Photosynthesis

1. Excitation of P700

a) greatly reduces its reduction potential c)greatly increases its reduction potential

b) has no effect on the reduction potential d)has effects on oxidation potential only.

2. The energy required to excite PSI is

a) less than that needed to excite PSII c) more than that needed to excite PSII

b) equal to that needed to excite PSII d) it can’t be told

3. Cytochrome b₆f complex is present:

a) in the grand lamellae c) in the stromal lamellae

b) throughout the thyllakoid membrane d) exclusively in stroma

4. Which of the following is not “one electron carrier”?

a) Cytochrome b) Fe-S protein c) Quinone d) None

5. During light reaction, the direction of proton flow is from

a) Stroma to thyllakoid membrane c)Thyllakoid membrane to stroma

b) Stroma to out of chloroplast d) Lamellae to lumen

6. During cyclic electron flow which of the following is produced?

a) ATP b) NADH c) NADPH d)O_{2 e)} all

7. No. of photons required to evolve O2 during oxygenic photosynthesis is

a) 4 b) 6 c) 8 d) 10

8. Which of the following is a soluble-Cu containing electron transfer protein?

a) Cytochrome b) Pheophytin c) Plastoquinone d) Plastocyanin

9. Plastocyanin is present on which side?

a) Stroma b) Lumen c) Lamellae d) All

10. During the electron flow from Cytochrome b₆f to plastocyanine which side has maximum protons?

a) Stroma b) Lumen c) Lamellae d) Grana

11. Cytochrome c₆ in Cyanobacteria is homologous to

a) Mitochondrial cytochrome c b) Plastocyanin as in plants

c) Mitochondrial cytochrome bc₁ d) a & b e) a,b & c

12. How does ATP synthesized in chloroplasts get into the cytosol?
A. It is transported as sucrose.
B. It is transported directly by a membrane transporter.
C. It is transported as triose phosphate.
D. It is transported as inorganic phosphate (P_i).

13. The net outcome of light reaction in green plant is:

a)3ATP & 3NADPH b)2NADPH & 2ATP c)3ATP & 2NADPH d)2ATP & 3 NADPH

14. The large and small subunits of Rubisco are encoded respectively in the

a) Chloroplast and nuclear genome b) nuclear and chlorophyll genome

c) both in nuclear genome d) Bone in chlorophyll genome

15. Chlorophyll contains all glycolytic enzymes except

a) Phosphoglycerate mutase b) Phosphoglycerate isomerase c) Triose –P- mutase d) Triose – P – isomerase

16. Glycine decarboxylase is present at very high levels in mitochondria of:-

a) C₄ plants b) CAM plants c) C₃ plants d) None

17. 11. Which of the following reactions is catalyzed by transketolase?
A. glyceraldehyde 3-phosphate + dihydroxyacetone phosphate fructose 1,6-bisphosphate
B. ribose 5-phosphate ribulose 5-phosphate
C. ribulose 5-phosphate ribulose 1,5-bisphosphate
D. fructose 6-phosphate + glyceraldehyde 3-phosphate erythrose 4-phosphate + xylulose 5-phosphate

18. CO₂ fixed by mesophyll cells gets transported to neighboring bundle-sheath cells by
A. the movement of oxaloacetate that diffuses between the neighboring cell membranes.
B. the movement of oxaloacetate that passes through channels that connect the cells.
C. the movement of malate that passes through channels that connect the cells.
D. the movement of pyruvate that passes through channels that connect the cells.

19. “Nocturnal inhibitor” 2-carboxyarabinitol1-phosphate is a structural analog of

a) Ribulose 1,5-bisphosphate b) Enediolate intermediate

c) Beta ketoacid intermediate d) Hydrated intermediate.

20. Central to the rubisco activity is the carbamoylated ____ residue

a) Lys201 b) lys 175 c) His 294 d) Leu 101.

21. Which of the following represents the sequence of electron flow in the light reactions of photosynthesis in higher plants?

