Biology - Chapter 5 - Membranes - Review Questions

Select the true statements comparing simple and facilitated diffusion.

1. Facilitated diffusion, but not simple diffusion, requires a transport protein. 2. Both simple and facilitated diffusion require concentration gradients.

Select functions of the selectively permeable plasma membrane.

1. Maintain a proper balance of ions within the cell. 2. Maintain a proper supply of essential molecules such as glucose and amino acids. 3. Remove waste products from within the cell.

Select the three types of endocytosis.

1. Phagocytosis 2. Receptor-mediated endocytosis 3. Pinocytosis

Place the steps involved in receptor-mediated endocytosis in the correct order, beginning with the first step at the top. 1. The cargo is released. 2. The vesicle fuses with an internal organelle. 3. Coat proteins bind to the membrane as it invaginates to form a vesicle. 4.Cargo binds to the receptor and receptors aggregate. 5. The vesicle is released into the cell. 6. The protein coat is shed.

4. 3. 5. 6. 2. 1.

Why can nitrogen gas diffuse through the lipid bilayer but a nitrogen ion cannot?

A nitrogen ion carries a charge.

An electrochemical gradient occurs in solutions that have...

A positive or negative charge.

Match each ion or molecule with its properties. A. Ions B. Oxygen gas (O2) C. Sugars D. DNA 1. Charged 2. Polar and organic 3. Uncharged and small 4. Macromolecule

A. 1. B. 3. C. 2. D. 4.

Match each type of membrane protein with the way it is associated with the plasma membrane. A. Transmembrane protein B. Lipid-anchored protein C. Peripheral membrane protein 1. A lipid molecule is covalently attached to an amino acid side chain of the membrane protein. 2. A segment of amino acids is inserted into the phospholipid bilayer. 3. Noncovalent associations form with phospholipids or other membrane proteins.

A. 2. B. 1. C. 3.

Match each type of transport with the correct description. A. Diffusion B. Facilitated Diffusion C. Active Transport 1. Movement of a substance from a region where its concentration is low to a region where its concentration is high with the aid of a transport protein and a source of energy. 2. Movement of a substance from a region where its concentration is high to a region where its concentration is low. 3. Movement of a substance from a region where its concentration is high to a region where its concentration is low through a passageway provided by a transport protein.

A. 2. B. 3. C. 1.

Match the following scenarios to the correct consequence. A. Animal cell in a hypotonic solution. B. Animal cell in a hypertonic solution. C. Plant cell in a hypertonic solution. 1. Plasmolysis 2. Crenation 3. Osmotic lysis

A. 3. B. 2. C. 1.

The sodium/potassium -ATPase transports Na+ and K+ ions against their gradients using the energy from ________ hydrolysis.

ATP

The transfer of phospholipids between leaflets requires the input of...

ATP

Which of the following molecules can pass through plasmodesmata?

ATP Ions Sugars

The transport of a substance that requires an input of energy is called _____ transport.

Active

ATP can be used to power which of the following processes?

Active Transport

Which type of transport requires a source of energy and a transport protein?

Active Transport

Active transport is the movement of a solute across the membrane _____ its concentration gradient.

Against

The Na+/K+-ATPase pump is considered a(n) _____ because it binds both Na+ and K+ and transports them in opposite directions.

Antiporter

Why is the Na+/K+-ATPase pump considered an antiporter?

Because it moves two substances in opposite directions.

_____ _____ are involved in many different cellular functions, including cell compartmentalization and the selective uptake of ions and molecules.

Biological membranes

Unlike transporters, _____ proteins provide an open passageway all the way across the plasma membrane.

Channel

What type of proteins form an open passageway for facilitated diffusion of ions or molecules across the membrane?

Channels

Proteins that assist in the movement of substances across membranes can be classified into two types based on how they move solutes across a membrane: _____ and _____.

Channels; transporters

Select all the characteristics that a solute with very low membrane permeability might have.

Charged; large

Plant cell can prevent the loss of water and nutrients from wounds by...

Closing their plasmodesmata.

How do conformational charges of the Na+/K+-ATPase pump relate to its function? Select all that apply.

Conformational changes expose binding surfaces for both Na+ and K+. Conformational changes allow the pump to access either the cytosol or the outside of the cell. Conformational changes allow solutes bound on one side of the membrane to be moved to the other side.

