Bio 101 exam 2 (chap 7-10)
Which component in the figure above represents a microfilament of the cytoskeleton?
C
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?
cotransport
The movement of glucose into a cell against its concentration gradient is most likely to be accomplished by which of the following?
cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
In which cell of the accompanying figure would elevated oxygen concentrations have the greatest inhibitory effect on carbon fixation reactions?
cell II only
An animal cell that lacks carbohydrates on the external surface of its plasma membrane would likely be impaired in which of the following functions?
cell-cell recognition
In what way do the membranes of a eukaryotic cell vary?
certain proteins are unique to each membrane
In some cells, there are many different ion electrochemical gradients across the plasma membrane even though there are usually only one or two types of proton pumps present in the membrane. The gradients of the other ions are most likely established by which of the following?
cotransport proteins
The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?
coupling of an endergonic reaction to an exergonic reaction
which of the following is least likely to be important in holding the components of a biological membrane together?
covalent interactions between the phospholipid and protein components of the membrane
Which curves on the graphs most likely represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline (basic) hot springs at temperatures of 70°C or higher?
cures 3 and 5
Which temperature and pH profile curves on the graphs are most likely associated with an enzyme isolated from a human stomach where conditions are strongly acidic?
curves 1 and 4
Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do?
hydrolysis reactions are exergonic and increase entropy of the system
Which of the following statements best summarizes a consequence of the second law of thermodynamics?
if entropy of a system decreases, there must be a corresponding increase in entropy of the universe
Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?
in all cells, with or without light
Which of the following statements best summarizes an important consequence of the first law of thermodynamics for living organisms?
each organism ultimately must obtain all of the necessary energy for life from its environment
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly...
embedded in a lipid bilayer
Which of the following terms best describes a chemical reaction for which ΔG is positive?
endergonic
Which of the following statements best describes the first law of thermodynamics?
energy cannot be created or destroyed
Which of the following processes is driven by the free energy released as electrons move through photosystem II and I in the thylakoid membranes?
establishment of a proton gradient
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?
exergonic and endergonic
The figure illustrates the energy states associated with the reaction A + B ↔↔ C + D. Which of the following terms best describe the forward reaction in the figure?
exergonic delta G<0
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______.
exergonic; endergonic
Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?
fatty acids
Which of the terms below best describes a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway?
feedback inhibition
How is photosynthesis similar in C4C4 plants and CAM plants?
in both cases, rubisco is not used to fix carbon intially
In chemiosmosis, the most direct source of energy used to convert ADP + Pi to ATP is energy released ________.
from movement of protons through ATP synthase, down their electrochemical gradient
Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy?
glucose
Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration?
glucose -> NADH -> electron transport chain -> oxygen
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
glycolysis
Which of the following metabolic processes normally occurs in yeast cells regardless of oxygen (O2) availability?
glycolysis
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?
glycolysis and fermentation
In which reactions of cellular respiration does substrate-level phosphorylation occur?
in both glycolysis and the citric acid cycle
Which of the following statements best describes a characteristic feature of osmosis?
in osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration
If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?
inner membrane
Diffusion of ions across membranes through specific ion channels is driven by...
ion electrochemical gradients
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?
2 NADH, 2 pyruvate, and 2 ATP
Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
30-32
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?
4
Based on the accompanying figure, which of the following wavelengths of light is most effective in driving photosynthesis?
440 nm
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following?
allosteric regulation
Which of the following types of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but is not metabolized
A series of enzymes catalyze the reactions in the metabolic pathway X →→ Y →→ Z →→ A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. Based on its interaction with the enzyme that converts X to Y substance A is best described as ________.
an allosteric inhibitor
Which of the following events is most immediately associated with the absorption of energy by chlorophyll molecules of the reaction-center complex?
an electron is excited
Which of the following types of reactions would decrease the entropy within a cell?
anabolic reactions
A defect in which of the following molecules would dramatically reduce the rate of diffusion of water across cell membranes?
aquaporins
Zinc is an essential trace element for most organisms. Zinc is required in the active site of the enzyme carboxypeptidase where it most likely functions in which of the following ways?
as a cofactor necessary for enzyme activity
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
as a consequence of the processes required for growth, the decrease in entropy of the organism is associated with a corresponding increase in the entropy of the universe
Which of the following statements best describes the electron transport chain?