(A) H2O → photosystem I → photosystem II → NADP

(B) H2O → photosystem II → photosystem I → NADP

(C) H2O → photosystem II → photosystem I → ATP

(D) NADPH → photosystem I → photosystem II → O2

(E) Photosystem I → photosystem II → NADPH → O₂

Enzyme kinetics

A catalyst alters the rate of a chemical reaction by:

A) always providing a surface on which molecules react

B) changing the products formed in the reaction

C) inducing an alternate pathway for the reaction with generallylower activation energy

D) changing the frequency of collisions between molecules

ANSWER: C

Choose the INCORRECT answer. The rate of a chemical reaction:

A) usually is increased when the concentration of one of the reactants is increased

B) is dependent on temperature

C) may be inhibited sometimes by certain catalytic agents

D) will be very rapid if the activation energy is large

ANSWER: D

If a reaction is first order with a rate constant of 5.48 x 10^-2 sec^-1, how long is required for 3/4 of the initial concentration of reactant to be used up?

A) 25.3 sec

B) 36.5 sec

C) 6.3 sec

D) 18.2 sec

E) none of these

ANSWER: A

The rate constant at 160 ^oC for the first order decomposition of ore is 0.032/min. The half-life of the reaction is:

A) 62.5 sec

B) 31.25 sec

C) 5000 sec

D) 111 sec

E) none of these

ANSWER: E

A reaction is first order. If its initial rate is 0.0200 M/sec and 25.0 days later its reaction is 6.25 x 10^-4 m/sec, then its half-life is:

A) 12.5 days

B) 5.0 days

C) 25.0 days

D) 50.0 days

E) none of these

ANSWER: B

For 2NO + O₂ --> 2NO₂ , initial rate data are:

[NO]	0.010	0.010	0.030 M
[O2 ]	0.010	0.020	0.020 M
rate	2.5	5.0	45.0 mM/sec

The rate law is Rate = k[O₂ ]^y and

A) x = 1 y = 2

B) x = 2 y = 1

C) x = 1 y = 1

D) x = 2 y = 2

E) none of these

ANSWER: B

A and B are mixed and the reaction is timed until a color change occurs. The data are:

[A]	0.100	0.050	0.100M
[B]	0.140	0.140	0.070M
time	25 sec	50 sec	100 sec

The order of the reaction in terms of [A] is:

A) second

B) half

C) zero

D) first

E) none of these

ANSWER: D

For the reaction 2HgCl₂ + C₂O₄^2- --> products, data are:

[HgCl2 ], M	0.0836	0.0836	0.0418
[C2O42- ] ,M	0.202	0.404	0.404
Init. rate, M/hr	0.26	1.04	0.53

The rate law is Rate = [HgCl ] ^x [C₂O₄^2-] ^y . Thus

A) x = 2 y = 1

B) x = 2 y = 2

C) x = 1 y = 2

D) x = 1 y = 1

E) none of these

ANSWER: C

The correct units of the specific rate constant for a zero order reaction are:

A) L/mol-sec

B) sec^-1

C) sec

D) L² /mol^{2 .}sec

E) none of these

ANSWER: E

If the half-life of a reaction depends on the concentration of the reactant, then the reaction cannot be __________ order.

A) second

B) zero

C) first

D) third

E) none of these

ANSWER: C

The reaction has the rate law Rate = k[A][B]². Which will cause the rate to increase the most?

A) doubling [A]

B) lowering temperature

C) tripling [B]

D) quadrupling [A]

E) doubling [B]

ANSWER: C

The reaction 2 H₂ + NO ---> H₂O + 1/2 N₂ is first order in H₂ and second order in NO. The rate law is:

A) k[H₂]² [NO]

B) k[H₂][NO]²

C) k[H₂]

D) k[H₂][NO]

E) none of these

ANSWER: B

For a reaction Rate = k[A][B]², what factor will NOT change k?

