EXAM #3

Which of the following types of molecules will diffuse through a cell membrane most readily? A. small hydrophobic molecules B. large hydrophobic molecules C. small ionic molecules D. large polar molecules

A. small hydrophobic molecules

The ΔG of ATP hydrolysis in a test tube under standard conditions is -7.3 kcal/mol. The ΔG for the reaction A + B = C under the same conditions is +4.0 kcal/mol. What is the overall free-energy change for the coupled reactions under these conditions?

-3.3 kcal/mol

Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones? A. anabolism (anabolic pathways) B. metabolism C. catabolism (catabolic pathways) D. dehydration

C. catabolism (catabolic pathways)

Which component in the figure above represents a protein fiber of the extracellular matrix?

A

An enzyme-catalyzed reaction has a ΔG of -20 kcal/mol under standard conditions. What will be the ΔG for the reaction if the amount of enzyme is doubled? A. -20 kcal/mol B. -40 kcal/mol C. -10 kcal/mol D. +20 kcal/mol

A. -20 kcal/mol

Which of the following statements best describes the central role that ATP plays in cellular metabolism? A. ATP provides energy coupling between exergonic and endergonic reactions. B. The terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules. C. Hydrolysis of ATP provides an input of free energy for exergonic reactions. D. Hydrolysis of the terminal phosphate group from ATP stores free energy that is used for cellular work

A. ATP provides energy coupling between exergonic and endergonic reactions.

Which of the following statements best describes induced fit? A. Binding of substrate to the active site changes the shape of the active site of an enzyme. B. Substrate binds to an allosteric site rather than to the active site of an enzyme. C. Binding of an activator molecule changes the shape of the active site of an enzyme. D. The conformation of the active site is determined by the tertiary or quaternary structure of the enzyme.

A. Binding of substrate to the active site changes the shape of the active site of an enzyme.

Which of the following statements best explains why the sodium-potassium pump is an electrogenic pump? A. It generates voltage across the membrane. B. It is used to drive the transport of glucose against a concentration gradient. C. It transports equal quantities of Na+ and K+ across the membrane in opposite directions. D. It decreases the voltage difference across the membrane.

A. It generates voltage across the membrane.

Select the correct statement about chemical energy, a term used by biologists to refer to potential energy available for release in a chemical reaction. A. Light energy is converted to chemical energy during photosynthesis. B. When a glucose molecule is catabolized to CO2 and H2O, chemical energy is lost. C. A photosynthetic cell within a plant leaf produces chemical energy, stored within glucose molecules.

A. Light energy is converted to chemical energy during photosynthesis.

Which of the following statements best describes a characteristic of biological membranes? A. Phospholipids move laterally within the plane of the membrane. B. Phospholipids generally occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. C. Phospholipids are arranged with hydrophilic tails in the interior of the membrane. D. Phospholipids frequently flip-flop from one layer of the membrane to the other.

A. Phospholipids move laterally within the plane of the membrane.

Will the artificial cell become more flaccid, more turgid, or stay the same? A. The artificial cell will become more turgid. B. The artificial cell will become more flaccid. C. The artificial cell will burst. D. The artificial cell will stay the same.

A. The artificial cell will become more turgid.

Which of the following statements best describes how addition of a catalyst will affect a chemical reaction? A. The catalyzed reaction will have the same ΔG as the uncatalyzed reaction. B. The catalyzed reaction will consume all of the catalyst. C. The catalyzed reaction will have a lower ΔG than the uncatalyzed reaction. D. The catalyzed reaction will have a higher ΔG than the uncatalyzed reaction.

A. The catalyzed reaction will have the same ΔG as the uncatalyzed reaction.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A. The pH of the matrix increases. B. ATP synthase pumps protons by active transport. C. NAD+ is oxidized. D. The electrons gain free energy.

