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Based on the first law of thermodynamics, which of the following statements about a living organism is true?
A. The entropy of an organism decreases with time as the organism grows in complexity.
B. An organism grows by converting energy into organic matter.
C. The organism ultimately must obtain all of the necessary energy for life from its environment.
D. The energy content of an organism is constant.
C. The organism ultimately must obtain all of the necessary energy for life from its environment.
Anabolic pathways share which of the following characteristics?
A. They are usually spontaneous chemical reactions that do not require an input of energy.
B. They are not dependent on enzymes.
C. They consume energy to synthesize polymers from monomers.
D. They release energy as they degrade polymers to monomers.
C. They consume energy to synthesize polymers from monomers.
The ∆G for a particular enzyme-catalyzed reaction is -20 kcal/mol. If the amount of enzyme in the reaction is doubled, what will be the ∆G for the new reaction?
A. -20 kcal/mol
B. -40 kcal/mol
C. 0 kcal/mol
D. +40 kcal/mol
E. +20 kcal/mol
A. -20 kcal/mol
An aminoacyl-tRNA synthetase is the enzyme that catalyzes the attachment of a particular amino acid to its corresponding tRNA. This reaction requires energy from ATP. The enzyme initially binds the amino acid and ATP, but it is unable to bind the tRNA at this point. Which of the following would be a likely next step in the reaction by which the enzyme ultimately binds the tRNA and attaches the amino acid?
A. Hydrolysis of ATP phosphorylates the amino acid, which results in a conformational change in the active site that allows the tRNA to bind.
B. Transfer of the ATP to the tRNA opens the active site, which allows the tRNA to bind.
C. Alteration in the conformation of the tRNA allows it to bind to the active site along with the amino acid and ATP.
D. Hydrolysis of ATP activates the amino acid, which is released, opening up the active site to allow binding of the tRNA, followed by binding of a new amino acid.
A. Hydrolysis of ATP phosphorylates the amino acid, which results in a conformational change in the active site that allows the tRNA to bind.
Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)
A. noncompetitive inhibitor of the enzyme.
B. cofactor necessary for enzyme activity.
C. allosteric activator of the enzyme.
D. competitive inhibitor of the enzyme.
E. coenzyme derived from a vitamin.
B. cofactor necessary for enzyme activity.
A chemical reaction that has a positive ΔG is best described as
A. exergonic.
B. endergonic.
C. spontaneous.
D. at equilibrium.
B. endergonic.
Which of the following is the most comprehensive definition of metabolism in living organisms?
A. Metabolism depends on a constant supply of energy from food.
B. Metabolism consists of all the energy transformation reactions in an organism.
C. Metabolism refers to the sum of all biochemical pathways involved in synthesis of macromolecules.
D. Metabolism manages the increase of entropy in an organism.
B. Metabolism consists of all the energy transformation reactions in an organism.
Which of the following statements is a logical consequence of the second law of thermodynamics?
A. Every chemical reaction must increase the total entropy of the universe.
B. Every energy transfer requires activation energy from the environment.
C. If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
D. If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe.
A. Every chemical reaction must increase the total entropy of the universe.
A noncompetitive inhibitor decreases the rate of an enzymatic reaction by
A. changing the ∆G for the reaction.
B. binding to the active site of the enzyme.
C. changing the shape of the enzyme active site.
D. decreasing the activation energy required for the reaction.
C. changing the shape of the enzyme active site.
ATP hydrolysis in a test tube releases only about half as much energy as ATP hydrolysis in the cell. Which of the following statements is the best explanation for this observation?
A. Reactant and product concentrations in the cell are different from the standard conditions used in a test tube.
B. Cells maintain higher internal pressure, which speeds up the reaction rate.
C. ATP hydrolysis in cells is catalyzed by enzymes, which release more energy than the uncatalyzed reaction in a test tube.
D. ATP hydrolysis in a cell produces different products than ATP hydrolysis in a test tube.
A. Reactant and product concentrations in the cell are different from the standard conditions used in a test tube.
What is the proton-motive force?
