Deck 4: Membrane Structure and Function

Question 1

Which of the following molecules add stiffness and strength to the plasma membrane?

A) glycoproteins
B) cholesterol
C) phospholipids
D) enzymatic proteins
E) phosphate groups

Answer 1

B
Explanation: Cholesterol stiffens and strengthens the membrane. The other things are present in membranes but do not fulfill that function.

Question 2

Proteins do NOT pass through cell membranes because

A) the membrane is made of protein.
B) they contain nitrogen.
C) they are very large molecules.
D) they cause emulsification.
E) they cause digestion of the cell.

Answer 2

C
Explanation: Proteins are too large to pass through the membrane. Proteins do contain nitrogen and may digest the cell but that does not explain why they cannot pass through the membrane. The membrane is made of proteins and phospholipids but again, that does not explain why proteins cannot pass. Proteins do not cause emulsification.

Question 3

In certain cancerous cells,the cell divides continuously even in the absence of a growth factor (signaling molecule)that indicates the cell should divide.Which of the following could NOT explain this?

A) a receptor molecule that is always turned off
B) a receptor molecule that is always activated
C) a transduction pathway that is always turned on
D) a target protein that is always activated
E) a gene for cell division that is expressed when it should not be

Answer 3

A
Explanation: The cell is behaving as if a signal has bound to a receptor even when one has not. This could be due to any of the products of a signaling pathway being activated when it should not be. The only thing it could not be is a receptor that is inactive or turned off.

Question 4

The cell membrane is composed of

A) proteins and microtubules.
B) lipids and actin filaments.
C) lipids and microtubules.
D) lipids and proteins.
E) proteins and actin filaments.

Question 5

Which statement is false concerning movement of molecules across the cell membrane?

A) Water and gas molecules have no difficulty.
B) Small uncharged molecules pass through easily.
C) Large molecules do not pass through easily.
D) Charged molecules do not pass through easily.
E) Lipid molecules do not pass through easily.

Question 6

The inside and outside of the plasma membrane are

A) identical in both the phospholipid bilayer and the embedded proteins.
B) identical in phospholipid bilayer but have cytoskeletal filaments on the outside and carbohydrate chains of glycolipids and proteins on the inside.
C) identical in phospholipid bilayer but have cytoskeletal filaments on the inside and carbohydrate chains of glycolipids and proteins on the outside.
D) different with a phospholipid bilayer on the inside and carbohydrate chains of glycolipids and proteins on the outside.
E) different with a phospholipid bilayer on the outside and carbohydrate chains of glycolipids and proteins on the inside.

Question 7

The same signaling molecule that binds to the receptor on the outside of the cell is used to alter gene expression in the nucleus.

Question 8

Which is a correct association of protein types?

A) carrier proteins-provide a pathway for substances to move across a membrane
B) cell recognition proteins-allow a specific molecule to bind to it and may cause a cell response
C) channel proteins-combine with a substance to help it move across a membrane
D) receptor proteins-variations in these proteins cause tissue transplant rejection
E) enzymatic proteins-carry out metabolic reactions directly

Question 9

Certain individuals with a Y chromosome develop into females because testosterone is not able to induce the formation of male sexual characteristics.This is most likely due to a defect in

A) the signaling molecule
B) the receptor
C) the transduction pathway
D) the target protein
E) the Y chromosome

Question 10

Red blood cells come in many blood types including A,B,AB and type O (lacking proteins A and B),Rh positive,Rh negative (lacking Rh+),and many others.If blood is transfused,the recipient detects any new or foreign proteins.The blood type proteins are

A) in the red blood cell nucleus.
B) inside the red blood cell cytoplasm.
C) on the outer surface of the red blood cell membrane.
D) in the nuclear membrane.
E) in the endoplasmic reticulum of the red blood cells.

Question 11

Which components of a cell membrane are used for cell-to-cell recognition?

A) phospholipids
B) proteins
C) glycolipids
D) glycoproteins
E) cholesterol molecules

Question 12

Permeability refers to

A) the movement of molecules from an area of greater concentration to an area of lesser concentration.
B) the extent to which a membrane allows a substance to pass through.
C) the amount of solute in a solution.
D) the state of being permanent.
E) the ability to establish a permanent solute level in a solution.

Question 13

Which of the following is not a function of the cell membrane?

A) It provides mechanical strength to the cell.
B) It gives shape to the cell.
C) It regulates passage of molecules into and out of the cell.
D) It is largely responsible for cellular homeostasis.
E) Serves as a site for protein synthesis.