it consists of a series of redox reactions
Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved?
it does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms
Which of the following statements best describes a characteristic feature of a carrier protein in a plasma membrane?
it exhibits specificity for a particular type of molecule
Which of the following statements best explains why the sodium-potassium pump is an electrogenic pump?
it generates voltage across the membrane
Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction?
it loses a hydrogen atom and gains potential energy
When ATP is hydrolyzed to activate a target protein, what is often the fate of the inorganic phosphate that is released?
it may be used to form a phosphorylated intermediate
Which of the following statements best describes the accompanying figure?
it represents a C4 photosynthetic system
Which of the following statements best describes the primary role played by oxygen in cellular respiration?
it serves as the final acceptor for electrons from the electron transport chain
Which of the following statements best explains the shape of the rate curve at high reactant concentration?
most enzyme molecules are occupied by a substrate at high reactant concentrations
The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?
most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis
Inhibition of which of the following metabolic pathways would result in a decrease of CO2 production compared to fully functional cellular respiration?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
Which of the following processes is driven by chemiosmosis?
oxidative phosphorylation
In mechanism, photophosphorylation is most similar to
oxidative phosphorylation in cellular respiration
The mechanism of photophosphorylation is most similar to which of the following processes?
oxidative phosphorylation in cellular respiration
When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.
oxidized
Which of the following processes includes all of the others?
passive transport
Which of the following types of molecules are most likely to be excluded from the hydrophobic portion of the phospholipid bilayer?
peripheral membrane proteins
An organism with a cell wall would most likely be unable to take in materials through which of the following processes?
phagocytosis
Which of the following processes is used by white blood cells when engulfing bacteria?
phagocytosis
ATP is synthesized in plant cells by chemiosmosis in which of the following processes?
photosynthesis and cellular respiration
Which of the following statements best describes the relationship between photosynthesis and cellular respiration?
photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules
Which of the following statements best describes the difference between pinocytosis and receptor-mediated endocytosis?
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity
In which of the following organisms did the process of photosynthesis most likely originate?
prokaryotes
Which of the following statements best explains the observation that proton pumps are used by organisms in every domain of life?
proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life
In mitochondria, exergonic redox reactions
provide the energy that establishes the proton gradient
Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria?
pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space
In the following reaction which molecule functions as the oxidizing agent? Pyruvate + NADH + H+ → Lactate + NAD+
pyruvate
What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+→Lactate+NAD+
pyruvate
Which of the following processes is directly associated with photosystem I?
receiving electrons from the thylakoid membrane electron transport chain
When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.
reduced, and the energy is released
Which of the following processes occurs in the calvin cycle?
reduction of CO2
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?
released as CO2 and H2O
Paper chromatography is a technique used to separate molecules based upon their polarity. If pigments from oak leaves are extracted and subjected to paper chromatography, which of the following statements best describes the pigment bands that would be observed?
several bands that appear green, yellow, or orange
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Which of the following statements best describes the relationship between the solutions on both sides of the U-tube?
side A is isotonic to side B
Which of the following types of molecules will diffuse through a cell membrane most readily?
small hydrophobic molecules
Which of the following types of molecules are least likely to diffuse through the phospholipid bilayer of a cell membrane?
small ions
The oxygen released by photosynthesis is produced by which of the following processes?
splitting water molecules
In which cellular structure are the enzymes of the Calvin cycle localized?
stroma of the chloroplast
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?
succinate is the substrate, and fumarate is the product in the reaction
Which of the following processes would be most directly affected if a thylakoid membrane is punctured so that the interior of the thylakoid is no longer separated from the stroma?
synthesis of ATP
Most cells cannot harness heat to perform work because
temperature is usually not uniform throughout a cell
Which of the following is the most likely effect on the amount of ATP and CO2 yeast cells will be able to produce with only acetyl-CoA as a fuel source versus glucose as the fuel source?
the amount of both ATP and CO2 produced per fuel molecule will decrease
Which of the following statements best describes the normal tonicity conditions for typical plant and animal cells in their native environments?
the animal cell is an isotonic solution, and the plant cell is in a hypotonic solution
Which of the following results is most likely result if a portion of an animal's blood is replaced with distilled water?
the animal's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells
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?
the cell will swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC
Most CO2 from catabolism is released during
the citric acid cycle
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?
