Mastering Biology Test Bank 5

Front 1

The ________(BLANK) molecules of membranes act as barriers to the passage of many materials

and serve to maintain the membrane's physical integrity.

Back 1

lipid

Front 2

In a complex solution, the ________(BLANK) of each substance is independent of that of the other

substances.

Back 2

diffusion

Front 3

Lipids and proteins can move ________(BLANK) but not across biological membranes.

Back 3

laterally

Front 4

Some materials move through biological membranes more readily than others. This

characteristic of biological membranes is called selective ________.

Back 4

permeability

Front 5

You place a cell into a solution, and the cell shrinks. This solution is ________ (BLANK)relative to the cell.

Back 5

hypertonic

Front 6

The cells of the intestinal epithelium are joined to one another by ________(BLANK) that prevent

substances from passing between the cells of this tissue.

Back 6

tight junctions

Front 7

The coupled transport system by which glucose and sodium ions enter intestinal

epithelial cells is called ________.

Back 7

symport

Front 8

Mammalian embryos have protein complexes that couple cells together, allowing

communication by small molecules between cells. These complexes of proteins are called ________.

Back 8

gap junctions

Front 9

Diffusion occurs ________ (BLANK)a concentration gradient.

Back 9

down

Front 10

Three things that influence the diffusion rate are the ________(BLANK), ________(BLANK), and the

________.

Back 10

size, temperament and concentration gradient

Front 11

Membrane synthesized on the ER moves to other points of the cell as ________.

Back 11

vesicles

Front 12

The process of one cell engulfing another is called ________.

Back 12

phagocytosis

Front 13

The chemical makeup, physical organization, and function of a biological membrane depend on which of the following classes of biochemical compounds?

Back 13

proteins, lipids and carbohydrates

Front 14

Integral membrane proteins have

Back 14

hydrophobic regions within the lipid portion of the bilayer.

Front 15

Specialized cell junctions include

Back 15

gap junctions, tight junctions and desmosomes.

Front 16

Substances move through biological membranes against concentration gradients via

Back 16

active transport

Front 17

Because the sodium-potassium pump imports K+ ions while exporting Na+ ions, it is a

coupled transport system termed a(n)

Back 17

antiport

Front 18

When placed in water, wilted plants lose their limpness because of

Back 18

osmosis of water into the plant cells

Front 19

Houseplants adapted to indoor temperatures might die when accidentally left outdoors in

the cold because their

Back 19

membranes lack adequate fluidity

Front 20

The interior of the phospholipid bilayer is

Back 20

hydrophobic

Front 21

In biological membranes, the phospholipids are arranged in a

Back 21

bilayer with the fatty acids pointing toward each other

Front 22

A protein that forms an ion channel through a membrane is most likely to be

Back 22

an integral protein

Front 23

When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because

Back 23

many proteins can move around within the bilayer.

Front 24

The hydrophilic regions of a membrane protein are most likely to be found

Back 24

exposed on the surface of the membrane.

Front 25

Biological membranes are composed of

Back 25

lipids, proteins, and carbohydrates.

Front 26

Structures that contain networks of keratin fibers and hold adjacent cells together are

called

Back 26

desmosomes

Front 27

You fill a shallow pan with water and place a drop of red ink in one end of the pan and a drop of green ink in the other end. Which of the following is true at equilibrium?

Back 27

The red and green inks are both uniformly distributed throughout the pan

Front 28

Which of the following does not affect the rate of diffusion of a substance?

Back 28

Presence of other substances in the solution

Front 29

For cells where carbon dioxide crosses the plasma membrane by simple diffusion, what

determines the rate at which carbon dioxide enters the cell?

Back 29

The concentration of carbon dioxide on each side of the membrane

Front 30

Plant cells transport sucrose across the vacuole membrane against its concentration

gradient by a process known as

Back 30

active transport

Front 31

When placed in a hypertonic solution, plant cells

Back 31

shrink

Front 32

You place cells in a solution of glucose and measure the rate at which glucose enters the cells. As you increase the concentration of the glucose solution, the rate at which glucose enters the cells increases. However, when the glucose concentration of the solution is increased above 10 M, the rate at which glucose enters the cells no longer increases. Which of the following is the most likely mechanism for glucose transport into the cell?

