BIO 1030 Mastering- The Working Cell

in cells, what is usually the immediate source of energy for an endergonic reaction?

ATP

most cellular work is accomplished by ___ energizing molecules by ___ them

ATP, phosphorylating

cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. oxygen will diffuse more quickly into cell ___ because ___

B...the diffusion gradient there is steeper

the concentration of solutes in a red blood cell is about 2%. sucrose cannot pass through the membrane, but water and urea can. osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? a hypertonic sucrose solution a hypotonic sucrose solution a hypertonic urea solution a hypotonic urea solution

a hypertonic sucrose solution

which of these is exhibiting kinetic energy? an archer with a flexed bow the high-energy phosphate bonds of a molecule of ATP a space station orbiting earth a person sitting on a couch while watching TV a rock on a mountain ledge

a space station orbiting earth

an enzyme speeds up reactions by lowering the ___

activation energy

an enzyme is specific because the shape of its ____ matches only particular reactants

active site

diffusione across a biological membrane is called ___

active transport

requires energy from the cell. molecules move against their concentration gradient

active transport

the sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. this is an example of ___

active transport

when in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. this molecule rapidly enters the cell regardless of whether its concentration is higher inside or outside the cell. using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across the plasma membrane?

active transport

which of the following is an accurate comparison of active transport and facilitated diffusion? facilitated diffusion requires the use of ATP; active transport does not require ATP active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient in both types of movement, phosphate groups alter the shape of transport proteins active transport requires membrane proteins; facilitated diffusion does not require membrane proteins

active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient

in a sodium-potassium pump, sodium and potassium ions are transported ___ their concentration gradients

against

cellular respiration is an example of ___

an exergonic process

cells store energy that they use for work in the ___

arrangement of atoms within molecules

which statements about the fluid mosaic structure of a membrane are correct? select the THREE correct statements. because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. the framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center the kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer. the diverse proteins found in and attached to membranes perform many important functions.

because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane the framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center the diverse proteins found in and attached to membranes perform many important functions

an enzyme is considered a(n) ___ because it speeds up a chemical reaction without being used up

catalyst

in plant cells, carbon dioxide and water are joined to form carbohydrates. plant cells can also break down carbohydrates such as glucose, releasing carbon dioxide, water, and energy. no one has ever observed such reactions between water and carbon dioxide outside of living cells. what allows simple molecules to assemble into more complex molecules, and also disassemble, in cells but not in other, nonbiological environments?

cells couple energy-releasing reactions to energy-requiring reactions

in your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

cellular respiration

during enzymatic reactions, substrates are converted to products. a property of enzymes that facilitates this reaction is that they are catalysts and therefore ___

change the rate of a reaction without being consumed by the reaction

a(n) ___, which is often a vitamin, binds to an enzyme and plays a role in catalysis

coenzyme

high temperatures or changes in pH can ___ an enzyme, causing it to lose its shape and biological activity

denature

a form of passive transport. molecules move across the plasma membrane by coursing the lipid bilayer

diffusion

the movement of atoms, ions, or molecules from a region of higher contraction to regions of lower concentration is called ___

diffusion

the reaction ADP + P --> ATP is a(n) ___ reaction

endergonic

the phosphorylation of ADP to form ATP is an ___ reaction that ___ energy

endergonic, requires an input of

the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell

endocytosis

the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. this describes the process of ___

endocytosis

which of these reactions requires a net input of energy from its surroundings? hydrolysis exergonic ATP --> ADP + P endergonic catabolic

energonic

"conservation of energy" refers to the fact that ___

energy cannot be created or destroyed, but can be converted from one form to another

a(n) ___ reaction occurs spontaneously

exergonic

the energy for an endergonic reaction comes from a(n) ___ reaction

exergonic

the reaction A --> B + C + heat is released in a(n) ___ reaction

exergonic

select the INCORRECT association enzyme...protein exergonic...uphill exergonic...spontaneous kinetic energy...motion potential energy...positional energy

exergonic...uphill

a vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell

exocytosis

a form of passive transport. molecules move across the plasma membrane using a transport protein

facilitated diffusion

a molecule moves down its concentration gradient using a transport protein in the plasma membrane. this is an example of ___

facilitated diffusion

which of these statements describers what occurs in facilitated diffusion? facilitated diffusion of solutes occurs through phospholipid pores in the membrane facilitated diffusion of solutes occurs through protein pores in the membrane facilitated diffusion is another name for osmosis facilitated diffusion requires energy from the cell to drive a concentration gradient

facilitated diffusion of solutes occurs through protein pores in the membrane

water crosses the plasma membrane through...