A) raising temperature

B) adding inhibitor

C) increasing [A]

D) adding catalyst

E) none of these

ANSWER: C

A variable that has NO EFFECT on reaction rate is:

A) energy of activation

B) temperature

C) catalyst

D) concentration

E) none of these

ANSWER: E

What is the main difference between a Pt catalyst and an enzyme catalyst?

ANSWER: enzyme has greater substrate specificity

What is the order of reaction for the following reaction. Rate = k[A]^-1/2[B]^1/2 ?

ANSWER: zero order overall

Substance A decomposes by a first-order reaction. Starting initially with [A] = 2.00 M, after 150 min [A] = 0.50 M. For this reaction what is t_1/2 ?

ANSWER: 75.0 min

For the above reaction, what is k?

ANSWER: 9.24 x 10^-3 min^-1

-------------------------------------

In the first order reaction A ---> products, [A] = 0.400 M initially and 0.250 M after 15.0 min.

What is the value of the rate constant, k?

ANSWER: 0.034 min^-1

What is the half-life of the reaction?

ANSWER: 20.4 min

At what time will [A] = 0.200 M?

ANSWER: 20.4 min

What will [A] be after 175 min.?

ANSWER: 1.04 x 10^-3 M

-------------------

The reaction A + B --> C + D is second order in A and zero order in B. The value of k is 0.012 M^-1 min^-1 . What is the rate of this reaction when [A] = 0.125 M and [B] = 0.435 M?

ANSWER: 1.88 x 10^-4 M min^-1

Which of the following statements is true about the reaction 2A --->B + C which is first order in A and first order overall:

A) The rate of the reaction will decrease at higher concentrations of B and C.

B) The time required for one half of A to react is directly proportional to the quantity of A.

C) The rate of formation of C is twice the rate of reaction of A.

D) The rate of formation of B is the same as the rate of reaction of A.

E) none of these

ANSWER: E

A catalyst

A) takes part in a reaction and speeds it up

B) appears in the rate equation of a chemical reaction

C) provides an alternate reaction pathway

D) raises the activation energy of a reaction

E) none of the above

ANSWER: C

Define heterogeneous catalysis.

ANSWER: The catalyst is present in a different phase of matter than are the reactants and products.

The rate of a specific chemical reaction is independent of the

concentrations of the reactants. Thus the reaction is

A) first order

B) second order

C) exothermic

D) catalyzed

E) none of these

ANSWER: E

Which of the following does not determine the rate of a reaction?

A) value of DELTA H⁰

B) activation energy

C) presence of a catalyst

D) temperature of reactants

E) none of these

ANSWER: A

Which of the following lowers the activation energy of a reaction?

A) adding reactants

B) lowering the temperature

C) removing products

D) adding a catalyst

E) raising the temperature

ANSWER: D

If a reaction has a rate equation of rate = k[A][B][C] then it is

A) second order

B) first order

C) third order

D) zero order

E) cannot be determined

ANSWER: C

The first-order reaction A --> Products has a half-life, t_1/2, of 55.0 min at 25 ^oC and 6.8 min at 100 ^oC. What is the activation energy for this reaction?

ANSWER: 25.8 kJ/mol

Which of the following statements is CORRECT

A) A zero order reaction depends on the concentration ofreactants.

B) A reaction rate cannot be calculated from the collision frequency alone.

C) A commonly stated rule of thumb is that reaction rates triple for a temperature increase of about 10 ^oC.

D) none of these

ANSWER: B

The first order reaction A---> products has t_1/2 = 150 sec. What percent of the sample remains unreacted after 300 sec?

ANSWER: 25%

Define rate law.

ANSWER: An experimentally determined equation that describes how the rate of reaction depends on the concentration of reactants

Define activation energy.

ANSWER: The minimum total kinetic energy that molecules must bring to their collisions for a chemical reaction to occur.

The rate constant for a first-order reaction is k = 0.00073 s^-1.

Determine the percent of reactant that has decomposed after 500 s.

