Deck 5: Lifes Border: the Plasma Membrane

Question 1

Membrane proteins perform all of the following functions except:

A)structural support.
B)cell recognition.
C)communication.
D)transport.
E)maintainance of membrane fluidity.

Answer 1

E

Question 2

Which statement below is true?

A)All internal cell membranes are similar in structure to the plasma membrane.
B)The only internal membrane of a cell that is similar to the plasma membrane is the nuclear membrane.
C)All internal membranes of a cell are just giant invaginations from the plasma membrane.
D)Vesicle membranes degrade as they fuse with the plasma membrane during exocytosis.

Answer 2

A

Question 3

The plasma membrane is composed of phospholipids,which are free to move laterally,and is peppered with both stationary and mobile proteins.This view of the plasma membrane is known as the:

A)peppered membrane model.
B)phospholipid bilayer model.
C)fluid-mosaic model.
D)semipermeable membrane model.

Answer 3

C

Question 4

The phospholipids of membranes are:

A)hydrophilic molecules.
B)hydrophobic molecules.
C)both hydrophilic and hydrophobic molecules.
D)oils.

Question 5

The fatty-acid tails of a phospholipid are:

A)hydrophilic.
B)proteins.
C)polar.
D)hydrophobic.
E)carbohydrates.

Question 6

The ________ of a phospholipid molecule will seek water,whereas the ________ of the molecules will avoid water.

A)tail; head
B)head; tail
C)hydrophobic portion; hydrophilic portion
D)fatty acid; phosphate group

Question 7

Which of the following is true of the plasma membrane?

A)It controls the passage of substances into and out of the cell.
B)It only allows hydrophilic materials to pass through.
C)It is a rigid, nonchanging structure.
D)Its capabilities are primarily determined by carbohydrates in the membrane.

Question 8

A component of the plasma membrane that helps to maintain its fluidity is:

A)protein.
B)carbohydrate.
C)nucleic acid.
D)the phospholipid bilayer.
E)cholesterol.

Question 9

Which type of proteins are involved in nutrient transport across the plasma membrane and why?

A)integral proteins, because they span the membrane and are able to carry nutrients across the membrane
B)peripheral proteins, because they are smaller and can travel across the membrane, thereby carrying nutrients across the membrane
C)integral proteins, because they are smaller and can travel across the membrane, thereby carrying nutrients across the membrane
D)peripheral proteins, because they span the membrane and are able to carry nutrients across the membrane
E)receptor proteins, because their carbohydrate chains bind to nutrients and carry them across the membrane

Question 10

Which of the following is an accurate description of the plasma membrane?

A)It is a phospholipid bilayer embedded with proteins.
B)It separates the nuclear contents from the environment.
C)It is permeable to all substances.
D)It is a solid material.

Question 11

Short chains of sugars attached to proteins or phospholipids in the cell membrane make up the:

A)phospholipid bilayer.
B)communication proteins.
C)cholesterol.
D)glycocalyx.

Question 12

Small,nonpolar molecules easily pass through the phospholipid bilayer because the molecules:

A)can dissolve in the hydrophobic portion of the bilayer.
B)are brought in by attaching to structural proteins in the membrane.
C)are brought in by attaching to cholesterol in the membrane.
D)dissolve in water and follow the water as it flows into the cell.

Question 13

The primary component of the plasma membrane is:

A)cholesterol.
B)phospholipid.
C)protein.
D)carbohydrate.

Question 14

The huge array of capabilities of the plasma membrane are performed by its:

A)carbohydrates.
B)proteins.
C)phospholipids.
D)cholesterol.

Question 15

A main function of the carbohydrates that form the glycocalyx is to:

A)move large molecules in and out of the cell.
B)regulate water movement into the cell.
C)bind cell membranes to the cytoskeleton.
D)act as binding sites for signaling molecules.
E)maintain the proper fluidity of the plasma membrane.

Question 16

Cystic fibrosis is the result of:

A)no sodium channel protein.
B)no sodium-potassium pump.
C)an abnormal sodium channel protein.
D)an abnormal chloride channel protein.
E)cysts in the lungs.

Question 17

What is the role of transport proteins within the plasma membrane?

A)Transport proteins prevent the passage of amino acids through the membrane.
B)Transport proteins allow movement of ions and polar molecules through the plasma membrane.
C)Transport proteins identify the cell.
D)Transport proteins interact with the cytoskeleton to stabilize various parts of the cell.
E)Transport proteins maintain membrane fluidity.