facilitated diffusion or diffusion

which of these are by-products of cellular respiration? heat and water glucose and water water ATP and water ATP

heat and water

in cellular respiration, most energy is released and transferred to ATP when ___

high-energy electrons "fall" to lower energy levels

in the process of osmosis, water displays a net movement from an area of ____ water concentration to an area a ___ water concentration

higher...lower

what type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

hydrolysis

a plant cell placed in a(n) __ solution will lose water and plasmolyze

hypertonic

there is a net diffusion of water outside of an animal cell when it is placed in a(n) ___ solution

hypertonic

an animal cell is placed in a(n) __ solution will gain water, swell, and possibly burst

hypotonic

the ideal osmotic environment for a plant cell is a(n) ___ environment

hypotonic

in a theoretical world where all things are possible, how could you increase the amount of energy that could be stored in a molecule of ATP?

increase the negative charge of each phosphate group

the ___ between an active site and its substrate often strains bonds and helps the reaction proceed

induced fit

endocytosis moves materials ___ a cell via ___

into, membranous vesicles

an enzyme ___

is an organic catalyst

as a result of its involvement in a reaction, an enzyme ___

is unchanged

a plant cell surrounded by a (n) ___ solution will be flaccid (limp)

isotonic

the ideal osmotic environment for an animal cell is a(n) ___ environment

isotonic

what is the fate of the phosphate group that is removed when ATP is converted to ADP?

it is acquired by a reactant in an endergonic reaction

light is ___ energy, which is converted by plants into molecules, which possess ___ energy

kinetic, chemical

when molecules move down their concentration gradient, they move from ___ to ___

low concentration, higher concentration

the mechanism of enzyme action is to ___

lower the energy of activation of a reaction

in active transport...

molecules move across the plasma membrane against their concentration gradient

you're on the pilot episode of a new game show called "The Transport Factor." the host hands you three different amino acids, four different sugars, and two different ions. then the host shouts, "how many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport?" quickly, you correctly respond: ___

nine

the synthesis of an amino acid follows this pathway: precursor A > intermediate B > amino acid C. each reaction is catalyzed by a different enzyme. this metabolic pathway is controlled by feedback inhibition with amino acid C inhibiting the conversion of precursor A to intermediate B. amino acid C acts as a ___ of the first enzyme in the pathway

noncompetitive inhibitor

which of the following is highest in chemical energy? one molecule of H2 one molecule of glucose one molecule of CO2 one molecule of ATP

one molecule of glucose

the diffusion of water across a selectively permeable membrane is called ___

osmosis

what name is given to the process by which water crosses a selectively permeable membrane?

osmosis

the plasma membrane is selectively permeable. which of the following can pass freely through the membranes with no assistance?

oxygen and carbon dioxide

facilitated diffusion is a type of ___

passive transport

which of the following statements is true about passive transport? passive transport operates indecently of concentration passive transport requires no expenditure of cellular energy passive transport phenomena can never reach equilibrium passive transport operates independently of diffusion

passive transport requires no expenditure of cellular energy

a white blood cell engulfing a bacterium is an example of ___

phagocytosis

chemical energy is a form of ___ energy

potential

most enzymes are ___

proteins

overall, membranes seem to have a great deal in common, but on closer inspection it is revealed that membranes of different cells have unique properties. what is the primary component of membranes that gives membranes cell-specific properties?

