Biology 107 Lecture Exam 2
Which of the following is a characteristic feature of a carrier protein in a plasma membrane?
It exhibits a specificity for a particular type of molecule.
Which of the following statements is correct about diffusion?
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 is (are) true of the enzyme ribulose bisphosphate carboxylase?
It participates in the Calvin cycle, it has an affinity for both O2 and CO2.
Microfilaments are well known for their role in which of the following?
ameboid movement, formation of cleavage furrows, contracting of muscle cells
What mechanisms do plants use to load sucrose produced by photosynthesis into specialized cells in the veins of leaves?
an electrogenic pump, a proton pump, a contransport protein
All of the following structures and proteins are directly associated with movement in cells or by cells except
centrosomes.
Many different things can alter enzyme activity. Which of the following underlie all types of enzyme regulation?
changes in the activation energy of the reaction, changes in the active site of the enzyme
Zinc an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n),
cofactor necessary for enzyme activity.
Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?
gap junctions
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through
gap junctions.
Which of the following normally occurs whether or not oxygen (O2) is present?
glycolysis
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
glycolysis
In the thylakoid membranes what is the main role of the antenna pigment molecules?,
harvest photons and transfer light energy to the reaction-center chlorophyll
Where is ATP synthase located in the mitochondrion?
inner membrane
reduction of oxygen which forms water
respiration
A primary objective of cell fractionation is to
separate the major organelles so their particular functions can be determined.
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
Where does the Calvin cycle take place?
stroma of the chloroplast
The ATP made during fermentation is generated by which of the following?
substrate-level phosphorylation
The mathematical expression for the change in free energy of a system is: ΔG = ΔH - TΔS. Which of the following is (are) incorrect?
ΔH is the change in enthalpy, the energy available to do work.
The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity?
All of the above correctly describe polar characteristics of the Golgi function.
Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements concerning phosphofructokinase is not true?
It is activated by AMP (derived from ADP).
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
Which of the following statements correctly describe(s) some aspect of energy in living organisms?
Living organisms can convert energy among several different forms, living organisms can use energy to do work, organisms expend energy in order to decrease their entropy
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
The double bonds form a kink in the fatty acid tail, forcing adjacent lipids to be further apart.
Which of the following represents the activation energy required for a noncatalyzed reaction?
c
Of the following what do both mitochondria and chloroplasts have in common?,
chemiosmosis, ATP synthase
Cellular respiration harvests the most chemical energy from which of the following?
chemiosmotic phosphorylation
Which of the following are capable of converting light energy to chemical energy?
chloroplasts
What is a nonprotein "helper" of an enzyme molecule called?
coenzyme
Ions diffuse across membranes down their
electrochemical gradients.
The presence of cholesterol in the plasma membranes of some animals
enables the membrane to stay fluid more easily when cell temperature drops.
A chemical reaction that has a positive ΔG is correctly described as
endergonic.
Which of the following is a statement of the first law of thermodynamics?
energy cannot be created or destroyed
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
energy coupling
Whenever energy is transformed there is always an increase in the
entropy of the universe
The primary function of the mitochondrion is the production of ATP. To carry out this function the mitochondrion must have all of the following except,
enzymes for glycolysis.
What does the chemiosmotic process in chloroplasts involve?
establishment of a proton gradient
During photosynthesis visible light has enough energy to,
excite electrons.
Which of the following terms best describes the reaction?
exergonic
All of the following processes take material into cells except
exocytosis.
All of the following are directly associated with photosystem I except
extraction of hydrogen electrons from the splitting of water.
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
facilitated diffusion
All of the following membrane activities require energy from ATP hydrolysis except
facilitated diffusion.
CAM plants keep stomata closed in daytime thus reducing loss of water. They can do this because they,
fix CO2 into organic acids during the night.
During aerobic respiration electrons travel downhill in which sequence?,
food → NADH → electron transport chain → oxygen
A molecule that is phosphorylated
has an increased chemical reactivity; it is primed to do cellular work.
The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via
integrins.
The active site of an enzyme is the region that
is involved in the catalytic reaction of the enzyme.
Water passes quickly through cell membranes because
it moves through aquaporins in the membrane.