A. The pH of the matrix increases.

Which of the following statements best describes an exergonic reaction? A. The reaction proceeds with a net release of free energy. B. The products have more total energy than the reactants. C. The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. D. A net input of energy from the surroundings is required for the reaction to proceed.

A. The reaction proceeds with a net release of free energy.

Which of the following statements best describes catabolic pathways? A. They are exergonic and provide energy that can be used to produce ATP from ADP and Pi. B. They are endergonic and release energy that can be used for cellular work. C. They require energy from ATP hydrolysis to break down polymers into monomers. D. They combine small molecules into larger, more energy-rich molecules.

A. They are exergonic and provide energy that can be used to produce ATP from ADP and Pi.

The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of __________. A. a catabolic pathway B. a pathway that occurs in animal cells but not plant cells C. a pathway that converts organic matter into energy D. an endergonic pathway E. a pathway in which the entropy of the system decreases

A. a catabolic pathway

The force driving simple diffusion is ________, while the energy source for active transport is ________. A. a concentration gradient; ATP hydrolysis B. transmembrane pumps; an electrochemical gradient C. a concentration gradient; ADP D. phosphorylated carrier proteins; ATP

A. a concentration gradient; ATP hydrolysis

What is the name of the barrier that must be overcome before products are formed in a spontaneous reaction? A. activation energy B. free energy C. entropy D. the equilibrium point

A. activation energy

Based on the figure above, which of these experimental treatments would increase the rate of sucrose transport into a plant cell? A. decreasing extracellular pH B. adding a substance that makes the membrane more permeable to hydrogen ions C. decreasing cytoplasmic pH D. decreasing extracellular sucrose concentration

A. decreasing extracellular pH

The relationship between the breakdown of macromolecules and the biosynthesis of macromolecules is most similar to the relationship between which of the following pairs of terms? A. exergonic and endergonic B. exergonic and spontaneous C. free energy and entropy D. work and free energy

A. exergonic and endergonic

In the process of cellular respiration, what is consumed and what is produced? A. glucose is consumed and carbon dioxide is produced B. ATP is consumed and oxygen is produced C. carbon dioxide is consumed and water is produced D. oxygen is consumed and glucose is produced E. water is consumed and ATP is produced Submit

A. glucose is consumed and carbon dioxide is produced

Which of the following metabolic processes normally occurs in yeast cells regardless of oxygen (O2) availability? A. glycolysis B. citric acid cycle C. lactate fermentation D. oxidative phosphorylation

A. glycolysis

The voltage across a membrane is called the ________. A. membrane potential B. electrochemical gradient C. osmotic potential D. chemical gradient

A. membrane potential

Which of the following processes is driven by chemiosmosis? A. oxidative phosphorylation B. reduction of NAD+ to NADH C. ATP hydrolysis D. substrate-level phosphorylation

A. oxidative phosphorylation

Which of the following processes includes all the others? A. passive transport B. diffusion of a solute across a membrane C. osmosis D. transport of an ion down its electrochemical gradient

A. passive transport

Which of the following types of molecules are least likely to diffuse through the phospholipid bilayer of a cell membrane? A. large hydrophobic molecules B. small ions C. small hydrophobic molecules D. carbon dioxide

B. small ions

Disruption of the active site of an enzyme would most likely result in which of the following? A. A decreased ability of the enzyme to bind products. B. A decreased ability of the enzyme to bind substrates. C. A decreased ability of the enzyme to bind allosteric regulators. D. An increase in the rate of the reaction catalyzed by the enzyme.

B. A decreased ability of the enzyme to bind substrates.

Which of the following statements best describes the first law of thermodynamics? A. Energy cannot be transferred or transformed. B. Energy cannot be created or destroyed. C. The entropy of the universe is constant. D. The entropy of the universe is decreasing.

B. Energy cannot be created or destroyed.

Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do? A. Hydrolysis reactions increase G, or Gibbs free energy of the system. B. Hydrolysis reactions are exergonic and increase entropy of the system. C. Hydrolysis reactions are exergonic and decrease entropy of the system. D. Hydrolysis reactions are endergonic and increase entropy of the system.