Which of the following are conformational states of the Na+/K+-ATPase pump? Select all that apply.

E1 E2

Moving a solute against its chemical or electrochemical gradient requires a source of _____.

Energy

Select the processes used by eukaryotic cells to transport large molecules such as proteins and polysaccharides.

Exocytosis Endocytosis

The leaflet of the plasma membrane that faces the outside of the cell is called the _____ leaflet.

Extracellular

A cell contains less sodium than the surrounding environment. What type of transport is required to import sodium ions into the cell?

Facilitated diffusion

True or False: The two leaflets of the plasma membrane have the same lipid composition.

False.

According to the _____ model, membrane proteins and lipids are able to move relative to one another within the plasma membrane.

Fluid-mosaic

When channel proteins are _____, it means they can open and close to regulate the movement of ions and molecules across the cell membrane.

Gated

Protein channels that open and close in response to the binding of a ligand are called...

Gated channels.

What organelle is the origin of the vesicles used in exocytosis?

Golgi apparatus

Select the interactions that are typically involved in peripheral proteins binding to biological membranes.

Hydrogen bonds Ionic bonds

Select all the regions that are likely binding sites for peripheral membrane proteins.

Hydrophilic regions of integral membrane proteins. Polar head groups of phospholipids.

Movements that keep the phospholipid nonpolar tail within the _____ region of the bilayer are energetically favorable.

Hydrophobic

Phospholipid bilayers are an effective barrier to many charged or polar solutes because of their ________ interior region.

Hydrophobic

A solution whose solute concentration is higher than the concentration of solutes inside a cell is...

Hypertonic

When the concentration of solutes outside the cell is lower than that intra-cellularly, the solution is said to be ________ relative to the inside of the cell.

Hypotonic

A contractile vacuole is an important feature of microorganisms living in a(n)...

Hypotonic environment.

Water diffuses through a membrane from a solution that is _____ (lower concentration of dissolved particles) into a solution that is _____ (higher concentration of dissolved particles). Solutions with identical concentrations are said to be _____.

Hypotonic; Hypertonic; Isotonic

When the concentrations of dissolved particles (solutes) on both sides of the plasma membrane are equal, the two solutions are said to be...

Isotonic

What changes might occur in the membranes of a polar bear's cells when hibernating over the winter?

It might incorporate more cholesterol into its membrane to make it more fluid.

The presence of a double bond in a phospholipid tail makes the membrane more fluid because...

It prevents phospholipids from packing tightly.

The double bonds in unsaturated lipids create ________ in the nonpolar tails, making it more difficult for neighboring lipids to interact.

Kinks

Most phospholipids move freely within a semifluid membrane...

Laterally along the plane of the membrane in two dimensions.

One layer, or half of a phospholipid bilayer, is termed a(n)...

Leaflet

A group of lipids that float together as a unit within the plasma membrane is called a(n) _____ _____.

Lipid raft

Which of the following can be found in lipid rafts? Select all that apply.

Lipid-anchored proteins; transmembrane proteins; high amount of cholesterol.

In osmosis, water moves from areas of...

Low solute concentration to areas of high solute concentration.

When plasmodesmata are dilated, they allow the passage of...

Macromolecules and viruses.

Select all of the following statements that are consistent with the fluid-mosaic model.

Many membrane proteins move within the plane of the membrane. Phospholipids can move within the plane of the membrane. Membranes are mainly composed of proteins and phospholipids.

Select the reason why it is more appropriate to describe membranes as semifluid.

Molecules move laterally within the membrane leaflet. Phospholipids usually move in two dimensions.

Select the reasons why it is more appropriate to describe membranes as semifluid.

Molecules move laterally within the membrane leaflet. Phospholipids usually move in two dimensions.

Shorter nonpolar tails make the membrane _____ fluid.

More

Because the plasma membrane contains lipids, proteins, and carbohydrates, it is often described as a(n)...

Mosaic.

In bacteria, fungi, algae, and plant cells, symporters usually rely on a proton gradient across the plasma membrane. In animal cells, however, most symporters rely on a(n) _____ gradient.