The lateral mobility (fluidity) of lipids and proteins in membranes is a consequence of
lack of covalent bonds between the lipid and protein components of the membrane; weak hydrophobic interactions among the components in the interior of the membrane
The advantage of light microscopy over electron microscopy is that
light microscopy allows one to view dynamic processes in living cells
produces NADPH
light reactions alone
produces molecular oxygen (O2)
light reactions alone
In animal cells hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization?,
lysosome
What is the voltage across a membrane called?
membrane potential
In C4 photosynthesis carbon fixation takes place in the ________ cells, and then is transferred as malic or aspartic acid to ________ cells, where carbon dioxide is released for entry into the Calvin cycle
mesophyll; bundle-sheath
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
Fermentation takes place in the
mitochondrial inner membrane.
During oxidative phosphorylation H2O is formed. Where does the oxygen for the synthesis of the water come from?
molecular oxygen (O2)
Which of the following bests describes the reaction?
negative ΔG, spontaneous
the splitting of carbon dioxide to form oxygen gas and carbon compounds
neither photosynthesis nor respiration
produces NADH
neither the light reactions nor the Calvin cycle
requires glucose
neither the light reactions nor the Calvin cycle
What is the change in free energy of a system at chemical equilibrium?
no net change
All of the following molecules are part of the cell membrane except
nucleic acids.
The chemical reactions involved in respiration are virtually identical between prokaryotic and eukaryotic cells. In eukaryotic cells ATP is synthesized primarily on the inner membrane of the mitochondria. Where are the corresponding reactions likely to occur in prokaryotic respiration?,
on the plasma membrane
An organism with a cell wall would have the most difficulty doing which process?
phagocytosis
White blood cells engulf bacteria through what process?
phagocytosis
Which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
reduction of NADP+
photosynthesis
The difference between pinocytosis and receptor-mediated endocytosis is that
pinocytosis brings only water into the cell, but receptor-mediated endocytosis brings in other molecules as well.
All of the following are functions of integral membrane proteins except
protein synthesis.
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
proteins
A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are not being absorbed by this pigment?
red and yellow
In alcohol fermentation NAD+ is regenerated from NADH during the,
reduction of acetaldehyde to ethanol (ethyl alcohol).
The regulation of enzyme function is an important aspect of cell metabolism. Which of the following is least likely to be a mechanism for enzyme regulation?
removing cofactors
During glycolysis when glucose is catabolized to pyruvate, most of the energy of glucose is,
retained in the pyruvate.
Which of the following compounds require the presence of the nuclear pores to move between the cytoplasm and the interior of the nucleus?,
ribosomal RNA, messenger RNA, proteins synthesized in the cytoplasm that are part of the ribosomes
Which structure is the site of the synthesis of proteins that may be exported from the cell?
rough ER
Of the following which is probably the most common route for membrane flow in the endomembrane system?,
rough ER → vesicles → Golgi → plasma membrane
Which type of organelle is primarily involved in the synthesis of oils phospholipids, and steroids?,
smooth endoplasmic reticulum
The ATP made during glycolysis is generated by
substrate-level phosphorylation.
Some photosynthetic organisms contain chloroplasts that lack photosystem II yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be,
to test for liberation of O2 in the light.
In mitochondria chemiosmosis translocates protons from the matrix into the intermembrane space,
whereas in chloroplasts, chemiosmosis translocates protons from, the stroma to the thylakoid space.
Grana
thylakoids, and stroma are all components found in, chloroplasts.
How can one increase the rate of a chemical reaction?
Add a catalyst.
Which of the following is not a known function of the cytoskeleton?
to maintain a critical limit on cell size
Which step consists of a phosphorylation reaction in which ATP is the phosphate source?
A
In which reaction does an intermediate pathway become oxidized?
C
Starting with one molecule of glucose the "net" products of glycolysis are,
2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O.
Photorespiration lowers the efficiency of photosynthesis by preventing the formation of
3-phosphoglycerate molecules
Which step involves an endergonic reaction?
A
Which of the following statements is true regarding enzyme cooperativity?
A substrate molecule bound to an active site affects the active site of several subunits.
What does cyclic electron flow in the chloroplast produce?
ATP
When glucose (C6H12O6) is oxidized to CO2 and water in cellular respiration approximately 40% of the energy content of glucose is transferred to,
ATP (adenosine triphosphate).
