Transport Accross Membrane

Question 1

Factors influence the diffusion rate of substances across plasma membranes:

Answer 1

Steepness of the concentration gradient
Temperature
Mass of the diffusing substance
Surface area
Diffusion distance

Question 2

Two sources of cellular energy can be used to drive active transport:

Answer 2

primary active transport and secondary active transport

Question 3

Energy obtained from hydrolysisof adenosine triphosphate (ATP) is the source in

Answer 3

primary active transport

Question 4

energy stored in an ionic concentration gradient is the source in

Answer 4

secondary active transport

Question 5

The greater the difference in concentration between the two sides of the membrane, the higher the rate of

Answer 5

diffusion

Question 6

energy source of primary active transport

Answer 6

atp

Question 7

is a well-known primary active transport mechanism.

Answer 7

sodium-potassium pump

Question 8

into the cell against their respective concentration gradients, using ATP as an energy source.

Answer 8

sodium-potassium pump

Question 9

Secondary Active Transport also known as

Answer 9

cotransport or coupled transport

Question 10

does not directly use ATP. Instead, it relies on the energy generated by primary active transport (usually the sodium gradient) to transport other molecules against their concentration gradients.

Answer 10

Secondary active transport

Question 11

the transported molecule moves in the same direction as the ion

Answer 11

Symport (cotransport)

Question 12

the transported molecule moves in the opposite direction to the ion

Answer 12

Antiport (exchanger):

Question 13

of the PM allows a living cell to maintain different concentrations of certain substances on either side of the plasma membrane

Answer 13

selective permeability

Question 14

is a difference in the concentration of a chemical from one place to another

Answer 14

concentration gradient

Question 15

Many ions and molecules are more concentrated in either the

Answer 15

cytosol or the extracellular fluid

Question 16

A difference in electrical charges between 2 regions constitutes an

Answer 16

electrical gradient

Question 17

Because it occurs across the plasma membrane, this charge difference is termed the

Answer 17

membrane potential

Question 18

Similarly, a positively charged substance will tend to move toward a

Answer 18

negatively charged area

Question 19

A negatively charged substance will tend to move toward a

Answer 19

positively charged area

Question 20

The combined influence of the concentration gradient and the electrical gradient on movement of a particular ion is referred to as its

Answer 20

electrochemical gradient

Question 21

Substances generally move across membranes via transport processes that can be classified as

Answer 21

passive or active

Question 22

a substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy

Answer 22

passive processes

Question 23

Another way that some substances may enter and leave cells is an active process in w/c tiny, spherical membrane sacs called

Answer 23

vesicles

Question 24

endocytosis, in which ___________________________________________ while bringing materials into a cell

Answer 24

vesicles detach from the plasma membrane

Question 25

exocytosis, the_________________________________ to release materials from the cell

Answer 25

merging of vesicles with the plasma membrane

Question 26

A passive process in w/c the random mixing of particles in a solution occurs because of the particles’

Answer 26

kinetic energy

Question 27

Both the solutes, the dissolved substances, and the solvent, the liquid that does the dissolving, undergo

Answer 27

diffusion

Question 28

If a particular solute is present in high concentration in one area of a solution and in low concentration in another area:

Answer 28

solute molecules will diffuse toward the area of lower concentration—they move down their concentration gradient

Question 29

A passive process in which substances move freely through the lipid bilayer of the PM of cells without the help of membrane transport proteins

Answer 29

simple diffusion

Question 30

Nonpolar, hydrophobic molecules move across the lipid bilayer through the process of

Answer 30

simple diffusion

Question 31

also pass through the lipid bilayer by simple diffusion

Answer 31

Small, uncharged polar molecules such as water, urea, and small alcohols

Question 32

Such molecules that can pass through the lipid bilayer through simple diffusion

Answer 32

oxygen, carbon dioxide, and nitrogen gases; fatty acids; steroids; and fat-soluble vitamins (A, D, E, and K)

Question 33

Simple diffusion through the PM is important in the movement of

Answer 33

O & CO2bet. blood & body cells, and between blood & air w/in the lungs during breathing

Question 34

It also is the route for absorption of some nutrients and excretion of some wastes by body cells

Answer 34

Simple Diffusion

Question 35

Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the PM by

Answer 35

facilatated diffusion

Question 36

In this process, an integral membrane protein assists a specific substance across the membrane