A. the energy required to remove an electron from a hydrogen atom
B. the energy that moves hydrogen into the intermembrane space
C. the energy that moves hydrogen atoms into the mitochondrion
D. the energy provided by a transmembrane hydrogen ion gradient
D. the energy provided by a transmembrane hydrogen ion gradient
Which of the following metabolic pathways occur(s) in mitochondria?
A. glycolysis and oxidation of pyruvate to acetyl CoA
B. oxidation of pyruvate to acetyl CoA and the citric acid cycle
C. glycolysis and fermentation
D. fermentation and chemiosmosis
E. fermentation and oxidative phosphorylation
B. oxidation of pyruvate to acetyl CoA and the citric acid cycle
Where does glycolysis occur in animal cells?
A. Inner mitochondrial membrane
B. Cytosol
C. Mitochondrial matrix
D. Outer mitochondrial membrane
B. Cytosol
In addition to ATP, what are the products of glycolysis?
A. CO2 and NADH
B. NADH and pyruvate
C. CO2 and pyruvate
D. H2O, FADH2, and citrate
E. CO2 and H2O
B. NADH and pyruvate
Which of the following metabolic pathways generates a proton gradient?
A. the citric acid cycle
B. glycolysis
C. the oxidation of pyruvate to acetyl CoA
D. the electron transport chain
E. chemiosmosis
D. the electron transport chain
Why are carbohydrates and fats considered high-energy foods?
A. They have a large number of electrons associated with hydrogen.
B. They have many carbon atoms bound together by single covalent bonds.
C. They have few nitrogen atoms.
D. They have many oxygen atoms.
A. They have a large number of electrons associated with hydrogen.
Which of the following terms describes metabolic pathways that break down complex molecules to release stored energy?
A. endergonic pathways
B. bioenergetic pathways
C. anabolic pathways
D. catabolic pathways
D. catabolic pathways
The oxygen consumed during cellular respiration is involved directly in which process or event?
A. accepting electrons at the end of the electron transport chain
B. glycolysis
C. the citric acid cycle
D. the phosphorylation of ADP to form ATP
E. the oxidation of pyruvate to acetyl CoA
A. accepting electrons at the end of the electron transport chain
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
A. It is found in prokaryotic cells but not in eukaryotic cells.
B. It relies on chemiosmosis, which is a metabolic mechanism present only in prokaryotic cells.
C. It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
D. It produces much less ATP than does oxidative phosphorylation.
C. It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Which of the following describes the result of transferring an electron from a less electronegative atom to a more electronegative atom?
A. The more electronegative atom is oxidized, and energy is consumed.
B. The more electronegative atom is oxidized, and energy is released.
C. The more electronegative atom is reduced, and energy is released.
D. The more electronegative atom is reduced, and energy is consumed.
C. The more electronegative atom is reduced, and energy is released.
In an oxidation-reduction reaction, how is the reducing agent changed?
A. It loses electrons and gains potential energy.
B. It gains electrons and gains potential energy.
C. It loses electrons and loses potential energy.
D. It gains electrons and loses potential energy.
C. It loses electrons and loses potential energy.
What is the source of the energy used to generate the proton gradient across the inner mitochondrial membrane?
A. redox reactions in the electron transport chain
B. ATP hydrolysis
C. splitting water to form oxygen and protons
D. decreasing the pH in the mitochondrial matrix
A. redox reactions in the electron transport chain
How many carbon atoms from one molecule of pyruvate enter the citric acid cycle?
A. 10
B. 6
C. 2
D. 4
E. 8
C. 2
Assuming glucose is the only energy source for a cell, what fraction of the carbon dioxide produced by aerobic respiration is generated by the reactions of the citric acid cycle?
A. 1/6
B. 1/3
C. 1/2
D. 2/3
E. all of it
D. 2/3
Yeast cells with defective mitochondria are incapable of cellular respiration. Catabolism of which of the following energy sources would allow these to grow?
A. proteins
B. glucose
C. pyruvate
D> fatty acids
B. glucose
Which of the following statements about NAD+ is true?