B. Hydrolysis reactions are exergonic and increase entropy of the system.

Which of the following statements best describes a characteristic feature of osmosis? A. The process of osmosis requires energy from ATP hydrolysis. B. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. C. In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration. D. Osmosis only takes place in red blood cells.

B. In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

Which of the following statements best describes metabolism in its entirety in all organisms? A. Metabolism manages the increase of entropy in an organism. B. Metabolism consists of all the energy transformation reactions in an organism. C. Metabolism uses all of an organism's resources. D. Metabolism depends on a constant supply of energy from food.

B. Metabolism consists of all the energy transformation reactions in an organism.

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom? A. NAD+ becomes ionized. B. NAD+ becomes reduced. C. NAD+ becomes dehydrogenated. D. NAD+ becomes oxidized.

B. NAD+ becomes reduced.

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A.pyruvate. B. O2 C. water. D. NAD+

B. O2

Which of the following statements best describes the normal tonicity conditions for typical plant and animal cells in their native environments? A. The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution. B. The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution. C. The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution. D. The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution.

B. The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.

Which of the following statements about the citric acid cycle is correct? A. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. B. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. C. The citric acid cycle oxidizes glucose to carbon dioxide. D. The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. E. The oxidation of compounds by the citric acid cycle requires molecular oxygen.

B. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

Which of the following statements best describes characteristic activities of a sodium-potassium pump? A. The pump moves three sodium ions out of a cell and two potassium ions into a cell and generates an ATP in each cycle. B. The pump moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis. C. The pump moves three potassium ions out of a cell and two sodium ions into a cell while producing ATP for each cycle. D. The pump moves three potassium ions out of a cell and two sodium ions into a cell using energy from ATP hydrolysis.

B. The pump moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis.

Which of the following is a characteristic feature of anabolic pathways? A. They are usually spontaneous chemical reactions. B. They consume energy to build up polymers from monomers. C. They release energy by degrading polymers to monomers. D. They decrease the entropy of the organism and its environment.

B. They consume energy to build up polymers from monomers.

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? A. Water molecules continue to move from the hypotonic solution to the hypertonic solution. B. Water molecules move between the two solutions, but there is no net movement of water across the membrane. C. Water molecules no longer move between the solutions.

B. Water molecules move between the two solutions, but there is no net movement of water across the membrane.

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to A. add a noncompetitive inhibitor. B. add more of the enzyme. C. add more substrate. D. heat the solution to 90∘C∘C.

B. add more of the enzyme

Which of the following types of reactions would decrease the entropy within a cell? A. digestion B. anabolic reactions C. catabolic reactions D. hydrolysis

B. anabolic reactions

A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme ________. A. folds to form secondary and tertiary structures B. binds substrate C. interacts with water D. is denatured by low pH

B. binds substrate

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction? A. by binding to the active site of the enzyme, thus preventing binding of the normal substrate B. by binding to an allosteric site, thus changing the shape of the active site of the enzyme C. by decreasing the free-energy change of the reaction catalyzed by the enzyme D. by increasing the activation energy of the reaction

B. by binding to an allosteric site, thus changing the shape of the active site of the enzyme

A decrease in entropy is associated with which of the following types of reaction? A. catabolic B. dehydration C. hydrolysis D. depolymerization

B. dehydration

Which of the following terms best describes a chemical reaction for which ΔG is positive? A. exergonic B. endergonic C. enthalpic D. spontaneous

B. endergonic

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. A. exergonic; spontaneous B. exergonic; endergonic C. work; energy D. free energy; entropy

B. exergonic; endergonic

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A. reduction of pyruvate to lactate B. glycolysis C. the electron transport chain D. the citric acid cycle

B. glycolysis

Diffusion of ions across membranes through specific ion channels is driven by ________. A. electrical gradients only B. ion electrochemical gradients C. active transport pumps D. ion concentration gradients only

B. ion electrochemical gradients

Which of the following membrane activities requires energy from ATP hydrolysis? A. facilitated diffusion of chloride ions across the membrane through a chloride channel B. movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid C. movement of carbon dioxide out of a paramecium D. movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell

B. movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

Inhibition of which of the following metabolic pathways would result in a decrease of CO2 production compared to fully functional cellular respiration? A. oxidative phosphorylation and fermentation B. oxidation of pyruvate to acetyl CoA and the citric acid cycle C. glycolysis and the oxidation of pyruvate to acetyl CoA D. fermentation and glycolysis

B. oxidation of pyruvate to acetyl CoA and the citric acid cycle

Which of the following is the most important result of the process of cellular respiration in biological systems? A. breaking down ATP so that ADP and Pi can be reused B. transforming the energy in glucose and related molecules into a chemical form that cells can use for work C. catabolism of sugars and related compounds D. the breakdown of glucose to carbon dioxide and water E. producing complex molecules from chemical building blocks

B. transforming the energy in glucose and related molecules into a chemical form that cells can use for work

Which component in the figure above represents a microfilament of the cytoskeleton?

C

Which of the following statements best describes enzyme function? A. Enzymes increase the rate of chemical reactions by stimulating ATP hydrolysis. B. Enzyme function is generally increased if the 3-D structure or conformation of an enzyme is altered. C. Enzymes increase the rate of chemical reactions by lowering activation energy barriers. D. Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.

C. Enzymes increase the rate of chemical reactions by lowering activation energy barriers.

When chemical, transport, or mechanical work is performed by an organism, what happens to the heat that is generated? A. It is captured to store energy as more ATP. B. It is used to generate ADP from nucleotide precursors. C. It is lost to the environment. D. It is used to power yet more cellular work.

C. It is lost to the environment.

In the citric acid cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. This reaction is inhibited by malonate, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate molecules to those of malonate in the reaction reduces the inhibitory effect of malonate. What role does malonate play with respect to succinate dehydrogenase? A. Malonate is a noncompetitive inhibitor. B. Malonate blocks the binding of fumarate. C. Malonate is a competitive inhibitor. D. Malonate is an allosteric regulator.

C. Malonate is a competitive inhibitor.

Which of the following molecules would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? A. an amino acid B. Na+ C. O2 D. sucrose

C. O2

Which of the following results is most likely when a plant cell is submerged in a hypertonic solution? A. The cell will become turgid. B. The cell will burst. C. Plasmolysis will shrink the interior of the cell. D. The cell will become flaccid.

C. Plasmolysis will shrink the interior of the cell.

What will happen to a red blood cell (RBC), which has an internal ion content of about 0.9%, if it is placed into a beaker of pure water? A. The cell will shrink because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. B. The cell will shrink because the water in the beaker is hypertonic relative to the cytoplasm of the RBC. C. The cell will swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. D. The cell will remain the same size because the solution outside the cell is isotonic.

C. The cell will swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.

Which of the following statements about the chemiosmotic synthesis of ATP is correct? A. The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. B. The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. C. The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. D. Oxygen participates directly in the reaction that makes ATP from ADP and P. E. Chemiosmotic ATP synthesis requires oxygen.

C. The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.

Eventually, will the two solutions have the same or different solute concentrations? A.The solute concentration will always be changing. B. The two solutions will have a different solute concentration. C. The two solutions will have the same solute concentration. D. The solute concentration will stay the same for each solution.

C. The two solutions will have the same solute concentration.

When the interior of a cell is in equilibrium with its environment, which of the following statements best describes the relative movement of molecules that can diffuse through the plasma membrane? A. There is no movement of molecules into or out of the cell. B. All movement of molecules across the plasma membrane occurs by active transport. C. There is random movement of molecules into and out of the cell. D. There is directed movement of molecules into or out of the cell.

C. There is random movement of molecules into and out of the cell.

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

C. a greater proportion of unsaturated phospholipids

A defect in which of the following molecules would dramatically reduce the rate of diffusion of water across cell membranes? A. ATP B. gated ion channels C. aquaporins D. sodium-potassium pump

C. aquaporins

The 3-D structure of an enzyme composed of a single polypeptide chain includes a large substrate-binding domain. It also has a separate binding site for a regulatory molecule. Based on these structural observations the enzyme is most likely regulated by which of the following mechanism? A.cooperativity B. competitive activation C. noncompetitive inhibition D. competitive inhibition

C. noncompetitive inhibition

In receptor-mediated endocytosis, membrane receptors bind to molecules outside of the cell. Immediately following endocytosis where will the membrane receptors be located? A. on the outside of vesicles B. on the outer surface of the nucleus C. on the inside surface of the vesicle D. on the inside surface of the cell membrane

C. on the inside surface of the vesicle

Which of the following cellular processes includes all of the others? A. transport of an ion down its electrochemical gradient B. facilitated diffusion C. passive transport D. osmosis

C. passive transport

Which of the following statements best describes the difference between pinocytosis and receptor-mediated endocytosis? A. pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area B. pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot C. pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity D. pinocytosis brings only water molecules into the cell, but receptor-mediated endocytosis brings in other molecules as well

C. pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity

In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis? A. four ATP B. none, because all of the available energy remains in either lactate or ethanol C. two ATP D. up to 30 ATP E. none, because in the absence of oxygen no ATP can be made

C. two ATP

The mathematical expression for the change in free energy of a system is ΔG = ΔH - TΔS. Which of the following statements best describes a term in this equation? A. ΔH is the change in entropy, the energy available to do work. B. T is the temperature in degrees Celsius. C. ΔG is the change in free energy. D. ΔS is the change in enthalpy, a measure of randomness.

C. ΔG is the change in free energy.

Which of the following statements best describes a system at chemical equilibrium? A. The system releases energy at a steady rate. B. The system consumes energy at a steady rate. C. The kinetic energy of the system is zero. D. The system can do no work.

D. The system can do no work.

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule? A. 2 NAD+, 2 pyruvate, and 2 ATP B. 6 CO2, 2 pyruvate, and 2 ATP C. 4 NADH, 2 pyruvate, and 4 ATP D. 2 NADH, 2 pyruvate, and 2 ATP

D. 2 NADH, 2 pyruvate, and 2 ATP

In which of the following ways do the membranes of a eukaryotic cell vary? A. Only certain membranes of the cell are selectively permeable. B. Phospholipids are found only in certain membranes. C. Some membranes have hydrophobic surfaces exposed to the cytoplasm while others have hydrophilic surfaces facing the cytoplasm. D. Certain proteins are unique to each membrane.

D. Certain proteins are unique to each membrane.

Which of the following statements best describes a characteristic feature of a carrier protein in a plasma membrane? A. It requires the expenditure of cellular energy to function. B. It has no hydrophobic regions. C. It works against a concentration gradient. D. It exhibits specificity for a particular type of molecule.

D. It exhibits specificity for a particular type of molecule.

Which of the following statements best describes a characteristic feature of diffusion? A. It is very rapid over long distances. B. It is an active process in which molecules move from a region of lower concentration to a region of higher concentration. C. It requires an expenditure of energy by the cell. D. It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

D. It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

Which of the following statements describing the process of glycolysis is correct? A. Glycolysis occurs in the mitochondria. B. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. C. Glycolysis produces 30 ATP from each molecule of glucose. D. It represents the first stage in the chemical oxidation of glucose by a cell. E. It requires ATP and NADH.