Answer 36

facilatated diffusion

Question 37

The integral membrane protein can be either a

Answer 37

membrane channel or a carrier

Question 38

A solute moves down its concentration gradient across the lipid bilayer through a membrane channel

Answer 38

Channel-Mediated Facilitated Diffusion

Question 39

These channels allow passage of small, inorganic ions

Answer 39

ion channels

Question 40

Most membrane channels are

Answer 40

ion channels, integral transmembraneproteins

Question 41

Diffusion of ions through channels is _________________ than free diffusion through the lipid bilayer

Answer 41

generally slower

Question 42

A channel is said to be ____________ when part of the channel protein acts as a “plug” or “gate”

Answer 42

gated

Question 43

Some gated channels randomly alternate between the

Answer 43

open and closed positions

Question 44

is used to move a solute down its concentration gradient across the plasma membrane

Answer 44

carrier

Question 45

Carrier also called a

Answer 45

transporter

Question 46

The rate of carrier-mediated facilitated diffusion is determined by

Answer 46

the steepness of the concentration gradient across the membrane

Question 47

The no. of carriers available in a PM places an upper limit, called the _________________________, on the rate at which facilitated diffusion can occur

Answer 47

transport maximum

Question 48

Once all of the carriers are occupied, the ________________________ is reached

Answer 48

transport maximum

Question 49

Substances that move across the plasma membrane by carrier-mediated facilitated diffusion include

Answer 49

glucose, fructose, galactose, and some vitamins

Question 50

The selective permeability of the plasma membrane is often regulated to achieve

Answer 50

homeostasis

Question 51

An inability to produce or utilize insulin is called

Answer 51

diabetes mellitus

Question 52

A type of diffusion in which there is net movement of a solvent through a selectively permeable membrane

Answer 52

Osmosis

Question 53

Like the other types of diffusion, osmosis is a

Answer 53

passive process

Question 54

water moves through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration

Answer 54

Osmosis

Question 55

During osmosis, water molecules pass through a plasma membrane in two ways:

Answer 55

(1) by moving through the lipid bilayer via simple diffusion, as previously described, and (2) by moving through aquaporins, integral membrane proteins that function as water channels

Question 56

occurs only when a membrane is permeable to water but is not permeable to certain solutes

Answer 56

Osmosis

Question 57

The solution with the impermeable solute also exerts a force, called the

Answer 57

osmotic pressure

Question 58

is proportional to the concentration of the solute particles that cannot cross the membrane

Answer 58

osmotic pressure

Question 59

The higher the solute concentration, the higher the solution’s

Answer 59

osmotic pressure

Question 60

When body cells are placed in a solution having a different osmotic pressure than cytosol, however, the

Answer 60

shape and volume of the cells change

Question 61

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

Answer 61

tonicity

Question 62

the concentrations of solutes that cannot cross the plasma membrane are the same on both sides of the membrane in this solution

Answer 62

Isotonic

Question 63

a solution that has a lower concentration of solutes than the cytosol inside the cell

Answer 63

Hypotonic

Question 64

The rupture of other types of cells due to placement in a hypotonic solution is referred to simply as

Answer 64

lysis

Question 65

Pure water is very _____________ and causes rapid _____________

Answer 65

hypotonic; hemolysis

Question 66

has a higher concentration of solutes than does the cytosol inside the cell

Answer 66

hypertonic solution

Question 67

In such a solution, water molecules move out of the cells faster than they enter, causing the

Answer 67

cells to shrink

Question 68

Such shrinkage of cells is called

Answer 68

crenation

Question 69

Some polar or charged solutes that must enter or leave body cells cannot cross the plasma membrane through any form of passive transport This is because they would need to move “uphill,” against their concentration gradients Such solutes may be able to cross the membrane by a process called

Answer 69

active transport

Question 70

is an active process because energy is required for carrier proteins to move solutes across the membrane against a concentration gradient

Answer 70

active transport

Question 71

Two sources of cellular energy can be used to drive active transport:

Answer 71

(1) Energy obtained from hydrolysis of adenosine triphosphate (ATP) is the source in primary active transport; (2) energy stored in an ionic concentration gradient is the source in secondary active transport

Question 72

is the source in primary active transport

Answer 72

Energy obtained from hydrolysis of adenosine triphosphate (ATP)

