Cell Membrane & Transport Study Guide

Name: 

True/False
Indicate whether the statement is true or false.

During diffusion, molecules diffuse from a region where their concentration is low to a region where their concentration is higher, until the particles are evenly dispersed.

When the concentration of dissolved particles outside a cell is equal to the concentration of dissolved particles inside the cell, the cell solution is isotonic.

Membranes are selectively permeable if they allow only certain substances to move across them.

A cell placed in a strong salt solution would probably burst because of osmosis.

Water will diffuse out of a cell when the cell is placed in a hypertonic solution.

Osmosis is the diffusion of starch molecules through a selectively permeable membrane.

The binding of specific molecules to ion channels controls the ability of particular ions to cross the cell membrane.

To pass through a cell membrane, water requires carrier proteins.

In facilitated diffusion, carrier proteins require energy to transport substances across the cell membrane.

The transport of specific particles down their concentration gradient through a membrane by carrier proteins is known as facilitated diffusion.

Diffusion is an active process that requires a cell to expend a great deal of energy.

Diffusion through ion channels is a form of active transport.

Facilitated diffusion moves molecules and ions against their concentration gradient, while active transport moves molecules and ions down their concentration gradient.

Passive transport uses ATP to move molecules against their concentration gradient.

In active transport, energy is required to move a substance across a cell membrane.

The sodium-potassium pump requires energy to move ions across the cell membrane.

The sodium-potassium pump moves sodium ions and potassium ions against their concentration gradient.

The sodium-potassium pump transports sodium ions out of a cell while causing potassium ions to move into the cell.

The sodium-potassium pump uses ATP.

Exocytosis is a process that uses vesicles to capture substances and bring them into a cell.

Exocytosis helps the cell rid itself of wastes.

During the process of exocytosis, the cell membrane extends to engulf substances that are too big to pass through the cell membrane.

Exocytosis does not use energy to expel proteins from the cell.

Receptor proteins pump sodium ions into a cell.

Receptor proteins may cause the formation of a second messenger molecule inside a cell.

A receptor protein sends signals into a cell by transporting a specific molecule through the cell membrane.

Modified True/False
Indicate whether the statement is true or false.  If false, change the identified word or phrase to make the statement true.

One way that cells maintain homeostasis is by controlling the movement of substances across the cell membrane. _________________________

The cell membrane is made up of a double layer called the DNA bilayer. _________________________

A phospholipid is made up of a lipid “head” and two fatty acid “tails.” _________________________

The nonpolar tails of a phospholipid are attracted to water. _________________________

Cell-surface markers face the inside of the cell. _________________________

A concentration gradient exists when one area has a higher concentration of a substance than another area does. _________________________

The movement down a concentration gradient is called diffusion. _________________________

When the solute concentration outside a cell is equal to the solute concentration inside the cell, the cell’s environment is hypotonic. _________________________

A cell placed in a high salt solution would swell because of osmosis. _________________________

Osmosis is the diffusion of starch molecules through a selectively permeable membrane. _________________________

To pass through a cell membrane, water requires carrier proteins. _________________________

Facilitated diffusion is an active process that requires a cell to expend a great deal of energy. _________________________

Passive transport uses ATP to move molecules against their concentration gradient. _________________________

Exocytosis is a process that uses vesicles to capture substances and bring them into a cell. _________________________

Cells use exocytosis to export proteins modified by the Golgi apparatus. _________________________

Cells communicate by sending chemical signals that carry information to other cells. _________________________

Receptor proteins bind only to signals that match the specific color of the binding site. _________________________

Receptor proteins may cause the formation of a second messenger molecule inside the cell. _________________________

Multiple Choice
Identify the choice that best completes the statement or answers the question.

As a result of diffusion, the concentration of many types of substances

a.	always remains greater inside a membrane.
b.	eventually becomes balanced on both sides of a membrane.
c.	always remains greater outside of a membrane.
d.	becomes imbalanced on both sides of a membrane.

