Biology Chapter 5
D
A white blood cell engulfing a bacterium is an example of... a) receptor-mediated endocytosis b) pinocytosis c) exocytosis d) phagocytosis e) facilitated diffusion
A
Endocytosis moves materials _______ a cell via ________. a) into...membranous vesicles b) out of...membranous vesicles c) into...facilitated diffusion d) into...a transport protein e) out of...diffusion
Entropy
Measure of disorder or randomness.
B
Some enzymes involved in the hydrolysis of ATP cannot function without the help of sodium ions. Sodium in this case functions as... a) a substrate b) a cofactor c) an active site d) a noncompetitive inhibitor e) a vitamin
T
T or F: All reactions are reversible.
A
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of... a) endocytosis b) active transport c) exocytosis d) passive transport e) diffusion
peptidoglycan
What are the cells walls of prokaryotes made up of?
C
When water moves toward the solution with the _____ solute concentration, the solution is _____. a) lesser...hypertonic b) greater...hypotonic c) greater...hypertonic d) greater...isotonic
D
Which of the following enables a cell to pick up and concentrate a specific kind of molecule? a) diffusion b) passive transport c) osmosis d) receptor-mediated endocytosis
exergonic reaction
an energy-releasing chemical reaction in which the reactants contain more potential energy than the products
endergonic reaction
an energy-requiring chemical reaction, which yields products with more potential energy than the reactants
endocytosis
cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane
active transport
moves solute against the concentration gradient
passive transport
the diffusion of substance across a biological membrane, without any input of energy
chemical, mechanical, and transport
3 main types of cellular work
activation, inhibition, and cooperativity
3 major factors that affect enzyme activity
ammonia, uric acid, urea
3 ways to secrete nitrogenous wastes
Gibbs Free Energy
A measurement of the amount of useful energy that a system can use.
some
Are all or some competitive inhibitors irreversible?
chemical energy
Energy available in molecules for release in a chemical reaction; a form of potential energy.
D
Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms? a) High salt concentrations lower the pH, thus inhibiting the process of glycolysis. b) High salt concentrations raise the pH, thus inhibiting the process of glycolysis. c) Bacterial cell walls are shriveled up by salt, causing the cell to burst. d) Bacteria can't survive in a hypertonic solution because they lose water.
D
In an oil-based, nonpolar environment, phospholipids would arrange themselves so that they... a) would not pack together at all b) would pack more tightly together than they would in a watery environment c) would never associate but instead would remain as individual molecules completely dissolved in the oil d) would stay together but in a reverse orientation, with their tails projecting outward
C
In oil-based liquids, phospholipids are arranged so that their _____ face outward and their _____ are orientated inward. a) hydrophilic tails...hydrophobic heads b) hydrophobic heads...hydrophilic tails c) hydrophobic tails...hydrophilic heads d) hydrophilic heads...hydrophobic tails
C
LDLs enter cells by means of... a) osmosis b) active transport c) receptor-mediated endocytosis d) protein-mediated exocytosis
E
Living things transform kinetic energy into potential chemical energy in the _____, when _____ is made. a) mitochondrion...ATP b) chloroplast...ADP c) chloroplast...an enzyme d) mitochondrion...glucose e) chloroplast...glucose
cooperativity
Sometimes, enzymes are made of multiple subunits, each with an active site. Subunits tend to flip between open and closed. When a substrate binds to one active site, all active sites will remain open. What is the term for this?
F
T or F: cellular respiration is an endergonic reaction.
induced fit
The change in shape of the active site of an enzyme, induced by entry of the substrate so that it binds more snugly to the substrate.
D
The first enzyme in a metabolic pathway that makes ATP is blocked by ATP itself. This would appear to be an example of a) induced fit b) energy coupling c) active transport d) feedback inhibition e) receptor mediated endocytosis
B
The secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of _____. a) pinocytosis b) exocytosis c) endocytosis d) phagocytosis
osmoregulators
What are organisms that regulate the osmolarity of the body so it stays constant called?
1) must use a protein 2) energy (ATP) is required
What are two essential conditions for active transport?