ANSWER: 30.6%

---------------

For the reaction A---> products, the following data are obtained:

First Experiment		Second Experiment
[A] = 1.512 M	t = 0 min	[A] = 3.024 M	t = 0 min
[A] = 1.490 M	t = 1.0 min	[A] = 2.935 M	t = 1.0 min
[A] = 1.469 M	t = 2.0 min	[A] = 2.852 M	t = 2.0 min

Determine the order of the above reaction.

ANSWER: second order

What is the rate constant, k?

ANSWER: 9.62 x 10^-3 mol^-1 min^-1

What is the concentration of [A] in the first experiment after 4.0 min?

ANSWER: 1.429 M

What is the initial rate of the reaction in each experiment?

ANSWER: First experiment = 0.022 mol/min Second experiment = 0.089 mol/min

sources: http://itl.chem.ufl.edu/2041_f97/kinetics_quiz.html

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more question for bioenergetics and oxidative phosphorylation

1. Which one of the following statements is most correct?
A Oxidation of pyruvate to carbon dioxide and water does not involve the TCA cycle.
B The major pathway for electron transfer to oxygen in the electron transport system does not involve pyridine nucleotides.
C An adequate supply of ADP is required for maximal respiration by mitochondria.
D Coenzyme Q is a prosthetic group of a flavoprotein.
E Substrate level phosphorylation cannot occur in the absence of oxygen

2.	Which one of the following enzyme systems may be used as a marker enzyme for mitochondrial electron transport system?
A	Glucose 6-phosphate dehydrogenase
B	Succinate dehydrogenase (succinate-cytochrome c reductase)
C	Phosphoenolpyruvate carboxykinase
D	Lactate dehydrogenase
E	Acetyl-CoA carboxylase 3. Rotenone inhibits malate oxidation but not succinate oxidation because A it is a competitive inhibitor of malate dehydrogenase. B it does not react with flavoprotein enzymes. C it inhibits at the NADH dehydrogenase while succinate dehydrogenase interacts with the respiratory chain at ubiquinone, bypassing this site of inhibition. D it inhibits at cytochrome b while succinate dehydrogenase interacts with the respiratory chain at cytochrome c. E it inhibits at the cytochrome oxidase but succinate is oxidized by a flavin oxidase. 4. Cyanide is a deadly poison because it A binds to myoglobin. B interferes with respiratory control. C forms addition compounds with important aldehydes such as pyridoxal. D reacts with cytochrome oxidase. E inhibits the cytochrome P-450 monooxygenases. 5. The main function of the mitochondrial electron transport chain is to A generate a P/O ratio of 2.5. B recycle NAD for glycolysis. C provide reducing equivalents. D lower the oxidation state of the cell. E generate energy for ATP formation. 7. Which of the following tissues has the lowest respiratory rate? A adipose tissue B brain C liver D red blood cell E skeletal muscle sources: https://med-eval.med.uiuc.edu/cgi-bin/exam/practicefeedback.p

question for oxidative phosphorylation

1. Which of the following is true about the difference between oxidative phosphorylation and photophosphorylation?
A. Photophosphorylation occurs only in photosynthetic organisms and oxidative phosphorylation occurs only in non-photosynthetic organisms.
B. In oxidative phosphorylation, NADH donates electrons; in photophosphorylation NADPH donates electrons.
C. Photophosphorylation occurs only in light; oxidative phosphorylation occurs only in darkness.
D. In oxidative phosphorylation, O2 is reduced to H2O; in photophosphorylation, H2O is oxidized to O2.


2. Which of the following processes takes place in the mitochondrial matrix?
A. cellular respiration
B. glycolysis
C. fatty acid oxidation
D. photosynthesis


3. Which of the following is true about the expression of mitochondrial genes?
A. Mitochondria encode all of the proteins needed to make new mitochondria.
B. Mitochondria can translate their own genes.
C. Mitochondria import all of their proteins from the cytoplasm.
D. Mitochondrially-encoded genes are expressed in the cytoplasm.