Refer to the illustration above. The process shown is called

a.	osmosis.	c.	active transport.
b.	facilitated diffusion.	d.	diffusion.

Refer to the illustration above. The process shown is called

a.	osmosis.	c.	active transport.
b.	facilitated diffusion.	d.	diffusion.

Diffusion is the movement of a substance

a.	only through a lipid bilayer membrane.
b.	from an area of low concentration to an area of higher concentration.
c.	only in liquids.
d.	from an area of high concentration to an area of lower concentration.

The dispersal of ink in a beaker of water is an example of

a.	diffusion.	c.	active transport.
b.	osmosis.	d.	endocytosis.

The diffusion of water into or out of a cell is called

a.	solubility.	c.	selective transport.
b.	osmosis.	d.	endocytosis.

Osmosis is a type of

a.	active transport.	c.	facilitated diffusion.
b.	passive transport.	d.	endocytosis.

A cell will swell when it is placed in a(n)

a.	hypotonic solution.	c.	isotonic solution.
b.	hypertonic solution.	d.	None of the above

The interior portion of a cell membrane forms a nonpolar zone that

a.	allows polar molecules to pass through the membrane.
b.	allows food to pass through the membrane.
c.	prevents ions and most large molecules from passing through the membrane.
d.	None of the above

Ions move through ion channels by

a.	endocytosis.	c.	passive transport.
b.	diffusion.	d.	active transport.

Ion channel gates close the pores of some ion channels in response to

a.	stretching of the cell membrane.
b.	a change in electrical charge.
c.	the binding of specific molecules to the channel.
d.	All of the above

Proteins that act like selective passageways in the cell membrane are known as

a.	marker proteins.	c.	receptor proteins.
b.	channel proteins.	d.	None of the above

Transport proteins that allow ions to pass through the cell membrane are called

a.	receptor proteins.	c.	ion channels.
b.	marker proteins.	d.	None of the above

Sugar molecules cross the cell membrane by

a.	active transport.	c.	osmosis.
b.	facilitated diffusion.	d.	gated channels.

Proteins involved in facilitated diffusion are

a.	carrier proteins.	c.	Both (a) and (b)
b.	receptor proteins.	d.	None of the above

Sugar molecules can enter cells through the process of

a.	exocytosis.	c.	osmosis.
b.	facilitated diffusion.	d.	ion pumps.

Which of the following does not require energy?

a.	diffusion	c.	active transport
b.	endocytosis	d.	sodium-potassium pump

Unlike passive transport, active transport

a.	requires energy.
b.	moves substances down their concentration gradient.
c.	does not involve carrier proteins.
d.	All of the above

Both active transport and facilitated diffusion involve

a.	ATP.
b.	movement against a concentration gradient.
c.	carrier proteins.
d.	All of the above

Which of the following is a form of active transport?

a.	osmosis	c.	facilitated diffusion
b.	diffusion	d.	sodium-potassium pump

The sodium-potassium pump

a.	is a carrier protein	c.	is located in the cytoplasm of a cell.
b.	uses passive transport.	d.	transports sugar molecules.

The sodium-potassium pump usually pumps

a.	potassium ions out of the cell.
b.	sodium ions into the cell.
c.	potassium ions into the cell.
d.	only potassium ions and sugar molecules.

The sodium-potassium pump

a.	increases the concentration of sodium ions inside a cell.
b.	decreases the concentration of sodium ions inside a cell.
c.	increases the concentration of potassium ions inside a cell.
d.	Both (b) and (c)

Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by

a.	exocytosis.	c.	the sodium-potassium pump.
b.	endocytosis.	d.	None of the above

Molecules that are too large to be moved through the membrane can be transported into the cell by

a.	osmosis.	c.	exocytosis.
b.	endocytosis.	d.	diffusion.

Molecules that are too large to be moved across a cell membrane can be removed from the cell by

a.	diffusion.	c.	endocytosis.
b.	exocytosis.	d.	osmosis.

Ridding the cell of materials by discharging the materials in vesicles is called

a.	osmosis.	c.	exocytosis.
b.	diffusion.	d.	endocytosis.

