Mastering Biology: Chapter 5

Which of the following particles could diffuse easily through a cell membrane? Oxygen (O2) Glucose Hydrogen ion (H+) Sodium ion (Na+)

Oxygen (O2)

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group. True False

True

Immediately following binding of a growth factor, an activated receptor would most likely stimulate activation of a calcium-binding protein. activation of a protein phosphatase. activation of adenylyl cyclase. activation of a protein kinase.

activation of a protein kinase

An integral membrane protein would have to be hydrophobic. hydrophilic. exposed to water on only one surface of the membrane. amphipathic, with at least one hydrophobic region.

amphipathic, with at least one hydrophobic region

Select all that apply. Signal transduction pathways convert a signal on a cell's surface to a specific cellular response. Signal transduction pathways allow different types of cells to respond differently to the same signal molecule. Signal transduction pathways amplify the effect of a signal molecule.

All the above

True or false? Osmosis is a type of diffusion. True False

True

Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane? Lipid soluble molecule Water Glucose Hydrogen ion Water, Glucose, Hydrogen ion

Water, glucose, hydrogen ion

The fluid mosaic model of the membrane proposed that membranes -consist of protein molecules embedded in a fluid bilayer of phospholipids. -consist of a phospholipid bilayer composed of a variety of fatty acids. -consist of a phospholipid bilayer between two layers of hydrophilic proteins. -consist of a single layer of phospholipids and proteins.

consist of protein molecules embedded in a fluid bilayer of phospholipids.

Which of the following is a substance that acts at a long distance from the site at which it is secreted? local regulator paracrine signal synaptic signal hormone neurotransmitter

hormone

Endocytosis moves materials _____ a cell via _____. into ... facilitated diffusion into ... a transport protein into ... membranous vesicles out of ... membranous vesicles out of ... diffusion

into...membranous vesicles

Submerging a red blood cell in a hypertonic solution will result in the cell wall shriveling. the cell becoming turgid. plasmolysis of the cell. lysis of the cell.

the cell wall shriveling

Active and passive transport of solutes across a membrane typically differ in which of the following ways? Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. Active transport is always faster than passive transport. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. Active transport is used for ions; passive transport is used for uncharged solutes.

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.

Which of the following sequences is/are correct? binding of a growth factor to its receptor → phosphorylation cascade → activation of transcription factor → transcription binding of a signaling molecule to its receptor → G protein activation → adenylyl cyclase activation → cAMP production → protein phosphorylation diffusion of a signaling molecule across the plasma membrane → binding of the signaling molecule to its receptor → movement of the signaling molecule-receptor complex into the nucleus → transcription All of the listed choices are correct.

All of the listed choices are correct

The sodium-potassium pump is called an electrogenic pump because it contributes to the membrane potential. pumps electrons across the plasma membrane. pumps hydrogen ions out of the cell. ionizes sodium and potassium atoms.

Contributes to the membrane potential

Why are there often so many steps between the original signal event and the cell's response? Each transduction is a checkpoint. Lengthy pathways provide the opportunity for the initial pathway molecules to recycle back to inactive forms should additional signaling molecules be present. Each step in a cascade produces a large number of activated products, causing signal amplification as the cascade progresses. Long, highly specific pathways minimize the possibility that a relay molecule accidentally could activate a pathway leading to a secondary response. The accumulation of genetic mutations over time has added redundant steps to the pathway.

Each step in a cascade produces a large number of activated products, causing signal amplification as the cascade progresses.

Which of the following correctly describes some aspect of exocytosis or endocytosis? The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane. Endocytosis and exocytosis involve active transport. These two processes require the participation of mitochondria. Exocytosis and endocytosis change the surface area of the plasma membrane. Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol.

Exocytosis and endocytosis change the surface area of the plasma membrane.

Cholesterol's function?

Helps stabilize the structure of the plasma membrane

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? Osmotic Isotonic Hypotonic Hypertonic

Hypotonic

Select the statement that correctly distinguishes between relay proteins and second messengers in signal transduction pathways. Signal transduction pathways are multistep pathways in which relay proteins and second messengers alternate. Signal transduction pathways are multistep pathways that include relay proteins and small, nonprotein, water-soluble molecules or ions called second messengers. Relay proteins are the "first messengers," the extracellular signaling molecules that bind to the membrane receptor. The signal transduction pathways are then formed by the second messengers, which are the relay molecules that respond to the first messengers.

Signal transduction pathways are multistep pathways that include relay proteins and small, nonprotein, water-soluble molecules or ions called second messengers.

In facilitated diffusion, what is the role of the transport protein? Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. Transport proteins provide a low-resistance channel for water molecules to cross the membrane. Transport proteins provide a hydrophilic route for the solute to cross the membrane. Transport proteins organize the phospholipids to allow the solute to cross the membrane. Transport proteins provide the energy for diffusion of the solute.

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

Which of the following factors would tend to increase membrane fluidity? a lower temperature a greater proportion of unsaturated phospholipids a relatively high protein content in the membrane a greater proportion of saturated phospholipids

a greater proportion of unsaturated phospholipids

A primary function of cholesterol in the plasma membranes of some animals is to facilitate the removal of hydrogen atoms from saturated phospholipids. enable the membrane to stay fluid more easily when the temperature drops. make the membrane more rigid, allowing it to resist pressure from outside the cell. facilitate cell-cell interactions by binding to receptors on neighboring cells.

enable the membrane to stay fluid more easily when the temperature drops.