Question 73

is the source in secondary active transport

Answer 73

energy stored in an ionic concentration gradient

Question 74

Like carrier-mediated facilitated diffusion, active transport processes exhibit a

Answer 74

transport maximum and saturation

Question 75

carrier proteins that mediate primary active transport are often called

Answer 75

pumps

Question 76

The most prevalent primary active transport mechanism expels sodium ions from cells and brings potassium ions Because of the specific ions it moves, this carrier is called the

Answer 76

sodium-potassium pump

Question 77

If these transporters move two substances in the same direction they are called

Answer 77

symporters/symport

Question 78

move two substances in opposite directions across the membrane

Answer 78

Antiporters/antiport

Question 79

is a small, spherical sac

Answer 79

vesicle

Question 80

materials move into a cell in a vesicle formed from the plasma membrane

Answer 80

endocytosis

Question 81

materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell

Answer 81

exocytosis

Question 82

Both endocytosis and exocytosis require

Answer 82

energy supplied by ATP

Question 83

transport in vesicles is an

Answer 83

active process

Question 84

Three types of endocytosis:

Answer 84

Receptor-mediated endocytosis, phagocytosis, and bulk-phase endocytosis

Question 85

A highly selective type of endocytosis by which cells take up specific ligands

Answer 85

Receptor-mediated endocytosis

Question 86

A vesicle forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the extracellular fluid

Answer 86

Receptor-mediated endocytosis

Question 87

Receptor-mediated endocytosis of LDLs (and other ligands) occurs as follows:

Answer 87

- Binding - Vesicle formation - Uncoating - Fusion with endosome - Recycling of receptors to plasma membrane - Degradation in lysosomes

Question 88

On the extracellular side of the PM, an LDL (low-density lipoprotein) cholesterol particle that contains cholesterol binds to a specific receptor in the PM to form a receptor,

Answer 88

LDL complex

Question 89

The receptors are integral membrane proteins that are concentrated in regions of the plasma membrane called

Answer 89

clathrin-coated pits

Question 90

a protein called ____________ attaches to the membrane on its cytoplasmic side

Answer 90

clathrin

Question 91

The invaginatededges of the membrane around the clathrin-coated pit fuse, and a small piece of the membrane pinches off. The resulting vesicle, known as a

Answer 91

clathrin-coated vesicle

Question 92

clathrin-coated vesicle, contains the receptor,

Answer 92

LDL complexes

Question 93

Almost immediately after it is formed, the clathrin-coated vesicle loses its clathrincoat to become an

Answer 93

uncoated vesicle

Question 94

A form of endocytosis in which the cell engulfs large solid particles, such as worn-out cells, whole bacteria, or viruses

Answer 94

Phagocytosis

Question 95

Only a few body cells, termed _________________, are able to carry out phagocytosis

Answer 95

phagocytes

Question 96

Two main types of phagocytes are

Answer 96

macrophages and neutrophils

Question 97

located in many body tissues

Answer 97

macrophages

Question 98

a type of white blood cell

Answer 98

neutrophils

Question 99

In most cases, any undigested materials in the phagosomeremain indefinitely in a vesicle called a

Answer 99

residual body

Question 100

a vital defense mechanism that helps protect the body from disease

Answer 100

phagocytosis

Question 101

a form of endocytosis in which tiny droplets of extracellular fluid are taken up

Answer 101

bulk-phase endocytosis (pinocytosis)

Question 102

No receptor proteins are involved; all solutes dissolved in the extracellular fluid are brought into the cell

Answer 102

bulk-phase endocytosis (pinocytosis)

Question 103

releases materials from a cell

Answer 103

exocytosis

Question 104

All cells carry out exocytosis, but it is especially important in two types of cells:

Answer 104

(1) secretory cells that liberate digestive enzymes, hormones, mucus, or other secretions (2) nerve cells that release substances called neurotransmitters

Question 105

liberate digestive enzymes, hormones, mucus, or other secretions

Answer 105

secretory cells

Question 106

release substances called neurotransmitters

Answer 106

nerve cells

Question 107

During exocytosis, membrane-enclosed vesicles called _________________________ form inside the cell, fuse with the plasma membrane

Answer 107

secretory vesicles

Question 108

vesicles undergo endocytosis on one side of a cell, move across the cell

Answer 108

Transcytosis