Question 14

According to the fluid-mosaic model of membrane structure,

A) proteins make up the bulk of the membrane.
B) only lipids are found in the membrane.
C) cholesterol is the main constituent of the membrane.
D) glycolipids form a mosaic pattern inside the cell.
E) proteins float inside or within the phospholipid bilayer.

Question 15

Which type of membrane protein will be used to bind to hormones?

A) channel proteins
B) carrier proteins
C) cell recognition proteins
D) receptor proteins
E) enzymatic proteins

Question 16

Which function does the lipid bilayer component of the plasma membrane NOT provide for the cell?

A) defines a permeable boundary between the organized interior and the chaotic external environment
B) provides an impermeable, self-sealing membrane that keeps all internal living processes sealed inside
C) controls the exchange of molecules between one cell and adjacent cells or the environment
D) provides a fluid and flexible boundary that insulates the interior from the variations in humidity, food, and other external conditions
E) provides a matrix for proteins that regulate the exchange of molecules between the inside and outside of the cell

Question 17

What property of phospholipids make them suitable for the formation of the double layer found in membranes?

A) they are uncharged
B) they can interact with proteins
C) they are composed of fatty acids
D) they have both a hydrophobic and a hydrophilic end
E) they serve as an attachment site for carbohydrates

Question 18

Our body recognizes the foreign nature of a parasite or disease agent and we soon build up antibodies.A few parasites can change their identity to evade our immune system.How could cells do this on a regular basis?

A) Replace the cholesterol within the membrane with host cholesterol.
B) Wait for evolution of new protein membrane molecules.
C) Because the membrane is "set," a cell must reproduce and then the cell with the old membrane must die.
D) A whole new phospholipid bilayer is generated to replace the old layer.
E) New glycoproteins are produced in the cell and moved into the plasma membrane.

Question 19

In the new procedures developed to clone a mammalian cell,the nucleus is removed from an egg cell and the nucleus from the adult to be cloned is injected inside this cell.If we did this process with a basketball,we would permanently damage the shell.What property of the cell repairs this damage?

A) diffusion of cell membrane proteins
B) carrier proteins restore the membrane lipids
C) isotonic solutions
D) the outer and inner sides of the plasma membrane have identical carbohydrate chains
E) the fluid-mosaic nature of the membrane

Question 20

Radioactive isotopes are used to tag proteins in the cell membranes of mouse cells.These cells are then fused with human cells in cultures.What is the likely consequence of the tagged mouse proteins?

A) The tagged proteins remain in the mouse cells and keep their position on the membrane.
B) The tagged proteins remain in mouse cells but move anywhere across the mouse cell membrane.
C) The tagged proteins drift across cell membranes and are soon found dispersed across both human and mouse cell membranes.
D) None of these will occur since mouse cell membranes are unlike human cell membranes.
E) None of these will occur since radioactive cells will soon die.

Question 21

The definition of osmosis is the

A) the movement of solute molecules from a higher concentration to a lower concentration.
B) diffusion of water across a selectively permeable membrane.
C) likelihood that water will diffuse in a particular direction.
D) lower concentration of a solute in a solution.
E) movement of water toward a higher water concentration.

Question 22

The term hypertonic means

A) to lose water.
B) to gain water.
C) a higher solute concentration.
D) a lower solute concentration.
E) an equal solute concentration.

Question 23

If you have a 10% sugar solution and a 35% sugar solution how does the 10% solution compare to the 35% solution?

A) isotonic
B) sweeter
C) osmotic
D) hypotonic
E) hypertonic

Question 24

When blood supplies oxygen and food to a cell surface and these molecules diffuse across,we might expect some "resting time." However,if we inspected most cell membranes in a living human body,we would find a nearly continuous flow of substances back-and-forth across the plasma membrane.Which of the following is not a reason why?

A) Cell metabolism is constantly using up oxygen and raw materials; this lowers their concentration so more will diffuse into the cell.
B) Cell metabolism is constantly producing waste molecules; this increases their concentration so more will diffuse out of the cell.
C) Cells produce useful secretions; this increases their concentration and more will diffuse out of the cell.
D) Cell metabolism constantly produces carbon dioxide in respiration; this increases its concentration so more will diffuse out of the cell.
E) Cells are living entities and in order to live can never "rest".

Question 25

Kidney dialysis relies on diffusion of various dissolved waste molecules (solutes)across a non-living semipermeable membrane.If the concentration of solutes in the blood increases over time before dialysis is administered,what will happen to the rate of dialysis when it occurs?