4. Diseases caused by mutations in mitochondrial genes are invariably inherited from the mother because
A. mitochondrial genes are encoded on the X chromosome.
B. males do not have mitochondrial DNA.
C. all of the mitochondria of a developing embryo are derived from the mother's egg.
D. mitochondrial genes of males are turned off.


5. How do mitochondria eliminate the harmful superoxide free radical ·O2- that is generated with low frequency during oxidative phosphorylation?
A. Glutathione reductase reduces ·O2- to H2O.
B. Superoxide dismutase converts ·O2- to H2O2.
C. Glutathione peroxidase converts ·O2- to O2.
D. ·O2- is transported out of mitochondria.


6. Which of the following processes yields the greatest number of ATP molecules when a molecule of glucose is completely oxidized?
A. lactate fermentation
B. pyruvate oxidation
C. glycolysis
D. the citric acid cycle


7. How does thermogenin keep newborn mammals warm?
A. It makes oxidative phosphorylation more efficient.
B. It causes the transfer of electrons from ubiquinone directly to oxygen.
C. It uncouples electron transport from ATP synthesis.
D. It stimulates the accumulation of brown fat.


8. The light-dependent and carbon-assimilation reactions of photosynthesis are linked in that
A. the light-dependent reactions generate the chemical energy needed for carbon-assimilation.
B. the oxidation of carbohydrates from the carbon-assimilation reactions drives the synthesis of ATP in the light-dependent reactions.
C. carbon dioxide generated in the light-driven reactions is converted to triose phosphates in the carbon-assimilation reactions.
D. NADPH generated in the carbon-assimilation reactions drives the synthesis of ATP in the light-dependent reactions.


9. In which part of the chloroplast do the light-dependent reactions of photosynthesis take place?
A. in the thylakoid lumen
B. in the thylakoid membrane
C. in the stroma
D. in the inner membrane


10. What is the role of antenna molecules in photosynthesis?
A. to donate their electrons for use in oxidation-reduction reactions
B. to release absorbed energy as fluorescence
C. to transmit light energy to reaction centers
D. to transduce light energy into chemical energy


11. The F0 complex of mitochondrial ATP synthase
A. is inhibited by oligomycin.
B. synthesizes ATP.
C. pumps protons into the mitochondrial matrix.
D. is a peripheral membrane protein.


12. Which complex of the respiratory chain is inhibited by cyanide?
A. Complex IV
B. ATP synthase
C. Complex I
D. Complex III


13. How will oxidative phosphorylation be affected by placing intact mitochondria in a weak acid that can readily diffuse across the mitochondrial membranes?
A. Electron transfer reactions will be inhibited.
B. No H2O will be generated.
C. ATP will be able to be synthesized in the absence of an oxidizable substrate.
D. ATP synthesis will be inhibited.


14. Complexes I and II of the mitochondrial respiratory chain
A. have heme prosthetic groups.
B. transfer electrons directly to ubiquinone.
C. pump protons from the matrix to the intermembrane space.
D. transfer electrons from NADH.


15. How does NADH generated by glycolysis in the cytosol get conveyed into mitochondria for oxidation in the respiratory chain?
A. It diffuses through the inner mitochondrial membrane.
B. Its reducing equivalents are transported across the inner mitochondrial membrane.
C. It is transported across the inner mitochondrial membrane as aspartate.
D. It is transported directly across the inner mitochondrial membrane by an NADH transporter.


sources: http://bcs.whfreeman.com/lehninger/pages/bcs-main.asp?v=chapter&i=19070.01&s=19000&n=00070&o=|00510|00520|0

Lehninger Principles of Biochemistry

questions for amino acids and nucleotide biosynthesis

1. Which chemical reaction depicts nitrification?
A. N₂ ® NH₄⁺
B. NO₃^- ® NH₄⁺
C. NO₂^-® NO₃^-
D. NO₃^- ® N₂

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2. Glutamine is derived from which glycolysis or citric acid cycle intermediate?
A. pyruvate
B. a-ketoglutarate
C. oxaloacetate
D. 3-phosphoglycerate

---

3. Newborn infants sometimes develop jaundice because of an accumulation of
A. heme.
B. biliverdin.
C. urobilin.
D. bilirubin.