Refer to the illustration above. What happens when the structure labeled A binds to the structure labeled B?

a.	Information is sent into the cell.	c.	The cell begins to undergo mitosis.
b.	Proteins enter the cell.	d.	None of the above

Refer to the illustration above. What happens when the structure labeled A binds to the structure labeled B?

a.	Information is sent into the cell.	c.	The cell begins to swell.
b.	Proteins enter the cell.	d.	Ions enter the cell.

Refer to the illustration above. The structure labeled B in the diagram is an example of a(n)

a.	channel protein.	c.	receptor protein.
b.	signal molecule.	d.	ion pump.

Signal molecules bind to

a.	carbohydrates.	c.	receptor proteins.
b.	marker proteins.	d.	transport proteins.

When a signal molecule binds to a receptor protein, the receptor protein may

a.	change the permeability of the membrane.
b.	cause the formation of a second messenger molecule.
c.	catalyze certain chemical reactions in the cell.
d.	All of the above

Which of the following transmit information into a cell by binding to signal molecules?

a.	channel proteins	c.	marker proteins
b.	receptor proteins	d.	end proteins

cell membrane : cell ::

a.	window : house	c.	door : house
b.	roof : house	d.	wall : house

Which type of molecule forms the cell membrane?

a.	protein	c.	nucleic acid
b.	phospholipid	d.	carbohydrate

Phospholipids are molecules that have

a.	one polar phosphate head and two polar fatty acid tails.
b.	one polar phosphate head and two nonpolar fatty acid tails.
c.	one polar phosphate head and one polar fatty acid tail.
d.	one nonpolar phosphate head and two polar fatty acid tails.

The interior of the lipid bilayer of a cell membrane forms a nonpolar zone that

a.	allows most polar molecules to pass through the membrane.
b.	allows food to pass through the membrane.
c.	repels ions and most polar molecules.
d.	makes the membrane permeable to most molecules.

Refer to the illustration above. The structure labeled A is composed of

a.	lipids.	c.	proteins.
b.	carbohydrates.	d.	DNA.

Refer to the illustration above. The structure labeled D is a(n)

a.	cell-surface marker.	c.	enzyme.
b.	receptor protein.	d.	transport protein.

Refer to the illustration above. The structure labeled C is a(n)

a.	cell-surface marker.	c.	enzyme.
b.	receptor protein.	d.	transport protein.

Proteins in the cell membrane that identify the cell are called

a.	cell-surface markers.	c.	enzymes.
b.	receptor proteins.	d.	transport proteins.

As a result of diffusion, the concentration of many types of substances

a.	always remains greater inside a membrane.
b.	eventually becomes balanced on both sides of a membrane.
c.	always remains greater outside of a membrane.
d.	becomes imbalanced on both sides of a membrane.

Diffusion is the movement of a substance

a.	only through a lipid bilayer membrane.
b.	from an area of low concentration to an area of higher concentration.
c.	only in liquids.
d.	from an area of high concentration to an area of lower concentration.

The dispersal of ink in a beaker of water is an example of

a.	diffusion.	c.	active transport.
b.	osmosis.	d.	endocytosis.

Proteins that serve as tunnels for specific substances through the lipid bilayer are

a.	cell-surface markers.	c.	receptor proteins.
b.	channel proteins.	d.	enzymes.

Sugar molecules cross the cell membrane by

a.	active transport.	c.	osmosis.
b.	facilitated diffusion.	d.	simple diffusion.

Which of the following does not require energy?

a.	diffusion	c.	active transport
b.	endocytosis	d.	sodium-potassium pump

Ions move through ion channels by

a.	endocytosis.	c.	passive transport.
b.	simple diffusion.	d.	active transport.

The diffusion of water into or out of a cell is called

a.	solubility.	c.	selective transport.
b.	osmosis.	d.	endocytosis.

Osmosis is a type of

a.	active transport.	c.	simple diffusion.
b.	passive transport.	d.	endocytosis.