Back 32

Facilitated diffusion via a carrier protein

Front 33

Transporting substances across a membrane from an area of lower concentration to an

area of higher concentration requires

Back 33

energy

Front 34

In the parietal cells of the stomach, the uptake of chloride ions is coupled to the transport

of bicarbonate ions out of the cell. This type of transport system is called

Back 34

an antiport.

Front 35

When a red blood cell is placed in an isotonic solution, which of the following will

occur?

Back 35

Nothing

Front 36

When a plant cell is placed in a hypotonic solution, what occurs?

Back 36

The cell takes up water until the osmotic potential equals the pressure potential of the

cell wall.

Front 37

Insulin is a protein secreted by cells of the pancreas. What is the pathway for the

synthesis and secretion of insulin?

Back 37

Rough ER, Golgi apparatus, vesicle, plasma membrane

Front 38

Carbohydrates associated with cellular membranes are expected to be found associated

with

Back 38

proteins outside the cell

Front 39

The site where transmembrane proteins are embedded into membranes is the

Back 39

rough E.R

Front 40

The site where carbohydrates are initially added to membrane proteins is the

Back 40

E.R.

Front 41

An important function of certain integral proteins of a eukaryotic cell's plasma membrane

is

Back 41

binding with signals in the cell's environment

Front 42

Cholesterol molecules act to

Back 42

alter the fluidity of the membrane

Front 43

The rate of facilitated diffusion of a molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases.

Why?

Back 43

The transport protein must be of the carrier type

Front 44

Active transport is important because it can move molecules

Back 44

from their low concentration to a higher concentration

Front 45

Active transport usually moves molecules

Back 45

in the opposite direction as does diffusion

Front 46

Osmosis is a specific form of

Back 46

diffusion

Front 47

Osmosis moves water from a region of

Back 47

low concentration of dissolved material to a region of high concentration.

Front 48

Clathrin-coated pits are structures associated with

Back 48

receptor-mediated endocytosis

Front 49

Which of the following molecules is probably the most likely to diffuse across a cell

membrane?

Back 49

A steroid

Front 50

Membrane molecules that help individual cells organize themselves into tissues are

known as

Back 50

cell adhesion molecules

Front 51

For each molecule of ATP consumed during active transport of sodium and potassium,

Back 51

2 potassium ions are imported and 3 sodium ions are exported.

Front 52

Materials can be limited from moving through the spaces between cells by

Back 52

tight junctions between the cells.

Front 53

Keratin is a protein found in

Back 53

desmosomes

Front 54

A concentration gradient of glucose across a membrane means

Back 54

glucose molecules are more crowded on one side of the membrane than the other.

Front 55

Connexons occur in

Back 55

gap junctions

Front 56

Transport proteins that simultaneously move two molecules across a membrane in the

same direction are called

Back 56

symports

Front 57

The only process that could possibly bring glucose molecules into cells that does not

involve the meta-bolic energy of ATP is

Back 57

diffusion

Front 58

The functional roles for different proteins found in membranes include all except which

of the following?

Back 58

Stabilizing the lipid bilayer

Front 59

The tensile strength of connections between adjacent cells in tissues comes from

Back 59

desosomers

Front 60

Desmosomes include or associate with all except

A) dense plaque-like regions.

B) keratin fibers.

C) external cell adhesion molecules.

D) internal channel proteins.

E) All of the above

Back 60

E) All of the above

Front 61

Secondary active transport involves all the following except

A) the direct use of ATP.

B) coupling to another transport system.

C) use of regained energy from an existing gradient.

D) the requirement for energy.

Back 61

A) the direct use of ATP

Front 62

How do amino acids get into cells against concentration gradients?

Back 62

Secondary active transport