the citric acid cycle
To identify the molecule that first reacts with CO2 in the light-independent reactions of photosynthesis, Calvin and Benson manipulated the carbon-fixation cycle by either elminating CO2 or light from cultures of photosynthetic algae. Which of the following statements best predicts the immediate effects of these manipulations on the concentration of the molecule that initially reacts with CO2?
the concentration would increase when the CO2 is eliminated, but decrease when the light is eliminated
Which of the following statements best summarizes how the ATP cycle illustrated the accompanying figure functions in cells?
the cycle is used to regenerate ATP
Which of the following statements best describes how unsaturated fatty acids increase membrane fluidity at lower temperatures?
the double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly
When a cell is deprived of oxygen, which of the following processes will be inhibited first?
the electron transport chain
Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions?
the enzyme has two distinct active sites
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?
the fresh water is hypotonic, and the salt solution is hypertonic to the cells of the celery stalks
Which of the following events takes place in the electron transport chain?
the harnessing of energy from redox reactions to generate a proton gradient
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?
they are lethargic and readily tire from exercise
Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis?
two molecules of ATP are used, and four molecules of ATP are produced
A plant with unique photosynthetic pigments has leaves that appear reddish yellow. Which of the following wavelengths of visible light are most effectively absorbed by this pigment?
violet and blue
When a filament of algae is illuminated with light that is passed through a prism, different segments of algae are exposed to different wavelengths of light. When aerobic bacteria are present, they congregate in highest concentrations in the areas illuminated by the red and blue light. These data suggest a relationship between which of the following variables?
wavelength of light and the rate of photosynthesis
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?
ΔG is the change in free energy
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
H+ concentration gradient across the membrane holding ATP synthase
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O -> NADPH -> calvin cycle
Which of the following sequences correctly represents the flow of electrons in photosynthesis?
H2O -> NADPH -> calvin cycle
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?
ATP, CO2, and ethanol
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?
-20 kcal/mol
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. When the system is illustrated above reaches equilibrium, the sugar concentrations on both sides of the U-tube will be...
1.5 M glucose, 1.5 M glucose
If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?
1/3
Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?
100%
If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
12.5
0.4 M, 0.6 M, 0.8 M, and 1.0 M. Cubes of sweet potato (1 cm3) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. Which unknown solution contains the highest concentration of sucrose?
5
Which component in the figure above represents a protein fiber of the extracellular matrix?
A
If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), which of the following molecules produced by the algae (refer to the accompanying figure) would be least likely to contain 18O in subsequent analyses?
ADP
In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased production of which of the following below?
ATP
The light reactions supply the Calvin cycle with
ATP and NADPH
What are the products of linear electron flow in the light reactions of photosynthesis?
ATP and NADPH
Which of the following molecules will accumulate if light reactions occur normally, but the Calvin Cycle is inhibited?
ATP and NADPH
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?
ATP and citrate
Which of the following statements best summarizes the figure?
ATP is a molecule that acts as an intermediary to store energy for cellular work
Which of the following statements best summarizes the metabolic results of photorespiration?
ATP is hydrolyzed, carbon dioxide is produced, and oxygen is consumed
Which of the following statements best describes the central role that ATP plays in cellular metabolism?
ATP provides energy coupling between exergonic and endergonic reactions
Which component of the figure plays a critical role in cell-cell recognition?
B
Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic to the solution in the beaker at 50 minutes?
B
Which of the following metabolic processes can occur without a net influx of energy from some other process?
C6H12O6 + 6O2 -> 6CO2 + 6H2O
Which of the summary statements below best describes the results of the following reaction?C6H12O6 + 6O2 →→ 6CO2 + 6H2O + Energy
C6H12O6 is oxidized and O2 is reduced
Which of the statements below best explains the use of lactate as an indicator of exercise capacity?
During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
Which component in the figure above represents cholesterol?
E
Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?
FADH2
Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?
NAD+ becomes reduced
Which of the following statements best describes a characteristic of NAD+?
NAD+ is reduced to NADH in glycolysis, pyruvate oxidation and the citric acid cycle
Which of the following molecules is the final electron acceptor for electrons from photosystem I?
NADP+
Which of the following molecules is the primary reducing agent in the Calvin cycle reactions?
NADPH
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
O2
Which of the following molecules would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?