A. NAD+ has more chemical energy than NADH.
B. NAD+ is reduced to NADH during glycolysis.
C. NAD+ is oxidized by the action of dehydrogenase enzymes.
D. NAD+ is the source of electrons used in oxidative phosphorylation.
B. NAD+ is reduced to NADH during glycolysis.
Which of the following indicates a primary path by which electrons travel downhill energetically during aerobic respiration?
A. glucose → citric acid cycle → ATP → NAD+
B. glucose → glycolysis → electron transport chain → NADH → ATP
C. glucose → NADH → electron transport chain → oxygen
D. glucose → pyruvate → acetyl CoA → ATP → oxygen
E. glucose → glycolysis → citric acid cycle → NADH → ATP
C. glucose → NADH → electron transport chain → oxygen
Approximately what percentage of the ATP formed by the reactions of glycolysis is produced by substrate-level phosphorylation?
A. 100%
B. 10%
C. 38%
D. 2%
0%
A. 100%
Which chemical process generates the ATP produced in glycolysis?
A. chemiosmosis
B. substrate-level phosphorylation
C. oxidative phosphorylation
D. photophosphorylation
E. electron transport
B. substrate-level phosphorylation
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the glucose molecule becomes
A. hydrogenated.
B. oxidized.
C. hydrolyzed.
D. an oxidizing agent.
E. reduced.
B. oxidized.
How many carbon dioxide molecules are used to make one molecule of glucose photowynthesis?
A. 6
B. 8
C. 4
D. 2
A. 6
Many students and professors might consider the Calvin cycle to be very similar to the Kreb Cycle.
Where does the Calvin cycle take place?
A. intermembrane space of the chloroplast
B. in the electron transport chain
C. in the cytoplasm of the cell
D. stroma of the chloroplast
D. stroma of the chloroplast
In photosynthesis, the electron transport chain pumps protons from the thylakoid space into the stroma. In what direction are protons pumped by the electron transport chain in mitochondria?
A. from the matrix into the cytosol
B. from the matrix into the intermembrane space.
C. from the matrix to to stroma
D. from the stroma into the matrix
B. from the matrix into the intermembrane space.
Which of the following reactions produces the oxygen released by photosynthesis?
A. splitting of water molecules
B. chemiosmosis
C. electron transfer in photosystem I.
D. reduction of NADP+
A. splitting of water molecules
Many students and professors might consider the Calvin cycle photosynthesis to be very similar to the Krebs Cycle cellular respiration.
Where does the Krebs cycle take place?
A. matrix of the mitochondria
B. cytoplasm of the cell
C. in the electron transport chain
D. the intermembrane space of the mitochondria
A. matrix of the mitochondria
Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
A. ATP and NADPH
B. electrons and H+
C. H2O and O2
D. ADP, ℗i, and NADP+
A. ATP and NADPH
In mitochondria, the electron transport chain pumps protons from the matrix into the intermembrane space. In what direction are protons pumped by the electron transport chain in chloroplasts?
A. from the stroma to the cytosol
B. from the matrix to the stroma
C. from the intermembrane space to the stroma
D. from the stroma to the thylakoid space
E. from the thylakoid space to the stroma
D. from the stroma to the thylakoid space
How many carbon dioxide molecules are produced from one molecule of glucose in cellular respiration
A. 2
B. 6
C. 4
D. 8
B. 6
Which of the following reactions uses the oxygen required by cellular respiration?
A. reduction of FAD
B. chemiosmosis
C. formation of water molecules
D. reduction of NAD+
C. formation of water molecules
Which of the following molecules are products of the glycolysis of cellular respiration?
A. ATP and NADH
B. ADP, ℗i, and NADP+
C. Electrons and H+
D. H20 and O2
A. ATP and NADH
P680+ is often considered the strongest biological oxidizing agent. Given its function, why is this necessary?
A. It obtains electrons from the oxygen atom in a water molecule, so it must have a greater affinity for electrons than oxygen has.
B. It transfers its electrons directly to NADP+ to produce NADPH.
C. It is the molecule that transfers electrons to the photosynthetic electron transport chain.
D. It has a positive charge.
E. It is the receptor for the most excited electrons in either photosystem.
A. It obtains electrons from the oxygen atom in a water molecule, so it must have a greater affinity for electrons than oxygen has.
CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
A. fix CO2 into organic acids during the night when temperatures are cooler.
B. fix CO2 into by combining it with RuBP in the Calvin cycle.
C. fix CO2 into organic acids in the bundle-sheath cells, which do not rely on stomata.
C. fix CO2 into organic acids in the mesophyll cells, which do not rely on stomata.
D. obtain CO2 through their roots during the day.
A. fix CO2 into organic acids during the night when temperatures are cooler.
In mitochondria, the electron transport chain pumps protons from the matrix into the intermembrane space. In what direction are protons pumped by the electron transport chain in chloroplasts?
A. from the stroma to the cytosol
B. from the thylakoid space to the stroma
C. from the stroma to the thylakoid space
D. from the intermembrane space to the stroma
E. from the matrix to the stroma
C. from the stroma to the thylakoid space
What is the primary function of cyclic electron flow?
A. to produce additional oxygen
B. to produce additional ATP
C. to produce additional carbon dioxide
D. to produce additional NADPH
B. to produce additional ATP
Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
A. ATP and NADPH
B. electrons and H+
C. H2O and O2
D. CO2 and glucose
E. ADP, ℗i, and NADP+
A. ATP and NADPH
Where does the Calvin cycle take place?
A. outer membrane of the chloroplast
B. interior of the thylakoid (thylakoid space)
C. thylakoid membrane
D. stroma of the chloroplast
D. stroma of the chloroplast
If plants are grown in the light with CO2 containing a radioactive isotope of oxygen (18O), subsequent analysis will show that 18O incorporated in organic molecules first appears in
A. the stroma.
B. the thylakoid membranes.
C. the thylakoid space.
D. mitochondria.
A. the stroma.
Why does photorespiration decrease the efficiency of photosynthesis?
A. It reduces the amount of water consumed.
B. It produces excess NADPH but less ATP.
C. It reduces the amount of sugar produced.
D. It inhibits electron transfers from photosystem II.
E. It increases the amount of carbon dioxide consumed.
C. It reduces the amount of sugar produced.
What is the relationship between wavelength of light and the quantity of energy per photon?
A. They have a direct, linear relationship.
B. They are logarithmically related.
C. They are only related in certain parts of the spectrum.
D. They are inversely related.
D. They are inversely related.
Which of the following reactions produces the oxygen released by photosynthesis?
A. splitting of water molecules
B. chemiosmosis
C. electron transfer in photosystem I.
D. reduction of NADP+
A. splitting of water molecules
At which phase of mitosis do the sister chromatids become daughter chromosomes?
A. prophase
B. prometaphase
C. anaphase
D. cytokinesis
E. metaphase
C. anaphase
Which of the following components make(s) up eukaryotic chromatin?
A. DNA and carbohydrates
B. DNA and RNA
C. condensed DNA only
D. DNA and ribosomes
E. DNA and proteins
E. DNA and proteins
For a chemotherapeutic drug to be useful for treating cancer cells, which of the following characteristics is most desirable?
A. It only attacks cells that are density dependent.
B. It targets only rapidly dividing cells.
C. It does not affect metabolically active cells.
D. It is safe enough to limit all apoptosis.
B. It targets only rapidly dividing cells.
Somatic cells in elephants have 56 chromosomes. How many chromosomes would be carried by the gametes produced by elephants?
A. 112
B. 28
C. 56
D. 14
B. 28
What will be the result if a eukaryotic cell completes mitosis but does not undergo cytokinesis?
A. two cells, each cell with half of the genetic material of the parent cell
B. one cell with two nuclei, each containing half of the genetic material of the parent cell
C. one cell with two nuclei, each identical to the nucleus of the parent cell
D. one cell with one nucleus containing half of the genetic material of the parent cell
E. two cells, one cell containing two nuclei and a second cell without a nucleus
C. one cell with two nuclei, each identical to the nucleus of the parent cell
When a cell is in late anaphase of mitosis, which of the following may be observed?