Question 18

How does glucose enter a cell if levels of blood glucose are high?

A)An electrical signal is passed through the blood, opening glucose channels within the membranes of cells.
B)Insulin molecules bind to glucose receptors, causing cellular responses to take up glucose.
C)The glucose molecules diffuse through the membrane.
D)Glucose pokes a hole in the cell's membrane, creating a channel through which it can move.

Question 19

The outer living limit of the cell is called the:

A)cell wall.
B)edge.
C)plastid.
D)plasma membrane.

Question 20

A purpose of the plasma membrane is to:

A)form the outer boundary of a cell.
B)produce proteins.
C)allow no contact with other cells.
D)keep harmful substances within the cell.
E)form ribosomes.

Question 21

You have lost a lot of blood in an accident.In the emergency room the first thing the doctors will need to do is replace lost fluids.The fluids they give you should be:

A)isotonic to your cells.
B)hypotonic to your cells.
C)hypertonic to your cells.
D)either hypertonic or isotonic to your cells.
E)either hypertonic or hypotonic to your cells.

Question 22

Diffusing molecules move ________ until they are ________.

A)down their concentration gradients; evenly distributed
B)up their concentration gradients; evenly distributed
C)through channels of active transport proteins; evenly distributed
D)up their concentration gradients; unevenly distributed
E)down their concentration gradients; unevenly distributed

Question 23

It seems that bacteria and molds should grow well in jam.It's extremely high in sugar,a substance many cells can use for energy,and contains enough other nutrients to support cell growth.Yet jam can be left unrefrigerated for a very long time without contamination by microorganisms.How can this be?

A)Bacteria and molds cannot grow on fruit products.
B)The high sugar concentration causes bacterial and mold cells to swell and rupture.
C)The high sugar concentration damages cell membranes.
D)Bacteria and molds cannot get into the jam because its high concentration of sugar makes it so sticky.
E)The high sugar concentration causes bacterial and mold cells to shrink and die.

Question 24

Peripheral proteins:

A)usually span the entire membrane.
B)have no known functions in membranes.
C)act as channels through which materials can pass.
D)are defective in cystic fibrosis.
E)usually attach to integral proteins.

Question 25

Water moves from a:

A)hypotonic environment to a hypertonic environment.
B)hypertonic environment to a hypotonic environment.
C)low free-water solution toward a high free-water solution.
D)solution with more salt to a solution with less salt.

Question 26

Active transport:

A)moves only large molecules into the cell.
B)causes the production of ATP within the cell.
C)increases the concentration of solute inside the cell.
D)moves substances against their concentration gradient.

Question 27

The plasma membrane is a semipermeable membrane.This means that it is:

A)permeable to small molecules except water.
B)permeable to small and uncharged molecules but not to larger or charged substances.
C)only permeable to cholesterol.
D)permeable to large charged molecules but not to small uncharged molecules.

Question 28

Facilitated diffusion occurs with the help of:

A)recognition proteins.
B)peripheral proteins.
C)transport proteins.
D)communication proteins.
E)ribosomes.

Question 29

If you transferred a phospholipid bilayer from water to oil,what effect would this have on the membrane?

A)The membrane would become very rigid.
B)The membrane would form four layers instead of its normal two.
C)The membrane would be unaffected by the oil.
D)The membrane would invert its normal structure by positioning the heads on the inside of the bilayer and the fatty-acid tails outside.
E)The phospholipid bilayer would split into two separate layers, which each would be maintained in the oil.

Question 30

Diffusion is a process by which a substance:

A)goes from lesser to greater concentration.
B)goes down its concentration gradient.
C)goes up its concentration gradient.
D)is at equilibrium.

Question 31

The central vacuoles of some plant cells you are studying fill with water and press the cell contents against their cell walls because of osmosis.What can you predict about the concentration of solutes in the solution that bathes the turgid plant cells?

A)The concentration of solutes outside the cell must be significantly lower than the concentration within the cell.
B)The concentration of solutes outside the cell must be significantly higher than the concentration within the cell.
C)There must be no solutes either outside or inside the cell.
D)The concentration of solutes outside the cell must be about the same as that of seawater.
E)The concentration of solutes outside the cell can't be predicted, because it's the concentration inside the cell that's important.