D
What happens to the chemical energy that is extracted from molecules by cellular activities but that is not used for cellular work? a) The energy is recycled by the cell. b) The energy is captured by other cells. c) It is used by plant cells for photosynthesis. d) The energy contributes to the entropy of the system.
small and nonpolar (hydrophobic)
What type of molecules can freely pass through the membrane?
A
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule? a) hydrolysis b) dehydration decomposition c) entropic d) dehydration synthesis e) anabolism
B
When considering the formation of membranes, they _____. a) are constructed using specialized scaffolding proteins b) form spontaneously in aqueous environments c) require enzymes to form into bilayer structures d) are formed under the direction of the cell's DNA
equilibrium
When ΔG is zero, what state is reached?
C
Which fact is most important in explaining how enzymes speed reactions? a) Very low potential energy tends to make molecules unstable. b) Large molecules collide more energetically than small molecules. c) High-energy collisions are less common than low-energy collisions. d) Every reaction step adds to the time required for the overall reaction. e) It takes less energy to break a hydrogen bond than a covalent bond.
D
Which of the following is an accurate comparison of active transport and facilitated diffusion? a) In both types of movement, phosphate groups alter the shape of transport proteins. b) Facilitated diffusion requires the use of ATP; active transport does not require ATP. c) Active transport requires membrane proteins; facilitated diffusion does not require membrane proteins. d) Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.
C
Which of the following is not true of an enzyme? An enzyme... a) is usually a protein b) acts as a biological catalyst c) supplies energy to start a chemical reaction d) is specific e) lowers the energy barrier for a chemical reaction
B
Which of the following statements is true about membrane proteins? a) Proteins form the basis of the semipermeable membrane. b) Proteins can bind other molecules, which may trigger specific cellular functions. c) Proteins facilitate membrane stabilization. d) Proteins keep the membrane fluid.
E
Which statement is true of enzymes? a) (a) Enzymes can be either proteins or RNA molecules. b) (b) When a cell makes an enzyme, it makes many copies. c) (c) Their substrate specificity involves matching of shapes. d) Both (a) and (b). e) (a), (b), and (c).
B
Zoologists discovered that the blood cells of a certain African lungfish were much slower to swell or shrink with water when faced with changes in blood solute concentration, a useful adaptation to drought and dehydration. The researches suspected that this might have something to do with the number of ______ in the blood cells. a) phospholipids b) aquaporins c) ATPs d) competitive inhibitors e) enzymes
pinocytosis
cellular drinking, a type of endocytosis whereby a cell engulfs a particle, and fluids are taken into small vesicles
exocytosis
fusion of membrane-bound vesicle with membrane, and dumping of contents outside of cell
active transport
how a cell maintains a higher K+ concentration and lower Na+ concentration than its surroundings
passive transport
how oxygen and carbon dioxide enter and leave cells
energy coupling
in cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction
activators
substances that bind to the allosteric site and activate the enzyme by changing the shape of the active site
exocytosis
the movement of materials out of the cytoplasm of a cell by the fusion of vesicles with the plasma membrane
receptor-mediated endocytosis
the movement of specific molecules into a cell by the inward budding of membranous vesicles
C
A cell uses energy released by _______ reactions to drive the _____ reactions that make ATP. Then it uses the energy released by the hydrolysis of ATP, an _______ reaction, to do various kinds of work in the cell. a) exergonic...exergonic...endergonic b) endergonic....exergonic...endergonic c) exergonic...endergonic...exergonic d) endergonic...endergonic...exergonic e) exergonic...endergonic...endergonic
feedback inhibition
A method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
D
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of... a) active transport b) exocytosis c) diffusioin d) facilitated diffusion e) endocytosis
E
A molecule that has the same shape as the substrate of an enzyme would tend to... a) speed metabolism by guiding the enzyme to its substrate b) speed metabolism because it would also be a catalyst c) speed metabolism by acting as a cofactor for the enzyme d) save the cell energy by substituting for the substrate e) slow metabolism by blocking the enzyme's active site
Cofactor
A nonprotein molecule or ion that is required for the proper functioning of an enzyme.