---

4. In the de novo pathway, what is the immediate precursor to dTMP?
A. dUMP
B. TMP
C. thymidine
D. dCMP

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5. Which of the following is true about the de novo synthesis of nucleotides?
A. Deoxyribonucleotides are precursors of ribonucleotides.
B. Pyrimidines are precursors of purines.
C. Bases are synthesized then attached to ribose or deoxyribose.
D. Amino acids are precursors of nucleotides.

---

6. Plants carry out
A. reduction of nitrate.
B. denitrification.
C. nitrification.
D. nitrogen fixation.

---

7. Which of the following molecules is not derived from glycine?
A. glutathione (GSH)
B. heme
C. serotonin
D. phosphocreatine

---

8. The conversion of serine to glycine requires which of the following?
A. S-adenosylmethionine (adoMet)
B. 5-phosphoribosyl-1-pyrophosphate (PRPP)
C. NADH
D. tetrahydrofolate (H₄ folate)

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9. Nucleoside diphosphate kinase catalyzes which reaction?
A. ATP + AMP 2 ADP
B. ATP + dCDP ADP + dCTP
C. ATP + dGMP ADP + dGDP
D. ATP + UMP ADP + UDP

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10. Adenosine deaminase deficiency leads to
A. gout.
B. Lesch-Nyhan syndrome.
C. severe immunodeficiency disease.
D. porphyria.

---

11. Which of the following molecules does not result from decarboxylation of an amino acid?
A. histamine
B. spermidine
C. g-aminobutyrate (GABA)
D. dopa

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12. Which of the following is true about the symbiotic relationship between leguminous plants and nitrogen-fixing bacteria?
A. Leguminous plants produce leghemoglobin to prevent oxygen from interfering with the bacterial electron-transfer system.
B. Nitrogen-fixing bacteria obtain citric acid intermediates from the leguminous plants.
C. Nitrogen-fixing bacteria are present on the leaves of the leguminous plants.
D. Leguminous plants produce the nitrogenase complex used by the bacteria to fix nitrogen.

---

13. Chorismate is an intermediate in the synthesis of which amino acid?
A. phenylalanine
B. proline
C. serine
D. cysteine

---

14. In the salvage pathway, how are nucleotides generated?
A. Free bases are attached to ribose, which is then phosphorylated to generate the corresponding NMPs.
B. Free bases exchange with the bases on NMPs.
C. Free bases react with 5-phosphoribosyl-1-pyrophosphate (PRPP) to generate the corresponding NMPs.
D. Purine and pyrimidine bases are built up while attached to ribose throughout the process.

---

15. Parkinson's disease is associated with
A. an underproduction of dopamine.
B. an underproduction of g-aminobutyrate (GABA).
C. an overproduction of histamine.
D. an overproduction of dopamine.

---

16. AMP is converted to adenosine by what enzyme?
A. nucleotidase
B. 5'-nucleotidase
C. adenosine deaminase
D. ribonucleotide reductase

---

17. Which of the following occurs in the degradation pathway of AMP?
A. Adenine is converted to hypoxanthine.
B. The end product is urea.
C. AMP is converted to adenosine.
D. Adenosine is converted to adenine.

sources: http://bcs.whfreeman.com/lehninger/pages/bcs-main.asp?v=chapter&s=22000&n=00070&i=22070.01&o=|00510|00520|00530|00540|00550|00PRS

questions for glycolysis

1. Which process does not generate CO₂?
A. the citric acid cycle
B. the conversion of pyruvate to lactic acid
C. the conversion of pyruvate to acetyl-CoA
D. the conversion of pyruvate to ethanol

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2. Which of the following is true about the fermentation of glucose?
A. It can occur under aerobic or anaerobic conditions, depending on the products generated.
B. There is no net yield of ATP.
C. The hydrogen to carbon ratio (H:C) of the reactants and products remains the same.
D. It always generates CO₂.