How does water pass through the cell membrane?

a.	directly through the lipid bilayer
b.	through a water ion pump
c.	through water carrier proteins
d.	through channel proteins just for water

Which of the following statements about an isotonic solution and a cell is correct?

a.	The solution has the same solute concentration that the cytoplasm does.
b.	The solution has a higher solute concentration than the cytoplasm does.
c.	A cell in the solution will lose water.
d.	A cell in the solution will gain water.

Unlike passive transport, active transport

a.	requires energy.
b.	moves substances down their concentration gradient.
c.	does not involve carrier proteins.
d.	moves water across the cell membrane.

Both active transport and facilitated diffusion involve

a.	ATP.
b.	movement against a concentration gradient.
c.	carrier proteins.
d.	channel proteins.

Which of the following is a form of active transport?

a.	osmosis	c.	facilitated diffusion
b.	simple diffusion	d.	sodium-potassium pump

The sodium-potassium pump

a.	is a carrier protein.	c.	is located in the cytoplasm of a cell.
b.	uses passive transport.	d.	transports sugar molecules.

The sodium-potassium pump usually pumps

a.	potassium ions out of the cell.
b.	sodium ions into the cell.
c.	potassium ions into the cell.
d.	only potassium ions and sugar molecules.

How many potassium ions does the sodium-potassium pump move into a cell if it moves six sodium ions out of the cell?

a.	two	c.	six
b.	four	d.	eight

Proteins and polysaccharides that are too large to move into a cell through diffusion or active transport move in by

a.	exocytosis.	c.	the sodium-potassium pump.
b.	endocytosis.	d.	channel proteins.

Molecules that are too large to be moved across a cell membrane can be removed from the cell by

a.	diffusion.	c.	endocytosis.
b.	exocytosis.	d.	osmosis.

Removing materials from a cell in vesicles is called

a.	osmosis.	c.	exocytosis.
b.	diffusion.	d.	endocytosis.

Which of the following descriptions of hormones is correct?

a.	signal molecules distributed throughout the body
b.	signal molecules that affect all cells in the body
c.	target molecules that communicate through direct contact
d.	target molecules that originate outside the body

Signal molecules bind to

a.	carbohydrates.	c.	receptor proteins.
b.	marker proteins.	d.	transport proteins.

Which of the following transmit information into a cell by binding to signal molecules?

a.	channel proteins	c.	marker proteins
b.	receptor proteins	d.	signal proteins

What change takes place in the cell membrane if a signal molecule causes a transport protein to open?

a.	permeability change	c.	formation of a second messenger
b.	activation of an enzyme	d.	change in chemical reactions

Completion
Complete each statement.

The random motion of particles of a substance that causes the substance to move from an area of high concentration to an area of lower concentration is called ____________________.

The diffusion of ____________________ through cell membranes is called osmosis.

Substances always flow from an area of high concentration to an area of ____________________ concentration.

When the concentration of free water molecules is higher outside a cell than inside the cell, water will diffuse ____________________ the cell.

If a cell is placed in a(n) ____________________ solution, water will flow out of the cell.

If a cell is placed in a(n) ____________________ solution, water will flow into the cell.

If a cell is placed in a(n) ____________________ solution, water flows into the cell at a rate that is equal to the rate at which water flows out of the cell.

Diffusion of ions through ion channels is a form of ____________________ transport.

If the interior of a typical cell is negatively charged, ____________________ charged ions will not require energy to diffuse into the cell using an ion channel.

In facilitated diffusion, ____________________ proteins are used to transport substances down their concentration gradient.

In ____________________ ____________________, carrier proteins do not require energy to transport amino acids into a cell.

Carrier proteins ____________________ shape to transport sugars to the interior of cells.

A cell does not expend ____________________ when diffusion takes place.

Active transport requires the use of ____________________ by a cell.

The ____________________-____________________ pump transports ions against their concentration gradients.

The sodium-potassium pump uses energy supplied by ____________________.

The sodium-potassium pump prevents the accumulation of ____________________ ions inside the cell.

The movement of a substance into a cell by a vesicle is called ____________________.

