosis transports small molecules into cells, and pinocytosis transports large molecules out of cells.
B)Receptor-mediated endocytosis transports all molecules out of cells, and pinocytosis transports small molecules into cells.
C)Receptor-mediated endocytosis transports large molecules into cells, and pinocytosis transports large molecules out of cells.
D)Receptor-mediated endocytosis transports specific molecules into cells, and pinocytosis transports nonspecific liquids into cells.

Question 69

Identify the structures indicated in this drawing of a typical plasma membrane.
peripheral proteins

Question 70

Identify the structures indicated in this drawing of a typical plasma membrane.
integral proteins

Question 71

Explain why the transport of molecules across the cell membrane is considered to be both specific and directional.

Question 72

Identify the structures indicated in this drawing of a typical plasma membrane.
cholesterol

Question 73

What is the sequence of signal transduction?

A)transduction ? response ? reception
B)reception ? transduction ? response
C)response ? reception ? transduction
D)transduction ? reception ? response

Question 74

Carrier proteins share several characteristics with enzymes used to catalyze metabolic reactions. In what ways are carrier proteins and enzymes similar?

Question 75

Which cell organelle helps pinocytosis and phagocytosis to occur?

A)the endoplasmic reticulum
B)the lysosome
C)the plasma membrane
D)the nucleus

Question 76

An animal cell placed in a hypertonic solution will swell and perhaps burst.

Question 77

Match each mechanism of cellular transport with its correct definition.
a.movement of a molecule from an area of high concentration to an area of lower concentration
b.cells internalize molecules into a cell by the inward budding of vesicles possessing receptors specific to the molecule being transported
c.movement of water from a hypotonic solution into a hypertonic solution across a selectively permeable membrane
d.large particles are enveloped by the cell membrane and internalized
e.a process in which liquid droplets are ingested by living cells
f.diffusion of molecules across the plasma membrane with the assistance of transport proteins
osmosis

Question 78

A hypertonic environment would be ideal for a healthy plant.

Question 79

Match each mechanism of cellular transport with its correct definition.
a.movement of a molecule from an area of high concentration to an area of lower concentration
b.cells internalize molecules into a cell by the inward budding of vesicles possessing receptors specific to the molecule being transported
c.movement of water from a hypotonic solution into a hypertonic solution across a selectively permeable membrane
d.large particles are enveloped by the cell membrane and internalized
e.a process in which liquid droplets are ingested by living cells
f.diffusion of molecules across the plasma membrane with the assistance of transport proteins
phagocytosis

Question 80

A water concentration gradient is influenced by the number of solute molecules present on both sides of the membrane.