A) It will remain the same since there are no carrier molecules in a non-living membrane.
B) The rate will slow down since the solute is more viscous.
C) The rate will speed up since the concentration gradient is higher.
D) It will remain the same since there is no active transport in a non-living membrane.
E) The rate will depend on the amount of time given for diffusion to take place.

Question 26

Once a solute and a solvent are evenly distributed in a solution,they will

A) stop moving about.
B) move back toward a concentration of the solvent.
C) continue to move about but with no net movement to higher concentration.
D) be totally out of equilibrium.
E) move from a liquid to gaseous solution.

Question 27

A cell placed in a hypotonic solution will

A) lose water.
B) gain water.
C) neither gain nor lose water.
D) lose water initially and then gain water.
E) gain water initially and then lose water.

Question 28

Of the following conditions,which is absolutely necessary for diffusion to take place?

A) a differentially permeable membrane
B) a true solution
C) a concentration difference
D) a non-permeable membrane
E) a living cell

Question 29

Which is a correct example of tonicity?

A) Water is hypertonic to red blood cells.
B) Turgor pressure is created when a plant cell swells in a hypotonic solution.
C) Plasmolysis results from plant cells in hypotonic solutions.
D) Crenated red blood cells result when they are placed in a hypotonic solution.
E) If a cell is placed in a hypertonic solution, water enters the cell.

Question 30

A student sitting on the back row opened a bottle of foul-smelling perfume and dabbed it on her wrists.One-by-one (beginning from the back of the room)the students began to cough due to the foul smell.This phenomena was due to

A) osmosis.
B) molecules moving from an area of low concentration to high concentration.
C) an allergic reaction.
D) diffusion.
E) active transport.

Question 31

Oxygen diffuses into the capillaries of the lungs because there is

A) a higher concentration of O₂ in the alveoli than the capillaries.
B) a higher concentration of O₂ in the capillaries than the alveoli.
C) a higher concentration of CO₂ in the alveoli than the capillaries.
D) a higher concentration of CO₂ in capillaries than the alveoli.
E) an equal concentration of O₂ in the alveoli and the capillaries.

Question 32

When water enters a plant cell

A) it bursts.
B) the vacuole becomes enlarged.
C) the vacuole shrinks.
D) it undergoes plasmolysis.
E) it undergoes crenation.

Question 33

The pressure that is generated when water flows through a differentially permeable membrane is termed

A) osmotic pressure.
B) turgor pressure.
C) plasmolysis.
D) crenation.
E) tonicity.

Question 34

When you add sugar to your coffee or tea,the sugar is the

A) permeable.
B) solvent.
C) gradient.
D) solution.
E) solute.

Question 35

A membrane sac filled with large molecules of potassium is suspended in a beaker of water.What will happen?

A) The potassium will leave and the water will enter until both sides reach equal concentrations.
B) Water will enter the sac and it will swell.
C) Because the potassium cannot leave, the water cannot enter.
D) We cannot determine the outcome unless we know the tonicity of the solutions.
E) The potassium will leave the sac and it will shrink.

Question 36

Osmosis can occur when a membrane is

A) impermeable.
B) semipermeable.
C) permeable.
D) plasmolyzed.
E) absent.

Question 37

When you cut into most active plant tissue,water appears almost immediately because plant cells are in

A) a hypertonic solution that produces turgor pressure.
B) a hypotonic solution that produces turgor pressure.
C) an isotonic condition and you cut the cell open.
D) a hypertonic condition and cutting it reversed this to hypotonic.
E) a hypotonic condition and cutting it reversed this to hypertonic.

Question 38

If 0.9% NaCl were isotonic to a cell,then

A) 0.9% would also be hypotonic.
B) 0.9% would also be hypertonic.
C) 1.0% would be hypertonic.
D) 1.0% would be hypotonic.
E) 0.1% would be hypertonic.

Question 39

What will happen to dye crystals if placed in the bottom of a beaker of water over a long period of time?

A) They will undergo osmosis to a different location.
B) They will undergo active transport to a different location.
C) They will all diffuse to the top of the beaker.
D) They will diffuse equally throughout the beaker.
E) They will stay at the bottom of the beaker.

Question 40

An isotonic solution means that the solute concentration outside the cell

A) is greater than inside the cell.
B) is less than inside the cell.
C) is the same as inside the cell.
D) has no effect on the cell.
E) is greater than outside the cell.

Question 41

Macrophages,a type of white blood cells,are able to remove bacteria from our bloodstream and tissues by

A) passive transport.
B) facilitated diffusion.
C) osmosis.
D) pinocytosis.
E) phagocytosis.