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
Which of the following statements correctly indicate(s) the role of ATP or ADP as an allosteric regulator? Assume that the supply of energy for cellular processes is adjusted to meet cellular demand for energy. ATP is an allosteric inhibitor of catabolic pathways ADP is an allosteric activator of catabolic pathways,
ATP is an allosteric activator of anabolic pathways.
Of the following what do both mitochondria and chloroplasts have in common?,
ATP is produced, DNA is present, and Ribosomes are present
Which kind of metabolic poison would most directly interfere with glycolysis?
An agent that closely mimics the structure of glucose but is not metabolized
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 growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.
Which step shows a split of one molecule into two smaller molecules?
B
In which step is an inorganic phosphate added to the reactant?
C
During aerobic respiration which of the following directly donates electrons to the electron transport chain at the lowest energy level?,
FADH2
Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
C6H12O6 is oxidized and O2 is reduced.
Plants that fix CO2 into organic acids at night when the stomata are open and carry out the Calvin cycle during the day when the stomata are closed are called
CAM plants.
Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
CO2
Which of the following reactions is most likely to be coupled to the reaction ATP + H2O →ADP + Pi (ΔG = -7.3 kcal/mol)?
E + Pi → EP (ΔG = +5 kcal/mol)
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
When electrons move closer to a more electronegative atom what happens?
Energy is released, the more electronegative atom is reduced.
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of a reaction.
Which of the following statements is not representative of the second law of thermodynamics?
Every energy transformation by a cell decreases the entropy of the universe.
Glycolysis is thought to be one of the most ancient of metabolic processes. Which statement supports this idea?
Glycolysis is the most widespread metabolic pathway.
Which of the following structures is most directly associated with the secretion of compounds that will become part of the plant cell wall?
Golgi-derived vesicles
A young relative of yours has never had much energy. He goes to a doctor for help and is sent to the hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition?,
His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
ATP is often an allosteric inhibitor of key enzymes in catabolic pathways. Which of the following statements is inconsistent with the role of ATP?
Increasing availability of ATP increases the energy available to drive endergonic reactions.
All of the following are functions of the citric acid cycle except
adding electrons and protons to oxygen, forming water.
Which of the following statements about the cytoskeleton is incorrect?
Microfilaments are structurally rigid and resist compression, while microtubules resist tension (stretching).
Organelles other than the nucleus that contain DNA include
Mitchondria, Chloroplasts
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
Which of the following statements about NAD+ is false?
NAD+ has more chemical energy than NADH.
In addition to ATP what are the end products of glycolysis?,
NADH and pyruvate
All of the following are directly associated with photosystem II except
NADP+ reductase.
Which of the following statements best describes the relationship between photosynthesis and respiration?
Photosynthesis stores energy in complex organic molecules, while respiration releases it.
Which of the following statements correctly describes some aspect of protein excretion in prokaryotic cells?
Proteins that are excreted by prokaryotes are synthesized on ribosomes that are bound to the cytoplasmic surface of the plasma membrane.
Which of the following is most similar in structure to ATP?
RNA nucleotides
Consider the following: Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Which of the following is correct?,
Succinate is the substrate, and fumarate is the product.
Which best describes the reaction?
The amount of free energy released as a result of the catalyzed reaction is indicated by "d."
Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells?
The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
According to the induced fit hypothesis of enzyme catalysis which of the following is correct?,
The binding of the substrate changes the shape of the enzyme's active site.
Which of the following statements concerning the metabolic degradation of glucose (C6H12O6) to carbon dioxide (CO2) and water is (are) true?
The breakdown of glucose to carbon dioxide and water is exergonic, the breakdown of glucose to carbon dioxide and water has a free energy change of -686 kcal/mol, the breakdown of glucose to carbon dioxide and water involves oxidation-reduction or redox reactions.
In order for NAD+ to remove electrons from glucose or other organic molecules which of the following must be true?,
The free energy liberated when electrons are removed from the organic molecules must be greater than the energy required to give the electrons to NAD+.
Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH-8 solution. What would be likely to happen?
The isolated chloroplasts will make ATP.
Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.
Which of the following statements is (are) correct about an oxidation-reduction (or redox) reaction?
The molecule that is reduced gains electrons, the molecule that is oxidized loses electrons.
A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?,
The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells.
Which of the following statements is (are) true about enzyme-catalyzed reactions?