E
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via... a) osmosis b) passive transport c) exocytosis d) active transport e) endocytosis
E
A reaction is said to be unfavorable if ... a) (a) it will be very slow without a catalyst. b) (b) the free energy change for the reaction is positive. c) (c) equilibrium favors the reactants, not the products. d) Both (a) and (b). e) Both (b) and (c).
Non-competitive inhibitor
A substance that impedes the activity of an enzyme without entering an active site. By binding elsewhere on the enzyme, a noncompetitive inhibitor changes the shape of the enzyme so that the active site no longer functions.
Competitive inhibitor
A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate.
B
A white blood cell is capable of producing and releasing thousands of antibody molecules every second. Antibodies are large, complex protein molecules. How would you expect them to leave the cell? a) active transport b) exocytosis c) receptor-mediated endocytosis d) passive transport e) pinocytosis
B
A(n) _____ reaction occurs spontaneously. a) kinetic b) exergonic c) endergonic d) chemical e) anabolic
Catalyst
Any substance that increases the rate of a chemical reaction while not in the reaction.
Work
Anything that requires atoms to be moved around.
They can as long as they are not able to fit through the membrane.
Can substances defy diffusion?
A
Catalysts speed reactions mainly by... a) lowering EA. b) providing activation energy. c) raising the kinetic energy of the reactants. d) increasing of activation energy barrier. e) None of the above.
D
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 _____. a) B ... the oxygen molecules inside cell B have a higher kinetic energy b) A ... the diffusion gradient there is shallower c) A ... its membrane transport proteins will not be saturated d) B ... the diffusion gradient there is steeper
Second Law of Thermodynamics
Energy conversions increase the disorder of the universe. With every energy transfer, there is an increase in disorder.
C
Enzymes speed reactions mainly by... a) providing activation energy. b) protecting the catalysts. c) lowering EA. d) raising the kinetic energy of the reactants. e) None of the above.
D
Frequently, transplanted organs are rejected by the recipient's body. How is the reaction related to plasma membranes? a) Everyone's organs contain different amounts of cholesterol. b) The fibers of the extracellular matrix differ from individual to individual. c) The phospholipid bilayers become disrupted during transplant and may never re-form, causing tissues to lose their function. d) Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.
D
How can "induced fit" influence the specificity of an enzyme? a) (a) It can not influence the specificity of an enzyme. b) (b) It moves the reactive portion of the enzyme closer to the substrate. c) (c) The enzyme's active site changes shape to fit the correct substrate but not other molecules. d) Both (b) and (c). e) None of the above.
Rearranging atoms from higher to lower energy compounds.
How do cells obtain energy?
D
How do cells replace the energy-rich ATP that is destroyed in energy-coupled reactions? a) (a) Chloroplasts use light energy to synthesize ATP. b) (b) Mitochondria synthesize ATP using energy that's released by oxidizing sugars and fats. c) (c) Ribosomes use catalytic RNA to couple ADP with Pi. d) Both (a) and (b). e) (a), (b), and (c).
C
How do cells use ATP to raise the energy level of reaction substrates? a) ATP is hydrolyzed to release its energy. b) The ADP part of ATP is bound to the substrate. c) The terminal phosphate of ATP is bound to the substrate. d) All of the above
facilitated diffusion
How do molecules that cannot easily pass through the membrane get through (through what process)?
B
If a cell is like a factory, then enzymes are like a) the plans for the factory b) the machines for the factory c) the power plant for the factory d) the raw materials used by the factory e) the walls of the factory
A
If you have three different amino acids, four different sugars, and two different ions, how many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport? a) nine b) three c) five d) one
exergonic
If ΔG is negative, what type of reaction is it?
endergonic
If ΔG is positive, what type of reaction is it?
C
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? a) Alter the first and third groups to make them positive. b) Convert the negative charge of the phosphate groups to a positive charge. c) Increase the negative charge of each phosphate group. d) Change the middle phosphate group from a negative to a positive charge.
B
In active transport, a) a vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell. b) molecules move across the plasma membrane against their concentration gradient. c) the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. d) molecules move across the plasma membrane by crossing the lipid bilayer directly, rather than by using a transport protein. e) no energy input is required from the cell.