A	B

Refer to the illustration above. The process shown in figure B is called ____________________.

Refer to the illustration above. Cells often engulf extracellular particles and fluid, as shown in figure A. This is called ____________________.

Refer to the illustration above. The process shown in figure B is called ____________________.

Refer to the illustration above. The process shown in figure A is called ____________________.

Receptor proteins can change the ____________________ of the cell membrane.

Receptor proteins may act as ____________________, catalyzing certain chemical reactions inside the cell.

In the cell membrane, proteins that transmit information into the cell by responding to signal molecules are called ____________________.

One way cells maintain homeostasis is by controlling the movement of substances across the cell ____________________.

A(n) ____________________ is a specialized lipid made of a phosphate head and two fatty acid tails.

The phosphate head of a phospholipid is attracted to water because it is ____________________.

The fatty acid tails of a phospholipid are repelled by water because they are ____________________.

The phospholipids form a barrier through which only small, ____________________ substances can pass.

Ions and most polar molecules are repelled by the ____________________ interior of the lipid bilayer.

____________________ – ____________________ markers are attached to the cell surface and have sugars attached to their protein.

Proteins that aid in moving substances into and out of cells are called ____________________ proteins.

____________________ are proteins in the cell membrane that help with important biochemical reactions inside the cell.

____________________ proteins enable a cell to sense its surroundings by binding to certain substances outside the cell.

To reach equilibrium, substances always flow from an area of high concentration to an area of ____________________ concentration.

When one area has a higher concentration than another area does, a concentration ____________________ exists.

Substances diffuse through a cell membrane either through the lipid bilayer or through ____________________ proteins.

Oxygen and carbon dioxide pass through the lipid bilayer by ____________________ diffusion.

Diffusion of ions through ion channels is a form of ____________________ transport.

Carrier proteins change ____________________ to transport substances to the interior of cells.

A cell does not expend ____________________ when diffusion takes place.

The diffusion of ____________________ through cell membranes is called osmosis.

When the concentration of free water molecules is higher outside a cell than inside the cell, water will diffuse ____________________ the cell.

If a cell is placed in a(n) ____________________ solution, water will flow out of the cell.

If a cell is placed in a(n) ____________________ solution, water will flow into the cell.

If a cell is placed in a(n) ____________________ solution, water flows into the cell at a rate that is equal to the rate at which water flows out of the cell.

Active transport requires the use of ____________________ by a cell.

The ____________________ – ____________________ pump transports ions against their concentration gradients.

The sodium-potassium pump uses energy supplied by ____________________.

The sodium-potassium pump prevents the accumulation of ____________________ ions inside the cell.

The movement of a substance into a cell by a vesicle is called ____________________.

A signaling cell produces a signal that is detected by a ____________________ cell.

Light is an environmental ____________________ for the flowering of some plants.

In the cell membrane, proteins that bind to specific signal molecules and respond are called ____________________ proteins.

Receptor proteins can change the ____________________ of the cell membrane.

Receptor proteins may act as ____________________, triggering certain chemical reactions inside the cell.

In addition to its function as a gatekeeper, what are three other functions of the cell membrane?

What makes up the lipid bilayer?

In the lipid bilayer, what causes one layer of polar heads to face the cell’s cytoplasm and the other layer of heads to face the cell’s surroundings?

What characteristic of membrane proteins causes them to be held in the cell membrane?

What are four types of proteins in cell membranes?

What exists across a cell membrane if equilibrium is not reached?

What is the difference between how a molecule crosses the cell membrane in simple diffusion and in facilitated diffusion?

What are two types of transport proteins?

Why are some water molecules not free to move across the cell membrane?

Explain why osmosis is a form of facilitated diffusion.

What specific carrier protein moves sodium ions out of a cell and potassium ions into a cell?

What is the function of the cell membrane during endocytosis?

What are hormones, how are they distributed, and what cells do they affect?

What happens to a receptor protein once it binds to a signal molecule?

How can the cell’s response to a signal cause a permeability change?