Question 32

Which of the following would be least likely to diffuse through a phospholipid bilayer?

A)carbon dioxide
B)water
C)the small, nonpolar molecule of butane
D)oxygen
E)sodium ions

Question 33

Red blood cells placed in pure water will swell and burst.What process is causing this to happen?

A)Water is diffusing across the plasma membrane from a region of high (outside the cell)to low (inside the cell)"free" water concentration.
B)Water is being pulled into the cell by the cell's solutes.
C)Water is diffusing across the plasma membrane from a region of low (outside the cell)to high (inside the cell)"free" water concentration.
D)Solutes are being drawn into the cell across the plasma membrane.
E)Ions are diffusing across the plasma membrane and destabilizing the phospholipids.

Question 34

If you could add a colored label to one phospholipid in the cell's plasma membrane to observe this molecule,what kind of movement of the molecule would you see?

A)The molecule would move rapidly back and forth across the surface of the membrane.
B)The molecule would be locked in place by its tightly packed neighbors in the plasma membrane.
C)The molecule would be converted back and forth between a receptor protein and a phospholipid.
D)The molecule would move back and forth between the membrane and the surrounding watery solution.
E)The molecule would flip back and forth from one layer of the membrane to the other.

Question 35

Which statement about diffusion is correct?

A)Diffusion can occur only through a membrane.
B)Diffusion requires a protein channel.
C)Diffusion of water cannot occur.
D)Diffusion causes movement of materials toward equilibrium.

Question 36

You have isolated a cell that is unable to produce cholesterol for its cell membranes.Which of the following defects is this cell most likely to have?

A)The cell membrane will not have the correct fluidity.
B)The cell will not be able to communicate with other cells.
C)The cell will be unable to transport nutrients.
D)The cell will burst as a result of osmosis.
E)The cell will not be able to regulate the transportation of substances into and out of the cell.

Question 37

Plants stay standing upright because of turgor pressure caused by:

A)water rushing into the cells, keeping the cells tight.
B)solutes rushing into the cells, keeping the cells tight.
C)bones that run through the plant, holding it upright.
D)cell walls of the plants supporting and keeping the plants standing upright.

Question 38

One difference between passive and active transport through a cell membrane is that:

A)active transport makes ATP.
B)active transport requires ATP.
C)passive transport requires ATP.
D)passive transport makes ATP.

Question 39

Oxygen moving through the plasma membrane down its concentration gradient is an example of:

A)simple diffusion.
B)active transport.
C)facilitated diffusion.
D)osmosis.

Question 40

The term that describes the diffusion of water is:

A)simple diffusion.
B)equilibrium.
C)facilitated diffusion.
D)active transport.
E)osmosis.

Question 41

The hydrophilic heads of phospholipids in the plasma membrane face a water-based environment.

Question 42

Having defective proteins in the cell membrane can cause disease.

Question 43

Calcium ions (Ca²⁺)are present in the endoplasmic reticulum at concentrations 1,000 times higher than in the cytosol (the gel-like part of the cell outside organelles).One protein on the endoplasmic reticulum membrane is devoted to allowing Ca²⁺ to move from the endoplasmic reticulum to the cytosol,and another protein moves Ca²⁺ from the cytosol to the endoplasmic reticulum.These processes are not trivial-Ca²⁺ released into the cytosol allows,for example,for muscle contraction and communication between nerve cells.In this pair of Ca²⁺ transport proteins,you would predict that the protein moving Ca²⁺ from the endoplasmic reticulum to the cytosol ________,and the protein that moves Ca²⁺ from cytosol to the endoplasmic reticulum ________.

A)transports calcium slowly; transports calcium rapidly
B)works without ATP; requires ATP
C)requires ATP; works without ATP
D)is large; is small
E)is small; is large

Question 44

In cystic fibrosis,cells cannot pump out enough chloride ions.

Question 45

Signals sent between cells reach a cell at receptor proteins.

Question 46

Carbohydrate chains serve as the binding sites for many signaling molecules.

Question 47

Integral proteins always extend completely through the plasma membrane.

Question 48

Cholesterol helps to maintain the correct fluidity of the plasma membrane.

Question 49

Insulin and many other hormones are protein molecules.Based on your knowledge of transport processes,you can say that cells that secrete these types of hormones do so through:

A)facilitated diffusion.
B)pinocytosis.
C)passive diffusion.
D)receptor-mediated endocytosis.
E)exocytosis.

Question 50

The sodium-potassium pump is an example of:

A)passive transport.
B)receptor-mediated endocytosis.
C)facilitated diffusion.
D)active transport.

Question 51

The glycocalyx is found just inside the plasma membrane of the cell.

Question 52

Facilitated diffusion is similar to simple diffusion because:

A)each requires the use of energy.
B)each requires a protein channel for movement to occur.
C)in both, materials move down their concentration gradient.
D)each utilizes vesicles to move material around the cell.

Question 53

The 1985 Nobel Prize in Physiology or Medicine was awarded to Michael Brown and Joseph Goldstein for their work on cholesterol metabolism.Brown and Goldstein investigated the cause of remarkably high levels of circulating cholesterol found in certain families.Just as remarkable was the high incidence of heart disease in these families.What Brown and Goldstein found was not what might be expected-these individuals did not make too much cholesterol.Instead,most of these people had defects in receptor-mediated endocytosis (RME).What could possibly link high cholesterol levels in the blood and defective RME in these patients?

A)Cholesterol was being secreted from cells by RME at too high a rate and therefore accumulated in the blood.
B)Cholesterol was not transported into cells by RME and therefore accumulated in the blood.
C)Cholesterol was being secreted by facilitated diffusion at too high a rate and therefore accumulated in the blood.
D)Cholesterol was not transported into cells by active transport proteins and therefore accumulated in the blood.
E)Cholesterol was not transported into cells by facilitated diffusion and therefore accumulated in the blood.

Question 54

Cholesterol is a hormone receptor in the plasma membrane.

Question 55

The chief component of the plasma membrane is the phospholipid bilayer.

Question 56

Hydrophobic molecules easily pass through the fatty-acid region of the plasma membrane.

Question 57

Yeast cells take up glucose (a sugar)to use as their primary source of energy.Typically,glucose concentrations outside yeast cells are far lower than glucose concentrations inside the cells.Therefore,for yeast to take up glucose,the cells must use:

A)facilitated diffusion to move glucose down its concentration gradient.
B)active transport to move glucose up its concentration gradient.
C)facilitated diffusion to move glucose up its concentration gradient.
D)active transport to move glucose down its concentration gradient.
E)osmosis to directly absorb glucose.

Question 58

Phagocytosis is a type of ________ in which a cell engulfs another cell.

A)passive transport
B)active transport
C)facilitated diffusion
D)endocytosis
E)exocytosis

Question 59

The hydrophilic region of the phospholipid bilayer faces to the interior of the plasma membrane.

Question 60

All of the following processes bring materials into a cell except:

A)endocytosis.
B)receptor-mediated endocytosis.
C)exocytosis.
D)phagocytosis.

Question 61

The functioning of the immune system depends on recognition proteins.

Question 62

The most up-to-date explanation of the structure of the plasma membrane is called the fluid-mosaic model.

Question 63

Transport proteins are integral plasma membrane proteins.

Question 64

Active transport moves a substance against the concentration gradient.

Question 65

The phospholipid bilayer forms spontaneously in water.

Question 66

Facilitated diffusion occurs down a concentration gradient.

Question 67

Osmosis refers to the diffusion of ________ across a membrane.

Question 68

A cell wall stops a plant cell from taking in so much water that it will burst.

Question 69

Osmosis is an example of passive transport.

Question 70

A substance moving down the concentration gradient is an example of active transport.

Question 71

Phagocytosis is an example of passive transport.

Question 72

Exocytosis is an example of active transport of a substance into the cell.

Question 73

Diffusion occurs because of random molecular movement.

Question 74

Water moves freely through a semipermeable membrane.

Question 75

Facilitated diffusion occurs through membrane-bound transport proteins.

Question 76

To move a molecule into a cell against the concentration gradient requires energy.

Question 77

Some integral proteins can span the entire phospholipid bilayer.

Question 78

The phospholipid bilayer forms because fatty-acid tails do not dissolve in water.

Question 79

The ________ functions in cell lubrication,adhesion,and signaling.

Question 80

The plasma membrane proteins of a cell can be linked to colored marker molecules.In an experiment,you labeled the membrane proteins of one cell with a red marker and the membrane proteins of a second cell with a blue marker.Using your understanding of the fluid-mosaic model,what might you see happen if you connected the plasma membranes of the two cells so that they form one continuous membrane?