You can recognize the process of pinocytosis when _____. Click to launch animation a receptor protein is involved the cell is engulfing a large particle the cell is engulfing extracellular fluid

engulfing extracellular fluid

Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect ONLY target cells because __________. only target cells have enzymes that break down aldosterone only in target cells is aldosterone able to initiate the phosphorylation cascade that turns genes on intracellular receptors are present only in target cells only target cells retain the appropriate DNA segments

intracellular receptors are present only in target cells

Water passes quickly through cell membranes because it moves through hydrophobic channels. it is a small, nonpolar molecule. the bilayer is hydrophilic. water movement is tied to ATP hydrolysis. it moves through aquaporin channel proteins.

it moves through aquaporin channel proteins.

What is the voltage across a membrane called? membrane potential water potential electrochemical gradient osmotic potential chemical gradient

membrane potential

Which of the following best describes the structure of a biological membrane? -a fluid structure in which phospholipids and proteins move freely between sides of the membrane -a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot -two layers of phospholipids with proteins embedded between the -two layers two layers of phospholipids with proteins either crossing the layers or on the surface of the layers -two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? Amphipathic nature Permeability Solubility in water Hydrophobic nature

Amphipathic nature

Following activation of a receptor, which sequence below represents the correct order in which components will be involved in a signaling pathway that utilizes the second messenger cAMP? adenyl cyclase → cAMP → G protein → protein kinase cAMP → adenyl cyclase → protein kinase → G protein G protein → cAMP → adenyl cyclase → protein kinase protein kinase → G protein → adenyl cyclase → cAMP G protein → adenyl cyclase → cAMP → protein kinase

G protein → adenyl cyclase → cAMP → protein kinase

Which of the following is a characteristic feature of a carrier protein in a plasma membrane? It exhibits a specificity for a particular type of molecule. It works against a concentration gradient. It requires the expenditure of cellular energy to function. It is a peripheral membrane protein.

It exhibits a specificity for a particular type of molecule.

How can a lipid be distinguished from a sugar? Lipids are mostly saturated. Lipids are mostly nonpolar. A lipid is made up of only hydrocarbons. A lipid dissolves in water.

Lipids are mostly nonpolar

What name is given to the process by which water crosses a selectively permeable membrane? osmosis phagocytosis passive transport pinocytosis diffusion

Osmosis

Select the correct statement about osmosis. If a dead cell is placed in a solution hypotonic to the cell contents, osmosis will not occur. Osmosis is the diffusion of water molecules across a selectively permeable membrane. Osmotic equilibrium cannot be reached unless solute concentrations equalize across the membrane.

Osmosis is the diffusion of water molecules across a selectively permeable membrane.

A white blood cell engulfing a bacterium is an example of _____. exocytosis pinocytosis facilitated diffusion phagocytosis receptor-mediated endocytosis

Phagocytosis

Which of the following would increase the electrochemical gradient across a membrane? a potassium channel a sucrose-proton cotransporter a proton pump a chloride channel

Proton pump

Which statement is correct? A solution of seawater is hypertonic. A solution of distilled water is hypotonic. The contents of a red blood cell are hyperosmotic to distilled water.

The contents of a red blood cell are hyperosmotic to distilled water

How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures? The double bonds form kinks in the fatty acid tails that prevent adjacent lipids from packing tightly together. The double bonds result in shorter fatty acid tails and therefore thinner membranes. Unsaturated fatty acids have a higher cholesterol content that prevents adjacent lipids from packing tightly together. Unsaturated fatty acids are more polar than saturated fatty acids.

The double bonds form kinks in the fatty acid tails that prevent adjacent lipids from packing tightly together.

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water equal to the volume of blood lost is transferred directly into one of his veins. What will be the most probable result of this transfusion? The patient's red blood cells will swell because the blood fluid has become hypotonic compared to the cells. It will have no unfavorable effect as long as the water is free of viruses and bacteria. The patient's red blood cells will shrivel up because the blood fluid has become hypertonic compared to the cells. The patient's red blood cells will shrivel up because the blood fluid has become hypotonic compared to the cells.

The patient's red blood cells will swell because the blood fluid has become hypotonic compared to the cells.

Which of the following factors does not affect membrane permeability? Temperature The amount of cholesterol in the membrane The polarity of membrane phospholipids The saturation of hydrocarbon tails in membrane phospholipids

The polarity of membrane phospholipids

Which ofthe following molecular movements is due to diffusion or osmosis? The sodium-potassium pump pumps three sodium ions out of a neuron for every two potassium ions it pumps in. Cells of the pancreas secrete insulin into the bloodstream. When a plant cell is placed in concentrated salt water, water moves out of the cell.

When a plant cell is placed in concentrated salt water, water moves out of the cell.

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? receptor-mediated endocytosis passive diffusion of the glucose through the lipid bilayer movement of glucose into the cell through a glucose channel facilitated diffusion of the glucose using a carrier protein cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

Which of the following is least likely to be important in holding the components of a biological membrane together? hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane covalent interactions between the phospholipid and protein components of the membrane polar interactions among the phospholipid head groups on the same surface of the membrane

covalent interactions between the phospholipid and protein components of the membrane

Which of the following enzymes adds a phosphate group to target proteins? adenylyl cyclase kinase phosphatase glycogen phosphorylase

kinase

The difference between pinocytosis and receptor-mediated endocytosis is that pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot. pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis is highly selective. pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area. pinocytosis requires cellular energy, but receptor-mediated endocytosis does not. pinocytosis brings only water molecules into the cell, whereas receptor-mediated endocytosis brings in other molecules as well.

pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis is highly selective.

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because __________. they always lead to the same cellular response they amplify the original signal manifold they are species specific they counter the harmful effects of phosphatases

they amplify the original signal manifold