A. decondensing chromosomes clustered at the poles
B. a clear area in the center of the dividing cell
C. nuclear envelopes forming at the poles
D. chromosomes clustered tightly at the center of the dividing cell
E. individual chromatids beginning to separate from one another
B. a clear area in the center of the dividing cell
A cell in G2 of the cell division cycle contains 20 chromatids. How many centromeres are present in this cell?
A. 20
B. 10
C. 80
D. 30
E.40
B. 10
Progression through the M phase checkpoint is stimulated by a complex that does which of the following things?
A. activates separase to modify kinetochores
B. activates assembly of spindle microtubules
C. activates motor molecules at the centromere to begin disassembly of spindle microtubules
D. activates separase to cleave cohesin proteins
D. activates separase to cleave cohesin proteins
Where do the microtubules of the spindle originate during mitosis in animal cells?
A. chromatid
B. centromere
C. centriole
D. kinetochore
E. centrosome
E. centrosome
Density-dependent inhibition is explained by which of the following statements?
A. As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.
B. As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce growth factors.
C. As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
D. As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
A. As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.
If a horticulturist breeding plants known as gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following processes would be her most probable and efficient route to establishing a line of such plants with that particular set of traits?
A. Go back through her previous experiments to obtain another plant with the same traits.
B. Breed this plant with another plant with much weaker traits.
C. Force the plant to self-pollinate to obtain an identical one.
D. Clone the plant asexually to produce an identical one.
D. Clone the plant asexually to produce an identical one.
Which of the following statements correctly describes the differences between sexual and asexual reproduction?
A. Asexual reproduction, but not sexual reproduction, is characteristic of all living organisms.
B. In asexual reproduction, offspring are produced by fertilization of sperm and egg.
C. Asexual reproduction produces offspring that vary genetically from the parent.
D. In sexual reproduction, offspring vary genetically from their siblings and both parents.
D. In sexual reproduction, offspring vary genetically from their siblings and both parents.
Which of the following types of cells would be produced by meiosis?
A. a haploid animal cell
B. a diploid unicellular organism
C. a diploid animal cell
D. a diploid plant cell
A. a haploid animal cell
Scientists have produced a hybrid plant that was the result of the fertilization of gametes between one plant with a diploid number of 24 and another with a diploid number of 20. How many chromosomes would the diploid hybrid plant have?
A. 24
B. 44
C. 22
D. 20
C. 22
The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division malfunctions, and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following processes?
A. telophase II of one meiotic event
B. telophase I of one meiotic event
C. mitosis in her ovary
D. either anaphase I or II of meiosis
D. either anaphase I or II of meiosis
After telophase II of meiosis, the chromosomal makeup of each daughter cell is
A. diploid, and the chromosomes are each composed of two daughter chromosomes.
B. haploid, and the chromosomes are each composed of a single daughter chromosome.
C. haploid, and the chromosomes are each composed of two daughter chromosomes.
D. diploid, and the chromosomes are each composed of a single daughter chromosome.
B. haploid, and the chromosomes are each composed of a single daughter chromosome.
Which of the following events occurs in meiosis but not in mitosis?
A. production of daughter cells
B. condensation of chromatin
C. synapsis of pairs of homologous chromosomes
D. chromosome replication
C. synapsis of pairs of homologous chromosomes
In a cell undergoing meiosis, if homologous chromosomes are aligned at the equator of the meiotic spindle, what process has occurred?
A. prophase II
B. metaphase I
C. prophase I
D. metaphase II
B. metaphase I
Independent assortment of chromosomes during meiosis is a result of
A. the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
B. the relatively small degree of homology shared by the X and Y chromosomes.
C. the random distribution of the sister chromatids to the two daughter cells during anaphase II.
D. the random nature of the fertilization of ova by sperm.
A. the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
Which of the following statements correctly describes the characteristics of recombinant chromosomes?
A. At least one to three times per chromosome pair, they carry genes from two different parents.
B. They contain more genes than non-recombinant chromosomes.
C. They are identical in genetic makeup to the parental chromosomes.
D. They carry genes from only one parent.
A. At least one to three times per chromosome pair, they carry genes from two different parents.
Note 
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