B
In an experiment with an enzyme, the 58th amino acid seems to form a covalent bond with a substrate molecule as part of the catalytic process. What would you say? a) This is probably a case where the enzyme changes the position of equilibrium. b) At some point the bond between the amino acid and the substrate must break. c) This is possible in theory, but it's never been observed. d) There must be an error. Enzymes don't make covalent bonds with substrates. e) It couldn't happen. Catalysis doesn't alter the enzyme.
B
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? a) Cells possess properties not seen in nonliving things, which allow them to run physical processes in reverse. b) Cells couple energy-releasing reactions to energy-requiring reactions. c) Cells are subject to only the first law, not the second law, of thermodynamics. d) Cells are far more efficient in energy transactions than are nonliving substances.
A
Macrophages are white blood cells that roam the body searching for invading microbes. Inside macrophage vacuoles these invaders are destroyed. How do the microbes get inside the macrophages? a) Microbes are engulfed into the macrophage via phagocytosis. b) The invaders cross the membranes via facilitated transport through specific transport proteins. c) The invaders cross the membranes via active transport through specific transport proteins. d) They are taken in by the form of exocytosis known as pinocytosis.
The First Law of Thermodynamics
Matter and energy can not be created or destroyed, but can be transformed or transferred.
D
New drugs are being developed to lower levels of circulating cholesterol. A successful drug would be one that... a) increases exocytosis in cells that line blood vessels, especially those of the heart b) blocks the synthesis of LDL receptors c) binds to the LDL receptor and blocks receptor-mediated endocytosis d) increases the rate of LDL receptor-mediated endocytosis
C
Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis? a) the difference in the height of water columns on either side of a selectively permeable membrane b) the first law of thermodynamics c) the difference in water concentration across a selectively permeable membrane d) the difference in sugar or ion concentration across a selectively permeable membrane
B
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? a) cytoskeleton b) proteins c) cholesterol d) phospholipids
D
Stability of an animal cell plasma membrane is enhanced by _____. a) polyunsaturated triglycerides b) saturated phospholipids c) saturated triglycerides d) cholesterol molecules
T
T or F: ΔG is constant for a given relation.
A
The energy for an endergonic reaction comes from a(n) _____ reaction. a) exergonic b) synthesis c) ADP + P --> ATP d) anabolic e) glucose + glucose --> maltose
C
The eukaryotic cell has multiple membrane-enclosed compartments. This evolutionary innovation provides what advantage to the cell? a) They allowed eukaryotes to evolve forms of metabolism that no longer require the intake of any molecules from outside the cell. B) They allow for eukaryotic cells to be larger. c) They allow different parts of the cell to perform specific functions. d) They lead to the evolution of many different cell types when they are extruded to form daughter cells with novel functions.
B
The lipids in a cell membrane are arranged _____. a) on either side of a single layer of protein b) so that the nonpolar parts of two lipids point toward each other c) so that the hydrophilic components are arranged to face each other d) between two layers of protein
C
The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true? a) The fluid is phospholipid, and the mosaic is carbohydrate. b) The mosaic comprises the carbohydrate chains on the inner surface of the membrane. c) The fluid is phospholipid, and the mosaic is protein. d) The fluid is protein, and the mosaic is phospholipid.
D
The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance? a) starch and cellulose b) sodium and hydrogen ions c) glucose and lactose d) oxygen and carbon dioxide
phosphorylation
The process of ATP releasing energy by transferring its third phosphate from ATP to some other molecule. Causes membrane proteins to change shape.
D
The reaction A --> B + C + heat is released in a(n) _____ reaction. a) anabolic b) endergonic c) exchange d) exergonic e) dehydration synthesis
C
The reaction A → B is unfavorable by itself, but through energy-coupling, cells can use ATP to convert A into B. How is this done? a) (a) Hydrolysis of ATP releases heat that is used by the unfavorable reaction. b) (b) ATP acts as a catalyst to speed the unfavorable reaction. c) (c) The unfavorable reaction is replaced by two favorable reactions. d) Both (a) and (b). e) Both (b) and (c).