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3. Glycogen is degraded in a
A. phosphorylation reaction.
B. hydrolysis reaction.
C. dephosphorylation reaction.
D. phosphorolysis reaction.

---

4. Which of the following sugars does not get converted to D-glucose before entering the glycolytic pathway?
A. D-galactose
B. glycogen
C. sucrose
D. lactose

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5. Which of the following steps occurs during the payoff phase of glycolysis?
A. the conversion of phosphoenolpyruvate to pyruvate
B. the conversion of fructose 6-phosphate to fructose 1,6-biphosphate
C. the conversion of glucose 6-phosphate to fructose 6-phosphate
D. the conversion of glucose to glucose 6-phosphate

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6. Under what conditions will lactic acid accumulate in skeletal muscle?
A. when citric acid enzymes are depleted
B. when ATP is depleted
C. when O₂ is depleted
D. when NADH is depleted

---

7. The enzyme that converts 3-phosphoglycerate to 2-phosphoglycerate is a
A. transferase.
B. kinase.
C. mutase.
D. phosphorylase.

---

8. Glycolysis and the pentose phosphate pathway are the same in that
A. they both generate NADPH.
B. they both generate ATP.
C. they both involve the oxidation of glucose.
D. they are reversible.

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9. Which of the following reactions is catalyzed by transaldolase?
A. xylulose 5-phosphate + ribose 5-phosphate glyceraldehyde 3-phosphate + sedoheptulose 7-phosphate
B. ribose 5-phosphate xylulose 5-phosphate
C. sedoheptulose 7-phosphate + glyceraldehyde 3-phosphate erythrose 4-phosphate + fructose 6-phosphate
D. xylulose 5-phosphate + erythrose 4-phosphate glyceraldehyde 3-phosphate + fructose 6-phosphate

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10. What is the role of uridine diphosphate (UDP) in the conversion of galactose to glucose 1-phosphate?
A. Its hydrolysis is needed to provide the energy to convert galactose to glucose 1-phosphate.
B. It donates a phosphoryl group to galactose to generate galactose 1-phosphate.
C. It serves as a phosphate acceptor.
D. It serves as a carrier for galactose and glucose.

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11. The NADPH produced in the pentose phosphate pathway is used
A. to donate electrons to O₂ in mitrochondria.
B. to provide reducing power for biosynthetic reactions.
C. to convert superoxide free radicals (^·O₂^-) into hydrogen peroxide (H₂O₂) during detoxification.
D. to provide the energy for catabolic reactions.

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12. Which of the following is true about gluconeogenesis?
A. In mammals, gluconeogenesis occurs predominately in the liver.
B. Gluconeogenesis is the pathway by which glucose is converted to glycogen.
C. The gluconeogenesis pathway is the glycolysis pathway running in the opposite direction.
D. Plants do not undergo gluconeogenesis.

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13. Rapidly dividing cells have a high need for nucleotide precursors, which are provided by
A. the Cori cycle.
B. the pentose phosphate pathway.
C. glycolysis.
D. gluconeogenesis.

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14. All of the bypass reactions used in gluconeogenesis
A. require high-energy equivalents.
B. involve the removal of phosphate groups.
C. are irreversible.
D. requires mitochondrial enzymes.

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15. Mammals cannot convert fatty acids to glucose because
A. they have no pathway for breaking down fatty acids.
B. they cannot use pyruvate as a precursor of glucose.
C. the glycolysis pathway is not reversible.
D. they cannot convert acetyl-CoA to pyruvate.

sources: Lehninger's principle of Biochemistry

questions from Bioenergetics

1. A chemical reaction is more likely to occur spontaneously if
A. the products of the reaction are more complex than the reactants.
B. the system takes up heat from its surroundings.
C. the products of the reaction are more disordered than the reactants.
D. the system gains free energy.