O2
Which of the following molecules is most similar in structure to ATP?
a RNA nucleotide
Which of the following statements is consistent with the second law of thermodynamics?
a constant input of energy is required to maintain the high level of organization associated with living cells
Which of the following factors would tend to increase membrane fluidity?
a greater proportion of unsaturated phospholipids
Because the spaceship will be so far from the sun, an artificial light source will be needed to support photosynthesis. Which of the following wavelengths of light should be used to maximize plant growth?
a mixture of blue and red light
Which of the following molecules would decrease the electrochemical gradient across a membrane?
a potassium channel
In which of the following circumstances would the cell or organism have the greatest need for osmoregulation?
a salmon moving from a river into an ocean
Which of the following statements best describes some aspect of the function of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?
a substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose
A series of enzymes catalyze the reactions in the metabolic pathway X →→ Y →→ Z →→ A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What does substance X represent in this pathway?
a substrate
Which of the following examples describes a type of potential rather than kinetic energy?
a sucrose molecule
Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate?
acetyl CoA
What is the name of the barrier that must be overcome before products are formed in a spontaneous reaction?
activation energy
If the concentration of phosphate in the cytosol is 2.0 mM, and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?
active transport
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to
add more of the enzyme
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?
all of the electron transport system and ATP synthase
What types of cells carry out ATP synthesis by chemiosmosis?
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
The figure illustrates the energy states associated with the reaction A + B ↔↔ C + D. Which of the lower-case letters represents the activation energy required for the enzyme-catalyzed reaction in the figure?
b
Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones?
catabolism (catabolic pathways)
Which of the following statements best describes induced fit?
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 photosynthesis using C4 or CAM systems may be described as a metabolic compromise?
both pathways minimize photorespiration but also expend more ATP in the process of carbon fixation
How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?
by binding to an allosteric site, thus changing the shape of the active site of the enzyme
Which of the following occurs during the Calvin cycle?
carbon fixation
A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?
catabolic processes will be activated to generate additional ATP
The figure illustrates the energy states associated with the reaction A + B → C + D. Which of the lower-case letters in the figure represents a free energy change that would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
d
Based on the figure, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?
decreasing extracellular pH
Which of the following factors is a primary contributor underlying cause of familial hypercholesterolemia?
defective LDL receptors on the cell membranes
A decrease in entropy is associated with which of the following types of reaction?
dehydration
Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?
directly entering the citric acid cycle
A flask containing photosynthetic green algae and a control flask containing only water are exposed to a cycle of 12 hours of light and 12 hours of darkness. Which of the following statements best describes how the relative dissolved oxygen concentration in the flask with algae will compare to the control flask?
it will be lower in the control in the light, but higher in the control in the dark
A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?
its cells cannot transport pyruvate from the cytosol into the mitochondria
In addition to activating or inhibiting enzymes through allosteric regulation, which of these mechanisms do cells also use to control enzymatic activity?
localization of enzymes into specific organelles or membranes
What role does malonate play with respect to succinate dehydrogenase?
malonate is a competitive inhibitor
The voltage across a membrane is called the ________.
membrane potential
Which of the following statements best describes metabolism in its entirety in all organisms?
metabolism consists of all the energy transformation reactions in an organism
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?
mitochondrial intermembrane space
Which of the following membrane activities requires energy from ATP hydrolysis?
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
P680+ is said to be the strongest biological oxidizing agent. The strong oxidizing potential of P680+ is essential for its function because it ________.
obtains electrons from the oxygen atom in a water molecule
In receptor-mediated endocytosis, membrane receptors bind to molecules outside of the cell. Immediately following endocytosis where will the membrane receptors be located?
on the inside surface of the vesicle
Three lab groups carried out an experiment to identify the concentration of sucrose in six solutions. Each unknown solution (1-6) contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and -1.0 M. Cubes of sweet potato (1 cm3) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. From the data given, which statement below most accurately describes something that has occurred in response to a particular unknown solution?
osmosis of water molecules from unknown solution 2 likely caused the increase in mass observed
In autumn, chlorophyll is degraded in the leaves of deciduous trees. Which of the following statements best explains the change in color from green to shades of yellow, orange, or red?
other pigments such as carotenoids remain in the leaves after the chlorophyll is degraded
If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?
oxaloacetate will accumulate and citrate will decrease
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?
oxidation of NADH and NAD+
Which of the following processes is most directly driven by light energy?
oxidation of chlorophyll molecules
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?
the inside of the vesicles will become acidic
In a plant, which of the following reactions produces molecular oxygen (O2)?
the light reactions alone
Which of the following statements best describes the structure of a membrane based on the fluid mosaic model?
the membrane is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins
Which of the following statements best explains how the membranes in winter wheat are able to remain fluid in extremely cold temperatures?
the membranes contain an increased proportion of unsaturated phospholipids
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
the pH of the matrix increases
Which of the following events are associated with chemiosmosis in chloroplasts?
the pH of the stroma increases and ATP is synthesized
which of the following statements about osmosis is correct?
the presence of aquaporins (proteins that form water channels in the membrane) speeds up the process of osmosis
Which of the following statements best describes characteristic activities of a sodium-potassium pump?
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 statements best describes an exergonic reaction?
the reaction proceeds with a net release of free energy
What would be observed by live-cell fluorescence microscopy immediately after HIV entry if HIV enters the cell by endocytosis first, and then later fuses with the endocytotic vesicle membrane?
the red fluorescent dye-labeled lipids will appear in the infected cell's interior
A new drug designed for the treatment of lung cancer must specifically enter the cytoplasm of lung cells while not entering the cells of other tissues. Which of the following characteristics would likely enhance the specificity of this drug?
the similarity of the drug molecule to other molecules normally transported lung cells
Which of the following statements best describes a system at chemical equilibrium?
the system can do no work
Cell membranes have distinct inside and outside faces. Which of the following statements is the most plausible explanation for the asymmetrical nature of the two layers of the membrane?
the two layers of a cell membrane face different environments and carry out different functions
which of the following statements about a typical plasma membrane is correct?
the two sides of the plasma membrane have different lipid and protein composition
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Which of the following is the most likely result when the system has reached equilibrium?
the water level will be higher in side A than in side B
Some bacteria are metabolically active in hot springs because
their enzymes are high optimal temperatures
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?
there is random movement of molecules into and out of the cell
A mutation that eliminates a plant's ability to perform photorespiration will most likely have which of the following effects on the plant?
there would be more cellular damage from harmful products of the light reactions of photosynthesis
Which of the following describes the function of the pigment molecules in a light-harvesting complex in the thylakoid membranes?
they absorb and transfer light energy to the reaction-center chlorophyll
Which of the following statements best describes a characteristic of C4 plants?
they are able to fix CO2 at lower CO2 concentrations and higher oxygen concentrations than C3 plants
Which of the following statements best describes catabolic pathways?
they are exergonic and provide energy that can be used to produce ATP from ADP and Pi
Which of the following statements best describes the relationship between the wavelength of light and the quantity of energy per photon?
they are inversely related
which of the following bets describes the structure of a biological membrane?
two layers of phospholipids, with proteins either crossing the layers or on the surface of the layers
In most cells, not all of the carbon compounds that participate in glycolysis and the citric acid cycle are converted to carbon dioxide by cellular respiration. What happens to the carbon in these compounds that does NOT end up as CO2?
they are removed from these processes to serve as building blocks for other complex molecules
Which of the following is a characteristic feature of anabolic pathways?
they consume energy to build up polymers from monomers
Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?
they contain many electrons associated with oxygen atoms
Which of the following statements best explains the ability of CAM plants to synthesize sugars in the daytime while keeping their stomata closed to reduce water loss?
they fix CO2 into organic acids during the night
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. Which of the following statements best describes a related function they serve in plants?
they protect against oxidative damage from excessive light energy
Which of the following statements best explains the ability of C4 plants to perform photosynthesis with no apparent photorespiration?
they use PEP carboxylase to initially fix CO2
Which of the following statements describes a primary benefit of having photosystem reaction centers composed of several structurally different pigments?
this arrangement enables the plant to absorb light energy of a variety of wavelengths
If various plant organellar and/or cell membranes are isolated and incubated with a proton gradient across the isolated membrane in the presence of ADP and Pi, which of the following samples are most likely to be able to synthesize ATP?
thylakoid membrane and inner mitochondrial membrane
Which process is most directly driven by light energy?
transfer of energy from pigment molecule to pigment molecule
Which of the following is the most important result of the process of cellular respiration in biological systems?
transforming the energy in glucose and related molecules into a chemical form that cells can use for work