E
The reaction ADP + P --> ATP is a(n) _____ reaction. a) spontaneous b) exergonic c) chemical d) hydrolysis e) endergonic
E
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... a) passive transport b) exocytosis c) diffusion d) facilitated diffusion e) active transport
Diffusion
The spontaneous tendency of a substance to move down its concentration gradient from where it is more concentrated to where it is less concentrated.
A
Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must... a) actively pump water back into their cells to counter its loss due to osmosis b) actively pump water back out of their cells to counter its inflow due to osmosis c) synthesize membranes that are impermeable to substances that upset osmotic balance d) actively pump salt back out of their cells to counter its inflow due to osmosis
C
Water crosses the plasma membrane... a) through active transport b) through cotransport. c) through facilitated diffusion or diffusion. d) against its concentration gradient. e) using a process that requires energy from the cell.
hydrochloric acid
What activates pepsinogens?
osmoconformers
What are marine invertebrates that maintain internal osmolarity called?
C
What controls the direction of a molecule, such as oxygen, involved in passive transport? a) the type of cell the oxygen molecule is moving into or out of b) the amount of energy available to transport oxygen c) the direction of the oxygen concentration gradient d) the size of the oxygen molecule
cholesterol
What helps stabilize membranes at warmer temperatures and keep the membrane fluid at lower temperatures in animal cell membranes?
C
What is the fate of the phosphate group that is removed when ATP is converted to ADP? a) It is broken down into one phosphorus and four oxygen atoms. b) It is used to convert an ATP into an AQP. c) It is acquired by a reactant in an endergonic reaction. d) It is acquired by a reactant in an exergonic reaction. e) It is acquired by a reactant in a spontaneous reaction.
C
What substance is transported by aquaporins? a) urine b) proteins c) water d) salt
A
What's false? (1) Enzymes may change shape when they bind substrates; (2) Enzymes provide no energy for the reaction, except collision energy; (3) Enzymes may release substrates. a) None of the statements is false. b) Statement 1 is false. c) Statement 2 is false. d) Statement 3 is false. e) All three statements are false.
shriveled
When placed in a hypertonic solution, animal cells are ________.
plasmolyzed
When placed in a hypertonic solution, plant cells are _______.
D
When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will... a) go brown at the edges of its leaves b) die c) go limp and lifeless d) remain standing upright
lysed
When placed in a hypotonic solution, animal cells are _______.
turgid
When placed in a hypotonic solution, plant cells are ______.
normal
When placed in an isotonic solution, animal cells are ________.
flaccid
When placed in an isotonic solution, plant cells are _______.
C
Which of the following statements about cell membrane transport is true? a) Facilitated diffusion works without the assistance of proteins to move molecules from areas of high concentration to areas of low concentration. b) Facilitated diffusion works with the assistance of proteins and energy to move molecules from areas of high concentration to areas of low concentration. c) Active transport works with the assistance of proteins to move molecules from areas of low concentration to areas of high concentration. d) Passive transport works with the assistance of proteins to move molecules from areas of high concentration to areas of low concentration.
A
Which of the following would be least likely to diffuse through a cell membrane without the help of a transport protein? a) a large hydrophilic molecule b) a large hydrophobic molecule c) a small hydrophilic molecule d) a small hydrophobic molecule e) Any of the above would easily diffuse through the membrane.
D
Which of these reactions requires a net input of energy from its surroundings? a) ATP --> ADP + P b) exergonic c) hydrolysis d) endergonic e) catabolic
C
Which of these situations accurately represents osmoregulation in organisms? a) Marine animals cannot be isotonic to seawater. b) Seawater is hypotonic to human cells. c) Plant cells need a hypotonic environment in order to stay turgid. d) Freshwater fish must all be isotonic to their environments.
A
Why is ATP a good source of energy for biological reactions? a) Triphosphate chains are unstable. b) The answer is still unknown. c) Peroxide links are highly reactive. d) Links between sugar and phosphate are unstable. e) Links between adenine and sugar are unstable.
aquaporins
a transport protein in the plasma membrane of some plant or animal cells that facilitates the diffusion of water across the membrane
osmosis
causes plant cells to become turgid
phagocytosis
cellular eating; a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm