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2. If a chemical reaction starts with 1M concentrations each of reactants A and B and products C and D, under what conditions of K'_eq and DG'^o will the reaction proceed in the forward direction (DG'^o = RT ln K'_eq)?
A. If K'_eq is greater than 1 and DG'^o is negative.
B. If K'_eq is 0 and DG'^o is negative.
C. If K'_eq is negative and DG'^o is negative.
D. If K'_eq is less than 1 and DG'^o is positive.

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3. Living cells and organisms
A. exchange energy but not matter with their surroundings.
B. exchange energy and material with their surroundings.
C. are closed systems.
D. are at equilibrium with their surroundings.

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4. The standard free-energy changes of two sequential chemical reactions are additive only if
A. the reactions share a common intermediate.
B. each reaction has a negative DG' ^o.
C. the overall (net) reaction has a postive DG' ^o.
D. the exergonic reaction occurs first.

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5. Which of the following has a thioester bond?
A. PEP (phosphoenolpyruvate)
B. ATP
C. phosphocreatine
D. acetyl-CoA

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6. What provides the energy for the synthesis in an RNA polymer?
A. The transfer of an energy-rich ribonucleoside monophosphate to the polymer.
B. The hydrolysis of two anhydride bonds in ribonucleoside triphosphates.
C. The transfer of the g phosphate of a ribonucleoside triphosphate to the polymer.
D. The transfer of an energy-rich ribonucleoside triphosphate to the polymer.

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7. When a nucleophile attacks the a phosphorous atom of ATP, what kind of transfer occurs?
A. pyrophosphoryl transfer
B. phosphoryl transfer
C. adenylyl transfer
D. adenosine transfer

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8. When dNTPs become depleted in the cell, which of the following enzymes will regenerate dNTPs from dNDPs?
A. nucleoside diphosphate kinase
B. polyphosphate kinase
C. creatine kinase
D. adenylate kinase

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9. Which of the following enzymes can catalyze the conversion of AMP to ADP?
A. nucleoside diphosphate kinase
B. polyphosphate kinase
C. creatine kinase
D. adenylate kinase

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10. Conversion of NAD⁺ to NADH is accomplished by the addition of
A. a proton.
B. an electron.
C. a hydride ion.
D. a hydrogen atom.

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11. Which of the following carbon-containing molecules is most fully oxidized?
A. carbon monoxide
B. carbon dioxide
C. methane
D. ethanol

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12. The oxidation-reduction reaction Fe²⁺+ Cu²⁺ Fe³⁺+ Cu⁺, can be described in terms of two half-reactions:

(1) Fe²⁺ Fe³⁺ + e^-
(2) Cu²⁺ + e^- Cu⁺

Which of the following statements is true?
A. In the overall reaction at the top, the cupric ion (Cu²⁺) is the reducing agent.
B. In half-reaction (2), cupric ion (Cu²⁺) is being oxidized.
C. In half-reaction (1), Fe³⁺ and e^- constitute a conjugate redox pair.
D. In the overall reaction at the top, the ferrous ion (Fe²⁺) is oxidized by the cupric ion (Cu²⁺).

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13. Electrons can be transferred from one molecule (electron donor) to another molecule (electron acceptor) by all of the following ways except
A. as a hydride ion.
B. directly as an electron.
C. as a proton.
D. as a hydrogen atom.

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14. Which of the following is true of flavin nucleotides?
A. They have no reduction potential unless bound to a protein.
B. They always accept two electrons.
C. They are utilized by oxygenases.
D. They act as prosthetic groups.

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15. Below are the standard reduction potentials (E'^o) for two conjugate redox pair:

Pyruvate^-/lactate^- E'^o = –0.185

NAD+/NADH E'^o = –0.320


Which of the following is true?
A. The pyruvate/lactate conjugate redox pair has a greater tendency to lose electrons than the NAD⁺/NADH redox pair.
B. Pyruvate has a greater affinity for electrons than NAD⁺.
C. NAD⁺ is a reducing agent.
D. Under standard conditions, NAD⁺ is more likely to be converted to NADH, than pyruvate is to converted to lactate.

sources: Lehninger's principle of biochemistry