D. It represents the first stage in the chemical oxidation of glucose by a cell.

In the citric acid cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. This reaction is inhibited by malonate, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Which of the following statements best describes the role played by molecules described in the reaction? A. Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction. B. Succinate dehydrogenase is the enzyme, and malonate is the substrate in the reaction. C. Fumarate is the product, and malonate is a noncompetitive inhibitor in the reaction. D. Succinate is the substrate, and fumarate is the product in the reaction.

D. Succinate is the substrate, and fumarate is the product in the reaction.

Which of the following statements best describes how unsaturated fatty acids increase membrane fluidity at lower temperatures? A. Unsaturated fatty acids are more nonpolar than saturated fatty acids. B. Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. C. The double bonds block interaction among the hydrophilic head groups of the lipids. D. The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

D. The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

Celery stalks that are immersed in fresh water for several hours become stiff. Which of the following statements best explains the observation that similar stalks left in a 0.15 M salt solution become limp? A. The fresh water and the salt solution are both hypertonic to the cells of the celery stalks. B. The fresh water is isotonic and the salt solution is hypertonic to the cells of the celery stalks C. The fresh water is hypertonic and the salt solution is hypotonic to the cells of the celery stalks D. The fresh water is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

D. The fresh water is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

Which of the following statements best describes a characteristic feature of integral membrane proteins? A. They are hydrophobic. B. They are localized to the interior surface of the membrane. C. They are hydrophilic. D. They are amphipathic, with at least one hydrophobic region.

D. They are amphipathic, with at least one hydrophobic region

Which of the following examples describes a type of potential rather than kinetic energy? A. heat released by a campfire B. flashes of light emitted by a firefly C. water rushing out of Hoover Dam D. a sucrose molecule

D. a sucrose molecule

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Because phosphate import depends on a pH gradient across the membrane, phosphate transport is most likely an example of which of the following transport processes? A. active transport B. passive diffusion C. facilitated diffusion D. cotransport

D. cotransport

Which of the following metabolic processes take place in the cytosol of a eukaryotic cell? A. fermentation and chemiosmosis B. oxidation of pyruvate to acetyl CoA C. citric acid cycle D. glycolysis and fermentation

D. glycolysis and fermentation

In which reactions of cellular respiration does substrate-level phosphorylation occur? A. only in the citric acid cycle B. only in the electron transport chain C. only in glycolysis D. in both glycolysis and the citric acid cycle

D. in both glycolysis and the citric acid cycle

Which of the following organelles plays a primary role in the digestion of bacteria engulfed by white blood cells? A. vacuoles B. secretory vesicles C. Golgi vesicles D. lysosomes

D. lysosomes

Which of the following types of molecules are most likely to be excluded from the hydrophobic portion of the phospholipid bilayer? A. integral membrane proteins B. cholesterol C. transmembrane proteins D. peripheral membrane proteins

D. peripheral membrane proteins

Which of the following processes is used by white blood cells when engulfing bacteria? A. pinocytosis B. receptor-mediated exocytosis C. osmosis D. phagocytosis

D. phagocytosis

Which of the following events takes place in the electron transport chain? A. the breakdown of glucose into six carbon dioxide molecules B. substrate-level phosphorylation C. the breakdown of an acetyl group to carbon dioxide D. the harnessing of energy from redox reactions to generate a proton gradient

D. the harnessing of energy from redox reactions to generate a proton gradient

The permeability of a biological membrane to a specific polar solute may depend on which of the following? A. the types of polysaccharides present in the membrane B. the presence of unsaturated fatty acids in the membrane C. the amount of cholesterol in the membrane D. the types of transport proteins in the membrane E. the phospholipid composition of the membrane

D. the types of transport proteins in the membrane

Some bacteria are metabolically active in hot springs because A. high temperatures make catalysis unnecessary. B. they are able to maintain a lower internal temperature. C. their enzymes are completely insensitive to temperature. D. their enzymes have high optimal temperatures.

D. their enzymes have high optimal temperatures.

Which component in the figure above represents cholesterol?

E

Is the solution outside the cell isotonic, hypotonic, or hypertonic?

hypotonic