Na+

The structure of the Na/K+-ATPase pump allows the binding of which of the following? Select all that apply.

Na+ K+

The Na+/K+-ATPase pump establishes and maintains a gradient such that...

Na+ is higher outside the cell than inside, and K+ is higher inside the cell than outside.

Within the plasma membrane, where are glycolipids normally found?

On the extracellular leaflet.

The movement of charged ions through the Na+/K+ -ATPase pump creates a net charge difference because...

One cycle of pumping results in the net export of one positive charge.

Order the following solutes from highest membrane permeability at the top to lowest at the bottom. Water, oxygen gas, glucose, potassium ions.

Oxygen gas, water, glucose, potassium ions.

Small, uncharged molecules pass through the membrane via...

Passive Diffusion

The selective _____ of the plasma membrane allows the cell to maintain a favorable internal environment.

Permeability

Certain kinds of cells can engulf large particles, such as bacteria, through a type of endocytosis called _____.

Phagocytosis

The plasma membrane consists of a(n) _____ bilayer.

Phospholipid

The three main types of macromolecules that comprise the plasma membrane are _____, _____, and _____.

Phospholipids, proteins, and carbohydrates.

In a plasmodesma, the _____ of one cell is continuous with that of another cell.

Plasma membrane

What type of cell junctions form channels between adjacent plant cells?

Plasmodesmata

If the medium surrounding a plant cell is hypertonic, water exits the cell and the cell membrane pulls away from the cell wall in a process known as _____.

Plasmolysis

What is the result of place a plant cell into a hypertonic solution?

Plasmolysis

Phospholipids have a _____ head region that will interact with aqueous environments.

Polar

_____ active transport involves a pump that uses energy from ATP to transport solutes against a gradient.

Primary (or direct)

What type of transport uses a pre-existing gradient to drive the transport of another molecule?

Secondary active transport

The plasma membrane of a cell is considered to be...

Selectively permeable.

What organelle in adjacent cells is connected by the central tubules in plasmodesmata?

Smooth endoplasmic reticulum

Water is considered to be a _____ that dissolves _____ molecules.

Solvent; Solute

The Na+/K+-ATPase pump is considered to be electrogenic. This is because...

The actions of the pump create an electrical gradient.

What component of plant cells prevents changes in cell volume that result in osmotic lysis?

The cell wall.

Select all the processes that are coupled across cell membranes.

The export of Na+ ions. The import of K+ ions.

The cytosolic leaflet of the plasma membrane faces...

The inside of the cell.

What separates the internal contents of a cell from the extracellular environment?

The plasma membrane

The two leaflets of a lipid bilayer are formed because...

The polar head groups of phospholipids can interact with the polar interior and exterior of the cell.

"Flip flop" movements of phospholipids within the membrane are unfavorable because...

The polar head groups of phospholipids have to traverse the hydrophobic interior of the membrane.

Cellular membranes are described as fluid because...

Their lipids and proteins can move relative to each other.

Which of the following statements about plasmodesmata is true?

They can be closed, open, or dilated.

The Na+/K+-ATPase hydrolyzes ATP after the binding of...

Three Na+

Which of the following are pumped by the Na+/K+ -ATPase? Select all that apply.

Three Na+ out of the cell. Two K+ into the cell.

The Na+/K+-ATPase pumps _____ Na+ ions out of the cell and _____ K+ ions into the cell.

Three; two

A term that describes a situation in which the concentration of a solute is higher on one side of a membrane than the other is...

Transmembrane Gradient

Select all the membrane proteins that are integral membrane proteins.

Transmembrane proteins; lipid-anchored proteins

Transmembrane proteins called _____ proteins allow ions and hydrophilic molecules to cross the phospholipid bilayer.

Transport

How do transporters differ from channel proteins?

Transporters must change conformation to allow solutes to cross the membrane.

Endocytosis and exocytosis involve packaging substances into a membrane-enclosed _____.

Vesicle

During exocytosis, a protein-coated _____ loaded with cargo is released from the _____ apparatus, and then fuses with the _____ _____.

Vesicle; Golgi; plasma membrane

Osmosis is the flow of _____ across a membrane.

Water

An animal cell is placed in a hypertonic medium. Predict which way water will move.

Water will move from the inside of the cell to the outside.