Question 42

In the Malpighian tubules of an insect (blind,threadlike excretory tubule attached to the gut of an insect),salt molecules are actively transferred from body fluids to the inside of the tubule.Which of the following is NOT true?

A) Water is also "pulled" by osmosis into the Malpighian tubule.
B) The concentration of salt is normally higher in the body fluids than it is inside the tubule.
C) The process decreases the salt concentration of the body fluids.
D) Insects must excrete excess salt through the Malpighian tubules.
E) The tubules have the same tonicity as the body fluids.

Question 43

Which of the following is not true regarding active transport?

A) moves molecules or ions against their concentration gradient
B) involves protein pumps
C) is associated with large numbers of mitochondria
D) is associated with nerve and muscle cells
E) cannot be done by animal cells

Question 44

Which membrane transport process can continue whether the cell is alive or dead?

A) sodium/potassium pump
B) pinocytosis
C) phagocytosis
D) exocytosis
E) diffusion

Question 45

In the emergency room,saline solutions are often run into a person's vein.The saline solution must be

A) 0.1% NaCl
B) 0.5% NaCl
C) 0.75% NaCl
D) 0.9% NaCl
E) 9.0% NaCl

Question 46

The number of mitochondria in a cell would be a general indicator of the extent of

A) diffusion.
B) facilitated transport.
C) active transport.
D) osmosis.
E) both osmosis and diffusion.

Question 47

Which is true of facilitated transport by carrier proteins?

A) Facilitated transport only applies to small and lipid soluble molecules.
B) It is represented by the glucose carrier that can transport hundreds of molecules a second.
C) After a carrier has transported a molecule, it is unable to transport any more.
D) Facilitated transport requires expenditure of chemical energy and is therefore active transport.
E) One carrier protein can carry a variety of different molecules.

Question 48

A cell is placed in a solution of large nutrient molecules tagged with a red dye.Soon the cell is dark red,showing a concentration of the nutrient much higher than the external solution.We add a reagent that blocks the use of ATP.What result would you expect from this experiment?

A) The nutrient would continue to rapidly enter the cell by diffusion because as a nutrient it is constantly being used in cell metabolism, so the cell will get redder.
B) The color will remain the same since all future transfer will stop.
C) The color will fade as the import of the nutrient stops and diffusion evens the concentrations.
D) The cell will continue to get darker since the import of the nutrient does not involve ATP.
E) The cell will die without access to ATP.

Question 49

Insulin formed by the Golgi apparatus in insulin-producing cells leaves those cells by

A) special pore molecules that are embedded in the cell membrane.
B) the insulin-filled vesicles fusing with the cell membrane and spilling their contents externally.
C) moving along the endoplasmic reticulum until it is outside the cell membrane.
D) the Golgi apparatus being connected with external channels directly to the cell membrane.
E) diffusion across the cytoplasm.

Question 50

What will happen to the protein solution of side A in Figure 4.1?

A)It will become less concentrated since protein will move from A to B.
B)It will become more concentrated since water passes from B to A.
C)It will become more concentrated since water passes from A to B.
D)It will become less concentrated since water passes from B to A.
E)It will become more concentrated since protein will move from B to A.

Question 51

How can marine animals such as sharks live in a salt water?

A) They increase or decrease the amount of urea in their blood until the blood is isotonic with the environment.
B) They increase the amount of urea in their blood until the blood is hypertonic with the environment.
C) They decrease the amount of urea in their blood until the blood is hypotonic with the environment.
D) They contain impermeable membranes which do not allow the salt water to cross into their cells.
E) They contain blood that has the same salt concentration as is present in salt water.

Question 52

Carrier molecules are required for

A) osmosis.
B) both osmosis AND diffusion.
C) facilitated diffusion.
D) active transport.
E) both facilitated diffusion AND active transport.

Question 53

When an intestinal cell ingests substances inside very small vesicles that can only be seen with an electron microscope,this is

A) pinocytosis.
B) phagocytosis.
C) exocytosis.
D) active transport.
E) diffusion.

Question 54

What will happen to the water level in Figure 4.1?

A)It will rise in side A.
B)It will rise in side B.
C)It will remain the same on both sides.
D)It will rise on both sides of the membrane.
E)It will decrease on both sides of the membrane

Question 55

When a substance moves from an area of low concentration to an area of high concentration while using energy,the process is termed

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

Question 56

Molecules such as glucose and amino acids are NOT lipid soluble and therefore they

A) easily pass across the cell membrane.
B) require active transport to cross the cell membrane.
C) must be converted to lipids before they can enter a cell.
D) combine with carrier proteins and pass across by facilitated transport.
E) must be engulfed by a cell using endocytosis.

Question 57

Dead plants seen alongside a salted roadway died because the saline solution caused the cells to

A) undergo crenation.
B) undergo lysis.
C) undergo hemolysis.
D) undergo plasmolysis.
E) the saline solution did not have an effect on the plants.

Question 58

If a cell lacks ATP,which of the following processes would cease to operate immediately?

A) diffusion
B) sodium/potassium pump
C) facilitated diffusion
D) osmosis
E) tonicity

Question 59

A differentially permeable membrane separates a molasses solution from distilled water.Over time,the

A) molasses will be found in the water.
B) molasses will become more dilute.
C) molasses solution will become more concentrated.
D) molasses will be found in water and it will be more concentrated.
E) solutions will remain the same.

Question 60

When a plant cell is placed in a hypotonic solution,the cell wall prevents

A) diffusion.
B) active transport.
C) the cell from bursting.
D) the cell from shrinking.
E) water from entering the cell.

Question 61

Exocytosis and endocytosis are carried out by proteins in the cell membrane.

Question 62

Compare and contrast exocytosis and endocytosis.

Question 63

Which of the following factors could cause the cell membrane to become less permeable?

A) If the channel proteins were to denature and become inactive.
B) If the molecules trying to enter the cell were decreased in size.
C) If the hydrophilic head of the phospholipids were to become hydrophobic while the hydrophobic tails become hydrophilic.
D) If the size of the protein channel was to increase.
E) All of these choices would cause the cell membrane to become less permeable.

Question 64

List the three types of intercelluar junctions found in animal cells and indicate their function.

Question 65

Explain the difference between peripheral proteins and integral proteins as they relate to the cell membrane.

Question 66

If a particular molecule is brought into the cell by receptor-medicated endocytosis,then changing the receptors will change the molecule that is being transported.

Question 67

If the proteins forming the cell junctions within the stomach were denatured,what is a likely consequence?

A) The desmosome junctions would not hold together causing the cells in the stomach to pull apart.
B) The tight junctions would not hold together causing the cells in the stomach to pull apart.
C) The desmosome junctions would be bonded together more tightly causing the cells in the stomach to form a solid barrier.
D) The gap junctions would not hold together causing the cells in the stomach to be unable to pass ions back and forth.
E) The desmosome junctions would not hold together causing the cells in the kidney to pull apart.

Question 68

Receptor-mediated endocytosis involves all of the following EXCEPT

A) receptor proteins to bind to specific molecules.
B) a coated pit due to a layer of fibrous protein on the cytoplasmic side of the membrane.
C) various outcomes from destruction of the vesicle to restoration of the surface configuration.
D) the mechanism for regulating exchange between a mother and fetus.
E) secretion of materials from a cell.

Question 69

Which component of the extracellualr matrix is responsible for forming proteoglycans?

A) Amino sugars
B) Fibronectin
C) Collagen
D) Elastin
E) Integrin

Question 70

If a molecule crosses a plasma membrane faster than it diffuses in water,then the process is likely to involve active transport.

Question 71

Which of the following refers to materials only leaving the cell?

A) diffusion
B) exocytosis
C) endocytosis
D) pinocytosis
E) phagocytosis

Question 72

One way to determine whether something is being actively transported across a membrane,is to compare its rate of transport with and without a chemical that blocks ATP production.

Question 73

Which is the most common type of intercellular junction between skin cells?

A) adhesion junctions
B) gap junctions
C) tight junctions
D) plasmodesmata
E) None of these are found between skin cells.

Question 74

The extracellular matrix is responsible for which of the following features?

A) The extracellular matrix does all of these features.
B) The extracellular matrix helps the cell resist stretching.
C) The extracellular matrix enables the cell to adhere to neighboring cells.
D) The extracellular matrix plays a role in cell signaling.
E) The extracellular matrix acts as a structural feature.

Question 75

What two components are commonly found in the extracellular matrix that help resist stretching and provide resilience?

A) proteins & polysaccharides
B) proteins & phospholipids
C) polysaccharides & phospholipids
D) amino acids & phospholipids
E) nucleic acids & proteins

Question 76

Which intercellular junction allows for the rapid movement of small molecules or ions to flow from one animal cell to the next?

A) gap junctions
B) tight junctions
C) adhesion junctions
D) desmosomes
E) plasmodesmata

Question 77

Oxygen leaves the alveoli in the lungs and enters the capillaries by endocytosis.