proteins

pick the THREE TRUE statements about enzymes reactants cannot convert to products without an initial input of energy to start the reaction by binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart chemical reactions cannot occur without enzymes only reactions that are controlled by enzymes require activation energy enzymes lower the overall energy input needs for a reaction to occur.

reactants cannot convert to products without an initial input of energy to start the reaction by binding to reactant molecules, enzymes make it easier for the bonds in the molecules to break apart enzymes lower the overall energy input needed for a reaction to occur

enzymes work by ___

reducing activation energy

when placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will ___

remain standing uprighr

the lipids in a cell membrane are arranged ___

so that the non polar parts of two lipids point toward each other

kinetic energy is energy in motion. potential energy is ___ energy

sotred

the first law of thermodynamics ___

states that energy is neither created nor destroyed

in a catalyzed reaction, a reactant is often called a(n) ___

substrate

what name is given to the reactants in an enzymatically catalyzed reaction?

substrate

for an enzyme to catalyze a reaction, there must be a specific fit between the ___ and the enzyme's ___

substrate, active site

succinylcholine is structurally almost identical to acetylcholine, but if combined with the enzyme that normally hydrolyzes acetylcholine. this suggests that ___

succinylcholine must be a competitive inhibitor of acetylcholine

which of these statements about enzyme inhibitors is true? when the product of an enzyme or series of enzyme-catalyzed reactions acts as its inhibitor, this is known as positive feedback a competitive inhibitor binds to the enzyme outside the active site the action of competitive inhibitors may be reversible or irreversible a noncompetitive inhibitor does not change the shape of the active site

the action of competitive inhibitors may be reversible or irreversible

the hydrolysis of DNA into nucleotides constitutes an exergonic reaction. yet, DNA is quite stable. why is this the case?

the activation energy required to initiate this reaction is seldom reached

which of the following is an example of the second law of thermodynamics? CO2 is exhaled as a by-product of aerobic respiration the aerobic respiration of glucose generates heat all types of cellular respiration produce ATP photosynthesis enables plants to create energy fro sunlight

the aerobic respiration of glucose generates heat

you can recognize the process of pinocytosis when ___

the cell is engulfing extracellular fluid

the transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when ___

the concentration of the solute is lower inside the cell than outside it

osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. what really drives osmosis?

the difference in water concentration across a selectively permeable membrane

the eukaryotic cell has multiple membrane-enclosed compartments. this evolutionary innovation provides what advantage to this cell?

the different membrane-enclosed spaces allow different parts of the cell to perform specific functions

what controls the net direction of molecules, such as oxygen, involved in passive transport?

the direction of the oxygen concentration gradient

what happens to the chemical energy that is extracted fro molecules by cellular activities but that is not used for cellular work?

the energy contributes to the entropy of the system

according to the second law of thermodynamics, which of the following is true? the entropy of the universe is constantly decreasing the total amount of energy in the universe is constant the ordering of one system depends on the disordering of another energy conversions increase the order in the universe

the ordering of one system depends on the disordering of another

which of the following statements is true of an exergonic reaction, but NOT true of an endergonic reaction? activation energy exceeds net energy release activation energy is necessary no kinetic energy is released the potential energy of the products is less than the potential energy of the reactants

the potential energy the products is less than the potential energy of the reactants

you are working on a team that is designing a new drug. for this drug to work, it must enter the cytoplasm of specific target cells. which of the following would be a factor that determines whether the molecule selectively enters the target cells? the non polar, hydrophobic nature of the drug molecule the phospholipid composition of the target cells' plasma membrane the concentration of the drug molecule that is transported in the blood the similarity of the drug molecule to other molecules that are transported into the target cells

the similarity of the drug molecule to other molecules that are transported into the target cells

what is energy coupling?

the use of energy released from an exergonic reaction to drive an endergonic reaction

energy is conserved. this means that in any system ___

total energy input equals total energy output

a pharmaceutical company wishes to focus on an enzyme to develop new medications. what type of study would be of the greatest benefit?

understanding the enzyme's structure would help pharmaceutical companies design molecules that fit to the binding site and alter activity