The reaction is faster than the same reaction in the absence of the enzyme.
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
The movement of a substance across a biological membrane against its concentration gradient with the help of energy input is
active transport.
Which of the following statements about the light reactions of photosynthesis are true?
The splitting of water molecules provides a source of electrons, Chlorophyll (and other pigments) absorb light energy, which excites electrons, ATP is generated by photophosphorylation.
Which of the following statements about membrane structure and function is false?
The types of proteins that are exposed on one side of a membrane are nearly identical to those exposed on the other side of the membrane.
All of the following statements are correct regarding the Calvin cycle except:
These reactions begin soon after sundown and end before sunrise
Which of the following is (are) true for anabolic pathways?
They are highly regulated sequences of chemical reactions, they consume energy to build up polymers from monomers.
Which of the following statements is true concerning catabolic pathways?
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP
Which of the following is correct about integral membrane proteins?
They are usually transmembrane proteins.
According to the fluid mosaic model of cell membranes which of the following is a true statement about, membrane phospholipids?,
They can move laterally along the plane of the membrane.
Which of the following statements correctly describe(s) catabolic pathways?
They release energy as they degrade polymers to monomers.
Why are C4 plants able to photosynthesize with no apparent photorespiration?
They use PEP carboxylase to initially fix CO2
Under which of the following conditions would you expect to find a cell with a predominance of free ribosomes?
a cell that is producing cytoplasmic enzymes
Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive
The oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?
acetyl CoA
During cellular respiration
acetyl CoA accumulates in which location?, mitochondrial matrix
In the presence of oxygen the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate 1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. These three steps result in the formation of,
acetyl CoA, NADH, H+, and CO2.
Organisms that can exist with light as an energy source and an inorganic form of carbon and other raw materials
are called photoautotrophs.
Which of the following represents the activation energy required for the enzyme-catalyzed reaction?
b
An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
cell-cell recognition
generation of proton gradients across membranes
both photosynthesis and respiration
synthesis of ATP by the chemiosmotic mechanism
both photosynthesis and respiration
inactive in the dark
both the light reactions and the Calvin cycle
The hydrolysis of ATP to ADP and inorganic phosphate (ATP + H2O → ADP + Pi has a ΔG of about -7 kcal/mol under standard conditions, involves hydrolysis of a terminal phosphate bond of ATP,
can occur spontaneously under appropriate conditions.
A major function of the mitochondrial inner membrane is the conversion of energy from electrons to the stored energy of the phosphate bond in ATP. To accomplish this function the inner mitochondrial membrane must have all of the following features except
carrier proteins to accept electrons from NADH.
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
catabolic pathways
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
competitive inhibition
The sodium-potassium pump is called an electrogenic pump because it
contributes to the membrane potential.
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space the result is the
creation of a proton gradient.
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?
cytoskeletons
Where does glycolysis takes place?
cytosol
Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products?
d
Which of the following represents the ΔG of the reaction?
d
Which of the following would be the same in an enzyme-catalyzed or noncatalyzed reaction?
d
Which of the following types of reactions would decrease the entropy within a cell?
dehydration reactions
Which of the following describe(s) some aspect of metabolism?
synthesis of macromolecules, breakdown of macromolecules, control of enzyme activity
What is the primary function of the Calvin cycle?
synthesize simple sugars from carbon dioxide
produces three-carbon sugars
the Calvin cycle alone
requires ATP
the Calvin cycle alone
requires CO2
the Calvin cycle alone
Cells can be described as having a cytoskeleton of internal structures that contribute to the shape organization, and movement of the cell. All of the following are part of the cytoskeleton except,
the nuclear envelope.
What limits the resolving power of a light microscope?
the shortest wavelength of light used to illuminate the specimen
In the fractionation of homogenized cells using centrifugation the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is,
the size and weight of the component.
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
the synthesis of ATP
The selective permeability of biological membranes is dependent on which of the following?
the type of transport proteins that are present in the membrane, the lipid bilayer being permeable to primarily small, nonpolar molecules
Which of the following forms of energy is least available to accomplish cellular work?
thermal energy (heat
The reaction-center chlorophyll of photosystem I is known as P700 because
this pigment is best at absorbing light with a wavelength of 700 nm.
Where is the electron transport chain found in plant cells?
thylakoid membranes of chloroplasts